Use of serum and blood samples on filter paper to improve the surveillance of dengue in Pacific Island Countries

Abstract
Background: In Pacific Island Countries (PICs) the epidemiology of dengue is characterized by the long-term transmission of a single dengue virus (DENV) serotype. The emergence of a new serotype in one island country often indicates major outbreaks with this serotype will follow in other PICs.
Objectives: Filter paper (FP) cards on which whole blood or serum from dengue suspected patients had been dried were evaluated as a method for transportation of this material by standard mail delivery throughout the Pacific.
Study design: Twenty-two FP-dried whole blood samples were collected from patients in New Caledonia and Wallis & Futuna Islands, during DENV-1 and DENV-4 transmission, and 76 FP-dried sera collected from patients in Yap State, Majuro (Republic of Marshall Islands), Tonga and Fiji, before and during outbreaks of DENV-2 in Yap State and DENV-4 in Majuro, were tested for the presence of DENV RNA, by serotype-specific RT-PCR, at the Institut Louis Malardé in French Polynesia.
Results: The serotype of DENV could be determined, by a variety of RT-PCR procedures, in the FP-dried samples after more than three weeks of transport at ambient temperatures. In most cases, the sequencing of the envelope gene to genotype the viruses also was possible.
Conclusions: The serotype and genotype of DENV can be determined from FP-dried serum or whole blood samples transported over thousands of kilometres at ambient, tropical, temperatures. This simple and low-cost approach to virus identification should be evaluated in isolated and resource-poor settings for the surveillance of a range of significant viral diseases.