Browsing by Author "Vivek Kumar Scholar"

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Livestock and rodents within an endemic focus of Visceral Leishmaniasis are not reservoir hosts for Leishmania donovani
(Public Library of Science, 2022) Anurag Kumar Kushwaha; Ashish Shukla; Breanna M. Scorza; Tulika Kumari Rai; Rahul Chaubey; Dharmendra Kumar Maurya; Shweta Srivastva; Shreya Upadhyay; Abhishek Kumar Singh; Paritosh Malviya; Om Prakash Singh; Vivek Kumar Scholar; Puja Tiwary; Shakti Kumar Singh; Phillip Lawyer; Edgar Rowton; Scott A. Bernhardt; Christine A. Petersen; Shyam Sundar
Leishmaniasis on the Indian subcontinent is thought to have an anthroponotic transmission cycle. There is no direct evidence that a mammalian host other than humans can be infected with Leishmania donovani and transmit infection to the sand fly vector. The aim of the present study was to evaluate the impact of sand fly feeding on other domestic species and provide clinical evidence regarding possible non-human reservoirs through experimental sand fly feeding on cows, water buffalo goats and rodents. We performed xenodiagnosis using colonized Phlebotomus argentipes sand flies to feed on animals residing in villages with active Leishmania transmission based on current human cases. Xenodiagnoses on mammals within the endemic area were performed and blood-fed flies were analyzed for the presence of Leishmania via qPCR 48hrs after feeding. Blood samples were also collected from these mammals for qPCR and serology. Although we found evidence of Leishmania infection within some domestic mammals, they were not infectious to vector sand flies. Monitoring infection in sand flies and non-human blood meal sources in endemic villages leads to scientific proof of exposure and parasitemia in resident mammals. Lack of infectiousness of these domestic mammals to vector sand flies indicates that they likely play no role, or a very limited role in Leishmania donovani transmission to people in Bihar. Therefore, a surveillance system in the peri-/post-elimination phase of visceral leishmaniasis (VL) must monitor absence of transmission. Continued surveillance of domestic mammals in outbreak villages is necessary to ensure that a non-human reservoir is not established, including domestic mammals not present in this study, specifically dogs. © 2022 Kushwaha et al.
Monitoring of Leishmania transmission in the postelimination phase: The potential of serological surveys
(Elsevier B.V., 2024) Kristien Cloots; Om Prakash Singh; Abhishek Kumar Singh; Tulika Kumari Rai; Vishwa Deepak Tiwari; Aziza Neyaz; Sundaram Pandey; Vivek Kumar Scholar; Paritosh Malaviya; Epco Hasker; Shyam Sundar
Objectives: Monitoring of Leishmania transmission is considered a strategic priority for sustaining elimination of visceral leishmaniasis as a public health problem in the Indian subcontinent. The objective of this study was to evaluate whether serological surveys can distinguish between communities with and without Leishmania transmission, and to assess which serological marker performs best. Methods: Seven villages were selected from Bihar and Uttar Pradesh state, India, and categorized as either currently endemic (CE), previously endemic (PE) or nonendemic (NE). Blood samples were analyzed with the rK39 RDT, direct agglutination test (DAT), and rK39 ELISA. Results: Contrary to the rK39 RDT and DAT, the rK39 ELISA showed a significant difference between all three categories of endemicity, with a seroprevalence of 5.21% in CE villages, 1.55% in PE villages, and 0.13% in NE villages. Even when only looking at the seroprevalence among children aged <10 years, the rK39 ELISA was still able to differentiate between villages with and without ongoing transmission. Conclusion: Our findings suggest the rK39 ELISA to be the most promising marker for monitoring of Leishmania transmission. Further validation is required, and practical, context-adapted recommendations need to be formulated in order to guide policymakers toward meaningful and sustainable surveillance strategies in the post-elimination phase. © 2024 The Author(s)
Post kala azar dermal leishmaniasis and leprosy prevalence and distribution in the Muzaffarpur health and demographic surveillance site
(Public Library of Science, 2019) Epco Hasker; Paritosh Malaviya; Vivek Kumar Scholar; Pieter de Koning; Om Prakash Singh; Sangeeta Kansal; Kristien Cloots; Marleen Boelaert; Shyam Sundar
Introduction Post-kala-azar dermal leishmaniasis (PKDL) is a skin manifestation that is a late clinical outcome of visceral leishmaniasis (VL). Its presentation is similar to leprosy, and the differential diagnosis is not always easy. In VL endemic rural areas of Bihar, India, both infectious diseases co-exist. This observational study aimed to determine the prevalence and distribution of both conditions in an area that had until recently been highly endemic for VL. Methods We conducted a door-to-door survey in an area that belongs to the Health and Demographic Surveillance Site (HDSS) of Muzaffarpur, Bihar, India. Within the HDSS we selected the villages that had reported the highest numbers of VL cases in preceding years. All consenting household members were screened for skin conditions, and minor conditions were treated on the spot. Upon completion of screening activities at the level of a few villages, a dermatology clinic (“skin camp”) was conducted to which suspect leprosy and PKDL patients and other patients with skin conditions requiring expert advice were referred. We studied the association between distance from an index case of leprosy and the probability of disease in the neighborhood by fitting a Poisson model. Results We recorded a population of 33,319, out of which 25,686 (77.1%) were clinically screened. Participation in skin camps was excellent. Most common conditions were fungal infections, eczema, and scabies. There were three PKDL patients and 44 active leprosy patients, equivalent to a prevalence rate of leprosy of 17.1 per 10,000. Two out of three PKDL patients had a history of VL. Leprosy patients were widely spread across villages, but within villages, we found strong spatial clustering, with incidence rate ratios of 6.3 (95% C.I. 1.9–21.0) for household members and 3.6 (95% C.I. 1.3–10.2) for neighbors within 25 meters, with those living at more than 100 meters as the reference category. Discussion Even in this previously highly VL endemic area, PKDL is a rare condition. Nevertheless, even a single case can trigger a new VL outbreak. Leprosy is also a rare disease, but current prevalence is over 17 times the elimination threshold proclaimed by WHO. Both diseases require continued surveillance. Active case finding for leprosy can be recommended among household members and close neighbors of leprosy patients but would not be feasible for entire populations. Periodic skin camps may be a feasible and affordable alternative. © 2019 Hasker et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.