PHYSIOGRAPHIC AND ENTOMOLOGIC RISK FACTORS OF MALARIA IN ASSAM, INDIA

• Published in: The American journal of tropical medicine and hygiene Vol. 71; no. 4; pp. 451 - 456
• Main Authors: DEV, VAS, PHOOKAN, SOBHAN, SHARMA, VINOD P, ANAND, SURAJ P
• Format: Journal Article
• Language: English
• Published: Lawrence, KS ASTMH 01.10.2004; Allen Press
• Subjects: Animals; Anopheles - classification; Anopheles - parasitology; Anopheles - physiology; Anopheles minimus; Biological and medical sciences; Female; Human protozoal diseases; Humans; India - epidemiology; Infectious diseases; Insect Bites and Stings; Malaria; Malaria, Falciparum - epidemiology; Malaria, Falciparum - parasitology; Malaria, Falciparum - transmission; Malaria, Vivax - epidemiology; Malaria, Vivax - parasitology; Malaria, Vivax - transmission; Male; Medical sciences; Parasitic diseases; Plasmodium falciparum; Plasmodium falciparum - isolation & purification; Plasmodium vivax - isolation & purification; Prevalence; Protozoal diseases; Risk Factors; Seasons; Assam; Asia; India; Infection; Human; Protozoal disease; Malaria; Entomology; Risk factor; Tropical medicine; Parasitosis; Epidemiology
• ISSN: 0002-9637; 1476-1645
• DOI: 10.4269/ajtmh.2004.71.451

Fever surveys were conducted in several districts of the Indian state of Assam to ascertain the prevalence of malaria in relation to vector abundance, entomologic inoculation rates (EIRs), and geographic location of human settlements. Anopheles minimus were incriminated, but their relative abundance and biting rates varied among districts, and no significant correlation was observed between these two indicators (r = 0.43, P = 0.34). Plasmodium falciparum was the predominant parasite species except in two districts where P. vivax was the majority parasite. The EIRs per person/night were 0.46-0.71 in P. falciparum-predominant areas and 0.12 in the district where P. vivax predominated. The correlation of percentage of fever cases positive for malaria infection in each district with the corresponding EIR was not significant (r = 0.6, P = 0.21). Malaria cases were detected in all months of the year but peaked during May-June, which corresponded to the months of heavy rainfall. These were also the months with highest incidence of infection with P. falciparum. Malaria cases were observed in all age groups of both sexes, and there was clustering of cases in villages near the vector-breeding habitat (perennial seepage streams), and foothill villages. However, malaria incidences were consistently lower in villages within 5 km of the nearest health care facility, which were in town areas. The data presented are indicative of low-to-moderate levels of malaria transmission by An. minimus, and would be of value for developing future intervention strategies.