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Background & objectives: Sandflies are implicated as vectors of Chandipura virus (CHPV) (Vesiculovirus: Rhabdoviridae). The virus is prevalent in central India including Vidarbha region of Maharashtra. CHPV causes encephalitis in children below 15 yr of age with case fatality rates ranging from 56 to 78 per cent. The present study was undertaken to determine the sandfly fauna in the CHPV endemic Vidharba region. Methods: A year round survey of sandflies was conducted at 25 sites in three districts of Vidarbha region. Sandflies were collected from their resting sites using handheld aspirators and identified using taxonomical keys. Results: A total of 6568 sandflies were collected during the study. Approximately 99 per cent of the collection belonged to genus Sergentomyia, which was represented by Ser. babu, Ser. bailyi and Ser. punjabensis. Genus Phlebotomus was represented by Ph. argentipes and Ph. papatasi. Ser. babu was the predominant species (70.7%) collected during the study. Ph. argentipes was detected in four villages with 0.89 per cent, whereas Ph. papatasi was detected in only one village with 0.32 per cent of the total collection. CHPV could not be isolated despite processing all the sandflies for virus isolation in cell culture. Interpretation & conclusions: The present study showed influence of higher temperature and relative humidity on sandfly population dynamics. An important observation during the study was the absence or decline in the population of Ph. papatasi and Ph. argentipes in the study area. Surge in Sergentomyia population and their breeding/resting in close vicinity to humans pose a concern as they are known to harbour CHPV and other viruses of public health importance. [ABSTRACT FROM AUTHOR]

Visceral leishmaniasis or Kala-azar (KA) is a Vector-Borne Disease (VBD) that remains the second-largest parasitic killer across the globe (mortality rate: 75–95%). More than 60% of KA cases originate in South Asia, wherein India accounts for 2/3rd of the cases, and Bihar, a state in India, alone accounts for more than 50% of the Indian cases. Past studies suspected climate change vulnerabilities as a driving cause of KA outbreaks. The VBDs-based epidemic prediction systems have been developed to mitigate recurrent outbreaks; however, Machine Learning (ML) based approaches still need to be explored for modeling changing climate impacts on KA cases. This study, for the first time, develops a Radial Basis Function (RBF) kernel-based Support Vector Regression (SVR), hereinafter RBF-kernel-based-SVR model for the most-affected endemic districts of Bihar (northern-India), using the data from 2016 and 2021. Forward selection, backward elimination, and stepwise regression procedures were adopted while selecting influential climatic variables, followed by the k -fold cross-validation technique and, then, the RBF-kernel-based-SVR algorithm for classification. Results suggested that temperature, wind speed, rainfall, and population density significantly contributed to the KA outbreaks. This study also developed Multiple Linear Regression (MLR) and Multilayer Perceptron (MLP) models to compare SVR with other classification models. Findings indicated that the proposed RBF-kernel-based-SVR model [Correlation Coefficient (CC) = 0.82, Root-Mean-Square Error (RMSE) = 12.20, and Nash–Sutcliffe Efficiency (NSE) = 0.66] outperformed MLR (0.81, 14.20, 0.48) and MLP (0.81, 12.95, 0.61). Study recommends using the RBF-kernel-based-SVR model as a quick and efficient model capable of detecting KA cases with high predictability even under limited data availability. Such models can assist public health authorities, given monitoring KA spread, learning the climate impacts of outbreaks, and ensuring timelier health services. [ABSTRACT FROM AUTHOR]

The study aimed to explore epidemiological, serological, and entomological aspects of visceral leishmaniasis (VL) in suspected new VL foci and assess the knowledge, attitude, and practices of the community living in the alleged new VL foci. The study investigated new visceral leishmaniasis (VL) cases reported between 2019 and 2020 in four sub-districts (Dharmapasha, Hakimpur, Islampur and Savar) where we tested 560 members using the rK39 rapid test and conducted vector collections in six neighbouring houses of the index cases to assess sandfly density and distribution, examined sandflies' infection, and determined the spatial relationship with VL infection. Furthermore, we highlighted the importance of early detection, and community awareness in controlling the spread of the disease. The study screened 1078 people from 231 households in the four sub-districts for fever, history of visceral leishmaniasis (VL), and PKDL-like skin lesions. Among sub-districts, positivity rate for rK39 rapid test was highest (3.5 %) in Savar. Sandflies were present across all areas except in Dharmapasha, but all 21 collected female P. argentipes sandflies were negative for Leishmania parasite DNA. We found one person from Islampur with a history of VL, and one from Islampur and another one from Savar had PKDL. After the awareness intervention, more people became familiar with VL infection (91.2 %), and their knowledge concerning sandflies being the vector of the disease and the risk of having VL increased significantly (30.1 %). The study found no active case in the suspected new foci, but some asymptomatic individuals were present. As sandfly vectors exist in these areas, the National Kala-azar Elimination Programme (NKEP) should consider these areas as kala-azar endemic and initiate control activities as per national guidelines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023. Published by Elsevier B.V.)

Protozoan parasites Leishmania donovani (family: Trypanosomatidae) cause fatal visceral leishmaniasis (VL) and the infection relapses in apparently cured population as post kala-azar dermal leishmaniasis (PKDL) in the Indian subcontinent. In recent years co-infection of another Trypanosomatid parasite Leptomonas with L. donovani during VL/PKDL in this region has become prominent. The observation of clinically lesser-known insect parasite, Leptomonas in leishmaniasis is intriguing to researchers. The presence of Leishmania look alike Leptomonas in the cultures of clinical isolates of Leishmania has been worrisome to those, who prefer to work with pure Leishmania cultures for drug and vaccine development or immune response studies. The exact implications of such a co-habitation, which might lead to a delay in the diagnostics of VL and elevate mortality, need a thorough investigation. Also whether Leptomonas is involved in leishmaniasis manifestation needs to be ascertained. Thus we are currently witnessing a new paradigm of a parasitic co-infection in VL/PKDL cases in India and this review outlines various opportunities for further research in understanding such emerging co-infection. [ABSTRACT FROM AUTHOR]