By: Greg Simon

A new study published in the New England Journal of Medicine further strengthens the evidence that sleeping under insecticide treated bed-nets (ITNs) helps to eliminate Lymphatic filariasis (elephantiasis or LF) and malaria.

Lymphatic filariasis (elephantiasis or LF) is a parasitic-worm infection that affects approximately 120 million people worldwide. The World Health Organization (WHO) estimates that 120 million people suffer from LF — one-third of which have been disfigured or debilitated by the disease. The WHO has a goal of eliminating LF as a public health problem by the year 2020. With approximately 1.4 billion people living in endemic areas, the task is an enormous one which will require multiple interventions. Global efforts to eliminate LF have been based on the annual mass drug administration (MDA) of anti-filarial drugs to reduce the microfilaria reservoir available to the mosquito vector. While the stand alone MDA approach can work in areas where the infection rate is low, areas with high infection rates may need to incorporate other measures to reduce the incidence of LF.

The New England Journal of Medicine study titled: “Insecticidal Bed Nets and Filariasis Transmission in Papua New Guinea,” studied five villages in which five annual MDAs were performed in cooperation with ITN distribution. According to the research, the ITNs 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.

The study noted the rates of bites from mosquitoes were reduced 6.4 to 61.3 bites per person per day before the bed-net distribution to 1.1 to 9.4 bites for 11 months after distribution. During the same period, the rate of detection of parasite in mosquitoes decreased 78%, and the rate of detection of filarial DNA decreased 23%.  The study found the annual transmission potential was 5 to 325 infective larvae inoculated per person per year before the ITN distribution and 0 after the distribution. It noted that among all five villages with a prevalence of parasite of 2 to 38 percent, the probability of transmission cessation increased from less than 1.0 percent before the bed-net distribution to a range of 4.9 to 95 percent in the 11 months after distribution.

While this study demonstrates the power of combined interventions to prevent both LF and malaria, it is not the first. Another successful program was a five-year malaria treatment program in Togo initiated