Last data update: May 06, 2024. (Total: 46732 publications since 2009)
Records 1-4 (of 4 Records) |
Query Trace: Ogawa GM[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. |
Sero-identification of the aetiologies of human malaria exposure (Plasmodium spp.) in the Limu Kossa District of Jimma Zone, South western Ethiopia
Feleke SM , Brhane BG , Mamo H , Assefa A , Woyessa A , Ogawa GM , Cama V . Malar J 2019 18 (1) 292 BACKGROUND: Malaria remains a very important public health problem in Ethiopia. Currently, only Plasmodium falciparum and Plasmodium vivax are considered in the malaria diagnostic and treatment policies. However, the existence and prevalence of Plasmodium ovale spp. and Plasmodium malariae in Ethiopia have not been extensively investigated. The objective of this study was to use a multiplex IgG antibody detection assay to evaluate evidence for exposure to any of these four human malaria parasites among asymptomatic individuals. METHODS: Dried blood spots (DBS) were collected from 180 healthy study participants during a 2016 onchocerciasis survey in the Jimma Zone, southwest Ethiopia. IgG antibody reactivity was detected using a multiplex bead assay for seven Plasmodium antigens: P. falciparum circumsporozoite protein (CSP), P. falciparum apical membrane antigen-1 (AMA1), P. falciparum liver stage antigen-1 (LSA1), and homologs of the merozoite surface protein-1 (MSP1)-19kD antigens that are specific for P. falciparum, P. vivax, P. ovale spp. and P. malariae. RESULTS: One hundred six participants (59%) were IgG seropositive for at least one of the Plasmodium antigens tested. The most frequent responses were against P. falciparum AMA1 (59, 33%) and P. vivax (55, 28%). However, IgG antibodies against P. ovale spp. and P. malariae were detected in 19 (11%) and 13 (7%) of the participants, respectively, providing serological evidence that P. malariae and P. ovale spp., which are rarely reported, may also be endemic in Jimma. CONCLUSION: The findings highlight the informative value of multiplex serology and the need to confirm whether P. malariae and P. ovale spp. are aetiologies of malaria in Ethiopia, which is critical for proper diagnosis and treatment. |
Integrating multiple biomarkers to increase sensitivity for the detection of Onchocerca volvulus infection
Bennuru S , Oduro-Boateng G , Osigwe C , Del-Valle P , Golden A , Ogawa GM , Cama V , Lustigman S , Nutman TB . J Infect Dis 2019 221 (11) 1805-1815 Serological assessments for human onchocerciasis are based on IgG4 reactivity against the OV-16 antigen, with sensitivity around 60-80%. We previously identified 7 novel proteins that could enhance onchocerciasis sero-diagnosis. Further screening by luciferase immunoprecipitation assays identified OVOC10469 and OVOC3261 as the most promising candidates. IgG4-based ELISA using recombinant proteins, yielded sensitivities of 53% for rOVOC10469 and 78% for rOVOC3261, while specificity for each was >99%. Moreover, the newly-identified biomarkers detected some (but not all) of the mf-positive samples not detected by OV-16. The new antigens in combination with OV-16, increased the sensitivity for patent infections to 94%, demonstrating the benefits of adding a complementary antigen to OV-16-based serology. The kinetics of appearance of these IgG4 responses based on experimentally infected non-human primates indicated that they were patency driven. Of note, the IgG4 responses to both OVOC10469 and OVOC3261 (as well as to OV-16) drop significantly (p<0.05) following successful treatment for onchocerciasis. A prototype of a lateral flow rapid assay was developed and tested, showing an overall 94% sensitivity. These data showed that the combined use of rOVOC3261 with OV-16 improved case detection, a current and urgent need for the efforts to achieve the worldwide elimination of transmission of O. volvulus. |
Sandfly fauna (Diptera: Psychodidae) from caves in the state of Rondonia, Brazil
Ogawa GM , Pereira Junior AM , Resadore F , Ferreira RG , Medeiros JF , Camargo LM . Rev Bras Parasitol Vet 2016 25 (1) 61-8 This study had the aim of ascertaining the sandfly fauna and possible presence of Leishmania in these insects, collected in caves in the state of Rondonia, Brazil. Collections were conducted in eight caves located in two different areas of this state. Leishmania in the sandflies collected was detected using the polymerase chain reaction (PCR). This was the first study on sandflies from caves in Rondonia and, among the total of 1,236 individuals collected, 24 species and 10 genera were identified. The species Evandromyia georgii was collected for the first time in Rondonia and the most abundant species were Trichophoromyia ubiquitalis with 448 individuals (36.2%), followed by T. octavioi with 283 (22.9%) and E. georgii with 179 (14.5%). For the PCR, 17 pools were analyzed and five pools were positive (for T. auraensis in three pools and for Nyssomyia shawi and N. antunesi in one pool each). The kDNA region was amplified and the presence of Leishmania DNA was confirmed. The sandfly fauna in these caves can be considered diverse in comparison with similar studies in other regions. It may be that some species use caves as a temporary shelter and breeding site, while other species live exclusively in this environment. The detection of Leishmania DNA indicates that this pathogen is circulating in cave environments and that further studies are needed in order to ascertain the risks of infection by leishmaniasis in these locations with high touristic potential. |
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