Eradication Bill Brieger | 20 Apr 2008 06:47 am
Uzbekistan – a lesson for eradication
Uzbekistan describes the resurgence of malaria after successful elimination in its malaria proposal for Round 4 of the Global Fund to Fight AIDS, TB and Malaria. Below is a short description of the problem extracted from that proposal.
As the outcome of a large-scale malaria eradication campaign that started in the end-1940s, falciparum malaria was eradicated by 1951, whereas the local transmission of P. vivax continued. It was interrupted throughout the country by 1961, like in most other areas of Central Asia. Since then, small outbreaks of vivax malaria occurred from time to time following importation, mostly from Afghanistan. The situation changed dramatically in 1994 when a large-scale epidemic in Tajikistan developed. Following the course of this epidemic that started in the south Tajikistan, importation increased first into the Surkhan Darya Viloyat where a low-level local transmission established in 1999. After the epidemic moved to North Tajikistan and consequently to South Kyrgyzstan, the neighbouring areas of Uzbekistan became vulnerable. It needs to be emphasised that all the above areas of Tajikistan, Kyrgyzstan, and Uzbekistan belong to the same eco-geographic entity, namely the physiographic province of Ferghana. Receptivity of most of the areas now threatened by malaria remains probably as high as before the eradication, particularly due to the restoration of the populations of the most efficient malaria vector, Anopheles superpictus, that were at a very low level in the 1960-1980s.
Severini et al. (2004) also reported that although malaria was eliminated in 1961, “Due to resurgence of the disease in neighbouring states and massive population migration, there has been an increase of P. vivax malaria, imported from Tajikistan, resulting in a number of indigenous cases being identified in areas bordering that country.” CDC also reports “Sporadic cases reported in Uzunskiy, Sariassiskiy, and Shurchinskiy districts (Surkhanda-Rinskaya Region).”
One must remember that the word ‘eradication’ only applies to a situation where a disease is no longer being transmitted anywhere in the world. We can ‘eliminate’ malaria from specific countries or locations, but as has been experienced in Uzbekistan, elimination does not always guard against future transmission. Full application of available tools and development of new tools will be needed before we can use the words ‘malaria eradication’ in good faith.
[We would like to thank the Head of Uzbekistan’s State Sanitary-Epidemiological Surveillance Department who visited Jhpiego recently in a World Trade Center Institute sponsored delegation for stimulating our interest in this topic.]