It starts with a mosquito bite. Parasitic worms carried by the mosquito enter the bloodstream and find their way to lymph vessels—the human body’s highway for removing fluid from tissue.
Over their 6- to 8-year lifespan, the worms produce millions of immature larvae that circulate in the blood, waiting to be picked up by another mosquito. Once aboard the mosquito, they mature and are transmitted to a new human host.
At best, the infection ends with damage to the lymph system, kidneys, and immune system. At worst, it ends in profound disfigurement and disability—limbs and genitals so swollen that people cannot work, walk, or care for themselves.
A dreaded disease
Commonly known as elephantiasis, lymphatic filariasis is one of the world’s most dreaded diseases. It’s the second leading cause of permanent, long-term disability worldwide and a major contributor to poverty.
According to the World Health Organization, at least 36 million people are currently living with the pain and stigma of the condition; another 900 million are at risk and require preventive drugs to stop the spread of infection.
In India, the disease is a major public health problem. It is regularly found in 256 districts across 17 states.
Mass drug administration
India first started mass drug administration to prevent lymphatic filariasis in 2004. Once the rate of infection with microfilaria—the larval life stage of the parasitic worm—is reduced to less than 1 percent of the population, it becomes possible to interrupt transmission, making elimination an achievable goal.
So far, 99 of the 256 affected districts in India have successfully achieved this rate. In the remaining 157, transmission continues to be problematic, persisting even after five rounds of drug administration.
Switching to triple drug therapy
Courses of treatment have changed over the years. In 2017, the World Health Organization recommended an alternate regimen: triple drug therapy. Research has found that the triple drug regimen is faster and more effective at clearing microfilaria than the previous regimen.
In 2018, India introduced this new therapy on a pilot basis in several districts and plans to eventually use it in all 157 of the remaining endemic districts.
Development of the dose pole
To help India achieve its elimination goals, PATH is providing technical assistance to the government’s National Vector Borne Disease Control Program. With PATH support, the government program developed operational guidelines, training materials, and an innovative “dose pole” for determining the required dosage of ivermectin, a key ingredient in triple drug therapy.
How does the dose pole work?
The Indian government recommends administering ivermectin according to the height of the individual. Using height rather than weight is a practical solution in low-resource settings due to the need for frequent calibration and sometimes a power source for weighing machines. The use of height to determine dosage of ivermectin has been used in several other countries: Burkina Faso, Kenya, Sierra Leone, and Sudan.
But the dose pole is new. Designed by PATH in partnership with the Indian government, it is a simple six-foot pole that can be retracted into four foldable pieces, making it easy for health workers to carry. The pole is color-coded in sections, with each color corresponding to the proper dose. The pole has been used in mass drug administration campaigns across four districts in India.
This innovation will help bring India one step closer to ending the suffering caused by lymphatic filariasis.
India is one the first nations to roll out triple drug therapy, and the experience can inform introduction efforts in other countries. PATH will continue to support the Indian government and other partners in helping the country meet its ambitious goal of elimination—and free future generations from the heavy toll of this disease.