Prof. (Dr.) Dharmakanta Kumbhakar
(The writer can be reached at drkdharmakanta@yahoo.com)
Malaria continues to be a major public health problem, afflicting 36 percent of the world population in 107 tropical and sub-tropical countries. It imposes a great socio-economic burden on humanity worldwide. The WHO estimates 300–500 million malaria cases annually, and 90 percent of this burden is in Africa alone. In the Southeast Asian Region, out of about 1.4 billion people living in 11 countries, 1.2 billion are exposed to the risk of malaria, which contributes about 2.5 million cases to the global burden of malaria. India alone contributes about 70 percent of the 2.5 million reported cases in Southeast Asia. More than two-thirds of the Indian population lives in malaria zones, with the largest proportion of cases coming from the states of Orissa, Jharkhand, West Bengal, the North Eastern States, Chhattisgarh, and Madhya Pradesh. Most of the malaria-attributable mortality is reported in Orissa and other forested areas occupied by ethnic tribes in the country. Overall, out of 4.2 million disability-adjusted life years lost due to vector-borne diseases, malaria alone accounts for an estimated 1.85 million years lost per year in India.
It is now well accepted that the reported incidence of malaria at the national level on the basis of surveillance carried out in the primary health care system at best reflects a trend and not the true burden of malaria. The actual incidence is definitely far greater than presently known. The reasons attributed to such a gap are deficiencies in coverage, collection and examination of blood smears, and the reporting system. Malaria continues to be one of India’s leading public health problems. It constitutes one of the most important causes of economic misfortune, engendering poverty, which lowers the physical and intellectual standards of the nation and hampers prosperity and economic progress in every way.
The annual parasite incidence (API) is a malariometric index to express malaria cases per thousand populations. As per the NVBDCP incidence records, in most parts of India the API was less than two, whereas 2–5 API was in scattered regions, while regions with more than five API were scattered in the states like Rajasthan, Gujarat, Karnataka, Goa, southern Madhya Pradesh, Chhattisgarh, Jharkhand, and Orissa, and in the northeastern states. The proportion of P. vivax and P. falciparum varies in different parts of India. Although most of the Indo-Gangetic plains and northern hilly states, north-western India and southern Tamil Nadu state have less than 10 percent P. falciparum and the rest are P. vivax infections, in the forested areas inhabited by ethnic tribes, the situation is reversed and the P. falciparum proportion is 30–90 percent, and in the remaining areas it is between 10 percent and 30 percent.
Malaria transmission dynamics are highly affected by socio-economic and environmental factors. There are six major and three minor malaria vectors, of which Anopheles culicifacies transmits malaria in rural areas and Anopheles stephensi in towns. Other vectors are of local importance. Although vivax malaria is perceived as a benign disease, recent reports indicate an increasing incidence of severe disease and chloroquine therapy failures associated with plasmodium vivax, and the economic loss due to the disease is enormous. The emergence of vector resistance to widely used insecticides and parasite resistance to first-line drugs have resulted in a rise in malaria incidence in many endemic areas, resulting in the need to resort to more costly chemotherapeutic agents with greater toxicity. In India, chloroquine resistance in P. falciparum was first reported from Manjha in Karbi Anglong district in 1973 and then from Nowgaon in 1974 in the northeastern state of Assam. More cases were then detected in the next 3–4 years in Assam, Arunachal Pradesh, Mizoram, and Nagaland.
In India, pregnant women constitute an important risk group for malaria infection. The well-known effects include the effectiveness of the placental barrier, parasite sequestration in the placenta, suboptimal nutrition of the foetus, congenital malaria, severe anaemia, intrauterine growth retardation, low birth weight, premature interruption of pregnancy, ortions, stillbirths, ininfant mortality, and maternal death. In India, malaria is one of the most important causes of direct or indirect infant, child, and adult mortality. Reports suggest that mortality in complicated P. falciparum is due to cerebral malaria, acute renal failure, hepatic involvement, and multiple organ dysfunction or failure, which is becoming a common feature. P. vivax had severe manifestations, which included jaundice, severe anaemia, respiratory distress with acidosis, acute renal failure, cerebral dysfunction with multiple convulsions, abnormal bleeding, shock, pulmonary edoema, and hemoglobinuria.
In pre-independent India, the death toll due to malaria was estimated at one million during normal years and two million during epidemic years. Malaria mortality steeply declined after the National Malaria Eradication Programme was launched in 1958. The National Programme reported 879, 666, 1057, 946, and 938 deaths due to complicated P. falciparum malaria from 1997 to 2001 showing a Specific Malaria Mortality Ratio (SMMR) of 0.30 to 0.48 in these years. The age-sex distribution of malaria deaths shows that in general, malaria mortality across all ages was comparatively higher in males than in females. This mortality gap between genders widens after the age of 25. The overall number of deaths in males was 2827 (63.1%) as compared to 1654 (36.9%) in females, with a male:female ratio of 1:0.56.
Health planners and administrators need estimates of the true burden of malaria for the allocation of much-needed resources for interventions. Drug resistance, insecticide resistance, a lack of knowledge of the actual disease burden, and new paradigms of malaria pose a challenge for malaria control in the country. Considering the existing gaps in reported and estimated morbidity and mortality, the need for an estimation of the true burden of malaria has been stressed. A good investment in malaria control not only makes good public health sense but also makes economic sense in the present era of economic liberalization. A firm malaria control system is imperative for human resource development, which in turn is imperative for equitable and sustained economic growth.