Detection of microfilaria in Myanmar immigrant workers by modified Knott’s Concentration Technique

Abstract

Filariasis in Thailand is caused by Wuchereria bancrofti (W. bancrofti) and Brugia malayi         (B. malayi). It is endemic in the border areas of Thailand and Myanmar in such places as Tak province and is often spread by immigrant laborers. Currently, the number of immigrant workers from Myanmar is increasing each year and this may increase the incidence of the disease for Thai people. This study aimed to compare the efficiency of two methods of detecting microfilaria, the wet mount preparation and the modified Knott’s concentration, in 400 blood samples of Myanmar immigrant workers living in Mae Sot district of Thailand. The results showed the modified Knott’s concentration can detect microfilaria in 10% of blood samples while the wet mount preparation provided a negative result. Moreover, the modified Knott’s concentration was also able to identify that all microfilaria found in this study was W. bancrofti with a density of 1 microfilaria per 1 ml of a blood sample. The prevalence of the disease among the immigrant workers was 100 per 1,000 of the population. The study suggests that the modified Knott’s concentration is an appropriate method in the diagnosis and control of filariasis as it is easy to perform, is ten times more sensitive in the detection of microfilaria than the wet mount preparation, and can also classify the type of microfilaria.