Lymphatic Filariasis

  • Category
    Public Health
  • Published
    24th Jan, 2019

Context

  • A pilot project to administer triple drug therapy with the long term aim of eradicating lymphatic filariasis was launched in Nagpur.
  • Nagpur is one of the five districts in the country and only one in Maharashtra, where this triple drug therapy campaign is being launched.

About

More on news

  • Over 40% of worldwide cases are found in India and to eradicate the disease a concerted effort is needed.
  • Since 2004, two drug therapy for lymphatic filariasis has been in place but the addition of the third drug now will give boost to the overall campaign.
  • The third drug used in this therapy will help control adult worms of lymphatic filariasis.
  • Micro filariasis, which is produced by adult worms, is the cause of swollen leg. Previously the adult worms were sterilized by drugs and remained inactive for a year. Now that period will increase to two years.

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.
  • Currently, 856 million people in 52 countries are living in areas that require preventive chemotherapy.

Causes 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 lodge 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 life time, produce millions of microfilariae (immature larvae) that circulate in the blood.
  • Mosquitoes are infected with microfilariae by ingesting blood when biting an infected host. Microfilariae mature into infective larvae within the mosquito.
  • When infected mosquitoes bite people, mature parasite larvae are deposited on the skin from where they can enter the body.
  • The larvae then migrate to the lymphatic vessels where they develop into adult worms, thus continuing a cycle of transmission.
  • It is transmitted by different types of mosquitoes for example by the Culex mosquito, widespread across urban and semi-urban areas, Anopheles, mainly found in rural areas, and Aedes, mainly in endemic islands in the Pacific.

Symptoms

  • Lymphatic filariasis infection involves asymptomatic, acute, and chronic conditions. The majority of infections are asymptomatic, showing no external signs of infection while contributing to transmission of the parasite.
  • These asymptomatic infections still cause damage to the lymphatic system and the kidneys, and alter the body's immune system.
  • When lymphatic filariasis develops into chronic conditions it leads to lymphoedema (tissue swelling) or elephantiasis (skin/tissue thickening) of limbs and hydrocele (scrotal swelling). Involvement of breasts and genital organs is common.
  • Such body deformities often lead to social stigma and sub-optimal mental health, loss of income-earning opportunities and increased medical expenses for patients and their caretakers. The socioeconomic burdens of isolation and poverty are immense.

WHO response

  • To eliminate lymphatic filariasis as a public health problem; in 2000, Global Programme to Eliminate Lymphatic Filariasis (GPELF) was launched. In 2012, the WHO neglected tropical diseases roadmap reconfirmed the target date for achieving elimination by 2020.
  • WHO’s strategy is based on 2 key components:
  • stopping the spread of infection through large-scale annual treatment of all eligible people in an area or region where infection is present; and
  • Alleviating the suffering caused by lymphatic filariasis through provision of the recommended basic package of care.

    Neglected Tropical Diseases (NTDs), a group of infectious diseases, include:

    • Buruli ulcer
    • Chagas disease
    • Cysticercosis
    • Dengue fever
    • Dracunculiasis (Guinea Worm Disease)*
    • Echinococcosis
    • Fascioliasis
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