After seven rounds of annual Mass Drug Administration (MDA) to eliminate lymphatic filariasis, five districts in the State are ready to undergo a Transmission Assessment Survey (TAS) to determine whether the MDA can be stopped.
In these districts — Kollam, Alappuzha, Kottayam, Ernakulam, and Thrissur — the microfilariae (mf) rate (the density of the microfilariae in the blood of infected persons) has been found to be low. The World Health Organisation (WHO) had set 2015 as the target year for total elimination of filariasis.
TAS is a standard surveillance methodology by the WHO to assess whether the series of MDA in a region has reduced the prevalence of microfilariae infection to such low levels that the infection cannot be transmitted in the community, even if mosquitoes are present.
A misconception“In Kerala, we have never been able to convince people that everyone is vulnerable to the infection. MDA has remained the least popular public health programme of the Health Department because the public believes that filariasis afflicts only the poor,” a senior Health official said.
Mass administration of the drugs diethylcarbamazine and albendazole to reduce microfilariae was launched in 2004 in the State. Delivering MDA annually in an endemic community for at least five years, to at least 65 per cent of the population, is enough to reduce the density of mf in an infected individual’s blood and also to reduce the prevalence of infection in the community.
Health Department statistics reveal that the actual percentage of the population believed to have consumed the drugs under MDA is less than 40 per cent – because people doubt the “safety” of the drugs and do not want to be treated for a disease which they believe they will not get.
The Health Department recently conducted an mf assessment survey in 61 random sites in the five low prevalence districts, including sites where the mf rates have been traditionally high.
From each site, 500 blood smear samples were collected. Of the total of 32,821 samples, only two – from Perumon in Kollam and Paika in Kottayam – showed the presence of mf, putting the mf rate in the population at 0.01 per cent. “Under the national guidelines, these five districts are now cleared for TAS, after the results of which, we might be able to stop MDA in these places. Next year, we hope that three more districts will be TAS-ready. The State is taking the first steps towards filariasis elimination, which will happen in phases as we move on to other districts,” senior Health officials said.
In other StatesThis year, the five districts were exempted from the MDA round. “In Tamil Nadu, except for two districts, all others have qualified for TAS. Goa and Pondicherry are also ready for TAS. But here, filariasis continues to be a problem in Palakkad, Malappuram, Thiruvananthapuram, Kozhikode, Kannur and Kasaragod, where new cases continue to be reported,” they said.
Lymphatic filariasis causes considerable morbidity and permanent disability. While the infection is generally acquired early in childhood, the disease may manifest only in adulthood, during which time, there will be no outward symptoms.
