Saturday, September 15, 2007

Malaria, Public Health & Environment

Spraying of DDT leads to its transfer of residues through food chain resulting in its bioconcentration culminating in its biomagnifications in primary and secondary consumers including man. An editorial “Resurrection of DDT: A critical appraisal” in the July 2007 issue of Indian Journal of Medical Research suggests, “Environmentalists must reassess the situation based on data obtained after its ban in agriculture in India and elsewhere.” This journal is published by the Indian Council of Medical Research.

It further submits, “In India, at present DDT is used against malaria vectors which are susceptible to DDT as in North Eastern States and hilly regions of the country. This regulated use of DDT exclusively for public health showed gains in reduction in DDT residue levels in many items of food. Anopheles culicifacies, major vector of malaria highly resistant to DDT since 1960s, now shows increased susceptibility in Gujarat and other parts of the country where DDT was withdrawn since 1969 (unpublished). These results dispel the misinformation that DDT is no longer effective in entire India.”

Commonly known as DDT, its scientific name is 1,1,1-trichloro-2,2-bis (p-chlorophenyl) ethane was synthesized by Othmar Zeidler in 1874, came to lime light with Paul Muller’s
discovery of its insecticidal properties in 1939. It is claimed that DDT achieved a unique distinction of saving millions of lives by preventing disease outbreaks than any other man made chemical in history for which Muller was awarded the Nobel Prize for medicine in 1945.

The WHO/UNICEF Roll back malaria (RBM) initiative to reduce 50 per cent deaths by 2010 in Africa it involved use of pyrethroid treated nets, pyrethroid IRS and artemisinin. Donor nations for RBM mandated only the use of pyrethroids in place of DDT. In India, the use of DDT in agriculture was banned in 1989 with a mandate to use a maximum of 10,000 tons of DDT per annum for the control of malaria and Kala-azar and this policy is strictly adhered to till date.

The global incidence of malaria is about 500 million cases and according to UN estimate malaria kills one child every 30 sec and more than a million people per annum mainly in Sub Saharan Africa.

One of the eight Millennium Development Goals is to “Halt and begin to reverse the incidence of malaria and other major diseases”. National Health Policy 2002 admits, “Out of the communicable diseases which have persisted over time, the incidence of Malaria staged a resurgence in the1980s before stabilising at a fairly high prevalence level during the 1990s. Over the years, an increasing level of insecticide-resistance has developed in the malarial vectors in many parts of the country, while the incidence of the more deadly P-Falciparum Malaria has risen to about 50 percent in the country as a whole.”

The National Rural Health Mission (NHRM) focuses on providing key attention to 18 Indian states, improving the availability and quality of health care in rural areas, synergy between health and determinants of good health, capacity building and involving the community in the planning process. For 2005-2012, the NRHM identified a list of disease reduction outcomes, including Malaria mortality among other things.

Phanishwarnath Renu in his novel Maila Anchal published in the very year the national malaria control programme captured its impact on the village of Maryganj. The government and global institutions argued that malaria control would increase agricultural productivity.

Malaria almost disappeared by the late 1950s. At the end of 1958, a total of 8,704 malaria squads were in operation who sprayed a total of 438 million houses. The number of recorded cases of malaria fell from 75 million in 1951 to just 50,000 in 1961. The malaria eradication programme employed 1,50,000 people by 1961. Malaria cases accounted for less than 1 per cent of all hospital admissions, an astonishing diminution in the burden of malaria.

There was a resurgence of malaria in the 1960s because of resistance to DDT and to anti-malarial drugs. Reliance on DDT was a consequence of the weakness of India’s health infrastructure. The success of DDT was dependent on medical surveillance that was absent. An active programme of “case-finding” constituted a crucial final stage in malaria eradication that could not be completed.

The development of malaria control policy in the 1950s encapsulates, in many ways, the political culture of public health that evolved after independence. This is, not least, because at its height, between 1959 and 1963, the national malaria eradication programme took up nearly 70 per cent of India’s budget for communicable disease control, itself accounting for nearly 30 per cent of the overall health budget under the second plan.

India became the world’s largest market for DDT. The malaria eradication programme was heavily dependent on outside funding: between 1952 and 1958, the US contributed more than 50 per cent of the cost of the programme, and nearly 40 per cent of the cost of the eradication programme between 1959 and 1961. The national malaria control programme turned into malaria eradication. The memoirs of D K Viswanathan, India’s foremost malariologist at the time refers to the effort as “worship at the altar of science”.

In 1963, the USAID stopped providing DDT to India due to debates in the US about the safety of DDT, following Rachel Carson’s seminal publication, Silent Spring. India was compelled to purchase DDT from US under a long-term loan agreement.

India has spent up to 25% of its health budget on malaria control from 1977-1997, and starting in 1997, India planned to spend $40 million on malaria control, a 60% increase from the previous year. This expenditure is part of a five-year program aimed to target 100 districts where 80% of all P. falciparum cases occur. 70-80% of the malaria control money in India is spent on insecticides.

in 1976, 6.45 million cases were recorded by the National Malaria Eradication Programme (NMEP), highest since resurgence. The implementation of urban malaria scheme (UMS) in 1971-72 and the modified plan of operation (MPO) in 1977 improved the malaria situation for 5-6 years. Malaria cases were reduced to about 2 million. The impact was mainly on vivax malaria. Easy availability of drugs under the MPO prevented deaths due to malaria and reduced morbidity, a peculiar feature of malaria during the resurgence. The Plasmodium falciparum containment programme (PfCP) launched in 1977 to contain the spread of falciparum malaria reduced falciparum malaria in the areas where the containment programme was operated but its general spread could not be contained. P. falciparum showed a steady upward trend during the 1970s and thereafter. Rising trend of malaria was facilitated by developments in various sectors to improve the national economy under successive 5 year plans.

Malaria at one time a rural disease, diversified under the pressure of developments into various ecotypes. These ecotypes have been identified as forest malaria, urban malaria, rural malaria, industrial malaria, border malaria and migration malaria; the latter cutting across boundaries of various epidemiological types.

Further, malaria in the 1990s has returned with new features not witnessed during the pre-eradication days. These are the vector resistance to insecticide(s); pronounced exophilic vector behaviour; extensive vector breeding grounds created principally by the water resource development projects, urbanization and industrialization; change in parasite formula in favour of P. falciparum; resistance in P. falciparum to chloroquine and other anti-malarial drugs; and human resistance to chemical control of vectors.

The US Environmental Protection Agency (EPA) in had special hearings during 1971-1972 regarding the continued use of DDT following which it declared the ban on DDT in 1972 owing to ecological and reproductive health problems. As a result of campaigns by Royal Malaria Foundation International and other agencies to prevent a ban on DDT its use in public health emergencies like outbreaks of malaria was exempted from the ban. During 1970 to 1986, a total of 34 countries mostly from developed nations implemented the ban.

India is a signatory to Stockholm Convention on persistent organic pollutants (POPs) that has identified DDT as one of the 12 POPs that are banned. But DDT ban has certain restrictions applicable to countries that have notified to the secretariat for its continued use. The restriction permits indoor residual sprays of DDT in malaria control as per the WHO specifications for its production and following safety precautions for its proper use and disposal. Phasing out of DDT is delayed till an effective, affordable and safe alternative is available. In such a backdrop, the strong recommendation of WHO for indoor use of DDT to fight against malaria in September, 2006 that gave a clean bill to use of DDT to combat malaria in Africa and other areas where the vectors are still susceptible to DDT is believed to be the result of corporate influence.

The currently used pesticides globally cause about 20,000 deaths annually by accidental and deliberate/intentional poisoning. DDT residues remain in topsoil up to 7-8 cm and being immobile rarely contaminates ground water. Half-life of DDT residues in temperate soil is estimated to be 2-15 yr as against 6-14 months in tropical and subtropical soils.

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