Exposure to high temperatures is likely to be a major contributor to poor performance of malaria RDTs. Transport from the manufacturer, and road transport within a country, are particularly vulnerable times. Prolonged exposure to high humidity will also rapidly degrade RDTs and may occur after removal of the RDT from the envelope or if the envelope is damaged.
Most manufacturers recommend RDT storage between 2° C and 30° C. Expiry dates are generally set according to these conditions. If kits are stored at temperatures exceeding the recommended limits, it is likely that the shelf life of the RDTs will be reduced and sensitivity lost prior to the expiry date.
The development of a ‘cool chain’ for shipment and storage of RDTs is essential. Control of RDT distribution may best be served by using the same agency which organizes the distribution of drugs and vaccines. Transport and distribution temperatures should be monitored and distribution arranged to minimize time left on airport tarmacs, in transport vehicles, and other situations where high temperatures may be encountered. Storage conditions should be considered carefully and RDTs kept in controlled conditions (air-conditioning) where possible. Elsewhere, local conditions such as thatch versus iron roofs, and shaded buildings, should be considered.
Transport and storage at temperatures above 30°C is sometimes unavoidable, as in many remote locations where RDTs are intended for use. Monitoring the sensitivity of RDTs at appropriate intervals is therefore essential. WHO is developing recommendations for quality assurance to address these issues.
Source: The Use of Malaria Rapid Diagnostic Tests.
Geneva, WHO, 2004.