Progress achieved in malaria control / elimination in South-East Asia Region, 2000-2011
In last 10 years, significant progress has been made in lowering malaria morbidity and mortality in the South-East Asia Region as well as infew selected countries in various auspects of disease control which are mentioned below:-
Preventive vector control focusing especially on population at risk
All countries in the region are implementing the two main vector control measures (ITNs / LLINs and selective IRS) depending on the epidemiological settings. Since the adoption of the WHO Global Malaria Control Strategy in 1992, IRS has been the main preventive vector control tool, especially in high-transmission areas and for the control of epidemics. However since the introduction of ITN/LLIN tremendous efforts have been made to scale-up the use of insecticide-treated nets, one of the main vector control priorities of the Revised Malaria Control Strategy 2006-2010 of the region.
IRS is used in high transmission settings and in case of major outbreaks. India, Nepal, Sri Lanka and Thailand are using IRS as a primary vector control measure. In other countries, the same is applied mostly to control epidemics. In Bangladesh, although there is a policy to apply IRS but they have stopped using it since 1991 where as DPRK has started using the same since 2008. In 2010, Timor Leste used IRS first time for malaria control programme. The criteria for applying IRS differ from country to country. In a big country like India IRS is practiced in areas with API>2. Sri Lanka, Thailand and Nepal are applying IRS to the areas with API< 1 as per their intervention policy. During 2000 -2011, the population covered under IRS were between 41–81 million where as total population at risk with API> 10 were around 106-203 million covering 22.8% - 64.3% of the population at high risk (API>10) under IRS. In 2011, 58.5 million population were covered under IRS in the Region. India alone sprayed 53.4 million population followed by DPRK (2.01 million), Indonesia(0.53 million),Thailand (0.42 million), Nepal (0.25 miliion) Sri Lanka (0.08 million), Bhutan (0.15 million), and Timor Leste (0.10 million).
The coverage under IRS in the Region is highly dependent on the performance of India as more than 95% of the population under IRS in the Region is covered by India alone. In all other countries spraying is insignificant. The population coverage under IRS is currently declining mainly because of high pesticide costs, operational cost and vector resistance to insecticides. The countries worst affected due to resistance development in vectors are India, Indonesia, Nepal and Sri Lanka. In Bangladesh, Myanmar and Thailand, anti-vector programmes with domiciliary spraying were impeded on account of the refractory behavior of An. dirus and An. minimus.
Access to LLINs has been very low until recently. The overall coverage under effective ITN / LLIN in the Region has increased slowly but steadily from 1.3% in 2005 to 17% in 2011 among the population at risk (with API>1) of malaria in the Region (Fig.2 ). The above mentioned figures were arrived at under the assumption that the ITN will be effective only for one year where as the life of LLIN will be 3 years. Currently, due to problems in re-treating twice a year, WHO recommends the use of LLINs instead of ITN. The procurement and supply of LLINs has been very low until recently in the Region. This increase in ITN / LLINs can be attributed to donor’s funds which was made available mainly from 2005 onwards. In 2011, the cumulative availability of effective ITN / LLIN was highest in India (11.3 million) followed by Indonesia (6.1 million) and Bangladesh (3.3 million) where as the lowest number in Bhutan(0.13 million) followed by Timor Leste (0.19 million). The access to ITNs/LLINs varies wildly across countries from 8.8% in India to 92.8% in Bhutan amongst population at risk with API>1. In countries like Sri Lanka and Bhutan where population at high risk (API>1) is nil or very little, situation is different and ITNs / LLINs are made available to the population with low risk also. Bhutan, Bangladesh, Thailand and Sri Lanka have made a significant progress in this direction. The various surveys shown that bednet coverage is not uniform and varies appreciably from place to place in the same country as well as between the countries
Integrated Vector Management (IVM)
Vector control under the revised malaria control strategy is primarily based on IRS and ITN/LLIN. In addition some countries are also using fishes in malaria control. In India, urban malaria control is based on: source reduction, chemical larviciding (temephos), biolarvicides (Bacillus thuringiensis and Bacillus sphaericus), Guppy, Gambusia and indigenous fishes, minor engineering interventions, thermal malathion fogging, repellents etc. All countries in the Region are primarily using the ITN/LLIN as preventive method of malaria control. Bhutan, India, Indonesia, Myanmar, Nepal, Sri Lanka, Thailand and Timor Leste are also using IRS. IRS is generally used in high transmission areas and to control outbreaks/epidemics or during emergencies like the floods, earth quakes etc. Chemical larvicides are used in India and Indonesia, and biological larvicides are used in India. Larvivorous fishes are used in Bhutan, India, Indonesia, Myanmar, Sri Lanka and Thailand. Although various methods of vector control are being applied in malaria control but IVM as a strategy to control disease vectors is not used in the Region. This is perhaps due to lack of training of professionals in IVM. Summary of various vector control methods adapted in the control of rural malaria by member countries is briefly given below. Because of the limited options in vector control and limitations in stratification, the Integrated Vector Management (IVM) is poorly implemented in the Region, except in Sri Lanka. The countrywise vector control methods adopted are as under:-
- ITN/LLIN: All countries of the SEA Region
- IRS: Bhutan (Pyrethroids); India (DDT, malation, Pyrethroids); Indonesia (Bendiocarb, L-Cyhalothrin and Etofenprox, Myanmar (DDT), Malathion and alphacypermethrin ; Nepal (Pyrethroids) ; Sri Lanka (Pyrethoids) ; Thailand (deltamethrin bifenthrin, alphacypermethrin); Timor Leste (lambdacyhalothrin)
- Chemical Larvicides: India (Temephos, Fenthion); Indonesia (Pyriproxyfen)
- Fogging: India (Malathion thermal fogging)
- Fishes: Bhutan, India, Indonesia, Myanmar, Sri Lanka and Thailand
- Biolarvicides: India (Bacillus thuringiensis and Bacillus sphaericus
Early Diagnosis and Prompt Treatment Coverage
During 2005-2011, significant progress has been made recently because of availability of resources through donors specially Global Funds and World Bank in deployment of RDTs and ACTs. In 2011, around 114 million blood examination (ABER = 8.6%) were performed in the public sector in the Region. In Bangladesh, Indonesia and Myanmar, intensive case finding was done and hard to reach population were also covered through RDTs. The usage of RDT’s increased from 1.2 million in 2005 to 11.9 million in 2011. In all countries of the Region Rapid Diagnostic Test (RDT) Kits are being used in malaria diagnosis. RDT are supplementing the microscopic diagnosis in areas where either the laboratory facilities are not available or during emergencies in hospitals, border areas, remote and inaccessible areas and alike. In addition laboratory services are being strengthened to minimize the RDTs. Most countries use mono-valent RDTs particularly to test P. falciparum. With increased sensitivity of RDTs and highly competitive cost structure of RDTs, bivalent RDTs are being deployed. There is a surge (see Fig. 3) in the demand of RDTs as Pf can be treated successfully in short time before the formation of gametocytes. ACT combined with RDT can substantially reduce P. falciparum transmission in early diagnosed cases This is an important strategy for SEA Region as this Region is considered as the epicenter of drug resistant malaria.
In the treatment of P. falciparum artemisinin monotherapies have been banned in the Region. All countries of the region have adopted the Artemisinin based combination therapy (ACT) for treatment of P.falciparum cases. The availability of ACT in the Region has increased from 0.08 million in 2005 to 3.5 millions in 2011, showing approximate 43 fold increase over the same period. However, at country level, it is essential to monitor it’s rational use, availability and utilization as the same is having self life.
Reduction in Malaria Incidence and Malaria Mortality
The confirmed malaria cases have sharply declined from 2002 to 2005, there after the trend continued but not so steep. This is particularly visible in Bhutan, DPR Korea, India, Sri Lanka, Nepal, and Thailand. In Bangladesh, Indonesia, Myanmar, and Timor Leste, malaria incidence (confirmed ) did not decline, as a result, the overall malaria incidence in the SEA Region has not declined appreciably between 2000-2011. It may be noted that in the above mentioned countries, due to increased funding, intensive case finding and use of RDT at community level as well as in “hard to reach areas” has resulted in decreased probable malaria cases an increase in confirmed malaria cases and not due to deteriorating malaria situation.
During 2000-2011, the confirmed malaria cases declined by 24% whereas malaria deaths declined by 68% in SEA Region. Out of 10 endemic countries of the Region, confirmed cases declined in 8 countries out of which in 3 countries have registered more than 75% decline namely, Sri Lanka (99.9%), Bhutan (96.1%), DPRK (77.3%), in 3 countries have registered more than 50% decline namely, Thailand (69.5%) , Nepal (55.3%) and Timor Leste (50%) Timor Leste data was compared). India has registered a decline of 35% and Bangladesh could able to manage 7% decline (Fig. 4). In remaining 2 countries namely Indonesia and Myanmar, the reported cases increased by 4% and 284% respectively. The increase in confirmed cases mainly in Myanmar, Bangladesh and very little decline in Indonesia was mainly due enhanced case finding activities employed through donor’s driven funds. The data for Timor Leste could not be compared due to non-availability of base year data. However, country has start reporting their data since 2004 steadily attaining independence in 2002 and compared to 2004 the malaria cases has declined by 50%.
The reported malaria deaths declined in all countries of the Region. During the above mentioned period the 68.2% decline was registered at Regional Level. The highest decline in reported malaria deaths was registered by Sri Lanka (100%) and Nepal (100%) followed by Bhutan (93.3%) Thailand (93.2%), Bangladesh (92.6%), Myanmar (78.9%), Indonesia (53.4%), and India (19.7%). In India, the reported malaria deaths not declined impressively mainly due to better malaria mortality reporting in programme. There was no change in the status of DPRK as P. vivax is not a killer parasite. Further, Timor Leste could not be compared due to non availability of data during the base year (Although, since 2004, in Timor Leste, the reported malaria deaths were declined by 77%).
Increased visibility and awareness of malaria in SEAR through strong, high level political commitment
countries have a national malaria control policy. National grant is supplemented by the GFATM, WHO, UNICEF and other international agencies and NGOs. Member countries have a national malaria control programme with separate budget earmarked for this purpose. All countries have been following the malaria control policies as per the recommendations of the WHO such as the conversion of malaria eradication to malaria control, adoption of the Global Malaria Control Strategy, Roll Back Malaria programme, and the Revised Malaria Control Strategy. As and when invited for the meetings by the WHO and other national organizations they actively participate in the deliberations. Minutes of these meetings become the basis of WHO policies and guidelines. Countries also celebrate Malaria Month/Day, organize popular lectures, circulate popular literature, and use media for information dissemination.
Malaria Elimination Status
Of the 10 malaria-endemic countries in the Region, Sri Lanka has reached to elimination phase of malaria where as Bhutan is in pre-elimination phase. In Indonesia (some islands namely, Bintam, Batam, Java Bali have reached malaria pre-elimination stage) and Thailand are engaged in sub-national level elimination whereas DPR Korea and Nepal are inching towards pre-elimination phase..