A comparative study on the vector competence of Anopheles stephensi from geographically distinct malarious and non-malarious urban areas in India to the malarial parasite, Plasmodium vivax

Autor: John Ravindran, Alex Eapen
Jazyk: angličtina
Rok vydání: 2024
Předmět:
Zdroj: Journal of Vector Borne Diseases, Vol 61, Iss 3, Pp 413-419 (2024)
Druh dokumentu: article
ISSN: 0972-9062
DOI: 10.4103/JVBD.JVBD_7_24
Popis: Background & objectives: Anopheles stephensi is responsible for the transmission of malaria in urban areas. Vector competence of An. stephensi from a non-malarious (Coimbatore) and highly malarious (Chennai) urban area were investigated to find out the reason for the non-transmission of malaria in Coimbatore. Methods: Vector competence (Susceptibility/refractoriness) of An. stephensi mosquitoes from Chennai (Malarious) and Coimbatore (Non-malarious), Tamil Nadu, India to Plasmodium vivax (Chennai) were investigated. Bioassays were carried out concurrently in both these strains by artificial membrane feeding technique using the same malaria infected blood. An. stephensi were dissected to observe infection in the midgut and salivary glands. The parasite infection, oocyst and sporozoite positivity rate, the oocyst load, correlation between male-female gametocyte ratio and infection, and Survival Analysis of parasitic stages during sporogony were analyzed and compared. Results: The overall infection rate was 45.8 and 41.2 per cent in Chennai and Coimbatore. Oocyst count ranged from 1-80 and 1-208 respectively and not statistically significant. Oocyst positivity was high from Day 8-21in both strains. The Mean Survival Day (MSD) for oocyst was Day 14 in both strains. Sporozoite was observed in four experiments in each of the strains and the MSD for sporozoites was Day 20 and Day 17 in Chennai and Coimbatore. Interpretation & conclusion: An. stephensi of Chennai and Coimbatore are equally susceptible to P. vivax infection and the non-transmission of malaria in Coimbatore can be attributed to external factors such as the presence of preferential breeding habitat, vector density, vector survival, and weather. The only difference observed was the comparatively shortened oocyst maturation time in the Coimbatore strain which requires further investigation.
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