Virological Surveillance of Dengue in Saint Martin and Saint Barthélemy, French West Indies, Using Blood Samples on Filter Paper

Abstract

* RT-PCR = reverse transcriptase-polymerase chain reaction. † Laboratory-confirmed dengue cases based on positive NS1 or/and IgM patients reported by the laboratories. DENGUE VIROLOGICAL SURVEILLANCE USING FILTER PAPERfor DENV-1 (336 of 352), 4.3% for DENV-2 (15 of 352), and 0.3% for DENV-4 (1 of 352) ( Table 3 ).The first epidemic reported in Saint Barthélemy began at the end of October 2008 (Week 43), within 3 weeks after the dengue epidemic alert was issued for Saint Martin ( Table 3 and Figure 2 ). The biological surveillance network reported 152 cases, of which 62 of them were analyzed by RT-PCR ( Table 3 ). This epidemic was similar to the one observed in neighboring Saint Martin in two characteristics: i) DENV-1 was the predominant serotype (91.9%; 57 of 62), and ii) the epidemic ended in February 2010 (Week 07). This dengue outbreak was followed by a 39-week long inter-epidemic period of sporadic transmission.In mid-November 2009, another dengue outbreak took place in Saint Barthélemy. Although the two epidemics had similar durations (17 weeks in 2008-2009 versus 16 weeks in 2009-2010), 2-fold more laboratory-confirmed dengue cases were reported for the latter Saint Barthélemy outbreak ( N = 379) than for the previous one ( N = 152). One hundred seventeen NS1-positive blood samples were subtyped by RT-PCR: 114 were DENV-1 (97.4%) and 3 were DENV-2 (2.6%). Although the DENV-1 serotype predominated during this period in Saint Barthélemy, the DENV-2 serotype was found to predominate among specimens provided from the same period in Saint Martin. DISCUSSIONDengue has become a major public health burden in tropical and sub-tropical regions of the world, partly because of the increased number of reported cases, particularly severe clinical forms, and the increased number of deaths attributable to this disease. With no specific treatments available for patient management and no vaccine yet available to protect vulnerable populations, prevention of this arboviral disease plays a crucial role in its control. Among the different approaches implemented, an active surveillance system was advocated in the 1980s notably to detect dengue outbreaks early and to monitor the introduction of new dengue subtypes. 6,[25][26][27] We reported here the epidemiological usefulness of collecting venous blood samples on filter paper to monitor the dengue serotypes in circulation in two French territories in the Caribbean region: the islands of Saint Martin and Saint Barthélemy. This prospective approach to the virological surveillance of dengue serotypes was evaluated during a 27-month period. It allows detecting dengue serotypes using RT-PCR in 90.1% of overall blood samples provided from NS1-positive dengue cases ( Table 1 ).For samples collected during the acute phase of the disease, the percentage in which dengue virus RNA was detected by RT-PCR analysis was 95.5%. First, these results show the relevance of using, as a first line, such highly specific diagnostic tools for acute dengue diagnosis in areas where techniques for den...

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

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Using Rapid Diagnostic Tests as a Source of Viral RNA for Dengue Serotyping by RT-PCR - A Novel Epidemiological Tool

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