Lymphatic Filariasis (Elephantiasis)
Lymphatic Filariasis (Elephantiasis)
Why in News?
The West Bengal Government launched a Mass Drug Administration (MDA) campaign to eliminate Lymphatic Filariasis (Elephantiasis) by 2030, administering Diethylcarbamazine (DEC) and Albendazole free of cost in endemic districts.
What is Lymphatic Filariasis?
• Lymphatic Filariasis (LF), commonly known as Elephantiasis (Hathipaon), is a Neglected Tropical Disease (NTD) caused by parasitic filarial worms that damage the lymphatic system.
• It spreads through the bite of infected mosquitoes and often remains asymptomatic for several years, allowing infected individuals to unknowingly transmit the disease.
• Chronic infection causes lymphoedema (swelling of limbs), elephantiasis (thickening of skin and tissues) and hydrocele (swelling of the scrotum), leading to disability, stigma and loss of livelihood.
Causative Organisms
Lymphatic filariasis is caused by three species of filarial nematodes (roundworms) such as Wuchereria bancrofti, Brugia malayi and Brugia timori
• Out of this, Wuchereria bancrofti – causes about 90% of global cases.
Adult worms live in the lymphatic vessels, where they can survive for 6–8 years and continuously produce microfilariae (larvae) that circulate in the bloodstream.
Mode of Transmission
The disease is transmitted through the bite of infected mosquitoes.
Important vectors include:
• Culex – Urban and semi-urban areas.
• Anopheles – Rural areas.
• Aedes – Mainly endemic Pacific islands.
Transmission cycle:
• Mosquito bites an infected person and ingests microfilariae.
• Inside the mosquito, larvae mature into the infective stage.
• The infected mosquito then transmits the larvae to another person during a subsequent bite.
• The larvae migrate to the lymphatic system and develop into adult worms.
Clinical Features
Early Stage
• Usually no visible symptoms for 6–8 years.
• Infected individuals can still transmit the parasite.
• Silent damage occurs to the lymphatic system and kidneys.
Chronic Disease
May result in:
• Lymphoedema (persistent swelling of limbs)
• Elephantiasis (abnormal enlargement and thickening of skin)
• Hydrocele (scrotal swelling)
• Recurrent inflammation of lymph nodes and lymphatic vessels.
• Permanent disability, social stigma and economic hardship.
Mass Drug Administration (MDA)
The Mass Drug Administration (MDA) programme is the principal WHO-recommended strategy to eliminate lymphatic filariasis.
Objective
Interrupt transmission by reducing microfilariae in the blood before mosquitoes can spread the parasite.
Medicines Used in India
• Diethylcarbamazine (DEC)
• Albendazole
Both medicines are distributed free of cost to eligible individuals every year in endemic areas.
India and Filariasis
• India accounts for about 40% of the global burden of lymphatic filariasis.
• Approximately 21.72 crore people remain at risk across 348 districts in 20 States and Union Territories.
Global Scenario (WHO)
• 657 million people in 39 countries remain at risk.
• Around 51 million people were infected globally (2018 estimate), representing a 74% decline since WHO launched the Global Programme to Eliminate Lymphatic Filariasis (GPELF) in 2000.
• More than 9.7 billion preventive treatments have been administered worldwide.
• 871 million people no longer require preventive chemotherapy due to successful elimination efforts.
WHO Elimination Strategy
The WHO recommends annual Mass Drug Administration (MDA) for 4–6 years with high population coverage to interrupt transmission.
According to data presented in a journal on the National Library of Medicine, India accounts for about 40% of the global filariasis burden, with approximately 21.72 crore people at risk of contracting the disease across 348 districts in 20 States and Union Territories (UTs).
