Under-represented in the Indian press, elephantiasis and kala-azar take their toll on poor communities. Sanjit Bagchi reports on these endemic parasitic infections

Terai region, in the foothills of the middle Himalayas, is a holiday haven for trekkers from all over the world. The picturesque valleys-of India, Nepal, Bangladesh and Bhutan-are also a happy hunting ground of sand flies, the deadly vectors of a fatal parasitic disease called kala-azar or visceral leishmaniasis. Those who become infected have irregular bouts of fever, substantial weight loss and anaemia. If the condition is left untreated mortality is about 100%.¹

In the top five

According to an estimate by Médicins Sans Frontières (MSF), kala-azar is one of the top five neglected diseases of the world, infecting about 500 000 people and killing 60 000 people each year.^{2 3} Most deaths occur in the Terai region because people in these areas are so impoverished that they cannot afford the $150 to buy the basic sodium stibogluconate treatment. The average annual income of a person in this area is mere $200.

Moreover in recent years the parasite leishmania has become resistant to this traditional treatment, which has led to several small outbreaks in areas of north Bihar (in India) and in adjoining Nepal and Bangladesh.

Treatment is a deterrent

Because of a lack of facilities for early diagnosis, poverty, and lack of awareness in rural people the disease rarely gets treated in its initial stages. In addition, the duration of the first line treatment--a course administered daily through injections over at least three weeks--is a deterrent for many patients, who cannot afford to stay away from work

At later stages of the disease, many associated problems such as malnutrition, immunosuppression, secondary infection, drug toxicity, and drug resistance further deteriorate the response to the drug. Moreover, untreated cases act as human reservoirs, spreading the disease far and wide beyond the endemic zone.

One major need is a new generation drug with a simpler regimen. But as visceral leishmaniasis mainly affects poor people, research and development of new diagnostics and drugs have been neglected. Projects rank low in the private sector, and only limited funds are available. Pharmaceutical companies prefer to invest money in research for anti-parasites for pets in rich countries rather than life saving drugs for millions in developing countries.⁴

However, in recent years organisations such as MSF, Drugs for Neglected Diseases (DNDi), and the Indian Council for Medical Research have come forward to develop vaccines and new drugs for visceral leishmaniasis as a part of the World Health Organization's Tropical Disease Research (WHO/TDR) initiative. They expect that in the next few years better treatment will appear.⁵

Controlling the sandfly

Until the new treatments appear the governments should channel their meagre resources into basic hygienic measures--for example, spraying malathion or pyrethroids in the endemic zones to get rid of the sandflies.

However, these simple steps are not implemented because of gross mismanagement. According to a report from India's health ministry, from the cash allocated by the central government of the state of Bihar to control sandflies a mere 15% of the money was used by the state health department.

Meanwhile the death toll of the disease is steadily increasing, particularly affecting children and young adults. The latest projections by WHO are even scarier. Cases of co-infections with leishmania and HIV are being reported in various parts of the Terai.

Elephantiasis

Another neglected disease is lymphatic filariasis (elephantiasis) spread by mosquito bites. This rarely hits headlines, for two major reasons. Firstly, it's not fatal, and secondly, it affects poor people, who either fail to recognise the symptoms in the early stages or simply don't have the resources to fight the disease.

Asia is bearing the brunt

Asia is believed to carry 60% of the global disease burden, with India contributing about 74% of the endemic population. According to estimates 28 million people are carriers of the filarial parasite, and there are 21 million clinical cases in India.⁶

Although the death toll due to filaria is negligible, the country loses money and manpower to this debilitating disease--through both incapacitation and stigmatisation. The external manifestation of the disease has a role in this. Externally it causes swollen heavy arms and legs because of lymphoedema, and internally, it can damage the lymphatic circulation system. In severe cases it painfully affects the genitals.

The disease is caused by slender, parasitic nematodes (Wuchereria bancrofti, Brugia malayi, or Brugia timori) which can stay undetected in the body for a long time--even up to a decade--showing up only at night, which is why a daytime blood test fails to detect anything. The adults, lying deep inside the lymphatic vessels, release the young (called microfilariae) in huge numbers to overwhelm the lymphatic system. Since it takes a long time to get to the stage when the limbs are swollen, victims may never know that they have been infected until it is too late. The disease is transmitted in rural areas and slum clusters through mosquito bites.

Failure of government

Although the disease is preventable, successive filarial control programmes by the Indian government since 1956 have failed to eradicate the disease.⁷ Recently WHO has resolved to eliminate the disease by 2020. Last year an elaborate strategy was devised at the second meeting of the Global Alliance for the Elimination of Lymphatic Filariasis at New Delhi.⁸ Although the ambitious strategy--identifying endemic zones, followed by mass administration of once yearly single doses of the drugs diethylcarbamazepine and albendazole--seems simple, it is easier to plan than execute. An alternative is to educate people about prevention methods. Simple rules of hygiene and cutting down mosquito breeding will help to stop the transmission chain. New diagnostic tools to detect the circulating parasites are also needed.

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