Background
Over the past 150 years, the strategy to gradually eliminate malaria worldwide has shown remarkable progress. In spite of 3 million lives being saved between 2000–2012, an estimated 627,000 people die from malaria each year. Increased resources has resulted in a dramatic expansion and scaling up of malaria control interventions with subsequent reductions in disease burden in some parts of the world. Malaria elimination is the ultimate goal of any malaria control programme and requires commitment at the highest level.
Strong malaria surveillance systems are fundamental to both programme design and implementation. Asymptomatic parasite carriers provide a reservoir of infection in low-endemic countries that may contribute to continuous low-grade transmission of the disease and ignite devastating epidemics. With emphasis being given to track every malaria case in a surveillance system, scaling up diagnostic testing to ensure detection of asymptomatic cases and treating them so as to interrupt indigenous transmission, is a major challenge for the successful implementation of a malaria elimination programme in any malaria-endemic country.
Following the devastating malaria epidemic which occurred in Sri Lanka in 1934–35, the country was successful in bringing down the number of cases to 17 in 1963. However, due to the early withdrawal of control measures such as indoor residual spraying as per the strategy adopted in the consolidation phase of the malaria eradication programme at that time, poor surveillance and withdrawal of funding for malaria control as malaria was not considered a priority due to the decreased disease burden, a major epidemic was recorded in 1967–1969. The most recent epidemic occurred in 1986/87 with 56 reported cases per 1,000 persons in malaria-endemic areas. During the 1990s, 70% of the reported cases were from Northern and Eastern Provinces of Sri Lanka. The number of reported cases and deaths declined more than ten-fold since 1999 and in 2008, during which 196 confirmed cases of malaria were reported. In 2012, 24 indigenous and 70 imported malaria cases were reported and no case of indigenous malaria has been reported since October 2012. The end of the civil conflict in 2009 and implementation of intense malaria control activities in the Northern and Eastern Provinces and the neighbouring districts by the Anti Malaria Campaign (AMC), together with close monitoring and evaluation of interventions, may have contributed to this reduction and absence of cases.
Sri Lanka embarked on a malaria elimination programme in 2009 with the aim of eliminating Plasmodium falciparum by end 2012, and Plasmodium vivax by end 2014. Tropical and Environmental Disease and Health Associates Private Limited (TEDHA) is one of the three principal recipients of the Round 8 Global Fund to fight against AIDS, Tuberculosis and Malaria grant to assist the AMC in surveillance. TEDHA established malaria diagnostic laboratories in 43 government hospitals in the Northern and Eastern provinces which bore the brunt of the civil war, as requested by the AMC, to carry out parasitological surveillance to supplement the services carried out by the AMC. APCD, PCD and ACD have been used in Sri Lanka. APCD where all fever cases were tested for malaria was the mainstay of disease surveillance. With the reduction of the disease burden, doctors were reluctant to refer all fever cases for malaria testing and most of the time only suspected cases were referred for malaria testing making the system more PCD than APCD. ACD has been used whenever outbreaks have occurred where mobile teams visited the areas and conducted surveys irrespective of whether persons had a history of fever or any symptoms suggestive of malaria.
All three surveillance techniques (PCD, APCD and ACD) are carried out by TEDHA by trained persons. This manuscript describes the importance of ACD in the malaria elimination efforts of Sri Lanka to interrupt malaria transmission.