Last data update: Jun 03, 2024. (Total: 46935 publications since 2009)
Records 1-30 (of 44 Records) |
Query Trace: Bern C [original query] |
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Hemi-nested PCR and RFLP methodologies for identifying blood meals of the Chagas disease vector, Triatoma infestans.
Roellig DM , Gomez-Puerta LA , Mead DG , Pinto J , Ancca-Juarez J , Calderon M , Bern C , Gilman RH , Cama VA . PLoS One 2013 8 (9) e74713 Trypanosoma cruzi, the etiologic agent of Chagas disease, is transmitted by hematophagous reduviid bugs within the subfamily Triatominae. These vectors take blood meals from a wide range of hosts, and their feeding behaviors have been used to investigate the ecology and epidemiology of T. cruzi. In this study we describe two PCR-based methodologies that amplify a fragment of the 16S mitochondrial rDNA, aimed to improve the identification of blood meal sources for Triatoma infestans: a.--Sequence analyses of two heminested PCRs that allow the identification of mammalian and avian species, and b.--restriction fragment length polymorphism (RFLP) analysis from the mammalian PCR to identify and differentiate multi-host blood meals. Findings from both methodologies indicate that host DNA could be detected and the host species identified in samples from laboratory reared and field collected triatomines. The implications of this study are two-fold. First, these methods can be used in areas where the fauna diversity and feeding behavior of the triatomines are unknown. Secondly, the RFLP method led to the identification of multi-host DNA from T. infestans gut contents, enhancing the information provided by this assay. These tools are important contributions for ecological and epidemiological studies of vector-borne diseases. |
Bovine Polyomavirus-1 (Epsilonpolyomavirus bovis): An Emerging Fetal Pathogen of Cattle That Causes Renal Lesions Resembling Polyomavirus-Associated Nephropathy of Humans.
Giannitti F , daSilvaSilveira C , Bullock H , Bern M , Fernndez-Ciganda S , Bentez-Galeano MJ , Rodrguez-Osorio N , Silva-Flannery L , Perdomo Y , Cabrera A , Puentes R , Colina R , Ritter JM , Castells M . Viruses 2022 14 (9) Bovine polyomavirus-1 (BoPyV-1, Epsilonpolyomavirus bovis) is widespread in cattle and has been detected in commercialized beef at supermarkets in the USA and Germany. BoPyV-1 has been questioned as a probable zoonotic agent with documented increase in seropositivity in people exposed to cattle. However, to date, BoPyV-1 has not been causally associated with pathology or disease in any animal species, including humans. Here we describe and illustrate pathological findings in an aborted bovine fetus naturally infected with BoPyV-1, providing evidence of its pathogenicity and probable abortigenic potential. Our results indicate that: (i) BoPyV-1 can cause severe kidney lesions in cattle, including tubulointerstitial nephritis with cytopathic changes and necrosis in tubular epithelial cells, tubular and interstitial inflammation, and interstitial fibroplasia; (ii) lesions are at least partly attributable to active viral replication in renal tubular epithelial cells, which have abundant intranuclear viral inclusions; (iii) BoPyV-1 large T (LT) antigen, resulting from early viral gene expression, can be detected in infected renal tubular epithelial cells using a monoclonal antibody raised against Simian Virus-40 polyomavirus LT antigen; and (iv) there is productive BoPyV-1 replication and virion assembly in the nuclei of renal tubular epithelial cells, as demonstrated by the ultrastructural observation of abundant arrays of viral particles with typical polyomavirus morphology. Altogether, these lesions resemble the "cytopathic-inflammatory pathology pattern" proposed in the pathogenesis of Human polyomavirus-1-associated nephropathy in immunocompromised people and kidney allograft recipients. Additionally, we sequenced the complete genome of the BoPyV-1 infecting the fetus, which represents the first whole genome of a BoPyV-1 from the Southern Hemisphere. Lastly, the BoPyV-1 strain infecting this fetus was isolated, causing a cytopathic effect in Madin-Darby bovine kidney cells. We conclude that BoPyV-1 is pathogenic to the bovine fetus under natural circumstances. Further insights into the epidemiology, biology, clinical relevance, and zoonotic potential of BoPyV-1 are needed. |
Incidence of typhoid and paratyphoid fever in Bangladesh, Nepal, and Pakistan: results of the Surveillance for Enteric Fever in Asia Project
Garrett DO , Longley AT , Aiemjoy K , Yousafzai MT , Hemlock C , Yu AT , Vaidya K , Tamrakar D , Saha S , Bogoch II , Date K , Saha S , Islam MS , Sayeed KMI , Bern C , Shakoor S , Dehraj IF , Mehmood J , Sajib MSI , Islam M , Thobani RS , Hotwani A , Rahman N , Irfan S , Naga SR , Memon AM , Pradhan S , Iqbal K , Shrestha R , Rahman H , Hasan MM , Qazi SH , Kazi AM , Saddal NS , Jamal R , Hunzai MJ , Hossain T , Marks F , Carter AS , Seidman JC , Qamar FN , Saha SK , Andrews JR , Luby SP . Lancet Glob Health 2022 10 (7) e978-e988 BACKGROUND: Precise enteric fever disease burden data are needed to inform prevention and control measures, including the use of newly available typhoid vaccines. We established the Surveillance for Enteric Fever in Asia Project (SEAP) to inform these strategies. METHODS: From September, 2016, to September, 2019, we conducted prospective clinical surveillance for Salmonella enterica serotype Typhi (S Typhi) and Paratyphi (S Paratyphi) A, B, and C at health facilities in predetermined catchment areas in Dhaka, Bangladesh; Kathmandu and Kavrepalanchok, Nepal; and Karachi, Pakistan. Patients eligible for inclusion were outpatients with 3 or more consecutive days of fever in the last 7 days; inpatients with suspected or confirmed enteric fever; patients with blood culture-confirmed enteric fever from the hospital laboratories not captured by inpatient or outpatient enrolment and cases from the laboratory network; and patients with non-traumatic ileal perforation under surgical care. We used a hybrid surveillance model, pairing facility-based blood culture surveillance with community surveys of health-care use. Blood cultures were performed for enrolled patients. We calculated overall and age-specific typhoid and paratyphoid incidence estimates for each study site. Adjusted estimates accounted for the sensitivity of blood culture, the proportion of eligible individuals who consented and provided blood, the probability of care-seeking at a study facility, and the influence of wealth and education on care-seeking. We additionally calculated incidence of hospitalisation due to typhoid and paratyphoid. FINDINGS: A total of 34 747 patients were enrolled across 23 facilitates (six tertiary hospitals, surgical wards of two additional hospitals, and 15 laboratory network sites) during the study period. Of the 34 303 blood cultures performed on enrolled patients, 8705 (26%) were positive for typhoidal Salmonella. Adjusted incidence rates of enteric fever considered patients in the six tertiary hospitals. Adjusted incidence of S Typhi, expressed per 100 000 person-years, was 913 (95% CI 765-1095) in Dhaka. In Nepal, the adjusted typhoid incidence rates were 330 (230-480) in Kathmandu and 268 (202-362) in Kavrepalanchok. In Pakistan, the adjusted incidence rates per hospital site were 176 (144-216) and 103 (85-126). The adjusted incidence rates of paratyphoid (of which all included cases were due to S Paratyphi A) were 128 (107-154) in Bangladesh, 46 (34-62) and 81 (56-118) in the Nepal sites, and 23 (19-29) and 1 (1-1) in the Pakistan sites. Adjusted incidence of hospitalisation was high across sites, and overall, 2804 (32%) of 8705 patients with blood culture-confirmed enteric fever were hospitalised. INTERPRETATION: Across diverse communities in three south Asian countries, adjusted incidence exceeded the threshold for "high burden" of enteric fever (100 per 100 000 person-years). Incidence was highest among children, although age patterns differed across sites. The substantial disease burden identified highlights the need for control measures, including improvements to water and sanitation infrastructure and the implementation of typhoid vaccines. FUNDING: Bill & Melinda Gates Foundation. |
Spatial heterogeneity of enteric fever in 2 diverse communities in Nepal
Tamrakar D , Vaidya K , Yu AT , Aiemjoy K , Naga SR , Cao Y , Bern C , Shrestha R , Karmacharya BM , Pradhan S , Qamar FN , Saha S , Date K , Longley AT , Hemlock C , Luby S , Garrett DO , Bogoch II , Andrews JR . Clin Infect Dis 2020 71 S205-s213 BACKGROUND: Typhoid fever is endemic in the urban Kathmandu Valley of Nepal; however, there have been no population-based studies of typhoid outside of this community in the past 3 decades. Whether typhoid immunization should be prioritized in periurban and rural communities has been unclear. METHODS: We performed population-based surveillance for enteric fever in 1 urban catchment (Kathmandu) and 1 periurban and rural catchment (Kavrepalanchok) as part of the Surveillance for Enteric Fever in Asia Project (SEAP). We recruited individuals presenting to outpatient and emergency departments at 2 study hospitals with suspected enteric fever and performed blood cultures. Additionally, we conducted a household survey in each catchment area to characterize care seeking for febrile illness. We evaluated spatial heterogeneity in febrile illness, care seeking, and enteric fever incidence. RESULTS: Between September 2016 and September 2019, we enrolled 5736 participants with suspected enteric fever at 2 study hospitals. Among these, 304 (5.3%) were culture positive for Salmonella Typhi (249 [81.9%]) or Paratyphi A (55 [18.1%]). Adjusted typhoid incidence in Kathmandu was 484 per 100 000 person-years and in Kavrepalanchok was 615 per 100 000 person-years. While all geographic areas for which estimates could be made had incidence >200 per 100 000 person-years, we observed spatial heterogeneity with up to 10-fold variation in incidence between communities. CONCLUSIONS: In urban, periurban, and rural communities in and around Kathmandu, we measured a high but heterogenous incidence of typhoid. These findings provide some support for the introduction of conjugate vaccines in Nepal, including outside urban areas, alongside other measures to prevent enteric fever. |
A cluster-based, spatial-sampling method for assessing household healthcare utilization patterns in resource-limited settings
Yu AT , Shakya R , Adhikari B , Tamrakar D , Vaidya K , Maples S , Date K , Bogoch II , Bern C , Qamar F , Yousafzai MT , Garrett DO , Longley AT , Hemlock C , Luby S , Aiemjoy K , Andrews JR . Clin Infect Dis 2020 71 S239-s247 BACKGROUND: Implementation of population-based surveys is resource intensive and logistically demanding, especially in areas with rapidly changing demographics and incomplete or no enumeration of the underlying population and their residences. To remove the need for pre-enumeration and to simplify field logistics for the population healthcare utilization survey used for the Surveillance for Enteric Fever in Asia Project in Nepal, we incorporated a geographic information system-based geosurvey and field mapping system into a single-stage cluster sampling approach. METHODS: A survey was administered to ascertain healthcare-seeking behavior in individuals with recent suspected enteric fever. Catchment areas were based on residential addresses of enteric fever patients using study facilities; clusters were randomly selected from digitally created grids using available satellite images and all households within clusters were offered enrollment. A tablet-compatible geosurvey and mapping system that allowed for data-syncing and use in areas without cellular data was created using the ArcGIS suite of software. RESULTS: Between January 2017 and November 2018, we surveyed 25 521 households in Nepal (16 769 in urban Kathmandu and 8752 in periurban Kavrepalanchok), representing 84 202 individuals. Overall, the survey participation rate was 90.9%, with geographic heterogeneity in participation rates within each catchment area. Areas with higher average household wealth had lower participation rates. CONCLUSION: A geographic information system-based geosurvey and field mapping system allowed creation of a virtual household map at the same time as survey administration, enabling a single-stage cluster sampling method to assess healthcare utilization in Nepal for the Surveillance for Enteric Fever in Asia Project . This system removed the need for pre-enumeration of households in sampling areas, simplified logistics and could be replicated in future community surveys. |
Epidemiology of sapovirus infections in a birth cohort in Peru.
Sanchez GJ , Mayta H , Pajuelo MJ , Neira K , Xiaofang L , Cabrera L , Ballard SB , Crabtree JE , Kelleher D , Cama V , Bern C , Oshitani H , Gilman RH , Saito M . Clin Infect Dis 2017 66 (12) 1858-1863 Background: Sapovirus is one of the primary viral causes of acute gastroenteritis, especially in settings where rotavirus vaccination has been implemented. The characteristics and impact of natural infection at the community level, however, have not been well documented. Methods: Stool samples were analyzed from 100 children randomly selected from a community-based birth cohort study in Peru. All diarrheal and one non-diarrheal stools collected trimonthly from children up to two years of age (n=1669) were tested for sapovirus detection. Viral shedding duration was determined by testing additional weekly samples (n=440), collected before and after a sapovirus positive sample. Results: The incidence of sapovirus infection in the first and second year of life was 4.3 and 11.1 per 100-child months, respectively. By two years of age, 82% of children had at least one sapovirus infection, and 64% had at least one sapovirus-associated diarrhea episode. The median shedding period was 18.5 days. In 112 of 175 infections, 14 genotypes from four genogroups (GI, GII, GIV and GV) were determined. Among genogroups, GI viruses were more frequently found in symptomatic infections than in asymptomatic infections (OR: 3.1 [CI: 1.3-7.4]). Fifty-nine children had serial sapovirus infections but only three had repeated infection of the same genotype. Conclusions: Sapovirus was frequently detected in children with acute gastroenteritis at the community level during the first two years of life. Serial sapovirus infections by multiple genotypes in a child suggest genotype-specific immunity from each infection, which need to be taken into account for vaccine development. |
Toxicological, enzymatic, and molecular assessment of the insecticide susceptibility profile of Triatoma infestans (Hemiptera: Reduviidae, Triatominae) populations from rural communities of Santa Cruz, Bolivia
Santo-Orihuela PL , Vassena CV , Carvajal G , Clark E , Menacho S , Bozo R , Gilman RH , Bern C , Marcet PL . J Med Entomol 2016 54 (1) 187-195 A wide range of insecticide resistance profiles has been reported across Bolivian domestic and sylvatic populations of Triatoma infestans (Klug, 1834) (Hemiptera, Reduviidae), including some with levels proven to be a threat for vector control. In this work, the insecticide profile of domestic T. infestans was studied with standardized toxicological bioassays, in an area that has not undergone consistent vector control. F1 first-instar nymphs hatched in laboratory from bugs captured in three communities from the Santa Cruz Department were evaluated with different insecticides. Moreover, the enzymatic activity of esterases and cytochrome P450 monooxygenases was measured in individual insects to evaluate the possible mechanism of metabolic resistance to pyrethroids. In addition, the DNA sequence of sodium channel gene (kdr) was screened for two point mutations associated with pyrethroid resistance previously reported in T. infestansAll populations showed reduced susceptibility to deltamethrin and alpha-cypermethrin, albeit the RR50 values varied significantly among them. Increased P450 monooxygenases and permethrate esterases suggest the contribution, as detoxifying mechanisms, to the observed resistance to deltamethrin in all studied populations. No individuals presented either mutation associated to resistance in the kdr gene. The level of susceptibility to alpha-cypermethrin, the insecticide used by the local vector control program, falls within an acceptable range to continue its use in these populations. However, the observed RR50 values evidence the possibility of selection for resistance to pyrethroids, especially to deltamethrin. Consequently, the use of pyrethroid insecticides should be closely monitored in these communities, which should be kept under entomological surveillance and sustained interventions. |
Estimating the burden of Chagas disease in the United States
Manne-Goehler J , Umeh CA , Montgomery SP , Wirtz VJ . PLoS Negl Trop Dis 2016 10 (11) e0005033 BACKGROUND: In recent years, there has been growing awareness of the significant burden of Chagas disease in the United States (US). However, epidemiological data on both prevalence and access to care for this disease are limited. The objective of this study is to provide an updated national estimate of Chagas disease prevalence, the first state-level estimates of cases of T. cruzi infection in the US and to analyze these estimates in the context of data on confirmed cases of infection in the US blood supply. METHODS: In this study, we calculated estimates of the state and national prevalence of Chagas disease. The number of residents originally from Chagas disease endemic countries were computed using data on Foreign-Born Hispanic populations from the American Community Survey, along with recent prevalence estimates for Chagas disease in Latin America from the World Health Organization that were published in 2006 and updated in 2015. We then describe the distribution of estimated cases in each state in relation to the number of infections identified in the donated blood supply per data from the AABB (formerly American Association of Blood Banks). FINDINGS: The results of this analysis offer an updated national estimate of 238,091 cases of T. cruzi infection in the United States as of 2012, using the same method as was used by Bern and Montgomery to estimate cases in 2005. This estimate indicates that there are 62,070 cases less than the most recent prior estimate, though it does not include undocumented immigrants who may account for as many as 109,000 additional cases. The state level results show that four states (California, Texas, Florida and New York) have over 10,000 cases and an additional seven states have over 5,000 cases. Moreover, since 2007, the AABB has reported 1,908 confirmed cases of T. cruzi infection identified through screening of blood donations. CONCLUSIONS: This study demonstrates a substantial burden of Chagas disease in the US, with state variation that reflects the distribution of at risk Latin American immigrant populations. The study lends important new insight into the distribution of this disease in the US and highlights the need for further research quantifying prevalence and incidence to guide interventions for control of Chagas disease across the US. |
Etiological role and repeated infections of sapovirus among children aged less than two years in a cohort study in a peri-urban community of Peru.
Liu X , Jahuira H , Gilman RH , Alva A , Cabrera L , Okamoto M , Xu H , Windle HJ , Kelleher D , Varela M , Verastegui M , Calderon M , Sanchez G , Sarabia V , Ballard SB , Bern C , Mayta H , Crabtree JE , Cama V , Saito M , Oshitani H . J Clin Microbiol 2016 54 (6) 1598-1604 Human sapovirus has been shown to be one of the most important etiologies in pediatric patients with acute diarrhea. However, very limited data are available about the causative roles and epidemiology of sapovirus in community settings. A nested matched case-control study within a birth cohort study of acute diarrhea in a peri-urban community in Peru from 2007 to 2010 was conducted to investigate the attributable fraction (AF) and genetic diversity of sapovirus. By quantitative reverse transcription real-time polymerase chain reaction (RT-qPCR), sapovirus was detected in 12.4% (37/299) of diarrheal and 5.7% (17/300) of non-diarrheal stools (p=0.004). Sapovirus AF (7.1%) was higher in the second (13.2%) than the first year (1.4%) of life of children. Ten known genotypes and one novel cluster (n=5) within four genogroups (GI, GII, GIV and GV) were identified by phylogenetic analysis of partial VP1 gene. Further sequence analysis of full VP1 gene revealed a possible novel genotype, tentatively named as GII.8. Notably, symptomatic reinfections with different genotypes within the same (n=3) or different genogroups (n=5) were observed in eight children. Sapovirus exhibited high attributable burden for acute gastroenteritis especially in the second year of life of children in a Peruvian community. Further large-scale studies are needed to understand better the global burden, genetic diversity, and repeated infections of sapovirus. |
Perinatal screening for Chagas disease in southern Texas
Edwards MS , Rench MA , Todd CW , Czaicki N , Steurer FJ , Bern C , Montgomery SP . J Pediatric Infect Dis Soc 2015 4 (1) 67-70 Perinatal screening for Trypanosoma cruzi in a cohort of 4000 predominantly Hispanic women in southern Texas revealed that Chagas disease occurs with sufficient frequency (0.25%) that targeted perinatal screening should be considered to identify infected mothers and infants at risk for congenital infection. |
Electrocardiographic and echocardiographic abnormalities in Chagas disease: findings in residents of rural Bolivian communities hyperendemic for Chagas disease
Fernandez AB , Nunes MC , Clark EH , Samuels A , Menacho S , Gomez J , Bozo Gutierrez RW , Crawford TC , Gilman RH , Bern C . Glob Heart 2015 10 (3) 159-66 BACKGROUND: Chagas disease is a neglected and preventable tropical disease that causes significant cardiac morbidity and mortality in Latin America. OBJECTIVES: This study sought to describe cardiac findings among inhabitants of rural communities of the Bolivian Chaco. METHODS: The cardiac study drew participants from an epidemiologic study in 7 indigenous Guarani communities. All infected participants 10 years or older were asked to undergo a brief physical examination and 12-lead electrocardiogram (ECG). A subset had echocardiograms. ECG and echocardiograms were read by 1 or more cardiologists. RESULTS: Of 1,137 residents 10 years or older, 753 (66.2%) had Trypanosoma cruzi infection. Cardiac evaluations were performed for 398 infected participants 10 years or older. Fifty-five participants (13.8%) had 1 or more ECG abnormalities suggestive of Chagas cardiomyopathy. The most frequent abnormalities were bundle branch blocks in 42 (11.3%), followed by rhythm disturbances or ventricular ectopy in 13 (3.3%), and atrioventricular blocks (AVB) in 10 participants (2.6%). The prevalence of any abnormality rose from 1.1% among those 10 to 19 years old to 14.2%, 17.3%, and 26.4% among those 20 to 39, 40 to 59, and older than 60 years, respectively. First-degree AVB was seen most frequently in participants 60 years or older, but the 4 patients with third-degree AVB were all under 50 years old. Eighteen and 2 participants had a left ventricular ejection fraction of 40% to 54% and <40%, respectively. An increasing number of ECG abnormalities was associated with progressively larger left ventricular end-diastolic dimensions and lower left ventricular ejection fraction. CONCLUSIONS: We found a high prevalence of ECG abnormalities and substantial evidence of Chagas cardiomyopathy. Programs to improve access to basic cardiac care (annual ECG, antiarrhythmics, pacemakers) could have an immediate impact on morbidity and mortality in these highly endemic communities. |
Prevalence and transmission of Trypanosoma cruzi in people of rural communities of the high jungle of northern Peru
Alroy KA , Huang C , Gilman RH , Quispe-Machaca VR , Marks MA , Ancca-Juarez J , Hillyard M , Verastegui M , Sanchez G , Cabrera L , Vidal E , Billig EM , Cama VA , Naquira C , Bern C , Levy MZ . PLoS Negl Trop Dis 2015 9 (5) e0003779 BACKGROUND: Vector-borne transmission of Trypanosoma cruzi is seen exclusively in the Americas where an estimated 8 million people are infected with the parasite. Significant research in southern Peru has been conducted to understand T. cruzi infection and vector control, however, much less is known about the burden of infection and epidemiology in northern Peru. METHODOLOGY: A cross-sectional study was conducted to estimate the seroprevalence of T. cruzi infection in humans (n=611) and domestic animals [dogs (n=106) and guinea pigs (n=206)] in communities of Cutervo Province, Peru. Sampling and diagnostic strategies differed according to species. An entomological household study (n=208) was conducted to identify the triatomine burden and species composition, as well as the prevalence of T. cruzi in vectors. Electrocardiograms (EKG) were performed on a subset of participants (n=90 T. cruzi infected participants and 170 age and sex-matched controls). The seroprevalence of T. cruzi among humans, dogs, and guinea pigs was 14.9% (95% CI: 12.2 - 18.0%), 19.8% (95% CI: 12.7- 28.7%) and 3.3% (95% CI: 1.4 - 6.9%) respectively. In one community, the prevalence of T. cruzi infection was 17.2% (95% CI: 9.6 - 24.7%) among participants < 15 years, suggesting recent transmission. Increasing age, positive triatomines in a participant's house, and ownership of a T. cruzi positive guinea pig were independent correlates of T. cruzi infection. Only one species of triatomine was found, Panstrongylus lignarius, formerly P. herreri. Approximately forty percent (39.9%, 95% CI: 33.2 - 46.9%) of surveyed households were infested with this vector and 14.9% (95% CI: 10.4 - 20.5%) had at least one triatomine positive for T. cruzi. The cardiac abnormality of right bundle branch block was rare, but only identified in seropositive individuals. CONCLUSIONS: Our research documents a substantial prevalence of T. cruzi infection in Cutervo and highlights a need for greater attention and vector control efforts in northern Peru. |
Global surveillance of cancer survival 1995-2009: analysis of individual data for 25 676 887 patients from 279 population-based registries in 67 countries (CONCORD-2)
Allemani C , Weir HK , Carreira H , Harewood R , Spika D , Wang XS , Bannon F , Ahn JV , Johnson CJ , Bonaventure A , Marcos-Gragera R , Stiller C , Azevedo e Silva G , Chen WQ , Ogunbiyi OJ , Rachet B , Soeberg MJ , You H , Matsuda T , Bielska-Lasota M , Storm H , Tucker TC , Coleman MP . Lancet 2014 385 (9972) 977-1010 BACKGROUND: Worldwide data for cancer survival are scarce. We aimed to initiate worldwide surveillance of cancer survival by central analysis of population-based registry data, as a metric of the effectiveness of health systems, and to inform global policy on cancer control. METHODS: Individual tumour records were submitted by 279 population-based cancer registries in 67 countries for 25.7 million adults (age 15-99 years) and 75 000 children (age 0-14 years) diagnosed with cancer during 1995-2009 and followed up to Dec 31, 2009, or later. We looked at cancers of the stomach, colon, rectum, liver, lung, breast (women), cervix, ovary, and prostate in adults, and adult and childhood leukaemia. Standardised quality control procedures were applied; errors were corrected by the registry concerned. We estimated 5-year net survival, adjusted for background mortality in every country or region by age (single year), sex, and calendar year, and by race or ethnic origin in some countries. Estimates were age-standardised with the International Cancer Survival Standard weights. FINDINGS: 5-year survival from colon, rectal, and breast cancers has increased steadily in most developed countries. For patients diagnosed during 2005-09, survival for colon and rectal cancer reached 60% or more in 22 countries around the world; for breast cancer, 5-year survival rose to 85% or higher in 17 countries worldwide. Liver and lung cancer remain lethal in all nations: for both cancers, 5-year survival is below 20% everywhere in Europe, in the range 15-19% in North America, and as low as 7-9% in Mongolia and Thailand. Striking rises in 5-year survival from prostate cancer have occurred in many countries: survival rose by 10-20% between 1995-99 and 2005-09 in 22 countries in South America, Asia, and Europe, but survival still varies widely around the world, from less than 60% in Bulgaria and Thailand to 95% or more in Brazil, Puerto Rico, and the USA. For cervical cancer, national estimates of 5-year survival range from less than 50% to more than 70%; regional variations are much wider, and improvements between 1995-99 and 2005-09 have generally been slight. For women diagnosed with ovarian cancer in 2005-09, 5-year survival was 40% or higher only in Ecuador, the USA, and 17 countries in Asia and Europe. 5-year survival for stomach cancer in 2005-09 was high (54-58%) in Japan and South Korea, compared with less than 40% in other countries. By contrast, 5-year survival from adult leukaemia in Japan and South Korea (18-23%) is lower than in most other countries. 5-year survival from childhood acute lymphoblastic leukaemia is less than 60% in several countries, but as high as 90% in Canada and four European countries, which suggests major deficiencies in the management of a largely curable disease. INTERPRETATION: International comparison of survival trends reveals very wide differences that are likely to be attributable to differences in access to early diagnosis and optimum treatment. Continuous worldwide surveillance of cancer survival should become an indispensable source of information for cancer patients and researchers and a stimulus for politicians to improve health policy and health-care systems. FUNDING: Canadian Partnership Against Cancer (Toronto, Canada), Cancer Focus Northern Ireland (Belfast, UK), Cancer Institute New South Wales (Sydney, Australia), Cancer Research UK (London, UK), Centers for Disease Control and Prevention (Atlanta, GA, USA), Swiss Re (London, UK), Swiss Cancer Research foundation (Bern, Switzerland), Swiss Cancer League (Bern, Switzerland), and University of Kentucky (Lexington, KY, USA). |
Circulating serum markers and QRS scar score in Chagas cardiomyopathy
Clark EH , Marks MA , Gilman RH , Fernandez AB , Crawford TC , Samuels AM , Hidron AI , Galdos-Cardenas G , Menacho-Mendez GS , Bozo-Gutierrez RW , Martin DL , Bern C . Am J Trop Med Hyg 2014 92 (1) 39-44 Approximately 8 million people have Trypanosoma cruzi infection, and nearly 30% will manifest Chagas cardiomyopathy (CC). Identification of reliable early indicators of CC risk would enable prioritization of treatment to those with the highest probability of future disease. Serum markers and EKG changes were measured in 68 T. cruzi-infected individuals in various stages of cardiac disease and 17 individuals without T. cruzi infection or cardiac disease. T. cruzi-infected individuals were assigned to stage A (normal EKG/chest x-ray [CXR]), B (abnormal EKG/normal CXR), or C (abnormal EKG/cardiac structural changes). Ten serum markers were measured using enzyme-linked immunosorbent assay (ELISA)/Luminex, and QRS scores were calculated. Higher concentrations of transforming growth factor-beta1 (TGFbeta1), and TGFbeta2 were associated with stage B compared with stage A. Matrix Metalloproteinase 2 (MMP2), Tissue Inhibitors of MMP 1, QRS score, and Brain Natriuretic Protein rose progressively with increasing CC severity. Elevated levels of several markers of cardiac damage and inflammation are seen in early CC and warrant additional evaluation in longitudinal studies. |
Population genetics of Cryptosporidium meleagridis in humans and birds: evidence for cross-species transmission.
Wang Y , Yang W , Cama V , Wang L , Cabrera L , Ortega Y , Bern C , Feng Y , Gilman R , Xiao L . Int J Parasitol 2014 44 (8) 515-21 Population genetic studies have been used to understand the transmission of pathogens in humans and animals, especially the role of zoonotic infections and evolution and dispersal of virulent subtypes. In this study, we analyzed the genetic diversity and population structure of Cryptosporidium meleagridis, the only known Cryptosporidium species that infects both avian and mammalian hosts and is responsible for approximately 10% of human cryptosporidiosis in some areas. A total of 62 C. meleagridis specimens from children, AIDS patients, and birds in Lima, Peru were characterized by sequence analysis of the ssrRNA gene and five minisatellite, microsatellite and polymorphic markers in chromosome 6, including the 60 kDa glycoprotein (gp60), 47 kDa glycoprotein (CP47), a serine repeat antigen (MSC6-5), retinitis pigmentosa GTPase regulator (RPGR) and thrombospondin protein 8 (TSP8). The multilocus sequence analysis identified concurrent infections with Cryptosporidium hominis in four AIDS patients and three children. Unique subtypes of C. meleagridis ranged from eight at the gp60 locus (gene diversity -Hd = 0.651), three at the RPGR (Hd = 0.556), three at the MSC6-5 locus (Hd = 0.242), two at TSP8 (Hd = 0.198), to one at CP47 (monomorphic), much lower than that of C. hominis in the same area. Intragenic linkage disequilibrium (LD) was strong and complete at all gene loci. Intergenic LD was highly significant (P < 0.001) for all pairs of polymorphic loci. Two major groups of subtypes were seen, with most subtypes belonging to group 1. Within group 1, there was no clear population segregation, and two of the 14 multilocus subtypes of C. meleagridis were found in both AIDS patients and birds. We believe that these results provide the first evidence of a clonal population structure of C. meleagridis and the likely occurrence of cross-species transmission of C. meleagridis between birds and humans. |
Regional variation in the correlation of antibody and T-cell responses to Trypanosoma cruzi
Martin DL , Marks M , Galdos-Cardenas G , Gilman RH , Goodhew B , Ferrufino L , Halperin A , Sanchez G , Verastegui M , Escalante P , Naquira C , Levy MZ , Bern C . Am J Trop Med Hyg 2014 90 (6) 1074-81 Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is a major cause of morbidity and mortality in Central and South America. Geographic variations in the sensitivity of serologic diagnostic assays to T. cruzi may reflect differences in T. cruzi exposure. We measured parasite-specific T-cell responses among seropositive individuals in two populations from South America with widely varying antibody titers against T. cruzi. Antibody titers among seropositive individuals were significantly lower in Arequipa, Peru compared with Santa Cruz, Bolivia. Similarly, the proportion of seropositive individuals with positive T-cell responses was lower in Peru than Bolivia, resulting in overall lower frequencies of interferon-gamma (IFNgamma) -secreting cells from Peruvian samples. However, the magnitude of the IFNgamma response was similar among the IFNgamma responders in both locations. These data indicate that immunological discrepancies based on geographic region are reflected in T-cell responses as well as antibody responses. |
Multiple norovirus infections in a birth cohort in a Peruvian periurban community
Saito M , Goel-Apaza S , Espetia S , Velasquez D , Cabrera L , Loli S , Crabtree JE , Black RE , Kosek M , Checkley W , Zimic M , Bern C , Cama V , Gilman RH . Clin Infect Dis 2014 58 (4) 483-91 BACKGROUND: Human noroviruses are among the most common enteropathogens globally, and are a leading cause of infant diarrhea in developing countries. However, data measuring the impact of norovirus at the community level are sparse. METHODS: We followed a birth cohort of children to estimate norovirus infection and diarrhea incidence in a Peruvian community. Stool samples from diarrheal episodes and randomly selected nondiarrheal samples were tested by polymerase chain reaction for norovirus genogroup and genotype. Excretion duration and rotavirus coinfection were evaluated in a subset of episodes. RESULTS: Two hundred twenty and 189 children were followed to 1 and 2 years of age, respectively. By 1 year, 80% (95% confidence interval [CI], 75%-85%) experienced at least 1 norovirus infection and by 2 years, 71% (95% CI, 65%-77%) had at least 1 episode of norovirus-associated diarrhea. Genogroup II (GII) infections were 3 times more frequent than genogroup 1 (GI) infections. Eighteen genotypes were found; GII genotype 4 accounted for 41%. Median excretion duration was 34.5 days for GII vs 8.5 days for GI infection (P = .0006). Repeat infections by the same genogroup were common, but repeat infections by the same genotype were rare. Mean length-for-age z score at 12 months was lower among children with prior norovirus infection compared to uninfected children (coefficient: -0.33 [95% CI, -.65 to -.01]; P = .04); the effect persisted at 24 months. CONCLUSIONS: Norovirus infection occurs early in life and children experience serial infections with multiple genotypes, suggesting genotype-specific immunity. An effective vaccine would have a substantial impact on morbidity, but may need to target multiple genotypes. |
Clinical and immunological aspects of post-kala-azar dermal leishmaniasis in Bangladesh
Islam S , Kenah E , Bhuiyan MA , Rahman KM , Goodhew B , Ghalib CM , Zahid MM , Ozaki M , Rahman MW , Haque R , Luby SP , Maguire JH , Martin D , Bern C . Am J Trop Med Hyg 2013 89 (2) 345-53 We conducted active surveillance for kala-azar and post-kala-azar dermal leishmaniasis (PKDL) in a population of 24,814 individuals. Between 2002 and 2010, 1,002 kala-azar and 185 PKDL cases occurred. Median PKDL patient age was 12 years; 9% had no antecedent kala-azar. Cases per 10,000 person-years peaked at 90 for kala-azar (2005) and 28 for PKDL (2007). Cumulative PKDL incidence among kala-azar patients was 17% by 5 years. Kala-azar patients younger than 15 years were more likely than older patients to develop PKDL; no other risk factors were identified. The most common lesions were hypopigmented macules. Of 98 untreated PKDL patients, 48 (49%) patients had resolution, with median time of 19 months. Kala-azar patients showed elevated interferon-gamma (IFNgamma), tumor necrosis factor-alpha (TNFalpha), and interleukin 10 (IL-10). Matrix metalloproteinase 9 (MMP9) and MMP9/tissue inhibitors of matrix metalloproteinases ratio were significantly higher in PKDL patients than in other groups. PKDL is frequent in Bangladesh and poses a challenge to the current visceral leishmaniasis elimination initiative in the Indian subcontinent. |
Early anthropometric indices predict short stature and overweight status in a cohort of Peruvians in early adolescence
Sterling R , Miranda JJ , Gilman RH , Cabrera L , Sterling CR , Bern C , Checkley W . Am J Phys Anthropol 2012 148 (3) 451-61 While childhood malnutrition is associated with increased morbidity and mortality, less well understood is how early childhood growth influences height and body composition later in life. We revisited 152 Peruvian children who participated in a birth cohort study between 1995 and 1998, and obtained anthropometric and bioimpedance measurements 11-14 years later. We used multivariable regression models to study the effects of childhood anthropometric indices on height and body composition in early adolescence. Each standard deviation decrease in length-for-age at birth was associated with a decrease in adolescent height-for-age of 0.7 SD in both boys and girls (all P < 0.001) and 9.7 greater odds of stunting (95% CI 3.3-28.6). Each SD decrease in length-for-age in the first 30 months of life was associated with a decrease in adolescent height-for-age of 0.4 in boys and 0.6 standard deviation in girls (all P < 0.001) and with 5.8 greater odds of stunting (95% CI 2.6-13.5). The effect of weight gain during early childhood on weight in early adolescence was more complex to understand. Weight-for-length at birth and rate of change in weight-for-length in early childhood were positively associated with age- and sex-adjusted body mass index and a greater risk of being overweight in early adolescence. Linear growth retardation in early childhood is a strong determinant of adolescent stature, indicating that, in developing countries, growth failure in height during early childhood persists through early adolescence. Interventions addressing linear growth retardation in childhood are likely to improve adolescent stature and related-health outcomes in adulthood. (Am J Phys Anthropol 148:451-461, 2012. (c) 2012 Wiley Periodicals, Inc.) |
Effects of the 1997-1998 El Nino episode on community rates of diarrhea
Bennett A , Epstein LD , Gilman RH , Cama V , Bern C , Cabrera L , Lescano AG , Patz J , Carcamo C , Sterling CR , Checkley W . Am J Public Health 2012 102 (7) e63-9 OBJECTIVES: To improve our understanding of climate variability and diarrheal disease at the community level and inform predictions for future climate change scenarios, we examined whether the El Nino climate pattern is associated with increased rates of diarrhea among Peruvian children. METHODS: We analyzed daily surveillance data for 367 children aged 0 to 12 years from 2 cohorts in a peri-urban shantytown in Lima, Peru, 1995 through 1998. We stratified diarrheal incidence by 6-month age categories, season, and El Nino, and modeled between-subject heterogeneity with random effects Poisson models. RESULTS: Spring diarrheal incidence increased by 55% during El Nino compared with before El Nino. This increase was most acute among children older than 60 months, for whom the risk of a diarrheal episode during the El Nino spring was nearly 100% greater (relative risk = 1.96; 95% confidence interval = 1.24, 3.09). CONCLUSIONS: El Nino-associated climate variability affects community rates of diarrhea, particularly during the cooler seasons and among older children. Public health officials should develop preventive strategies for future El Nino episodes to mitigate the increased risk of diarrheal disease in vulnerable communities. (Am J Public Health. Published online ahead of print May 17, 2012: e1-e7. doi:10.2105/AJPH.2011.300573). |
Temporal differences in blood meal detection from the midguts of Triatoma infestans
Pinto J , Roellig DM , Gilman RH , Calderon M , Bartra C , Salazar R , Bern C , Ancca-Juarez J , Levy M , Naquira C , Cama V . Rev Inst Med Trop Sao Paulo 2012 54 (2) 83-8 We used genus/species specific PCRs to determine the temporal persistence of host DNA in Triatoma infestans experimentally fed on blood from six common vertebrate species: humans, domestic dogs, guinea pigs, chickens, mice, and pigs. Twenty third or fourth instar nymphs per animal group were allowed to feed to engorgement, followed by fasting-maintenance in the insectary. At 7, 14, 21, or 28 days post-feeding, the midgut contents from five triatomines per group were tested with the respective PCR assay. DNA from all vertebrate species was detected in at least four of five study nymphs at seven and 14 days post-feeding. DNA of humans, domestic dogs, guinea pigs, pigs, and chickens were more successfully detected (80-100%) through day 21, and less successfully (20-100%) at day 28. Findings demonstrate that species-specific PCRs can consistently identify feeding sources of T. infestans within two weeks, a biologically relevant time interval. |
Population genetic analysis of Enterocytozoon bieneusi in humans.
Li W , Cama V , Feng Y , Gilman RH , Bern C , Zhang X , Xiao L . Int J Parasitol 2012 42 (3) 287-293 Genotyping based on sequence analysis of the ribosomal internal transcribed spacer has revealed significant genetic diversity in Enterocytozoon bieneusi. Thus far, the population genetics of E. bieneusi and its significance in the epidemiology of microsporidiosis have not been examined. In this study, a multilocus sequence typing of E. bieneusi in AIDS patients in Lima, Peru was conducted, using 72 specimens previously genotyped as A, D, IV, EbpC, WL11, Peru7, Peru8, Peru10 and Peru11 at the internal transcribed spacer locus. Altogether, 39 multilocus genotypes were identified among the 72 specimens. The observation of strong intragenic linkage disequilibria and limited genetic recombination among markers were indicative of an overall clonal population structure of E. bieneusi. Measures of pair-wise intergenic linkage disequilibria and a standardised index of association based on allelic profile data further supported this conclusion. Both sequence-based and allelic profile-based phylogenetic analyses showed the presence of two genetically isolated groups in the study population, one (group 1) containing isolates of the anthroponotic internal transcribed spacer genotype A, and the other (group 2) containing isolates of multiple internal transcribed spacer genotypes (mainly genotypes D and IV) with zoonotic potential. The measurement of linkage disequilibria and recombination indicated group 2 had a clonal population structure, whereas group 1 had an epidemic population structure. The formation of the two sub-populations was confirmed by STRUCTURE and Wright's fixation index analyses. The data highlight the power of MLST in understanding the epidemiology of E. bieneusi. 2012. |
A field trial of alternative targeted screening strategies for Chagas disease in Arequipa, Peru
Hunter GC , Borrini-Mayori K , Ancca Juarez J , Castillo Neyra R , Verastegui MR , Malaga Chavez FS , Cornejo del Carpio JG , Cordova Benzaquen E , Naquira C , Gilman RH , Bern C , Levy MZ . PLoS Negl Trop Dis 2012 6 (1) e1468 BACKGROUND: Chagas disease is endemic in the rural areas of southern Peru and a growing urban problem in the regional capital of Arequipa, population approximately 860,000. It is unclear how to implement cost-effective screening programs across a large urban and periurban environment. METHODS: We compared four alternative screening strategies in 18 periurban communities, testing individuals in houses with 1) infected vectors; 2) high vector densities; 3) low vector densities; and 4) no vectors. Vector data were obtained from routine Ministry of Health insecticide application campaigns. We performed ring case detection (radius of 15 m) around seropositive individuals, and collected data on costs of implementation for each strategy. RESULTS: Infection was detected in 21 of 923 (2.28%) participants. Cases had lived more time on average in rural places than non-cases (7.20 years versus 3.31 years, respectively). Significant risk factors on univariate logistic regression for infection were age (OR 1.02; p=0.041), time lived in a rural location (OR 1.04; p=0.022), and time lived in an infested area (OR 1.04; p=0.008). No multivariate model with these variables fit the data better than a simple model including only the time lived in an area with triatomine bugs. There was no significant difference in prevalence across the screening strategies; however a self-assessment of disease risk may have biased participation, inflating prevalence among residents of houses where no infestation was detected. Testing houses with infected-vectors was least expensive. Ring case detection yielded four secondary cases in only one community, possibly due to vector-borne transmission in this community, apparently absent in the others. CONCLUSIONS: Targeted screening for urban Chagas disease is promising in areas with ongoing vector-borne transmission; however, these pockets of epidemic transmission remain difficult to detect a priori. The flexibility to adapt to the epidemiology that emerges during screening is key to an efficient case detection intervention. In heterogeneous urban environments, self-assessments of risk and simple residence history questionnaires may be useful to identify those at highest risk for Chagas disease to guide diagnostic efforts. |
Trypanosoma cruzi and Chagas' disease in the United States
Bern C , Kjos S , Yabsley MJ , Montgomery SP . Clin Microbiol Rev 2011 24 (4) 655-81 SUMMARY: Chagas' disease is caused by the protozoan parasite Trypanosoma cruzi and causes potentially life-threatening disease of the heart and gastrointestinal tract. The southern half of the United States contains enzootic cycles of T. cruzi, involving 11 recognized triatomine vector species. The greatest vector diversity and density occur in the western United States, where woodrats are the most common reservoir; other rodents, raccoons, skunks, and coyotes are also infected with T. cruzi. In the eastern United States, the prevalence of T. cruzi is highest in raccoons, opossums, armadillos, and skunks. A total of 7 autochthonous vector-borne human infections have been reported in Texas, California, Tennessee, and Louisiana; many others are thought to go unrecognized. Nevertheless, most T. cruzi-infected individuals in the United States are immigrants from areas of endemicity in Latin America. Seven transfusion-associated and 6 organ donor-derived T. cruzi infections have been documented in the United States and Canada. As improved control of vector- and blood-borne T. cruzi transmission decreases the burden in countries where the disease is historically endemic and imported Chagas' disease is increasingly recognized outside Latin America, the United States can play an important role in addressing the altered epidemiology of Chagas' disease in the 21st century. |
Tubulinosema sp. microsporidian myositis in immunosuppressed patient
Choudhary MM , Metcalfe MG , Arrambide K , Bern C , Visvesvara GS , Pieniazek NJ , Bandea RD , Deleon-Carnes M , Adem P , Zaki SR , Saeed MU . Emerg Infect Dis 2011 17 (9) 1727-30 The Phylum Microsporidia comprises >1,200 species, only 15 of which are known to infect humans, including the genera Trachipleistophora, Pleistophora, and Brachiola. We report an infection by Tubulinosema sp. in an immunosuppressed patient. |
Economic consequences of post-kala-azar dermal leishmaniasis in a rural Bangladeshi community
Ozaki M , Islam S , Rahman KM , Rahman A , Luby SP , Bern C . Am J Trop Med Hyg 2011 85 (3) 528-34 Post-kala-azar dermal leishmaniasis (PKDL) is a complication of visceral leishmaniasis. Bangladesh national treatment guidelines during the study period called for 120 intramuscular injections of sodium antimony gluconate (SAG). We assessed care-seeking behavior, diagnosis and treatment costs, and coping strategies among 134 PKDL patients; 56 (42%) patients had been treated with SAG, and 78 (58%) remained untreated. The median direct cost per patient treated was US$367 (interquartile range [IQR] = 90-284), more than two times the estimated per capita annual income for the study population. The most common coping strategy was to take a loan; the median amount borrowed was US$98 (IQR = 71-150), with a median interest of US$32 (IQR = 16-95). Households lost a median of 123 work-days per patient treated. The current regimen for PKDL imposes a significant financial burden, reinforcing the link between poverty and visceral leishmaniasis. More practical shorter-course regimens for PKDL are urgently needed to achieve national and regional visceral leishmaniasis elimination goals. |
Acute and congenital Chagas disease
Bern C , Martin DL , Gilman RH . Adv Parasitol 2011 75 19-47 The acute phase of Chagas disease lasts 4-8 weeks and is characterized by microscopically detectable parasitaemia. Symptoms are usually mild with severe acute disease occurring in less than 1% of patients. Orally transmitted Trypanosoma cruzi outbreaks can have more severe acute morbidity and higher mortality than vector-borne infection. Congenital T. cruzi infection occurs in 1-10% of infants of infected mothers. Most congenital infections are asymptomatic or cause non-specific signs, requiring laboratory screening for detection. A small proportion of congenital infections cause severe morbidity with hepatosplenomegaly, anaemia, meningoencephalitis and/or respiratory insufficiency, with an associated high mortality. Infected infants are presumed to carry the same 20-30% lifetime risk of cardiac or gastrointestinal disease as other infected individuals. Most control programs in Latin America employ prenatal serological screening followed by microscopic examination of cord blood from infants of seropositive mothers. Recent data confirm that polymerase chain reaction (PCR) is more sensitive and detects congenital infections earlier than conventional techniques. For infants not diagnosed at birth, conventional serology is recommended at at 6 to 9 months of age. In programs that have been evaluated, less than 20% of at risk infants completed all steps of the screening algorithm. A sensitive, specific and practical screening test for newborns is needed to enable Chagas disease to be added to newborn screening programs. |
Post-kala-azar dermal leishmaniasis in Mymensingh, Bangladesh
Islam S , Ashraful Alam Bhuiyan M , Bern C . Am J Trop Med Hyg 2011 85 (2) 193-4 A 50-year-old man from Mymensingh district, Bangladesh, presented with a 3-month history of non-pruritic, painless hypopigmented papules, and plaques, beginning on the face and subsequently spreading to the forearms, torso, and legs (Figures 1–4) Fifteen months before the onset of skin lesions, the patient had visceral leishmaniasis (kala-azar), successfully treated with 30 intramuscular injections of sodium stibogluconate (SSG). Polymerase chain reaction showed Leishmania donovani DNA in a buffy coat specimen. |
Antitrypanosomal therapy for chronic Chagas' disease
Bern C . N Engl J Med 2011 364 (26) 2527-34 A 42-year-old woman presents to her physician with a letter stating that after she made a recent blood donation, a serologic test of her donated blood was positive for Chagas' disease. The patient was born in El Salvador and moved to the United States when she was 18 years of age. Her three children are 8, 13, and 16 years of age. Her medical history is remarkable only for a cholecystectomy 2 years earlier; she reports no cardiac or gastrointestinal symptoms. Her physical examination is unremarkable. Electrocardiography (ECG) shows sinus rhythm at a rate of 72 beats per minute and a complete right bundle-branch block. An echocardiogram shows mild left ventricular segmental wall-motion abnormalities, but a normal ejection fraction and left ventricular diameter. The patient is referred to an infectious-disease consultant, who recommends antitrypanosomal therapy. |
Anti-triatomine saliva immunoassays for the evaluation of impregnated netting trials against Chagas disease transmission
Schwarz A , Juarez JA , Richards J , Rath B , Machaca VQ , Castro YE , Malaga ES , Levy K , Gilman RH , Bern C , Verastegui M , Levy MZ . Int J Parasitol 2011 41 (6) 591-4 Insecticide-impregnated nets can kill triatomine bugs, but it remains unclear whether they can protect against Chagas disease transmission. In a field trial in Quequena, Peru, sentinel guinea pigs placed in intervention enclosures covered by deltamethrin-treated nets showed significantly lower antibody responses to saliva of Triatoma infestans compared with animals placed in pre-existing control enclosures. Our results strongly suggest that insecticide-treated nets prevent triatomine bites and can thereby protect against infection with Trypanosoma cruzi. Anti-salivary immunoassays are powerful new tools to evaluate intervention strategies against Chagas disease. |
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