Blog Details

  • 10/12/2023


Why in news?

Recently, The Union Health Ministry has launched a nationwide mass drug administration (MDA) campaign aimed at ending filariasis disease transmission through door-to-door administration of anti-filarial drugs, especially in 10 affected States.

About Filariasis:

  • Lymphatic filariasis, commonly known as elephantiasis, is a neglected tropical disease. Infection occurs when filarial parasites are transmitted to humans through mosquitoes. Infection is usually acquired in childhood causing hidden damage to the lymphatic system.
  • The painful and profoundly disfiguring visible manifestations of the disease, lymphoedema, elephantiasis and scrotal swelling occur later in life and can lead to permanent disability.
  • These patients are not only physically disabled, but suffer mental, social and financial losses contributing to stigma and poverty.
  • In 2020, 863 million people in 50 countries were living in areas that require preventive chemotherapy to stop the spread of infection.
  • The global baseline estimate of people affected by lymphatic filariasis was 25 million men with hydrocele and over 15 million people with lymphoedema. 
  • At least 36 million people remain with these chronic disease manifestations.
  • Eliminating lymphatic filariasis can prevent unnecessary suffering and contribute to the reduction of poverty.

Cause and transmission

Lymphatic filariasis is caused by infection with parasites classified as nematodes (roundworms) of the family Filariodidea. There are 3 types of these thread-like filarial worms:

  • Wuchereria bancrofti, which is responsible for 90% of the cases
  • Brugia malayi, which causes most of the remainder of the cases
  • Brugia timori, which also causes the disease.

Adult worms nest in the lymphatic vessels and disrupt the normal function of the lymphatic system. The worms can live for approximately 6–8 years and, during their lifetime, produce millions of microfilariae (immature larvae) that circulate in the blood.


About two in every three people who have lymphatic filariasis don’t have severe symptoms. But filariasis usually leads to a weakened immune system.

  • Inflammation — an overactivated immune system.
  • Lymphedema — fluid buildup in your lymphatic system.
  • Hydrocele — swelling and fluid buildup in the scrotum.
  • Edema — swelling and fluid buildup in your arms, legs, breasts and female genitals (vulva).


  • The recommended treatment for people outside the United States is albendazole combined with ivermectin.
  • A combination of diethylcarbamazine and albendazole is also effective. Side effects of the drugs include nausea, vomiting, and headaches.
  • All of these treatments are microfilaricides; they have no effect on the adult worms. While the drugs are critical for treatment of the individual, proper hygiene is also required.
  • There is good evidence that albendazole alone; or addition of albendazole to diethylcarbamazine or ivermectin, makes minimal difference in clearing microfilaria or adult worms from blood circulation.
  • Diethylcarbamazine-medicated salt is effective in controlling lymphatic filariasis while maintaining its coverage at 90% in the community for six months.
  • Different trials were made to use the known drug at its maximum capacity in absence of new drugs. In a study from India, it was shown that a formulation of albendazole had better anti-filarial efficacy than albendazole itself.

Trend and present endemicity of the filariasis in India

  • The estimates in 2001 indicate that about 473 million people are exposed to the risk of bancroftian infection and of these about 125 million live in urban areas and about 348 million in rural areas.
  • About 31 million people are estimated to be harbouring microfilaria (mf) and over 23 million suffer from filaria disease manifestations.
  • State of Bihar has highest endemicity (over 17%) followed by Kerala (15.7%) and Uttar Pradesh (14.6%). Andhra Pradesh and Tamil Nadu have about 10% endemicity. Goa showed the lowest endemicity (less than 1%) followed by Lakshadweep (1.8%), Madhya Pradesh (above 3%) and Assam (about 5%).
  • The seven states namely Andhra Pradesh, Bihar, Kerala, Orissa, Uttar Pradesh, Tamil Nadu, and West Bengal, where MDA pilot trials are being undertaken, contribute over 86% of mf carriers and 97% of disease cases in the country.
  • B malayi nocturnal periodic infection is prevalent in the states of Kerala, Tamil Nadu, Andhra Pradesh, Orissa, Madhya Pradesh, Assam and West Bengal.
  • The single largest tract of this infection lies along the west coast of Kerala, comprising districts of Trichur, Ernakulum, Alleppey, Kottayam, Quilon and Trivandrum, stretching over an area of 1800 square kilometer.
  • The infection in the other six states is confined to a few villages only. Surveys undertaken recently in Kerala and a few villages in other states revealed either reduction of foci or complete elimination of the parasite as well as the vector in many villages which were known to be endemic for B malayi infection four decades back.