Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-13 (of 13 Records) |
Query Trace: Thiele E[original query] |
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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. |
Linked surveillance and genetic data uncovers programmatically relevant geographic scale of Guinea worm transmission in Chad (preprint)
Ribado JV , Li N , Thiele E , Lyons H , Cotton JA , Weiss A , Tchindebet Ouakou P , Moundai T , Zirimwabagabo H , Guagliardo SAJ , Chabot-Couture G , Proctor JL . medRxiv 2020 2020.10.05.20207324 Background Guinea worm (Dracunculus medinensis) was detected in Chad in 2010 after a supposed ten year absence, posing a challenge to the global eradication effort. Initiation of a village-based surveillance system in 2012 revealed a substantial number of dogs infected with Guinea worm, raising questions about paratenic hosts and cross-species transmission.Methodology/Principal Findings We coupled genomic and surveillance data from 2012-2018 cases to investigate the modes of transmission between hosts and the geographic connectivity for genetically similar worm populations. Eighty-six variants across three loci on the mitochondrial genome identified 41 genetically distinct worm genotypes. Spatiotemporal modeling reveals genetically identical worms are within a median range of 18.6 kilometers of each other, but largely within approximately 50 kilometers. Genetically identical worms vary in their degree of spatial clustering, suggesting there may be different factors that favor or constrain transmission. Each worm is surrounded by five to ten genetically distinct worms within a 50 kilometer radius. In an independent population, we show that more variants revealed in whole mitochondrial genome data improved the discrimination between worm pairs.Conclusions/Significance In the largest study linking genetic and surveillance data to date of Guinea worm cases in Chad, we show genetic similarity and modeling can contribute to understanding local transmission. The overlap of genetically distinct worms in quantitatively identified transmission ranges highlights the necessity for genomic tools to link cases. The improved discrimination between worm pairs from variants identified across the complete mitochondrial genome indicates expanding genomic markers could link cases at a finer scale. These results suggest that scaling up genomic surveillance for Guinea worm may provide additional value for programmatic decision-making critical for monitoring cases and intervention efficacy to achieve elimination.Competing Interest StatementThe authors have declared no competing interest.Funding StatementJR, GCC, HL, and JLP would like to thank Bill and Melinda Gates for their active support of the Institute for Disease Modeling and their sponsorship through the Global Good Fund. JAC was supported by funding from The Carter Center and Wellcome, via their core support for the Wellcome Sanger Institute (grant WT206194).Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:N/A; Worm collection and associated metadata are routine in country surveillance efforts.All necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesGenomic data and source code will be made available upon publication. Requests for epidemiological data that includes case coordinates must be submitted to and approved by the Chad Guinea Worm Eradication Program. |
Self-Reported Mask Use among Persons with or without SARS CoV-2 Vaccination -United States, December 2020-August 2021 (preprint)
Calamari LE , Weintraub WS , Santos R , Gibbs M , Bertoni AG , Ward LM , Saydah S , Plumb ID , Runyon MS , Wierzba TF , Sanders JW , Herrington D , Espeland MA , Williamson J , Mongraw-Chaffin M , Bertoni A , Alexander-Miller MA , Castri P , Mathews A , Munawar I , Seals AL , Ostasiewski B , Ballard CAP , Gurcan M , Ivanov A , Zapata GM , Westcott M , Blinson K , Blinson L , Mistysyn M , Davis D , Doomy L , Henderson P , Jessup A , Lane K , Levine B , McCanless J , McDaniel S , Melius K , O'Neill C , Pack A , Rathee R , Rushing S , Sheets J , Soots S , Wall M , Wheeler S , White J , Wilkerson L , Wilson R , Wilson K , Burcombe D , Saylor G , Lunn M , Ordonez K , O'Steen A , Wagner L , McCurdy LH , Gibbs MA , Taylor YJ , Calamari L , Tapp H , Ahmed A , Brennan M , Munn L , Dantuluri KL , Hetherington T , Lu LC , Dunn C , Hogg M , Price A , Leonidas M , Manning M , Rossman W , Gohs FX , Harris A , Priem JS , Tochiki P , Wellinsky N , Silva C , Ludden T , Hernandez J , Spencer K , McAlister L , Weintraub W , Miller K , Washington C , Moses A , Dolman S , Zelaya-Portillo J , Erkus J , Blumenthal J , Romero Barrientos RE , Bennett S , Shah S , Mathur S , Boxley C , Kolm P , Franklin E , Ahmed N , Larsen M , Oberhelman R , Keating J , Kissinger P , Schieffelin J , Yukich J , Beron A , Teigen J , Kotloff K , Chen WH , Friedman-Klabanoff D , Berry AA , Powell H , Roane L , Datar R , Correa A , Navalkele B , Min YI , Castillo A , Ward L , Santos RP , Anugu P , Gao Y , Green J , Sandlin R , Moore D , Drake L , Horton D , Johnson KL , Stover M , Lagarde WH , Daniel L , Maguire PD , Hanlon CL , McFayden L , Rigo I , Hines K , Smith L , Harris M , Lissor B , Cook V , Eversole M , Herrin T , Murphy D , Kinney L , Diehl P , Abromitis N , Pierre TSt , Heckman B , Evans D , March J , Whitlock B , Moore W , Arthur S , Conway J , Gallaher TR , Johanson M , Brown S , Dixon T , Reavis M , Henderson S , Zimmer M , Oliver D , Jackson K , Menon M , Bishop B , Roeth R , King-Thiele R , Hamrick TS , Ihmeidan A , Hinkelman A , Okafor C , Bray Brown RB , Brewster A , Bouyi D , Lamont K , Yoshinaga K , Vinod P , Peela AS , Denbel G , Lo J , Mayet-Khan M , Mittal A , Motwani R , Raafat M , Schultz E , Joseph A , Parkeh A , Patel D , Afridi B , Uschner D , Edelstein SL , Santacatterina M , Strylewicz G , Burke B , Gunaratne M , Turney M , Zhou SQ , Tjaden AH , Fette L , Buahin A , Bott M , Graziani S , Soni A , Mores C , Porzucek A , Laborde R , Acharya P , Guill L , Lamphier D , Schaefer A , Satterwhite WM , McKeague A , Ward J , Naranjo DP , Darko N , Castellon K , Brink R , Shehzad H , Kuprianov D , McGlasson D , Hayes D , Edwards S , Daphnis S , Todd B , Goodwin A , Berkelman R , Hanson K , Zeger S , Hopkins J , Reilly C , Edwards K , Gayle H , Redd S . medRxiv 2022 10 Wearing a facemask can help to decrease the transmission of COVID-19. We investigated self-reported mask use among subjects aged 18 years and older participating in the COVID-19 Community Research Partnership (CRP), a prospective longitudinal COVID-19 surveillance study in the mid-Atlantic and southeastern United States. We included those participants who completed >=5 daily surveys each month from December 1, 2020 through August 31, 2021. Mask use was defined as self-reported use of a face mask or face covering on every interaction with others outside the household within a distance of less than 6 feet. Participants were considered vaccinated if they reported receiving >=1 COVID-19 vaccine dose. Participants (n=17,522) were 91% non-Hispanic White, 68% female, median age 57 years, 26% healthcare workers, with 95% self-reported receiving >=1 COVID-19 vaccine dose through August; mean daily survey response was 85%. Mask use was higher among vaccinated than unvaccinated participants across the study period, regardless of the month of the first dose. Mask use remained relatively stable from December 2020 through April (range 71-80% unvaccinated; 86-93% vaccinated) and declined in both groups beginning in mid-May 2021 to 34% and 42% respectively in June 2021; mask use has increased again since July 2021. Mask use by all was lower during weekends and on Christmas and Easter, regardless of vaccination status. Independent predictors of higher mask use were vaccination, age >=65 years, female sex, racial or ethnic minority group, and healthcare worker occupation, whereas a history of self-reported prior COVID-19 illness was associated with lower use. Copyright The copyright holder for this preprint is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. This article is a US Government work. It is not subject to copyright under 17 USC 105 and is also made available for use under a CC0 license. |
Epidemiological and molecular investigations of a point-source outbreak of Dracunculus medinensis infecting humans and dogs in Chad: a cross-sectional study.
Guagliardo SAJ , Thiele E , Unterwegner K , Narcisse Nanguita N , Dossou L , Tchindebet Ouakou P , Zirimwabagabo H , Ruiz-Tiben E , Hopkins DR , Roy SL , Cama V , Bishop H , Sapp S , Yerian S , Weiss AJ . Lancet Microbe 2022 3 (2) e105-e112 BACKGROUND: Dracunculiasis (also known as Guinea worm disease), caused by the Dracunculus medinensis nematode, is progressing towards eradication, with a reduction in cases from 3·5 million cases in the mid-1980s to only 54 human cases at the end of 2019. Most cases now occur in Chad. On April 19, 2019, a 19-year-old woman presented with D medinensis in an area within the Salamat region of Chad, where the disease had not been previously reported. We aimed to investigate the connection between this case and others detected locally and elsewhere in Chad using a combination of epidemiological and genetic approaches. METHODS: In this cross-sectional field study, we conducted household case searches and informal group interviews in the Bogam, Liwi, and Tarh villages in Chad. All community members including children were eligible for participation in the outbreak investigation. Adult female D medinensis associated with this outbreak were collected for genetic analysis (18 from humans and two from dogs). Four mitochondrial genes and 22 nuclear microsatellite markers were used to assess relatedness of worms associated with the outbreak in comparison with other worms from elsewhere in Chad. FINDINGS: Between April 12 and Sept 6, 2019, we identified 22 human cases and two canine cases of dracunculiasis associated with 15 households. Six (40%) of the 15 affected households had multiple human or canine cases within the household. Most cases of dracunculiasis in people were from three villages in Salamat (21 [95%] of 22 cases), but one case was detected nearly 400 km away in Sarh city (outside the Salamat region). All people with dracunculiasis reported a history of consuming fish and unfiltered water. Worms associated with this outbreak were genetically similar and shared the same maternal lineage. INTERPRETATION: Molecular epidemiological results suggest a point-source outbreak that originated from a single female D medinensis, rather than newly identified sustained local transmission. The failure of the surveillance system to detect the suspected canine infection in 2018 highlights the challenge of canine D medinensis detection, particularly in areas under passive surveillance. Human movement can also contribute to dracunculiasis spread over long distances. FUNDING: The Carter Center. |
Linked surveillance and genetic data uncovers programmatically relevant geographic scale of Guinea worm transmission in Chad.
Ribado JV , Li N , Thiele E , Lyons H , Cotton JA , Weiss A , Tchindebet Ouakou P , Moundai T , Zirimwabagabo H , Guagliardo SAJ , Chabot-Couture G , Proctor JL . PLoS Negl Trop Dis 2021 15 (7) e0009609 BACKGROUND: Guinea worm (Dracunculus medinensis) was detected in Chad in 2010 after a supposed ten-year absence, posing a challenge to the global eradication effort. Initiation of a village-based surveillance system in 2012 revealed a substantial number of dogs infected with Guinea worm, raising questions about paratenic hosts and cross-species transmission. METHODOLOGY/PRINCIPAL FINDINGS: We coupled genomic and surveillance case data from 2012-2018 to investigate the modes of transmission between dog and human hosts and the geographic connectivity of worms. Eighty-six variants across four genes in the mitochondrial genome identified 41 genetically distinct worm genotypes. Spatiotemporal modeling revealed worms with the same genotype ('genetically identical') were within a median range of 18.6 kilometers of each other, but largely within approximately 50 kilometers. Genetically identical worms varied in their degree of spatial clustering, suggesting there may be different factors that favor or constrain transmission. Each worm was surrounded by five to ten genetically distinct worms within a 50 kilometer radius. As expected, we observed a change in the genetic similarity distribution between pairs of worms using variants across the complete mitochondrial genome in an independent population. CONCLUSIONS/SIGNIFICANCE: In the largest study linking genetic and surveillance data to date of Guinea worm cases in Chad, we show genetic identity and modeling can facilitate the understanding of local transmission. The co-occurrence of genetically non-identical worms in quantitatively identified transmission ranges highlights the necessity for genomic tools to link cases. The improved discrimination between pairs of worms from variants identified across the complete mitochondrial genome suggests that expanding the number of genomic markers could link cases at a finer scale. These results suggest that scaling up genomic surveillance for Guinea worm may provide additional value for programmatic decision-making critical for monitoring cases and intervention efficacy to achieve elimination. |
Population genomic evidence that human and animal infections in Africa come from the same populations of Dracunculus medinensis.
Durrant Caroline, Thiele Elizabeth A, Holroyd Nancy, Doyle Stephen R, Sallé Guillaume, Tracey Alan, Sankaranarayanan Geetha, Lotkowska Magda E, Bennett Hayley M, Huckvale Thomas, Abdellah Zahra, Tchindebet Ouakou, Wossen Mesfin, Logora Makoy Samuel Yibi, Coulibaly Cheick Oumar, Weiss Adam, Schulte-Hostedde Albrecht I, Foster Jeremy M, Cleveland Christopher A, Yabsley Michael J, Ruiz-Tiben Ernesto, Berriman Matthew, Eberhard Mark L, Cotton James A. PLoS neglected tropical diseases 2020 Nov 14(11) e0008623 . PLoS neglected tropical diseases 2020 Nov 14(11) e0008623 Durrant Caroline, Thiele Elizabeth A, Holroyd Nancy, Doyle Stephen R, Sallé Guillaume, Tracey Alan, Sankaranarayanan Geetha, Lotkowska Magda E, Bennett Hayley M, Huckvale Thomas, Abdellah Zahra, Tchindebet Ouakou, Wossen Mesfin, Logora Makoy Samuel Yibi, Coulibaly Cheick Oumar, Weiss Adam, Schulte-Hostedde Albrecht I, Foster Jeremy M, Cleveland Christopher A, Yabsley Michael J, Ruiz-Tiben Ernesto, Berriman Matthew, Eberhard Mark L, Cotton James A. PLoS neglected tropical diseases 2020 Nov 14(11) e0008623 |
Population genetic analysis of Chadian Guinea worms reveals that human and non-human hosts share common parasite populations.
Thiele EA , Eberhard ML , Cotton JA , Durrant C , Berg J , Hamm K , Ruiz-Tiben E . PLoS Negl Trop Dis 2018 12 (10) e0006747 Following almost 10 years of no reported cases, Guinea worm disease (GWD or dracunculiasis) reemerged in Chad in 2010 with peculiar epidemiological patterns and unprecedented prevalence of infection among non-human hosts, particularly domestic dogs. Since 2014, animal infections with Guinea worms have also been observed in the other three countries with endemic transmission (Ethiopia, Mali, and South Sudan), causing concern and generating interest in the parasites' true taxonomic identity and population genetics. We present the first extensive population genetic data for Guinea worm, investigating mitochondrial and microsatellite variation in adult female worms from both human and non-human hosts in the four endemic countries to elucidate the origins of Chad's current outbreak and possible host-specific differences between parasites. Genetic diversity of Chadian Guinea worms was considerably higher than that of the other three countries, even after controlling for sample size through rarefaction, and demographic analyses are consistent with a large, stable parasite population. Genealogical analyses eliminate the other three countries as possible sources of parasite reintroduction into Chad, and sequence divergence and distribution of genetic variation provide no evidence that parasites in human and non-human hosts are separate species or maintain isolated transmission cycles. Both among and within countries, geographic origin appears to have more influence on parasite population structure than host species. Guinea worm infection in non-human hosts has been occasionally reported throughout the history of the disease, particularly when elimination programs appear to be reaching their end goals. However, no previous reports have evaluated molecular support of the parasite species identity. Our data confirm that Guinea worms collected from non-human hosts in the remaining endemic countries of Africa are Dracunculus medinensis and that the same population of worms infects both humans and dogs in Chad. Our genetic data and the epidemiological evidence suggest that transmission in the Chadian context is currently being maintained by canine hosts. |
Comparison of PCR methods for Onchocerca volvulus detection in skin snip biopsies from the Tshopo Province, Democratic Republic of the Congo
Prince-Guerra J , Cama V , Wilson N , Thiele EA , Likwela J , Gyamba NN , Muzinga Wa Muzinga J , Ayebazibwe N , Ndjakani YD , Pitchouna NA , Ngoyi DM , Tshefu AK , Ogawa G , Cantey PT . Am J Trop Med Hyg 2018 98 (5) 1427-1434 Defining the optimal diagnostic tools for evaluating onchocerciasis elimination efforts in areas co-endemic for other filarial nematodes is imperative. This study compared three published PCR methods: the Onchocerca volvulus-specific qPCR-O150, the pan-filarial qPCR melt curve analysis (MCA), and the O150-PCR ELISA currently used for vector surveillance in skin snip biopsies (skin snips) collected from the Democratic Republic of the Congo. The pan-filarial qPCR-MCA was compared with species-specific qPCRs for Loa loa and Mansonella perstans. Among the 471 skin snips, 47.5%, 43.5%, and 27% were O. volvulus positive by qPCR-O150, qPCR-MCA, and O150-PCR ELISA, respectively. Using qPCR-O150 as the comparator, the sensitivity and specificity of qPCR-MCA were 89.3% and 98%, respectively, whereas for O150-PCR ELISA, they were 56.7% and 100%, respectively. Although qPCR-MCA identified the presence of L. loa and Mansonella spp. in skin snips, species-specific qPCRs had greater sensitivity and were needed to identify M. perstans. Most of the qPCR-MCA misclassifications occurred in mixed infections. The reduced sensitivity of O150-PCR ELISA was associated with lower microfilaria burden and with lower amounts of O. volvulus DNA. Although qPCR-MCA identified most of the O. volvulus-positive skin snips, it is not sufficiently robust to be used for stop-mass drug administration (MDA) evaluations in areas co-endemic for other filariae. Because O150-PCR ELISA missed 43.3% of qPCR-O150-positive skin snips, the qPCR-O150 assay is more appropriate for evaluating skin snips of OV-16 + children in stop-MDA assessments. Although improving the sensitivity of the O150-PCR ELISA as an alternative to qPCR might be possible, qPCR-O150 offers distinct advantages aside from increased sensitivity. |
Characterizing reactivity to Onchocerca volvulus antigens in multiplex bead assays
Feeser KR , Cama V , Priest JW , Thiele EA , Wiegand RE , Lakwo T , Feleke SM , Cantey PT . Am J Trop Med Hyg 2017 97 (3) 666-672 Multiplex bead assays (MBAs) may provide a powerful integrated tool for monitoring, evaluation, and post-elimination surveillance of onchocerciasis and co-endemic diseases; however, the specificity and sensitivity of Onchocerca volvulus antigens have not been characterized within this context. An MBA was developed to evaluate three antigens (OV-16, OV-17, and OV-33) for onchocerciasis. Receiver operating characteristics (ROC) analyses were used to characterize antigen performance using a panel of 610 specimens: 109 O. volvulus-positive specimens, 426 non-onchocerciasis controls with filarial and other confirmed parasitic infection, and 75 sera from patients with no other parasitic infection. The IgG and IgG4 assays for OV-16 demonstrated sensitivities of 95.4% and 96.3%, and specificities of 99.4% and 99.8%, respectively. The OV-17 IgG and IgG4 assays had sensitivities of 86.2% and 76.1% and specificities of 79.2% and 82.8%. For OV-33, the IgG and IgG4 assays had sensitivities of 90.8% and 96.3%, and specificities of 96.8% and 98.6%. The OV-16 IgG4-based MBA had the best assay characteristics, followed by OV-33 IgG4. The OV-16 IgG4 assay would be useful for monitoring and evaluation using the MBA platform. Further evaluations are needed to review the potential use of OV-33 as a confirmatory test in the context of program evaluations. |
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. |
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. |
Potential sexual transmission of Trypanosoma cruzi in mice
Martin DL , Lowe KR , McNeill T , Thiele EA , Roellig DM , Zajdowicz J , Hunter SA , Brubaker SA . Acta Trop 2015 149 15-8 Infection with the protozoan parasite Trypanosoma cruzi, the etiologic agent of human Chagas disease, results in life-long infection. Infective trypomastigotes circulate in the bloodstream and have the capacity to infect any cell type, including reproductive tissue. This study sought to assess the potential for sexual transmission of T. cruzi in an experimental mouse model. The conditions used in this study, in which acutely infected males and immunosuppressing the females, created a worst-case scenario allowing for the greatest chance of measuring transmission through intercourse. Male BALB/c mice were infected and mated with uninfected females, and the females were subsequently examined for T. cruzi tissue parasitism. A single transmission event of 61 total matings was observed, indicating a low but non-zero risk potential for male-to-female sexual transmission of T. cruzi. |
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. |
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