Last data update: Jun 20, 2025. (Total: 49421 publications since 2009)
Records 1-25 (of 25 Records) |
Query Trace: Cama VA[original query] |
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Cyclospora genotypic variations and associated epidemiologic characteristics, United States, 2018-2021
Shen J , Cama VA , Jacobson D , Barratt J , Straily A . Emerg Infect Dis 2025 31 (2) 256-266 ![]() ![]() Seasonal cyclosporiasis outbreaks occur in the United States every year. To better understand the disease, the Centers for Disease Control and Prevention developed a novel genotyping system that successfully clusters nonclonal eukaryotes. We examined temporal-geographic distributions of Cyclospora cluster consensus genotypes (CCGs) and applied regression analyses to identify correlations between Cyclospora spp. parasites and clinical manifestations or epidemiologic risk factors, using data collected during 2018-2021. No CCG was uniquely associated with or consistently detected in a state during the study, suggesting that cyclosporiasis in the United States is likely caused by frequent parasite introductions. We identified positive associations between infection with C. ashfordi and C. cayetanensis and consumption of specific produce items: cilantro, mango, and onion for C. ashfordi and iceberg lettuce, carrot, and cauliflower for C. cayetanensis. Our findings can guide future research into public health interventions aimed at reducing the burden of cyclosporiasis in the United States. |
Progress toward global dracunculiasis (Guinea worm disease) eradication, January 2023-June 2024
Hopkins DR , Weiss AJ , Yerian S , Zhao Y , Sapp SGH , Cama VA . MMWR Morb Mortal Wkly Rep 2024 73 (44) 991-998 The effort to eradicate Dracunculus medinensis, the etiologic agent of dracunculiasis, or Guinea worm disease, began at CDC in 1980. In 1986, with an estimated 3.5 million global cases in 20 African and Asian countries, the World Health Assembly called for dracunculiasis elimination. The Guinea Worm Eradication Program (GWEP) was established to help countries with endemic dracunculiasis reach this goal. GWEP is led by The Carter Center and supported by partners, including the countries with endemic disease, CDC, UNICEF, and the World Health Organization. Since 2012, infections in dogs, cats, and baboons have posed a new challenge for GWEP, as have ongoing civil unrest and insecurity in some areas. As of June 2024, dracunculiasis remained endemic in five countries (Angola, Chad, Ethiopia, Mali, and South Sudan). Fourteen human cases and 886 animal infections occurred, including 407 dogs in Chad and 248 dogs in Cameroon, reported in 2023, and three human cases and 297 animal infections reported during January-June 2024. Animal infections, primarily in dogs in Cameroon and Chad, and impeded access due to civil unrest and insecurity in Mali, threaten the near-term possibility of global eradication. Nevertheless, countries appear poised to reach zero cases. |
Changes in anti-OV-16 IgG4 responses to onchocerciasis after elimination of transmission in the central endemic zone of Guatemala
Cama VA , Mendizabal-Cabrera R , de Leon O , White M , McDonald C , Thiele E , Ogawa GM , Morales Z , Prince-Guerra J , Cantey P , Rizzo N . Am J Trop Med Hyg 2024 Current WHO guidelines for onchocerciasis elimination provide requirements for stopping mass drug administration of ivermectin and the verification of elimination of transmission. These guidelines also recommend post-elimination surveillance (PES) based on entomological surveys. Serological markers in humans could complement entomological PES once the longevity of anti-OV-16 antibody responses is better understood. In 2014-2015 we evaluated ELISA anti-OV-16 IgG4 antibody persistence among previously seropositive people from the central endemic zone of Guatemala. The country stopped all onchocerciasis program interventions in 2012 and was verified by WHO as having eliminated transmission of onchocerciasis in 2016. A total of 246 participants with prior OV-16 ELISA results from 2003, 2006, 2007, or 2009 were enrolled in a follow-up study. Of these, 77 people were previously OV-16 seropositive and 169 were previously seronegative. By 2014 and 2015, 56 (72.7%) previously seropositive individuals had sero-reverted, whereas all previous negatives remained seronegative. The progression of antibody responses over time was estimated using a mixed-effects linear regression model, using data from seropositive participants who had sero-reverted. The temporal variation showed a mean activity unit decay of 0.20 per year (95% credible interval [CrI]: 0.17, 0.23), corresponding to an estimated antibody response half-life of 3.3 years (95% CrI: 2.7, 4.1). These findings indicate that the majority of seropositive people will sero-revert over time. |
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. |
Progress toward eradication of dracunculiasis - Worldwide, January 2022-June 2023
Hopkins DR , Weiss AJ , Yerian S , Sapp SGH , Cama VA . MMWR Morb Mortal Wkly Rep 2023 72 (45) 1230-1236 The effort to eradicate Dracunculus medinensis, the etiologic agent of dracunculiasis, or Guinea worm disease, commenced at CDC in 1980. In 1986, with an estimated 3.5 million cases worldwide in 20 African and Asian countries, the World Health Assembly called for dracunculiasis elimination. The Guinea Worm Eradication Program (GWEP) was established to help countries with endemic dracunculiasis reach this goal. GWEP is led by The Carter Center and supported by partners that include the World Health Organization, UNICEF, and CDC. In 2012, D. medinensis infections were unexpectedly confirmed in Chadian dogs, and since then, infections in dogs, cats, and baboons have posed a new challenge for GWEP, as have ongoing civil unrest and insecurity in some areas. By 2022, dracunculiasis was endemic in five countries (Angola, Chad, Ethiopia, Mali, and South Sudan), with only 13 human cases identified, the lowest yearly total ever reported. Animal infections, however, were not declining at the same rate: 686 animal infections were reported in 2022, including 606 (88%) in dogs in Chad. Despite these unanticipated challenges as well as the COVID-19 pandemic, countries appear close to reaching the eradication goal. GWEP will continue working with country programs to address animal infections, civil unrest, and insecurity, that challenge the eradication of Guinea worm. |
Progress toward global eradication of Dracunculiasis - Worldwide, January 2021-June 2022
Hopkins DR , Weiss AJ , Yerian S , Sapp SGH , Cama VA . MMWR Morb Mortal Wkly Rep 2022 71 (47) 1496-1502 Dracunculiasis (Guinea worm disease), caused by the parasite Dracunculus medinensis, is acquired by drinking water containing small crustacean copepods (water fleas) infected with D. medinensis larvae. Recent evidence suggests that the parasite also appears to be transmitted by eating fish or other aquatic animals. About 1 year after infection, the worm typically emerges through the skin on a lower limb of the host, causing pain and disability (1). No vaccine or medicine is available to prevent or treat dracunculiasis. Eradication relies on case containment* to prevent water contamination and other interventions to prevent infection, including health education, water filtration, treatment of unsafe water with temephos (an organophosphate larvicide), and provision of safe drinking water (1,2). CDC began worldwide eradication efforts in October 1980, and in 1984 was designated by the World Health Organization (WHO) as the technical monitor of the Dracunculiasis Eradication Program (1). In 1986, with an estimated 3.5 million cases(†) occurring annually in 20 African and Asian countries(§) (3), the World Health Assembly called for dracunculiasis elimination. The Guinea Worm Eradication Program (GWEP),(¶) led by The Carter Center and supported by partners that include WHO, UNICEF, and CDC, began assisting ministries of health in countries with endemic disease. In 2021, a total of 15 human cases were identified and three were identified during January-June 2022. As of November 2022, dracunculiasis remained endemic in five countries (Angola, Chad, Ethiopia, Mali, and South Sudan); cases reported in Cameroon were likely imported from Chad. Eradication efforts in these countries are challenged by infection in animals, the COVID-19 pandemic, civil unrest, and insecurity. Animal infections, mostly in domestic dogs, some domestic cats, and in Ethiopia, a few baboons, have now surpassed human cases, with 863 reported animal infections in 2021 and 296 during January-June 2022. During the COVID-19 pandemic all national GWEPs remained fully operational, implementing precautions to ensure safety of program staff members and community members. In addition, the progress toward eradication and effectiveness of interventions were reviewed at the 2021 and 2022 annual meetings of GWEP program managers, and the 2021 meeting of WHO's International Commission for the Certification of Dracunculiasis Eradication. With only 15 human cases identified in 2021 and three during January-June 2022, program efforts appear to be closer to reaching the goal of eradication. However, dog infections and impeded access because of civil unrest and insecurity in Mali and South Sudan continue to be the greatest challenges for the program. This report describes progress during January 2021-June 2022 and updates previous reports (2,4). |
Progress Toward Global Eradication of Dracunculiasis, January 2020-June 2021
Hopkins DR , Weiss AJ , Roy SL , Yerian S , Cama VA . MMWR Morb Mortal Wkly Rep 2021 70 (44) 1527-1533 Dracunculiasis (Guinea worm disease), caused by the parasite Dracunculus medinensis, is traditionally acquired by drinking water containing copepods (water fleas) infected with D. medinensis larvae, but in recent years also appears increasingly to be transmitted by eating fish or other aquatic animals. The worm typically emerges through the skin on a lower limb of the host 1 year after infection, causing pain and disability (1). There is no vaccine or medicine to prevent or medicine to treat dracunculiasis; eradication relies on case containment* to prevent water contamination and other interventions to prevent infection: health education, water filtration, treatment of unsafe water with temephos (an organophosphate larvicide), and provision of safe drinking water (1,2). The eradication campaign began in 1980 at CDC (1). In 1986, with an estimated 3.5 million cases(†) occurring annually in 20 African and Asian countries(§) (3), the World Health Assembly called for dracunculiasis elimination (4). The Guinea Worm Eradication Program (GWEP), led by The Carter Center and supported by the World Health Organization (WHO), UNICEF, CDC, and other partners, began assisting ministries of health in countries with endemic disease. With 27 cases in humans reported in 2020, five during January-June 2021, and only six countries currently affected by dracunculiasis (Angola, Chad, Ethiopia, Mali, South Sudan, and importations into Cameroon), achievement of eradication appears to be close. However, dracunculiasis eradication is challenged by civil unrest, insecurity, and epidemiologic and zoologic concerns. Guinea worm infections in dogs were first reported in Chad in 2012. Animal infections have now overtaken human cases, with 1,601 reported animal infections in 2020 and 443 during January-June 2021. Currently, all national GWEPs remain fully operational, with precautions taken to ensure safety of program staff and community members in response to the COVID-19 pandemic. Because of COVID-19, The Carter Center convened the 2020 and 2021 annual GWEP Program Managers meetings virtually, and WHO's International Commission for the Certification of Dracunculiasis Eradication met virtually in October 2020. Since 1986, WHO has certified 199 countries, areas, and territories dracunculiasis-free. Six countries are still affected: five with endemic disease and importations into Cameroon. Seven countries (five with endemic dracunculiasis, Democratic Republic of the Congo, and Sudan) still lack certification (4). The existence of infected dogs, especially in Chad, and impeded access because of civil unrest and insecurity in Mali and South Sudan are now the greatest challenges to interrupting transmission. This report describes progress during January 2020-June 2021 and updates previous reports (2,4,5). |
Cutaneous Leishmaniasis Caused by an Unknown Leishmania Strain, Arizona, USA
de Almeida M , Zheng Y , Nascimento FS , Bishop H , Cama VA , Batra D , Unoarumhi Y , Afghan AK , Shi VY , LeBoit PE , Liu EW , Donovan FM . Emerg Infect Dis 2021 27 (6) 1714-1717 We investigated an autochthonous case of cutaneous leishmaniasis caused by a genetically different Leishmania sp. in a patient in Arizona, USA. This parasite was classified into the subgenus Leishmania on the basis of multilocus DNA sequence and phylogenetic analyses of the rRNA locus and 11 reference genes. |
Surveillance of Human Guinea Worm in Chad, 2010-2018
Guagliardo SAJ , Ruiz-Tiben E , Hopkins DR , Weiss AJ , Ouakou PT , Zirimwabagabo H , Unterwegner K , Tindall D , Cama VA , Bishop H , Sapp SGH , Roy SL . Am J Trop Med Hyg 2021 105 (1) 188-195 The total number of Guinea worm cases has been reduced by 99.9% since the mid-1980s when the eradication campaign began. Today, the greatest number of cases is reported from Chad. In this report, we use surveillance data collected by the Chad Guinea Worm Eradication Program to describe trends in human epidemiology. In total, 114 human cases were reported during the years 2010-2018, with highest rates of containment (i.e., water contamination prevented) in the years 2013, 2014, 2016, and 2017 (P < 0.0001). Approximately half of case-patients were female, and 65.8% of case-patients were aged 30 years or younger (mean: 26.4 years). About 34.2% of case-patients were farmers. Cases were distributed across many ethnicities, with a plurality of individuals being of the Sara Kaba ethnicity (21.3%). Most cases occurred between the end of June and the end of August and were clustered in the Chari Baguirmi (35.9%) and Moyen Chari regions (30.1%). Cases in the northern Chari River area peaked in April and in August, with no clear pattern in the southern Chari River area. History of travel within Chad was reported in 7.0% of cases, and male subjects (12.5%) were more likely than female subjects (1.7%) to have reported a history of travel (P = 0.03). Our findings confirm that human Guinea worm is geographically disperse and rare. Although the proportion of case-patients with travel history is relatively small, this finding highlights an additional challenge of surveillance in mobile populations in the final stages of the global eradication campaign. |
Human infection with an unknown species of Dracunculus in Vietnam.
Thach PN , van Doorn HR , Bishop HS , Fox MS , Sapp SGH , Cama VA , Van Duyet L . Int J Infect Dis 2021 105 739-742 ![]() Guinea worm (GW) disease, caused by Dracunculus medinensis, is an almost eradicated waterborne zoonotic disease. The World Health Organization currently lists GW as endemic in only 5 African countries. In July 2020 the Vietnamese public health surveillance system detected a hanging worm in a 23-year -old male patient, who did not report any travel to Africa or any country previously endemic for GW. The patient was hospitalized with symptoms of fatigue, anorexia, muscle aches, and abscesses with worms hanging out of the skin in the lower limbs. The worms were retrieved from the lesions and microscopically examined in Vietnam, identifying structures compatible with Dracunculus spp. and L1-type larvae. A section of this parasite was sent to CDC Atlanta for confirmatory diagnosis of GW. The adult worm had cuticle structures compatible with Dracunculus parasites, although the length of L1 larvae was about 339 µm, substantially shorter than D. medinensis. The DNA sequence analysis of the 18S small subunit rRNA gene confirmed that this parasite was not GW, and determined that the sample belonged to a Dracunculus sp not previously reported in GenBank that clustered with the animal-infective D. insignis and D. lutrae, located in a different clade than D. medinensis. This study highlights the importance of effective public health surveillance systems and the collaborative work of local public health authorities from Vietnam with WHO and CDC in the efforts to achieve the eradication of GW. |
Duplex real-time PCR assay for clinical differentiation of Onchocerca lupi and Onchocerca volvulus
de Almeida M , Nascimento FS , Mathison BA , Bishop H , Bradbury RS , Cama VA , da Silva AJ . Am J Trop Med Hyg 2020 103 (4) 1556-1562 ![]() In the United States and Europe, human onchocerciasis is a rare disease caused by zoonotic or anthropophilic parasites in the genus Onchocerca. The zoonotic species identified in focal areas of Europe and United States is Onchocerca lupi, and Onchocerca volvulus, the anthroponotic species, may be found among people who had lived in endemic areas of Africa, the Arabian Peninsula, or Latin America. Onchocerciasis due to O. lupi is an emergent parasitic disease, with limited diagnostic methods, in addition to the lack of information on its biology, transmission, and epidemiology. Cutaneous nodules are the disease's most prevalent manifestation but lack diagnostic specificity. To address the diagnosis of onchocerciasis at reference laboratories, we developed a duplex TaqMan real-time PCR (qPCR) method, targeting the cytochrome oxidase subunit I locus which has species-specific probes to identify and differentiate O. lupi from O. volvulus. We determined the performance of the duplex with a panel of 45 samples: 11 positives for O. lupi, six for O. volvulus, five samples with negative results for Onchocerca spp., and 23 non-Onchocerca nematodes. The duplex qPCR correctly detected 10 of 11 O. lupi- and six of six O. volvulus-positive specimens. The new duplex assay allowed the simultaneous detection and discrimination of O. lupi and O. volvulus in clinical specimens, expediting and facilitating the clinical diagnosis of O. lupi in non-endemic settings where the disease is an infrequent finding. |
Evaluation of an OV-16 IgG4 enzyme-linked immunosorbent assay in humans and its application to determine the dynamics of antibody responses in a non-human primate model of Onchocerca volvulus infection
Cama VA , McDonald C , Arcury-Quandt A , Eberhard M , Jenks MH , Smith J , Feleke SM , Abanyie F , Thomson L , Wiegand RE , Cantey PT . Am J Trop Med Hyg 2018 99 (4) 1041-1048 Onchocerciasis is a neglected parasitic disease targeted for elimination. Current World Health Organization guidelines for elimination include monitoring antibody responses to the recombinant Onchocerca volvulus antigen OV-16 in children to demonstrate the absence of transmission. We report the performance characteristics of a modified OV-16 enzyme-linked immunosorbent assay (ELISA) and describe anti-OV-16 responses in serum samples from laboratory-inoculated nonhuman primates (NHPs) in relation to microfilariae (mf) in skin snip biopsies. This OV-16 IgG4 ELISA had sensitivity and specificity of 88.2% and 99.7%, respectively, as determined by receiver operator characteristic analysis using a serum panel of 110 positive and 287 negative samples from people infected with other filariae or other parasitic infections. Anti-OV-16 responses in inoculated NHP (N = 9) were evaluated at quarterly intervals for IgM and the four IgG subclasses. Enzyme-linked immunosorbent assay results showed a well-defined IgG4 reactivity pattern and moderate IgG1 antibody responses. Meanwhile, the reactivity by IgG2, IgG3, or IgM did not show a clear pattern. Temporal evolution of IgG4 reactivity was evaluated through monthly testing, showing that NHPs developed anti-OV-16 IgG4 on average at 15 months postinoculation (range: 10-18 months). The average time to detectable mf was also 15 months (range: 11-25). The OV-16 ELISA used in this study was robust and allowed the detection of IgG4 responses, which were observed only among animals with detectable mf (N = 5), four of which showed declines in antibody responses once mf cleared. These findings also confirmed that the most informative antibody subclass responses to OV-16 are IgG4. |
Risk for interspecies transmission of zoonotic pathogens during poultry processing and pork production in Peru: A qualitative study
Carnero AM , Kitayama K , Diaz DA , Garvich M , Angulo N , Cama VA , Gilman RH , Bayer AM . Zoonoses Public Health 2018 65 (5) 528-539 Interspecies transmission of pathogens is an unfrequent but naturally occurring event and human activities may favour opportunities not previously reported. Reassortment of zoonotic pathogens like influenza A virus can result from these activities. Recently, swine and birds have played a central role as "mixing vessels" for epidemic and pandemic events related to strains like H1N1 and H5N1. Unsafe practices in poultry markets and swine farms can lead to interspecies transmission, favouring the emergence of novel strains. Thus, understanding practices that lead to interspecies interactions is crucial. This qualitative study aimed to evaluate poultry processing practices in formal and informal markets and the use of leftovers by swine farmers in three Peruvian cities: Lima (capital), Tumbes (coastal) and Tarapoto (jungle). We conducted 80 direct observations at formal and informal markets and interviewed 15 swine farmers. Processors slaughter and pluck chickens and vendors and/or processors eviscerate chickens. Food safety and hygiene practices were suboptimal or absent, although some heterogeneity was observed between cities and chicken vendors versus processors. Both vendors (76%) and processors (100%) sold the chicken viscera leftovers to swine farmers, representing the main source of chicken viscera for swine farms (53%). Swine farmers fed the chicken viscera to their swine. Chicken viscera cooking times varied widely and were insufficient in some cases. Non-abattoired poultry leads to the sale of poultry leftovers to small-scale swine farms, resulting in indirect but frequent interspecies contacts that can lead to interspecies transmission of bacterial pathogens or the reassortment of influenza A viruses. These interactions are exacerbated by suboptimal safety and hygiene conditions. People involved in these activities constitute an at-risk population who could play a central role in preventing the transmission of pathogens between species. Educational interventions on hygiene and food safety practices will be important for reducing the risk of interspecies influenza transmission. |
Evaluation of lymphatic filariasis and onchocerciasis in three Senegalese districts treated for onchocerciasis with ivermectin
Wilson NO , Badara Ly A , Cama VA , Cantey PT , Cohn D , Diawara L , Direny A , Fall M , Feeser KR , Fox LM , Kabore A , Seck AF , Sy N , Ndiaye D , Dubray C . PLoS Negl Trop Dis 2016 10 (12) e0005198 In Africa, onchocerciasis and lymphatic filariasis (LF) are co-endemic in many areas. Current efforts to eliminate both diseases are through ivermectin-based mass drug administration (MDA). Years of ivermectin distribution for onchocerciasis may have interrupted LF transmission in certain areas. The Kedougou region, Senegal, is co-endemic for LF and onchocerciasis. Though MDA for onchocerciasis started in 1988, in 2014 albendazole had not yet been added for LF. The objective of this study was to assess in an integrated manner the LF and onchocerciasis status in the three districts of the Kedougou region after ≥10 years of ivermectin-based MDA. The study employed an African Programme for Onchocerciasis Control (APOC) onchocerciasis-related methodology. In the three districts, 14 villages close to three rivers that have Simulium damnosum breeding sites were surveyed. Convenience sampling of residents ≥5 years old was performed. Assessment for LF antigenemia by immunochromatographic testing (ICT) was added to skin snip microscopy for onchocerciasis. Participants were also tested for antibodies against Wb123 (LF) and Ov16 (onchocerciasis) antigens. In two districts, no participants were ICT or skin snip positive. In the third district, 3.5% were ICT positive and 0.7% were skin snip positive. In all the three districts, Wb123 prevalence was 0.6%. Overall, Ov16 prevalence was 6.9%. Ov16 prevalence among children 5-9 years old in the study was 2.5%. LF antigenemia prevalence was still above treatment threshold in one district despite ≥10 years of ivermectin-based MDA. The presence of Ov16 positive children suggested recent transmission of Onchocerca volvulus. This study showed the feasibility of integrated evaluation of onchocerciasis and LF but development of integrated robust methods for assessing transmission of both LF and onchocerciasis are needed to determine where MDA can be stopped safely in co-endemic areas. |
Detection of Onchocerca volvulus in Skin Snips by Microscopy and Real-Time Polymerase Chain Reaction: Implications for Monitoring and Evaluation Activities.
Thiele EA , Cama VA , Lakwo T , Mekasha S , Abanyie F , Sleshi M , Kebede A , Cantey PT . Am J Trop Med Hyg 2016 94 (4) 906-11 ![]() Microscopic evaluation of skin biopsies is the monitoring and evaluation (M and E) method currently used by multiple onchocerciasis elimination programs in Africa. However, as repeated mass drug administration suppresses microfilarial loads, the sensitivity and programmatic utility of skin snip microscopy is expected to decrease. Using a pan-filarial real-time polymerase chain reaction with melt curve analysis (qPCR-MCA), we evaluated 1) the use of a single-step molecular assay for detecting and identifying Onchocerca volvulus microfilariae in residual skin snips and 2) the sensitivity of skin snip microscopy relative to qPCR-MCA. Skin snips were collected and examined with routine microscopy in hyperendemic regions of Uganda and Ethiopia (N = 500 each) and "residual" skin snips (tissue remaining after induced microfilarial emergence) were tested with qPCR-MCA. qPCR-MCA detected Onchocerca DNA in 223 residual snips: 139 of 147 microscopy(+) and 84 among microscopy(-) snips, suggesting overall sensitivity of microscopy was 62.3% (139/223) relative to qPCR-MCA (75.6% in Uganda and 28.6% in Ethiopia). These findings demonstrate the insufficient sensitivity of skin snip microscopy for reliable programmatic monitoring. Molecular tools such as qPCR-MCA can augment sensitivity and provide diagnostic confirmation of skin biopsies and will be useful for evaluation or validation of new onchocerciasis M and E tools. |
A recombinant positive control for serology diagnostic tests supporting elimination of Onchocerca volvulus
Golden A , Stevens EJ , Yokobe L , Faulx D , Kalnoky M , Peck R , Valdez M , Steel C , Karabou P , Banla M , Soboslay PT , Adade K , Tekle AH , Cama VA , Fischer PU , Nutman TB , Unnasch TR , de Los Santos T , Domingo GJ . PLoS Negl Trop Dis 2016 10 (1) e0004292 BACKGROUND: Serological assays for human IgG4 to the Onchocerca volvulus antigen Ov16 have been used to confirm elimination of onchocerciasis in much of the Americas and parts of Africa. A standardized source of positive control antibody (human anti-Ov16 IgG4) will ensure the quality of surveillance data using these tests. METHODOLOGY/PRINCIPAL FINDINGS: A recombinant human IgG4 antibody to Ov16 was identified by screening against a synthetic human Fab phage display library and converted into human IgG4. This antibody was developed into different positive control formulations for enzyme-linked immunosorbent assay (ELISA) and rapid diagnostic test (RDT) platforms. Variation in ELISA results and utility as a positive control of the antibody were assessed from multiple laboratories. Temperature and humidity conditions were collected across seven surveillance activities from 2011-2014 to inform stability requirements for RDTs and positive controls. The feasibility of the dried positive control for RDT was evaluated during onchocerciasis surveillance activity in Togo, in 2014. When the anti-Ov16 IgG4 antibody was used as a standard dilution in horseradish peroxidase (HRP) and alkaline phosphatase (AP) ELISAs, the detection limits were approximately 1ng/mL by HRP ELISA and 10ng/mL by AP ELISA. Positive control dilutions and spiked dried blood spots (DBS) produced similar ELISA results. Used as a simple plate normalization control, the positive control antibody may improve ELISA data comparison in the context of inter-laboratory variation. The aggregate temperature and humidity monitor data informed temperature parameters under which the dried positive control was tested and are applicable inputs for testing of diagnostics tools intended for sub-Saharan Africa. As a packaged positive control for Ov16 RDTs, stability of the antibody was demonstrated for over six months at relevant temperatures in the laboratory and for over 15 weeks under field conditions. CONCLUSIONS: The recombinant human anti-Ov16 IgG4 antibody-based positive control will benefit inter-laboratory validation of ELISA assays and serve as quality control (QC) reagents for Ov16 RDTs at different points of the supply chain from manufacturer to field use. |
Thirty-seven human cases of sparganosis from Ethiopia and South Sudan caused by Spirometra spp
Eberhard ML , Thiele EA , Yembo GE , Yibi MS , Cama VA , Ruiz-Tiben E . Am J Trop Med Hyg 2015 93 (2) 350-355 Thirty-seven unusual specimens, three from Ethiopia and 34 from South Sudan, were submitted since 2012 for further identification by the Ethiopian Dracunculiasis Eradication Program (EDEP) and the South Sudan Guinea Worm Eradication Program (SSGWEP), respectively. Although the majority of specimens emerged from sores or breaks in the skin, there was concern that they did not represent bona fide cases of Dracunculus medinensis and that they needed detailed examination and identification as provided by the World Health Organization Collaborating Center (WHO CC) at Centers for Disease Control and Prevention (CDC). All 37 specimens were identified on microscopic study as larval tapeworms of the spargana type, and DNA sequence analysis of seven confirmed the identification of Spirometra sp. Age of cases ranged between 7 and 70 years (mean 25 years); 21 (57%) patients were male and 16 were female. The presence of spargana in open skin lesions is somewhat atypical, but does confirm the fact that populations living in these remote areas are either ingesting infected copepods in unsafe drinking water or, more likely, eating poorly cooked paratenic hosts harboring the parasite. |
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. |
Needs, acceptability, and value of humanitarian medical assistance in remote Peruvian Amazon riverine communities
Sanchez JF , Halsey ES , Bayer AM , Beltran M , Razuri HR , Velasquez DE , Cama VA , Graf PC , Quispe AM , Maves RC , Montgomery JM , Sanders JW , Lescano AG . Am J Trop Med Hyg 2015 92 (6) 1090-9 Much debate exists regarding the need, acceptability, and value of humanitarian medical assistance. We conducted a cross-sectional study on 457 children under 5 years from four remote riverine communities in the Peruvian Amazon and collected anthropometric measures, blood samples (1-4 years), and stool samples. Focus groups and key informant interviews assessed perspectives regarding medical aid delivered by foreigners. The prevalence of stunting, anemia, and intestinal parasites was 20%, 37%, and 62%, respectively. Infection with multiple parasites, usually geohelminths, was detected in 41% of children. The prevalence of intestinal parasites both individual and polyparasitism increased with age. Participants from smaller communities less exposed to foreigners expressed lack of trust and fear of them. However, participants from all communities were positive about foreigners visiting to provide health support. Prevalent health needs such as parasitic infections and anemia may be addressed by short-term medical interventions. There is a perceived openness to and acceptability of medical assistance delivered by foreign personnel. |
Infections by intestinal coccidia and Giardia duodenalis
Cama VA , Mathison BA . Clin Lab Med 2015 35 (2) 423-44 The coccidians Cryptosporidium spp, Cyclospora cayetanensis, and Cystoisospora belli and the flagellate Giardia duodenalis are pathogenic protozoa associated with gastrointestinal manifestations. Diagnosis relies heavily on microscopy, and although ova-and-parasite examinations can detect Giardia and Cystoisospora, Cryptosporidium and Cyclospora often require specific diagnostic requests. Approved non-microscopy methods are available for Giardia and Cryptosporidium, although negative results are frequently followed by microscopic assays. Polymerase chain reaction-based methods are not frequently used for diagnosis of Giardia and Cryptosporidium and have been used primarily for epidemiologic or outbreak investigations of Giardia and Cryptosporidium. |
First report of Dracunculus insignis in two naturally infected cats from the northeastern USA
Lucio-Forster A , Eberhard ML , Cama VA , Jenks MH , Jones C , Sanders SY , Pongratz JP , Bowman DD . J Feline Med Surg 2014 16 (2) 194-7 Dracunculiasis is rarely reported in cats, yet over the last few years we have identified two cats with filarioid-like spirurid infections. Case 1 was a 9-year-old cat with pituitary-dependent hyperadrenocorticism from New York state from which four adult dracunculoid nematodes were isolated from its torso. Based on morphometric characteristics and parasite geographic distribution, the specimens were identified as Dracunculus insignis females; at least one of the females was gravid, suggestive of patent infection. Species identification was confirmed through amplification and sequence analysis of nuclear and mitochondrial loci. Case 2 was a 14-year-old diabetic cat from Massachusetts. Formalin-fixed sections were obtained from a subcutaneous mass excised from the left foreleg. Histopathological examination revealed a large nematode with morphometrical characteristics of Dracunculus, surrounded by lymphocytes and sheets of eosinophils. These two cases appear to be the first published reports of dracunculiasis in domestic cats in the USA, and based on the findings from case 1, D insignis may be the species associated with both infections. |
The Peculiar epidemiology of dracunculiasis in Chad
Eberhard ML , Ruiz-Tiben E , Hopkins DR , Farrell C , Toe F , Weiss A , Withers PC Jr , Jenks MH , Thiele EA , Cotton JA , Hance Z , Holroyd N , Cama VA , Tahir MA , Mounda T . Am J Trop Med Hyg 2013 90 (1) 61-70 Dracunculiasis was rediscovered in Chad in 2010 after an apparent absence of 10 years. In April 2012 active village-based surveillance was initiated to determine where, when, and how transmission of the disease was occurring, and to implement interventions to interrupt it. The current epidemiologic pattern of the disease in Chad is unlike that seen previously in Chad or other endemic countries, i.e., no clustering of cases by village or association with a common water source, the average number of worms per person was small, and a large number of dogs were found to be infected. Molecular sequencing suggests these infections were all caused by Dracunculus medinensis. It appears that the infection in dogs is serving as the major driving force sustaining transmission in Chad, that an aberrant life cycle involving a paratenic host common to people and dogs is occurring, and that the cases in humans are sporadic and incidental. |
Short report: Molecular insights for Giardia, Cryptosporidium, and soil-transmitted helminths from a facility-based surveillance system in Guatemala.
Velasquez DE , Arvelo W , Cama VA , Lopez B , Reyes L , Roellig DM , Kahn GD , Lindblade KA . Am J Trop Med Hyg 2011 85 (6) 1141-1143 ![]() We molecularly characterized samples with Giardia, Cryptosporidium, and soil-transmitted helminths from a facility-based surveillance system for diarrhea in Santa Rosa, Guatemala. The DNA sequence analysis determined the presence of Giardia assemblages A (N = 7) and B (N = 12) and, Cryptosporidium hominis (N = 2) and Cryptosporidium parvum (N = 2), suggestive of different transmission cycles. All 41 samples with soil-transmitted helminths did not have the beta-tubulin mutation described for benzimidazole resistance, suggesting potential usefulness in mass drug administration campaigns. |
Wealth and its associations with enteric parasitic infections in a low-income community in Peru: use of principal component analysis
Nundy S , Gilman RH , Xiao L , Cabrera L , Cama R , Ortega YR , Kahn G , Cama VA . Am J Trop Med Hyg 2011 84 (1) 38-42 The association of wealth and infections with Giardia, Cryptosporidium, Cyclospora, and microsporidia were examined in a longitudinal cohort conducted in Peru from 2001 to 2006. Data from 492 participants were daily clinical manifestations, weekly copro-parasitological diagnosis, and housing characteristics and assets owned (48 variables), and these data were used to construct a global wealth index using principal component analysis. Data were analyzed using continuous and categorical (wealth tertiles) models. Participant's mean age was 3.43 years (range = 0-12 years), with average follow-up of 993 days. Univariate and multivariate analyses identified significant associations between wealth and infections with Giardia and microsporidia. Participants with greater wealth indexes were associated with protection against Giardia (P < 0.001) and persistent Giardia infections (> 14 days). For microsporidia, greater wealth was protective (P = 0.066 continuous and P = 0.042 by tertiles). Contrarily, infections with Cryptosporidium and Cyclospora were independent of wealth. Thus, subtle differences in wealth may affect the frequency of specific parasitic infections within low-income communities. |
Norovirus highly prevalent cause of endemic acute diarrhea in children in the peruvian Amazon
Yori PP , Schwab K , Gilman RH , Nappier S , Portocarrero DV , Black RE , Olortegui MP , Hall ER , Moe C , Leon J , Cama VA , Kosek M . Pediatr Infect Dis J 2009 28 (9) 844-7 To determine the burden of norovirus infections in children stools from a longitudinal community cohort were evaluated using reverse transcription polymerase chain reaction. Norovirus was detected in 21.3% of diarrheal and 8.0% of nondiarrheal stools (P < 0.01). Norovirus diarrhea was highly associated with age and the odds ratio for norovirus diarrhea fell by 2.8% per month (OR = 0.97, 95% CI: 0.95-0.99). Norovirus seems to be an important etiology of community acquired diarrhea in this study population. |
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