Die hard

Identified a century ago and viciously attacked by pesticides and drugs, the Anopheles mosquito and the malarial parasite still survive to prey on humanity

 
Published: Saturday 04 July 2015

Even as humankind exults in having unlocked the secrets of the insect kingdom, the war between humans and insects is far from over. Several conflicts between humans and insects have been won by humans, but they have been hollow victories at best.

In its desire to beat the pests, humanity has poisoned its rivers, its food and even the very air. But the bugs still remain. Today the Anopheles mosquito is still around to transmit the malaria bug and worse the disease shows signs of being resistant to traditional therapy. As the world celebrates the centenary of Ronald Ross's discovery of the malarial parasite, signs of defeat are very much in the air.

A hundred years ago Sir Ronald Ross, lived and worked in Calcutta. It was he who identified the malaria parasite. Today ten decades later scientists and civic authorities are still trying to grapple with this disease characterised by high fever and ague.

Malaria is often fatal. According to World Health Organization estimates, the disease claims about 2.7 million lives annually and afflicts 500 million people a year. ( Down To Earth , Vol 5, No 3). Ninety per cent of the cases occur in Africa and a large percentage of the rest mainly in India. Afghanistan, Brazil, Columbia, Sri Lanka and Thailand follow suit.

The disease is transmitted when a healthy human host is bitten by an infected mosquito and even at times through blood transfusion. In India officials claim the incidence of malaria in the country, has stabilised at about 2.5 million cases per year but health experts are of the opinion that these figures are gross underestimates.

Malaria eradication was believed to be around the corner in the 1950s and '60s. But it seemed the nimble vector was always ahead of the humans who tried to destroy it. The fragile looking mosquito developed resistance to insecticides and the single-celled parasite it carried became resistant to drugs leading to a resurgence of the disease. Health authorities found they were chasing a mirage. The programme was therefore downscaled to a strategy for control of malaria and later further down scaled to managing the epidemic.

But managing the epidemic may not be so easy. The situation is likely to deteriorate further. Public health institutions have virtually collapsed. Primary health care is becoming more and more inaccessible, poverty is on the increase and as the poor live on the fringes of the environment it provides an ideal breeding ground for the Anopheles mosquito. Shrinking health budgets contribute to the malady and improper surveillance and irrational use of pesticides and drugs compound the problem. Mismanagement, lack of information and coordination and of course corruption gnaw into the vitals of epidemic management schemes.

Ground realities are alarming. The mosquito has shown resistance to insecticides like dichloro diphenyl trichloro ethane ( ddt ), malathion and dieldrin. Resistance is also developing to multiple insecticide combinations. There are two types of malaria, the most common vivax malaria, a benign form which recurs unless treated effectively. The other is cerebral malaria, which is even fatal. India's entire population, with the exception of perhaps 15 million people living at high altitudes above 5,000 feet, is at risk.

Tribals, children, pregnant and lactating women and the poor stand at a higher risk. Malaria can also increase the chances of abortion, low birth weight, still births and complications during delivery. But this does not mean that the rich are immune. An epidemic is both secular and democratic and chooses its victims without distinction.

The failure of the major public health institutions in the country coincides with the resurgence of malaria. A countrywide view of control strategies was undertaken in 1995, following which a malaria action programme was launched. However, the emphasis still remained on the use of insecticides. Till date, we have unfortunately, pursued a policy of mutually assured destruction, in the war against malaria. In our zeal to exterminate the mosquito we have poisoned our environment and the time has come to review our strategy.

In the fight against malaria it is vital to develop new drugs and vaccines and concentrate on eradicating breeding centres. Environmental management of the disease is a major plank which has till date been neglected. If malaria has to be fought it has to be combated on a war footing, but with a new type of ammunition.

Health experts strongly argue for bio-environmental controls like spraying larvicidal microbes or through fish species such as the guppy. Bednets impregnated twice a year with synthetic pyrethroids are supposed to offer effective protection against mosquitoes. Lastly but not least, comes the involvement of the local communities. Local communities can play a much-needed role in keeping the environment clean and eradicating breeding sites, but bureaucratic responses to epidemics consistently fail to take the local community into consideration.

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