Paul M. V. Martin

Human herpesvirus 8 primary infection occurs during childhood in Cameroon, Central Africa

While in the United States and northern Europe, human herpesvirus 8 (HHV‐8) appears to be mainly sexually transmitted with primary infection occurring in adulthood, the modes of transmission remain unknown in East and Central Africa, where Kaposis sarcoma (KS) is a long‐standing endemic disease, occurring not only in adults but also in children. The aim of our present study was to determine the prevalence of HHV‐8 infection in children from Yaoundé, Cameroon, Central Africa. Specific antibodies directed against both latent and lytic HHV‐8 antigens were detected and titrated, with an immunofluorescence assay using the KS‐1 cell line, in the plasma of 258 children and adolescents, of 32 mother and child pairs and of 189 pregnant women. Two different HHV‐8 DNA‐specific sequences were searched in the buffy coat by PCR assays. The overall HHV‐8 seroprevalence was 27.5% among these children and adolescents. In newborns, seroprevalence reached 46%, reflecting passive transmission of maternal IgG. This was followed by a marked drop. Then, beginning around 4 years of age, a regular increase of HHV‐8 antibodies took place, reaching 39% in the 12‐ to 14‐year age group and 48% above 15 years, a rate similar (54.5%) to that observed in pregnant women. PCR detection of HHV‐8 sequences was negative in seronegative children and positive in the buffy coat in 17% of HHV‐8‐seropositive children, reflecting a low viral load in the peripheral blood. Our results establish that in Central Africa HHV‐8 infection takes place during childhood by casual routes, in contrast to the sexual transmission observed in adults in northern Europe and the United States. We hypothesize that the lymphadenopathic form of KS seen in African children is related to an early and massive infection by HHV‐8 in susceptible individuals. Int. J. Cancer 81:189–192, 1999.

env Sequences of Simian Immunodeficiency Viruses from Chimpanzees in Cameroon Are Strongly Related to Those of Human Immunodeficiency Virus Group N from the Same Geographic Area

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) group N from Cameroon is phylogenetically close, in env, to the simian immunodeficiency virus (SIV) cpz-gab from Gabon and SIVcpz-US of unknown geographic origin. We screened 29 wild-born Cameroonian chimpanzees and found that three (Cam3, Cam4, and Cam5) were positive for HIV-1 by Western blotting. Mitochondrial DNA sequence analysis demonstrated that Cam3 and Cam5 belonged to Pan troglodytes troglodytes and that Cam4 belonged to P. t. vellerosus. Genetic analyses of the viruses together with serological data demonstrated that at least one of the two P. t. troglodytes chimpanzees (Cam5) was infected in the wild, and revealed a horizontal transmission between Cam3 and Cam4. These data confirm that P. t. troglodytes is a natural host for HIV-1-related viruses. Furthermore, they show that SIVcpz can be transmitted in captivity, from one chimpanzee subspecies to another. All three SIVcpz-cam viruses clustered with HIV-1 N inenv. The full Cam3 SIVcpz genome sequence showed a very close phylogenetic relationship with SIVcpz-US, a virus identified in aP. t. troglodytes chimpanzee captured nearly 40 years earlier. Like SIVcpz-US, SIVcpz-cam3 was closely related to HIV-1 N inenv, but not in pol, supporting the hypothesis that HIV-1 N results from a recombination event. SIVcpz from chimpanzees born in the wild in Cameroon are thus strongly related inenv to HIV-1 N from Cameroon, demonstrating the geographic coincidence of these human and simian viruses and providing a further strong argument in favor of the origin of HIV-1 being in chimpanzees.

Molecular epidemiology of dengue 3 viruses and genetic relatedness among dengue 3 strains isolated from patients with mild or severe form of dengue fever in French Polynesia

The nucleotide sequences of a short fragment of the envelope protein gene encoding amino acids 25 to 89 of 27 dengue 3 viruses were determined by direct sequencing of PCR-amplified products, and the viruses were compared regarding their time of isolation and geographic distribution. Four distinct genotypic groups were discerned at 6% divergence between nucleotide sequences. The first group contained isolates from the South Pacific (1988 to 1992), Singapore (1973) and Indonesia (1973 to 1991). The second group comprised viruses from Asia (1956 to 1989) including the reference strain H-87. The third was composed of one isolate from Thailand (1971), and the fourth included the early strains from French Polynesia (1964 to 1969) and from Puerto Rico (1963). Furthermore, the difference between early and recent strains from the South Pacific was as high as 12.3%. This observation suggests that the recent epidemics in the South Pacific were probably the consequence of the spread of a new variant that emerged from New Caledonia. However, relatedness between nucleotide sequence and disease severity, or between strains from epidemics with mild disease (New Caledonia) and strains from epidemics with severe disease (French Polynesia) could not be demonstrated.

Low Rate of Mother-to-Child Transmission of HIV-1 After Nevirapine Intervention in a Pilot Public Health Program in Yaounde, Cameroon

Objective: To determine the percentage of infected children for whom nevirapine (NVP) was used to prevent peripartum mother‐tochild transmission (MTCT) of HIV in Yaoundé, Cameroon. Design: The study was a prospective Public Health Pilot Program covering a 3‐year period (January 2000‐December 2002). Methods: Counseled and consenting HIV‐1‐positive pregnant women were given a single dose of NVP at the onset of labor. Babies were given 2 mg/kg NVP syrup within the first 72 hours of life. NVPtreated children were regularly followed up and examined for HIV‐1 infection at 6‐8 weeks and 5‐6 months through plasma viral load (VL) quantification with the bDNA system. Results: One hundred twenty‐three children were diagnosed with perinatal HIV‐1 infection at 6‐8 weeks and 5‐6 months. Thirteen children (10.6% [13/123]; 95% confidence interval, 5.1‐16) were infected and presented with high VLs, in general >500,000 copies/mL. Two children had intermediate VLs (between 50 and 3500 copies/mL) at both time points. One hundred seven children (87%) were considered not infected at 6‐8 weeks of age. Conclusions: Our results indicate that the HIV‐1 MTCT rate 6‐8 weeks after NVP administration was not >13% (16/123), thus demonstrating the effectiveness of NVP for lowering the risk of HIV‐1 MTCT in real‐life settings.

Recent increase in meningitis caused by Neisseria meningitidis serogroups A and W135 Yaoundé Cameroon.

From 1991 to 1998, Neisseria meningitidis serogroups A, B, and C represented 2%-10% of strains isolated from cases of bacterial meningitis in Yaoundé. During 1999 to 2000, the percentage of meningococci reached 17%, a proportion never reported since recordkeeping began in 1984. The increase of serogroup A meningococci and the emergence of W135 strains highlight the need for increased surveillance for better diagnosis and prevention.

2,500-year Evolution of the Term Epidemic

The meaning has been evolving since Hippocrates first used this word 25 centuries ago.

Interactions between Schistosoma haematobium and Schistosoma mansoni in humans in north Cameroon

Objectives  To analyse the relationships between the frequency of ectopic localizations of Schistosoma haematobium and S. mansoni eggs.

Human T Lymphotropic Virus Type 1 Subtype C Melanesian Genetic Variants of the Vanuatu Archipelago and Solomon Islands Share a Common Ancestor

BACKGROUND Melanesia is endemic for human T lymphotropic virus type 1 (HTLV-1) subtype C. In 2005, we identified 4 infected women from Ambae Island, Vanuatu. Subsequently, 4247 Ni-Vanuatu originating from 18 islands were enrolled to define HTLV-1 epidemiological determinants and to characterize the viral strains molecularly. METHODS Plasma from 1074 males and 3173 females were screened for HTLV-1/2 antibodies by particle agglutination (PA) and an immunofluorescence assay (IFA). Positive and/or borderline samples were then tested by a Western blot (WB) confirmatory assay. DNAs were amplified to obtain a 522-bp env gene fragment. Phylogenetic and molecular-clock analyses were performed. RESULTS Of 4247 samples, 762 were positive and/or borderline by IFA/PA, and 26 of them were confirmed to be HTLV-1 positive by WB. The overall HTLV-1 seroprevalence was 0.62%. Viral transmission was found within families of infected index case patients. A geographic heterogeneity of HTLV-1 seroprevalence was observed among the islands. All 41 of the new env sequences belonged to HTLV-1 subtype C. Phylogenetic and molecular-clock analyses suggested that Ni-Vanuatu and Solomon Islander strains emerged from a common ancestor ~10,000 years ago. CONCLUSION The Vanuatu archipelago is endemic for HTLV-1 with a diversity of subtype C variants. These strains were probably introduced into Vanuatu during ancient migration of the original settlers a few thousand years ago.

SMALL SUBUNIT rDNA SEQUENCE ANALYSIS OF SYMBIOTIC DINOFLAGELLATES FROM SEVEN SCLERACTINIAN CORALS IN A TAHITIAN LAGOON

The diversity of symbiotic dinoflagellates from reef‐building corals collected in the lagoon of Tahiti (South Pacific ocean) was investigated by using a molecular approach. Populations of symbionts (strains or species) of 7 coral species (Fungia scutaria, F. paumotensis Stutchbury, Pavona cactus Forskål, Leptastrea transversa Kluzinger, Pocillopora verrucosa Ellis and Solender, Montastrea curta Dana, and Acropora formosa Dana) were delimited by phylogenetic analysis of small subunit rDNA sequences. Coral P. verrucosa harbored 2 populations of symbiont SSU rDNA sequences that may correspond to two different Symbiodinium species. Corals F. scutaria and M. curta also seemed to contain two different Symbiodinium species. SSU rDNA dinoflagellate sequences from P. cactus, L. transversa, F. scutaria, F. paumotensis, and P. verrucosa were in the same phylogenetic cluster and showed low variability. For these distantly related coral species, dinoflagellate strains from the same species, rDNA paralogues from the same strain, or closely related Symbiodinium species could not be distinguished because monophyletic subgroups were not observed. SSU rDNA dinoflagellate sequences from A. formosa and M. curta were clearly different from the other Symbiodinium sequences and may represent specific species. This molecular approach highlighted a greater diversity of symbiotic dinoflagellates from corals in South Pacific (Symbiodinium groups A, B, and C) than that observed in the rest of the Pacific ocean (Symbiodinium group C). The diversity of symbiotic associations in a restricted area of the lagoon of Tahiti may reflect the complexity of interactions between species of Symbiodinium and corals.

Diversity in symbiotic dinoflagellates (Pyrrhophyta) from seven scleractinian coral species : Restriction enzyme analysis of small subunit ribosomal RNA genes

ABSTRACT The diversity of symbiotic dinoflagellates (SD) from seven coral species (Fungia scutaria, Fungia paumotensis, Lep‐tastrea transversa, Pavona cactus, Pocillopora verrucosa, Montastrea curia, and Acropora fonnosa) was studied in a restricted geographical area, the Lagoon of Arue on the island of Tahiti. Their diversity was explored by small subunit ribosomal RNA gene (SSU rDNA) restriction fragment length polymorphism (RFLP). After a nested amplification with SD specific primers, RFLP analyses were performed directly and after a cloning step. The diversity of these different SSU rDNA was estimated in respect to possible technical artifacts. In an axenic culture of SD from the coral Galaxea fascicularis, both heterogeneous SSU rDNAs and artifact molecules were observed as in our SD samples. According to the number of patterns observed, corals Fungia paumotensis, Leptastrea transversa. Pavona cactus, Montastrea curia, and Acropora fonnosa contained one class of SD SSU rDNAs. whereas Fungia scutaria and Pocillopora verrucosa contained three and two classes of SD SSU rDNAs respectively. In the limited geographic area studied. SD from different coral species shared the same pattern, except SD from Montastrea curta, which showed a unique pattern. In addition to the possibility of SD flux among different coral species, specific mechanisms could also be involved in the establishment of a symbiosis.