Treated bed-nets helpful in eliminate elephantiasis

A study published in the New England Journal of Medicine has revealed sleeping under insecticide treated bed-net helps to eliminate elephantiasis and malaria, which infect several people across Africa and South-East Asia.

It said global efforts to eliminate lymphatic filariasis have been based on the annual mass administration of anti-filarial drugs to reduce the microfilaria reservoir available to the mosquito vector. Elephantiasis is the most spectacular symptom of lymphatic filariasis.

The study, however, noted that insecticide-treated bed nets were being widely used in areas in which filariasis and malaria were co-endemic.

The research dubbed: “Insecticidal Bed Nets and Filariasis Transmission in Papua New Guinea,” which was made available to the Ghana News Agency at the weekend, studied five villages in which five annual mass administrations of anti-filarial drugs, which were completed in 1998, reduced the transmission of Wuchereria bancrofti, one of the nematodes that cause lymphatic filariasis.

According to the research, the treated nets block female mosquitoes from securing blood, which is essential for them to produce offspring; the insecticide also cuts in half the insect's life span, preventing the parasite from being transmitted.

It said a total of 21,899 anopheles mosquitoes were collected for 26 months before and 11 to 36 months after bed nets treated with long-lasting insecticide were distributed in 2009.

The study evaluated the status of filarial infection and the presence of Wuchereria bancrofti deoxyribonucleic acid (DNA) in anopheline mosquitoes before and after the introduction of insecticide-treated bed nets.

A model of population dynamics was used to estimate the probabilities of transmission cessation.

“Village-specific rates of bites from anopheline mosquitoes ranged from 6.4 to 61.3 bites per person per day before the bed-net distribution and from 1.1 to 9.4 bites for 11 months after distribution.

“During the same period, the rate of detection of Wuchereria bancrofti in anopheline mosquitoes decreased from 1.8 per cent to 0.4 per cent, and the rate of detection of filarial DNA decreased from 19.4 per cent to 14.9 per cent,” it said.

The study said the annual transmission potential was 5 to 325 infective larvae inoculated per person per year before the bed-net distribution and 0 after the distribution.

It noted that among all five villages with a prevalence of microfilariae of 2 to 38 per cent, the probability of transmission cessation increased from less than 1.0 per cent before the bed-net distribution to a range of 4.9 to 95 per cent in the 11 months after distribution.

According to the study, which was funded by the United States Public Health Service and the National Institutes of Health, vector control with insecticide-treated bed nets was a valuable tool for Wuchereria bancrofti elimination in areas in which anopheline mosquitoes transmit the parasite.

Lymphatic filariasis, a parasitic-worm infection, affects approximately 120 million people in Africa, Asia, the Pacific, and the Americas.

The World Health Organization estimates that 120 million people suffer from lymphatic filariasis, of which about one-third have been disfigured or debilitated by the disease.

The World Health Organization has a goal of eliminating lymphatic filariasis as a public health problem by the year 2020.