Prospects of Malaria Control in Northeastern India with Particular Reference to Assam

Malaria is endemic in the entire northeastern region comprising of 7 states. P. falciparum is the most predominant species. P. falciparum has become resistant to chloroquine (CQ) and sulphadoxine pyremethamine (SP) drugs. The principal vectors viz. An. baimaii (formerly species D of An. dirus complex), An. minimus and An. fluviatilis are highly efficient in malaria transmission with exophilic and exophagic behavior, and maintain stable malaria in the region. Problems in malaria control and way forward in achieving sustainable malaria control are described. Introduction The present situation of malaria in India is best described as malaria endemic country with >95% of her population at risk of malaria. Reported cases of malaria vary from 1.8 to 2.0 million (1.2 million in 2006) and 1, 000 deaths per year. WHO SEARO estimates 15 million cases and 19,500 deaths, whereas WHO HQs estimates 70 million malaria cases (Sharma, 2005). The proportion of P. vivax and P. falciparum is almost equal but it varies greatly from place to place and seasonally. P. falciparum is a killer parasite and it has become resistant to chloroquine with reports of resistance to other antimalarial drugs. P. vivax is sensitive to chloroquine but in the last decade resistance to chloroquine has been reported from a few places in the country (Dua et. al. 1996). The total number of cases and the percentage of P. falciparum are rising as a result of fall in P. vivax. Furthermore clinical profile of P. falciparum patients is becoming more severe with increasing trend of renal and respiratory complications and multi-organ failure (B.S. Das, Personal Communication, formerly at the Ispat Hosptial Rourkela). The major vector of malaria An. culicifacies responsible for generating 65% malaria cases has developed resistance to DDT and Malathion (Sharma, 1996). Synthetic pyrethroids are being sprayed to control the emerging epidemics. Multiple insecticide resistant mosquito strains have emerged so that malaria control is attainable partially, if at all. Malaria returns year after year requiring spraying, but due to limited resources spraying is carried out in 10% endemic population. National Anti Malaria Programme (NAMP) has been renamed as the National Vector Borne Disease Control Programme (NVBDCP) making it accountable for the control of all vector borne diseases. Malaria epidemics have become commonplace and more devastating. Emergency measures are adopted to suppress the epidemics. This produces transient relief, but the over all picture remains unchanged. New diseases are emerging and spreading e.g. Dengue and Dengue Hemorrhagic Fever (DHF) and Chikungunya virus fever (CHIKV). NVBDCP is spending its limited resources in fighting the re-emerging arboviral diseases (Lahariya and Pradhan, 2006; Bhargava and Chatterjee, 2007; NVBDCP Website). Malaria control in the tribal settlements is to be seen in the above background of rapidly deteriorating situation of vector borne diseases and resource crunch. 22 Proceeding of National Symposium on Tribal Health 22 Tribal Malaria India has 635 tribes and constitutes 7.8 % of the country’s population. The tribal population is 87.7 million. Bulk of this population is scattered in 8 states. Almost all population of northeastern states belong to tribal group which has a separate funding mechanism i.e. malaria control in NE states is a centrally sponsored activity since December 1994. Therefore central government contribution has no restriction of 50% matching grant from the states. That makes malaria control more sustainable in as far as the resources are concerned. Tribal malaria control generally refers to the Enhanced Malaria Control Project (EMCP) launched with World Bank (WB) financing to cover 1,045 Primary Health Centre (PHCs) in 100 predominantly tribal and malaria endemic districts in 8 states namely, Andhra Pradesh, Bihar, Chhatisgarh, Gujarat, Jharkhand, Madhya Pradesh, Maharashtra and Orissa. Enhanced Malaria Control Project (EMCP) was launched with World Bank funds in September 1997 with the objective to strengthen malaria control by additional inputs through a mix of interventions. While malaria control in the EMCP areas of 8 states is being presented by other investigators (Sharma, 1999). I wish to briefly describe the tribal malaria situation in the northeastern states, in particular the state of Assam. Situation Analysis The population of northeastern (NE) states is 39 million i.e. 3.96% of the country’s population. Of the total burden of malaria in India, NE states contribute 10% malaria and 11% P. falciparum cases and 20% malaria deaths. Malaria control depends on effective vector control. In the NE region malaria vectors are viz., Anopheles minimus (perennial species), An. baimaii (monsoon species), and An. fluviatilis (winter species). All these mosquitoes are highly efficient in the transmission of malaria (Dev, 1996; Dev et. al. 2001). Malaria vectors are susceptible to DDT, HCH, Malathion and Synthetic Pyrethroids but because of the exophilic and or exophagic vector behavior they avoid resting on the sprayed walls, and thus avoid the killing action of insecticides. The situation is further complicated by high proportion of P. falciparum >60%), a killer parasite that has become multi-drug resistant (Dua et. al. 2003; Dev et al, 2003). Table 1 gives the areas and population involved in cross-border malaria. P. falciparum is the dominant parasite all along the international borders which is widely disseminated by the population movement on both sides of the international borders. Fig. 1 gives the location of districts in Assam. Fig. 2 gives the An. minimus man hour densities in Sonapur PHC villages. High densities are encountered from March-April till the end of August and these are related to rainfall. Fig 3. gives the malaria incidence (Pv and Pf) over a three year period. Malaria peaks during the rainy season. It is notable to mention that environmental determinants favor malaria transmission almost throughout the year except a brief period of interruption due to cold weather (Dev et. al. 2006a). Table 2 gives the epidemiological situation of malaria in Assam. NVBDCP reports declining trend of malaria each year and in 2006 1.2 million cases were reported (lowest since resurgence in 1976). It is notable to mention that malaria situation in Assam is grim as is evident by the fact that in 2006, malaria cases have doubled, and 300 malaria deaths were reported from 23 districts. An estimated one million population of 66 PHCs and 1,720 villages were severely affected in the outbreaks. Malaria is also affecting the economic zones of the state e.g. tea gardens and industrial belts of the state.