Lymphatic Filariasis

Introduction

• The national health policy had aimed at eliminating filariasis by 2015 but the deadline was extended to 2017 and now has been shifted to 2020.

• But India is likely to miss the target date of stamping out elephantiasis or lymphatic filariasis.

Filariasis

• Filariasis, called hathipaon (elephant foot) locally, can cause limbs, usually the leg, knee downwards, to swell enormously or hydrocele (swelling of the scrotum), causing disfigurement and disability.

• It is caused by various coiled and thread-like parasitic worms.

• These parasites after getting deposited on skin penetrate on their own or through the opening created by mosquito bites to reach the lymphatic system.

• The disease is caused by the nematode worm, either Wuchereria bancrofti or Brugia malayi and transmitted by ubiquitous mosquito species Culex quinquefasciatus and Mansonia  annulifera/M.uniformis respectively.

• The worms produce about 50,000 microfilariae (minute larvae) that enter a person’s blood stream and get passed on when a mosquito bites an infected person.

• The larvae develop into adult worms that can live upto 5-8 years and more in humans. They damage the lymphatic system though no symptoms may show for years.

• It is found that though changes to lymphatic vessels occurred early in the infection, treatment could reverse these in most cases.

Lymphatic filariasis (LF)

• Lymphatic Filariasis (LF), commonly known as elephantiasis is a disfiguring and disabling disease, usually acquired in childhood.

• In the early stages, there are either no symptoms or non-specific symptoms but the lymphatic system is damaged.

• The long term physical consequences are painful swollen limbs (lymphoedema or elephantiasis).

• Hydrocele in males is also common in endemic areas.

• Due to damaged lymphatic system, patients with lymphoedema have frequent attacks of infection causing high fever and severe pain.

National Filaria Control Programme (NFCP)

• After pilot project in Orissa from 1949 to 1954, the National Filaria Control Programme (NFCP) was launched in the country in 1955 with the objective of delimiting the problem, to undertake control measures in endemic areas and to train personnel to man the programme. The main control measures are:

1 Mass DEC administration

2 Antilarval measures in urban areas

3 Indoor residual spray in rural areas.

Strategy to tackle the disease

• Mass drug administration (MDA) in endemic districts ensuring coverage of over 65% population is the global strategy to eliminate the disease.

• Since 2004, the health ministry has been carrying out mass drug administration as part of the Hathipaon Mukt Bharat (Filaria Free India) programme for preventive medication.

• This involves giving at least 65% of the population in endemic districts two drugs:

1 Tablets of diethylcarbamazine citrate (DEC)

2 Albendazole once a year for five years

• Children below two years, pregnant women and seriously-ill people are not eligible for these drugs.

• After five years of MDA and 65% coverage, a transmission assessment survey is conducted to see if the district qualifies for stoppage of mass drug administration.

• The new three-drug combination, IDA, involves adding tablets of Ivermectin to the DEC and albendazole tablets and has been shown to reduce microfilariae by 99% with the first dose itself.

• The two-drug regimen (DEC and albendazole) reduces the disease by 60-80% and hence requires five rounds.

• The new drug regimen is expected to help clear the infection faster as IDA would require just two rounds.

Challenges

• India stopped the MDA in 96 of the 256 districts last year. But many of the 96 districts failed a treatment assessment survey by external evaluators.

• The surveillance that identified the 256 endemic districts is now outdated. A fresh survey could push up the number of endemic districts to over 300. This would require an overhaul of programme strategy and consequently, the chances of meeting the 2020 target are slim.

• It’s also a challenge to get people to take as many as four tablets simultaneously, especially when they have no symptoms. Health workers must ensure the person consumes the tablets right then which doesn’t always happen.

• Recently added drug Ivermectin has to be given according to bodyweight, which could mean adding 2-4 tablets to the existing drug regimen depending on the person’s body weight.

• That could be an additional challenge to the programme, the success of which hinges on community compliance (ensuring people take the medicine) and coverage (ensuring medicines reach at least 65% of the population).

• WHO gives India albendazole free of cost but it has to buy 70% of the required DE, 30% is free. Government will now have to find the funds to buy Ivermectin and meet the cost of expanding the programme. Budget approvals for the same are still in the pipeline.

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