Molecular prevalence of Dirofilaria sp. hongkongensis, among the dog population in Thiruvananthapuram, India.

Human dirofilariasis is an emerging vector-borne zoonotic parasitic disease in India. Humans are accidental hosts. Symptomatic dirofilariasis, although uncommon is typically manifested in humans as pulmonary, ocular, or subcutaneous nodules. The present research reports the prevalence of the species, Dirofilaria sp. hongkongensis among the dog population in the Kani tribal settlements within the Agasthyamala Biosphere Reserve located at the southernmost end of the Western Ghats, Kerala. To study the prevalence, we conducted a random blood survey among the dog population in these tribal settlements in Thiruvananthapuram. Whole blood was collected from stray and domesticated animals. Genomic DNA was extracted and the microfilariae in the blood were characterized using the slide smear and COI-based marker specific to nematodes. After processing the data from the Sanger sequencer using BLAST, the sequences were submitted to GenBank. Over 25 % of dogs were found positive for Dirofilaria sp. hongkongensis, which is genetically identical to the strain causing human dirofilariasis as is shown by the phylogenetic analysis. The study reveals that the Kani tribes, who reside in deep forests, are particularly vulnerable to this strain of Dirofilaria sp. hongkongensis. Human case reports of this specific strain have been recorded in Kerala over the past decade. The effective elimination is ultimately impacted by a lack of knowledge regarding the mosquito vectors. Dirofilariasis in dogs and humans is on the rise, which demands both active disease surveillance and proper treatment.

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.

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.

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.

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.

Nation-wide vector surveillance on Zika and Dengue did not indicate transmission of the American lineage-pandemic Zika virus in India.

OBJECTIVES: Following the Public Health Emergency of International Concern declared on Zika by the World Health Organization during 2016, the Indian Council of Medical Research carried out nationwide vector surveillance for Zika and Dengue viruses (ZIKV and DENV) in India as a preparedness measure in 2016-19. METHODS: High-risk zones distributed to 49 Districts in 14 states/union territories were included in the study. Seven ICMR institutions participated, following a standard operating protocol. Aedes specimens sampled weekly were processed by multiplex reverse transcriptase-polymerase chain reaction (RT-PCR) for ZIKV/DENV and random samples crosschecked with real-time RT-PCR for ZIKV. RESULTS: Altogether, 79 492 Aedes specimens in 6492 pools were processed; 3 (0.05%) and 63 (0.97%) pools, respectively, were found positive for ZIKV and DENV. ZIKV infections were recorded in Aedes aegypti sampled during the 2018 sporadic Zika outbreak in Jaipur, Rajasthan. However, these belonged to the Asian lineage of the virus, already circulating in the country. Both Ae. aegypti and Aedes albopictus distributed to 8 states/union territories were found to be infected with DENV. Both sexes of Ae. albopictus were infected, indicating transovarial transmission. CONCLUSION: This investigation evinced no active transmission of the American lineage-pandemic Zika virus in India during the pandemic period.