Prevalence of diurnally subperiodic bancroftian filariasis among the Nicobarese in Andaman and Nicobar Islands, India: effect of age and gender

We conducted a cross-sectional survey to assess the prevalence of disease and microfilaraemia caused by diurnally subperiodic strain of Wuchereria bancrofti transmitted by day biting Aedes niveus in Teressa Island, remotely located in the Nicobar district of Andaman and Nicobar Islands. Lymphatic filariasis is a considerable public health problem on this island with an overall endemicity rate of 16.2%. There was a gradual increase in microfilaraemia prevalence with age, reaching a plateau above 30 years. Both the microfilaraemia and disease rates were significantly higher in males (14.7% and 5.2%) than females (8.6% and 1.5%, P < 0.001). The age and gender specific distribution of chronic manifestations show a gradual increase with age, whereas acute disease started to occur from age 40 in males. Hydrocele (84.6%) was the commonest disease manifestation among males, whereas lymphoedema was the only manifestation encountered among females. As vector control measures are not practicable in this setting, chemotherapy using diethylcarbamazine (DEC) is the only potential option to control this disease.