Association of severe malaria with a specific Plasmodium falciparum genotype in French Guiana.

Why severe Plasmodium falciparum malaria occurs in only a small percentage of patients is unclear. The possibility that specific parasite characteristics contribute to severity has been investigated in French Guiana, a hypoendemic area, where parasite diversity is low and all patients with severe cases are referred to a single intensive care unit. Parasite genotyping in geographically and temporally matched patients with mild and severe disease showed that the association of a specific msp-1 allele (B-K1) with a specific var gene (var-D) was overrepresented among patients with severe versus mild disease (47% vs. 3%, respectively; P<.001). Moreover, this genotype combination was consistently observed in the most severe clinical cases. Reverse-transcription polymerase chain reaction demonstrated programmed expression of var-D in vivo, which is consistent with its potential implication in severe disease. These results provide field evidence of an association of severe malaria with specific genetic characteristics of parasites and open the way for intervention strategies targeting key virulence factors of parasites.

Health evaluation of translocated free-ranging primates in French Guiana.

Among over 40 mammal species threatened by the filling of a hydroelectric dam reservoir in French Guiana, three species of primates have been translocated, comprising 124 red howler monkeys, six white-faced sakis, and 95 golden-handed tamarins. Health status of the animals was evaluated by direct physical examination and by hematological, biochemical, virological, and parasitological surveys of collected blood. The physical condition of the howlers was slightly worse toward the end of the capture period, but that of sakis and tamarins remained satisfactory. Several ectoparasites (ticks, larvae of dipterous insects, fleas, and lice) were collected, and various wounds, apparently nondebilitating, were recorded in howlers. Hematological and biochemical profiles determined for the three species revealed a slight anemia in howlers. Entamoeba, Strongyloides, and Trypanoxyurus were common in fecal samples of howlers. A survey of blood smears from the three species revealed infection by several types of microfilaria, Trypanosoma rangeli-like and Plasmodium brasilianum in all three, and Trypanosoma cruzi-like in howlers. These infections had no significant impact on the health status or the hematological profiles. Serologic investigations revealed occasional reactions against Toxoplasma gondii, a strong anti-Plasmodium response in the two Cebidae species, and a weaker one in tamarins. Attempts to isolate arbovirus failed, but antibody responses to Mayaro and yellow fever viruses were strong, especially in the howlers. A strong correlation between age and serological status led to a better understanding of the epidemic cycles. Our survey indicates French Guianan primates are reservoirs for several anthropozoonoses, including malaria, Chagas disease, and arboviruses.

Plasmodium falciparum parasites in French Guiana: limited genetic diversity and high selfing rate.

The genetic characteristics of Plasmodium falciparum isolates collected in French Guiana, where malaria transmission is low and occurs in isolated foci, were studied. Blood samples were collected from 142 patients with symptomatic malaria and typed using a polymerase chain reaction-based strategy for merozoite surface protein-(MSP-1) block 2, the MSP-2 central domain, and glutamate-rich protein (GLURP) repeat domain polymorphism. This showed that the parasite population circulating in French Guiana presented a limited number of allelic forms (4, 2, and 3 for MSP-1 block 2, MSP-1, and GLURP, respectively) and a small number of mixed infections, contrasting with the large genetic diversity of parasite populations and infection complexity reported for Africa, Asia, and other parts of South America. Two groups of isolates displaying identical 3 loci allele combinations were further studied for the Pf332 antigen, histidine-rich protein-1, thrombospondin-related anonymous protein, and Pf60 multigene family polymorphism. Within each group, most isolates were identical for all markers tested. This suggests a high rate of self-fertilization of P. falciparum parasites in French Guiana, resulting in homogenization of the population. The implications of these findings for malaria control in areas of low endemicity are discussed.

Dengue encephalitis in French Guiana.

Thousands of cases of dengue fever (DF) and several cases of dengue haemorrhagic fever were recorded in French Guiana during the recent outbreak of dengue-2 virus (1991-1992) and in subsequent years. One case with clinical signs typical of classical DF with neurological complications is reported in this study. The neurological features (encephalitis) appeared during the acute phase, 2 days after the onset of fever. Dengue-2 virus was detected in both the cerebrospinal fluid and blood sample. This case was fatal. This first reported case of classical DF with encephalitis in French Guiana is a new demonstration of the potential neurovirulence of dengue viruses.

Fleas in French Guiana (Insecta: Siphonaptera).

Based on a collection of approximately 760 fleas, of which 520 were collected in 1994-1995 during scientific studies at the Petit Saut dam site in French Guiana, 12 species and subspecies are discussed. Two taxa, Rhopalopsyllus garbei Guimarães, 1940 and Adoratopsylla intermedia copha (Jordan, 1926), are new records for French Guiana. The fleas collected during the 1994-1995 study were obtained from 35 species of mammals (3,484 specimens); of which, 21 (60%) species were negative for fleas. The mammals were captured primarily by live-trapping during a capture-release study along a portion of the Sinnamary River and its tributaries up to a distance of 70 km upstream from the Petit Saut dam site.

Some epidemiological and entomological aspects of the dengue situation and the vector aedes aegypti (L) in French Guiana

General epidemiological and entomological aspect studies of the dengue fever (DF) situation and the mosquito vector, Aedes aegypti, in French Guiana were studied for two years, between 1st October 1993 and 30th September 1995. The methodology included epidemiological data gathered from patients recently infected by a dengue virus, and entomological investigations with sampling of all stages (eggs, larvae, pupae and adults) of Ae.aegypti in the suspected dengue-infected places. DF cases were reported from all parts of the country, mostly from the main city of Cayenne and its surroundings. Likewise, Ae.aegypti was found in all investigated inhabited areas, and infected vectors were collected in four locations. Sampling of immature Ae.aegypti showed that the small outdoor containers were the most important breeding-sites in French Guiana. The duration of development of Ae. aegypti was significantly different according to the type of breeding-site. The vertical transmission of Df viruses under naturual conditions in French Guiana was demonstrated and 2 DEN-2 and 2 DEN-4 strains were isolated. We conclude that DF viruses are endemic in French Guiana, all inhabitied areas of the country are susceptible to epidemic DF and the reponsible vector, Ae.aegypti, can also act as a reservoir for the dengue virus (AU)

[Dengue in French Guiana. History and present status]. / La dengue en Guyane Française. Historique et actualités.

The evolution of dengue in French Guiana has the same trend as in most tropical American countries, with emergence of dengue hemorrhagic fever (DHF) and endemicity of the disease. During the 1940's, several dengue-like outbreaks were reported from French Guiana. Then, the only dengue vector, Aedes aegypti, was eradicated between 1950 and 1963, when it started to reinfest the country. By the end of the 1960's, new dengue epidemics with serological confirmation were described. After 1970, the first dengue strains were isolated, firstly dengue-2 strains, then dengue-1 and dengue-4 strains. Between 1970 and 1990, several dengue outbreaks struck French Guiana with 2 to 6 years intervals. In July 1991, started the first DHF outbreak in French Guiana which spread in all the most important towns until October 1992. About 3,000 cases were reported, that is almost 3% of the population, from which about 1/3 had serological confirmation; more than 300 people were hospitalized and some 80 with hemorrhages. Finally 6 deaths were reported, 5 of which had hemorrhages but could not be included into DHF cases according to WHO criteria. The dengue-2 strain responsible for this outbreak is close to the Jamaïcan topotype known to be particularly virulent. Since the beginning of 1993 and actually, dengue is still circulating in French Guiana, but at low level and dengue-1 and dengue-4 strains are occasionally isolated.

Dengue in French Guiana, 1965-1993.

While it seems likely that dengue fever (DF) has existed in French Guiana for at least one century, data on outbreaks are sketchy before temporary eradication of the dengue vector mosquito Aedes aegypti and its reestablishment in the early 1960s. Dengue cases were serologically confirmed for the first time in 1965, and since then dengue epidemics have occurred at two to six year intervals, the most important occurring in 1968-1969, 1970, 1972, 1976, 1982, 1986, and 1992. Three of the four dengue virus serotypes (dengue-1, dengue-2, and dengue-4) have been implicated in these outbreaks. During the 1992 epidemic, which appears to have begun in 1991 and extended into 1993, cases of dengue hemorrhagic fever (DHF) were confirmed for the first time. In all, at least 40 DHF cases and several deaths were associated with this epidemic. This development has raised considerable concern about the public health threat posed by DHF in French Guiana. Such concern is only heightened by the fact that while vector control is the sole means of preventing or combating dengue outbreaks, it has proved difficult to maintain vector populations at low levels with the control measures currently employed.

The first epidemic of dengue hemorrhagic fever in French Guiana.

From July 1991 to October 1992, an outbreak of dengue spread into the main urban areas of French Guiana, where 90% of the country's 114,808 inhabitants live. In mid-July 1991 dengue-2 virus was identified as being responsible for most cases, while dengue-1 virus was rarely isolated and circulated at a low level. The number of dengue cases during this period was unknown because there was no clinically based dengue surveillance system. The only available data were for the number of suspected cases as indicated by the number of patients for whom blood samples were submitted to a laboratory for dengue diagnosis. Eight hundred forty-seven of the 2,948 suspected cases were diagnosed in the laboratory as dengue cases. Six fatal cases were reported. This outbreak was marked by the appearance of the first clinical cases of dengue hemorrhagic fever (DHF) in French Guiana. Forty cases met the World Health Organization definition of clinical DHF: 32 were grade II, seven were grade III, and one was grade IV and fatal. Eighteen cases were confirmed in the laboratory and 12 were probable; there was no proof of the dengue etiology for the remaining patients.