Maps of the Sri Lanka malaria situation preceding the tsunami and key aspects to be considered in the emergency phase and beyond

Abstract

Background: Following the tsunami, a detailed overview of the area specific transmission levels is essential in assessing the risk of malaria in Sri Lanka. Recent information on vector insecticide resistance, parasite drug resistance, and insights into the national policy for malaria diagnosis and treatment are important in assisting national and international agencies in their control efforts.

Methods: Monthly records over the period January 1995-October 2004 of confirmed malaria cases were used to perform an analysis of malaria distribution at district spatial resolution. Also, a focused review of published reports and routinely collected information was performed.

Results: The incidence of malaria was only 1 case per thousand population in the 10 months leading up to the disaster, in the districts with the highest transmission.

Conclusion: Although relocated people may be more exposed to mosquito bites, and their capacity to handle diseases affected, the environmental changes caused by the tsunami are unlikely to enhance breeding of the principal vector, and, given the present low parasite reservoir, the likelihood of a malaria outbreak is low. However, close monitoring of the situation is necessary, especially as December-February is normally the peak transmission season. Despite some losses, the Sri Lanka public health system is capable of dealing with the possible threat of a malaria outbreak after the tsunami. The influx of foreign medical assistance, drugs, and insecticides may interfere with malaria surveillance, and the long term malaria control strategy of Sri Lanka, if not in accordance with government policy.

Figure 1

Population. Map of population by divisional secretariat division in Sri Lanka estimated for mid December 2004. One dot represents 1,000 people. Sources: Department of Census and Statistics , North East Provincial Council and UNCHR .

Figure 2

Monthly parasite and blood smear examination incidence patterns. Monthly parasite incidence patterns of P. falciparum and P. vivax malaria combined per 1000 population (red line on logarithmic scale), blood smears examined per 1000 population (black line on logarithmic scale), and percentage of blood smears positive for malaria (blue line) from January 1995 to October 2004 in Sri Lanka.

Figure 3

Trends of parasite incidence. Trends of parasite incidence of P. falciparum (red bars) and P. vivax (blue bars) malaria over the years November 1995 – October 1996 (bar on far left) to November 2003 – October 2004 (bar on far right), at district resolution. The height of the bars in the legend represents an annual parasite incidence of 10 cases per 1000 persons.

Figure 4

Parasite incidence of Plasmodium vivax. Map of the districts of Sri Lanka with P. vivax malaria cases per 1000 population over the period January – October 2004.

Figure 5

Parasite incidence of Plasmodium falciparum. Map of the districts of Sri Lanka with P. falciparum malaria cases and mixed infections of both P. vivax and P. falciparum per 1000 population over the period January – October 2004.