Risk of Neglected Zoonotic Malaria in Western Ghats: How the Ecosystem Favors Transmission of an Impending Public Health Threat.

The threat of zoonotic malaria remains largely overlooked in India, particularly in regions such as the Western Ghats (WG), a biodiversity hotspot. The WG has diverse species of non-human primates that serve as reservoir hosts for simian malaria parasites. The presence of the Leucosphyrus group of mosquitoes and other vectors of human malaria makes WG vulnerable to the risk of parasite spillover. Natural and anthropogenic factors have contributed to rampant changes in the WG landscape, leading to increased interaction with the sylvatic hosts and vectors. The simian host-human-vector-environment interactions govern the transmission dynamics of zoonotic malaria; however, our knowledge of these interlinkages, encompassing the effect of anthropogenic disruptions in the WG is limited. The impending threat of zoonotic malaria in India could decelerate progress toward malaria elimination, warranting a comprehensive and systematic investigation of disease dynamics in the WG.

Characterisation of Anopheles species composition and genetic diversity in Meghalaya, northeast India, using molecular identification tools.

Malaria in India is declining, in part due to the use of long-lasting insecticide-treated nets (LLINs) and vector control. Historically, the north-eastern region of India has contributed ~10%-12% of the nation's malaria burden. The important mosquito vectors in northeast India have long been considered to be Anopheles baimaii and An. minimus, both associated with forest habitats. Local deforestation and increased rice cultivation, along with widespread LLIN use, may be changing vector species composition. Understanding if and how vector species composition is changing is critical to successful malaria control. In Meghalaya state, malaria is now at a low level of endemicity with occasional seasonal outbreaks. In a biodiverse setting like Meghalaya, where >24 Anopheles mosquito species have been recorded, accurate morphological identification of all species is logistically challenging. To accurately determine Anopheles species richness in the West Khasi Hills (WKH) and West Jaintia Hills (WJH) districts, adult and larval mosquitoes were collected and identified using molecular methods of allele-specific PCR and cytochrome oxidase I DNA barcoding. In 14 villages across both districts, we identified high species richness, 19 species in total. Molecular findings indicated that An. minimus and An. baimaii were rare, while four other species (An. maculatus, An. pseudowillmori, An. jeyporiensis and An. nitidus) were abundant. Anopheles maculatus was highly prevalent in WKH (39% of light trap collections) and An. pseudowillmori in WJH (45%). Larvae of these four species were found in rice fields, suggesting that land cover change is influencing species composition change. Our results suggest that rice fields might be contributing to the observed abundance of An. maculatus and An. pseudowillmori, which could be playing a role in malaria transmission, either independently due to their high abundance, or in combination with An. baimaii and/or An. minimus.