Filariasis which was thought to be eliminated as a public health problem has reared its head with 97 cases being detected this year in eight districts including in Colombo, primarily in the Southern Province, in the Galle District, in Balapitiya.
The microfilaria rate (the percentage of filarial parasites in people following night blood film testing) given by the World Health Organization (WHO) as a target for Sri Lanka is for it to be less than 1%.
Director of the Anti-Filariasis Campaign of the Ministry of Health, Dr. Devika Mendis said that the Districts of Puttalam, Kurunegala, Colombo, Gampaha, Kalutara, Galle, Matara and Hambantota had been affected (with the exemption of the Galle District, only a small number of cases have been detected in the other Districts), adding that continuous surveys are being conducted in these areas which are endemic for filariasis.
The microfilaria rate everywhere is 0.01% or 0.02% or 0.03% (all of which is less than 1%) except in the Galle District (a high risk area), where it was 0.24% last year.
The patients are unaware that they are harbouring the filarial worm/s as most of the cases are at the asymptomatic (no symptoms) stage, she added.
If the matter is not treated at this stage now, when they develop symptoms such as the swelling of limbs (arms and legs), at that stage it is difficult to bring the limb/s back to normal, she explained.
Where the mosquito carrying dengue lays eggs in clear water, the mosquito carrying the filarial parasite lays eggs in polluted water. While dengue spreads very fast, filariasis spreads very slowly.
“We had eliminated filariasis in that the incidence of it was at a very low level. We received WHO certification of such on 2016 July 21. We have not eradicated it. We are conducting a special survey,” Dr. Mendis said.