Emergence of imported cutaneous leishmaniasis caused by Leishmania major: a case series from Kerala, India.

Cutaneous leishmaniasis (CL) is often considered a 'great imitator' and is the most common form of leishmaniasis. The Leishmania species responsible for CL varies among countries, as these species exhibit specific distribution patterns. The increased mobility of people across countries has resulted in the imported incidences of leishmaniasis caused by non-endemic species of Leishmania. During 2023, we confirmed three CL cases caused by L. major from Kerala, India, and upon detailed investigation, these were identified to be imported from the Middle East and Kazakhstan regions. This is the first report of CL caused by L. major from Kerala. The lesion morphology, detection of anti-rK 39 antibody and Leishmania parasite DNA from the blood samples were the unique observations of these cases. Kerala, being an emerging endemic zone of visceral leishmaniasis (VL) and CL, the imported incidences of leishmaniasis by non-endemic species can pose a significant threat, potentially initiating new transmission cycles of leishmaniasis caused by non-endemic species.

Molecular Identification of Host Blood Meal from Phlebotomine Sandflies (Diptera: Psychodidae) from Kerala, India.

Female phlebotomine sandflies serve as vectors for the transmission of Leishmania parasites, perpetuating an enzootic cycle by disseminating between sylvatic and domestic animals. Humans form a part of this cycle because the sandflies search for a blood source required for egg development. The present study aimed to identify the feeding preferences of different sandfly fauna from six districts of Kerala, India, using molecular tools. An entomological survey was conducted during 2021-2023 in Kollam, Kottayam, Thiruvananthapuram, Thrissur, Malappuram, and Palakkad. Both indoor and outdoor habitats were targeted from sandfly collection using different standard tools and methods. Sandflies were identified using standard taxonomic keys, and DNA was extracted from blood meal collected from sandflies. A total of 7366 sandfly specimens were collected during the study period, which belonged to three different genera and 19 species. Blood source was successfully identified from 119 sandflies revealing that the Sergentomyia genus preferably fed on small reptiles and amphibians, whereas Phlebotomus genus was found to mainly feed on mammalian and avian blood. Sergentomyia zeylanica was an exception, as it primarily fed on mammalian blood sources. Interestingly, humans were the second feeding source for Phlebotomus species, which are the proven vectors. Comprehending the feeding patterns of sandflies is crucial, not just for public health but also for obtaining insights into the ecological dynamics between vectors and hosts, ultimately enabling more efficient strategies for disease control and prevention.

Genetic diversity of Leishmania donovani causing visceral and cutaneous leishmaniasis in the Western Ghats, India.

The visceral and atypical cutaneous leishmaniasis (VL and CL) caused by Leishmania donovani is an emerging infectious disease in the Western Ghats, Kerala, India. In this study, L. donovani specific kinetoplast minicircle DNA (k-DNA) sequence analysis was conducted to ascertain the genetic variability among the L. donovani isolates from the Western Ghats. Out of 23 CL and 5 VL suspected patient samples, 18 CL and 3 VL tested positive for k-DNA diagnostic PCR. Subsequently, 17 CL and 3 VL samples were found positive for L. donovani specific k-DNA PCR. Although the genetic diversity among the VL and CL isolates was low, there was clear variation from the parasites reported from other countries. The parasites characterized from the current study were more related to those reported from East Africa and India.

Comparative Analysis of Phlebotomus argentipes Vector of Leishmaniasis in India and Sri Lanka.

Phlebotomus argentipes is the predominant sandfly vector of leishmaniasis in the Indian subcontinent. India and Sri Lanka primarily report visceral and cutaneous leishmaniasis caused by Leishmania donovani. We compared Ph. argentipes from two locations, focusing on its morphological, molecular, and salivary protein characteristics. Sandflies were captured using CDC light traps and cattle-baited net traps. Species identification and morphological comparisons were carried out using standard taxonomic keys. DNA extracted from 12 Sri Lankan sandfly samples was PCR-amplified and sequenced for the variable region of Cytochrome oxidase subunit I. Existing DNA sequences of India from GenBank were utilized for a phylogenetic analysis between Sri Lanka and India. Salivary protein profiles were studied using SDS-PAGE, Western blot, and electrospray ionization/LC/MS/MS. The morphological similarities observed between female Ph. argentipes from India and Sri Lanka suggest the presence of Ph. argentipes var. glaucus. A phylogenetic analysis showed genetic divergence between Ph. argentipes populations, but both shared a similar salivary protein profile. A common, strong 30 kDa immunogenic band comprised PagSP05, PagSP06, and PagSP17 proteins of Ph. argentipes. The similarity between the immunogenic salivary proteins suggests their potential use as common markers for vector exposure or immune response stimulants across regions. The use of multiple samples for each category of serum would improve the comprehensiveness of the immunogenic profiles obtained.

Identification and molecular characterization of Culex flavivirus in Culex quinquefasciatus (Diptera: Culicidae): first report from India.

BACKGROUND: Culex quinquefasciatus is a notorious vector known to transmit pathogens such as Wuchereria bancrofti (causing Lymphatic filariasis) and flaviviruses such as West Nile virus in India and St. Louis Encephalitis virus in the USA. It is the vector of the Rift Valley Fever virus, also on the African continent. Mosquitoes also harbor other non-pathogenic insect-specific flaviviruses (ISFs), such as Culex flavivirus (CxFV) and Aedes flavivirus. Recent studies have implicated ISFs interfering with the vectorial efficiency of the pathogenic arbo-viruses. METHODS: One hundred specimens of the Cx. quinquefasciatus population in two urban areas in Kerala State, India, were screened to have an understanding of the prevalence of these flaviviruses in this vector species. Viral RNA was extracted from individual specimens and was subjected to RT-PCR towards amplification of the CxFV non-structural protein 5 (NS5) gene. RESULTS: Among the 100 specimens, 7.0% were found to be harboring CxFV infection. The phylogenetic analysis of the gene sequences showed that the virus isolates were genetically related to Kenya, with 98-99% sequence similarities. CONCLUSION: This is the first report on the occurrence of CxFV from Cx. quinquefasciatus from India. The occurrence of these viruses in mosquitoes could play a critical role in disease vector management.