We evaluated a one-step sandwich-format microplate enzyme immunoassay for detecting dengue virus NS1 antigen (Ag) in human serum by use of Platelia Dengue NS1 Ag kits (Bio-Rad Laboratories, Marnes La Coquette, France). We collected 299 serum samples from patients with dengue disease and 50 serum samples from patients not infected with dengue virus. For the 239 serum samples from patients with acute infections testing positive by reverse transcription-PCR and/or virus isolation for one of the four dengue virus serotypes, the sensitivity of the Platelia Dengue NS1 Ag kit was 88.7% (95% confidence interval, 84.0% to 92.4%). None of the serum samples from patients not infected with dengue virus tested positive with the Platelia Dengue NS1 Ag kit. A diagnostic strategy combining the Platelia Dengue NS1 Ag test for acute-phase sera and immunoglobulin M capture enzyme-linked immunosorbent assay for early-convalescent-phase sera increased sensitivity only from 88.7% to 91.9%. Thus, NS1 antigen detection with the Platelia Dengue NS1 Ag kit could be used for first-line testing for acute dengue virus infection in clinical diagnostic laboratories.

We have studied 52 new HHV8 strains by sequencing the complete hypervariable K1 gene and genotyping the K14.1/K15 loci located at both sides, respectively, of the viral genome. The samples originated from 49 patients with Kaposi's sarcoma (KS; 32 patients), multicentric Castleman's disease (MCD; 12 patients), or primary effusion lymphoma (PEL; 5 patients). Among these patients, 32 were of African origin (West and Central African countries and Creoles from French Guiana) and the 17 others were mostly French homosexuals. Comprehensive phylogenetic studies allowed the identification of distinct groups within the three already known main subtypes. Interestingly, two new sequences that did not cluster within a known subtype or group could be considered as prototypes of early/ancient variants of the C subtype and A/C set, respectively. Among the 32 African strains, the majority were either of the B subtype (13 cases) or of the A5 group (11 cases), indicating that this latter genotype is frequent and widespread in Africa. In contrast, a subtype C strain infected most of the 17 other patients. PCR-based genotyping of the K14.1/K15 loci revealed an overall predominance of P subtype, except in the A5 and B K1 groups, in which the P and M alleles were equally represented. The implications of these data on the evolution and spread of HHV8 among human African populations are discussed.

Several KS and PEL lesions are monoclonal expansions of a single infected cell, suggesting that HHV8 infection precedes tumor growth and thus supporting an etiologic role of latent HHV8 in these proliferations. Our finding that nodular KS lesions display all possible patterns of clonality supports the model according to which KS begins as a polyclonal disease with subsequent evolution to a monoclonal process.

In South America, dengue is the arbovirus-transmitted disease with the highest incidence. Unlike other arboviruses, wild mammals have no confirmed role in the cycle of dengue in the neotropics, although serological studies have suggested a possible secondary amplification cycle involving mammals other than nonhuman primates. In French Guiana, where all four serotypes (DENV-1, DENV-2, DENV-3, DENV-4) are present, the disease is endemic with outbreak events. To determine whether wild mammals can be infected by DENV, rodents, marsupials, and bats were captured over several periods, from 2001 to 2007, at two sites. The first location is a secondary forest surrounded by an urban area where dengue is endemic. The second location is a forest edge site where the disease has not yet emerged. A total of 10,000 trap-nights were performed and 616 mammals were captured. RNAs representing the four DENV serotypes were detected at both sites by reverse-transcriptase polymerase chain reaction in the livers and/or sera of 92 mammals belonging to 14 out of 32 species distributed among all the orders investigated: Rodentia (33 positive/146 tested), Marsupialia (40/318), and Chiroptera (19/152). Sequence analyses of a portion of the capsid and premembrane junction revealed that mammal strains of DENV-1, DENV-2, DENV-3, and DENV-4 had only 92.6%, 89%, 95%, and 95.8% identity, respectively, with strains circulating in the human population during the same periods. Regarding DENV-2, strains related (99% identity) to those responsible for an epidemic event in humans in French Guiana concurrent to the capture sessions were also evidenced, suggesting that wild mammals in edge habitats can be infected by circulating human strains. Our results demonstrate, for the first time, that neotropical wild mammals can be infected with dengue virus. The question of whether mammals maintain DENV in enzootic cycles and can play a role in its reemergence in human populations remains to be answered.

Dengue-malaria co-infection reports are scarce. Of 1,723 consecutive febrile patients in Cayenne Hospital, 238 had dengue (174 early dengue fever cases) and 393 had malaria (371 acute malaria); 17 had both. Diagnosis of 1 of these 2 infections should not rule out testing for the other infection.

A serologic survey for Mayaro virus (Alphavirus, Togaviridae) in 28 wild nonflying forest mammal species in French Guiana showed a prevalence ranging from 0% to 52% and increasing with age. Species active during the day and those who spent time in trees were significantly more infected, results consistent with transmission implicating diurnal mosquitoes and continuous infectious pressure.

To study a 2001 dengue fever outbreak in Iracoubo, French Guiana, we recorded the location of all patients’ homes and the date when symptoms were first observed. A geographic information system was used to integrate the patient-related information. The Knox test, a classic space-time analysis technique, was used to detect spatiotemporal clustering. Analysis of the relative-risk (RR) variations when space and time distances vary, highlighted the maximum space and time extent of a dengue transmission focus. The results show that heterogeneity in the RR variations in space and time corresponds to known entomologic and epidemiologic factors, such as the mosquito feeding cycle and host-seeking behavior. This finding demonstrates the relevance and potential of the use of GIS and spatial statistics for elaborating a dengue fever surveillance strategy.

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