A.J. Georges

Evaluation of the efficacy of a low-passage bovine rotavirus (strain WC3) vaccine in children in Central Africa

The safety and efficacy of a WC3 rotavirus vaccine was evaluated in a double-blind placebo-controlled trial involving 472 children in Bangui (Central African Republic). Each child received two doses of either placebo (235 children) or vaccine (237 children) at a 1-month interval, the first dose being given at 3 months of age. During the follow-up survey 9 months after the first dose, 117 rotavirus diarrhoeas were observed, 59 in the placebo group, 58 in the vaccinated group. The only positive effect of the vaccine was a significantly higher proportion of mild rotavirus diarrhoeal episodes in the vaccinated group than in the placebo group. Of the children in the vaccinated group, 60% had a positive immune response to WC3 rotavirus when tested by plaque reduction seroneutralization.

Antibody prevalence against haemorrhagic fever viruses in randomized representative central african populations

Between 1985 and 1987, 5,070 randomly selected persons living in 6 central African countries (Cameroon, Central African Republic, Chad, Congo, Equatorial Guinea and Gabon) were checked for serological evidence of haemorrhagic fever. Rural and urban areas were studied, including ecoclimatic zones ranging from dry savana to tropical rain forest. Virus-reactive antibodies were found with all antigens tested, and the global prevalence of positive sera was distributed as follows: Crimean-Congo haemorrhagic fever virus, 0.22%; Rift Valley fever virus, 0.18%; Ebola virus, 12.40%; Marburg virus, 0.39%; Lassa virus, 0.06%; and Hantaan virus, 6.15%. A significant variation in antibody prevalence was observed within the study regions. Association between the viruses was not observed.

Peripheral facial paralysis and HIV infection: report of four African cases and review of the literature.

SummaryFour cases of infranuclear facial palsy associated with infection by the human immunodeficiency virus in young heterosexual African patients are reported. Two cases were healthy HIV carriers, one patient manifested AIDS-related complex, and one case fulfilled the CDC criteria for AIDS. Two patients had a typical Bells palsy, one presented with manifest cephalic Herpes zoster infection and one, who suffered from facial diplegia, could be considered to have a cephalic form of Guillain-Barré syndrome. A review of the literature confirmed that peripheral facial palsy can occur at any stage of HIV infection and in various clinical contexts. In stages I and II of the HIV infection, patients may develop either Bells palsy or Guillain-Barré syndrome. In stages III and IV, when the cellular immunity has begun to decline, Herpes zoster-related facial paralysis, seventh cranial nerve involvement secondary to meningeal lymphomatosis, and peripheral facial paralysis as one aspect of widespread chronic peripheral neuropathy may also occur.

Fatal hepatitis from West Nile virus

Summary Four cases of clinical hepatitis confirmed by biological and pathological examination are documented. In all cases, West Nile virus was isolated from blood and liver biopsies. Two patients died, while 2 others recovered. This is the first report on West Nile virus involvement in fatal acute hepatitis.

An arenavirus isolated from wild-caught rodents (Praomys species) in the Central African Republic.

We isolated nine arenavirus strains from blood and/or tissues of Praomys sp. rodents wild-caught in derived savannah and forest gallery areas of the Central African Republic (CAR). Convalescent serum from either humans or animals infected by Lassa, Mozambique, or lymphocytic choriomeningitis virus cross-reacted with the strains from the CAR. However, monoclonal antibodies to these three viruses gave a profile against the CAR strains suggesting major antigenic differences between each of them and the CAR virus. These data along with the fact that other African arenaviruses have been recovered from Mastomys natalensis and not Praomys suggest that this virus is significantly different from the others.

Filovirus activity among selected ethnic groups inhabiting the tropical forest of equatorial Africa

Seroepidemiological surveys were conducted to determine the frequency and distribution of filovirus activity among selected ethnic groups inhabiting the tropical forests of the Central African Republic. 427 serum specimens were collected from hunter-gatherers and subsistence farmers living in forest environs in the Lobaye District south of the river Lobaye and west of the river Oubangui. Striking serological evidence for filovirus activity was found in both populations. Ebola virus appears to be the most active filovirus; 17.6% (75/427) of the Lobaye survey population were seropositive for Ebola virus reactive antibody while 1.2% (5/427) were seroreactive with Marburg viral antigens. Ethnic background appeared to be an important risk factor influencing filovirus exposure in the forest communities. The filovirus antibody prevalence among 21-40 years old male Aka Pygmy hunter-gatherers was significantly (P = 0.03) 3 times higher (37.5%) than that in similarly aged male Monzombo and Mbati subsistence farmers (13.2%). Continued epidemiological investigations are needed to define ethnic-related events influencing human filovirus activity in the Congo basin of equatorial Africa.

Haemorrhagic fever virus activity in equatorial Africa : distribution and prevalence of filovirus reactive antibody in the Central African Republic

Seroepidemiological surveys were conducted to determine the frequency and distribution of haemorrhagic fever virus (HFV) activity in the Central African Republic. Human serum specimens (4295) were collected from 5 ecologically distinct zones. Serological evidence of HFV activity was found in all the zones. The filovirus antibody prevalence (24.4%, 1051/4295) was greater than the combined prevalence for Lassa virus, Rift Valley fever virus and Crimean-Congo HFV antibody (1.1%, 45/4295; P < 0.01). Evidence of filovirus activity was found in all zones: 21.3% (914/4295) of the population were seropositive for Ebola virus antibody while only 3.2% (137/4295) were seroreactive with Marburg viral antigens. Age and sex were important host-related factors influencing filovirus activity, particularly in dry grassland and moist forest communities. These communities shared many factors, but differences, such as agricultural practices and ethnic backgrounds, may also affect the risk of infection. Filovirus infections appear to occur without apparent disease. Continued investigations are needed to evaluate the true pathogenicity of the African filoviruses and the likelihood that unidentified serologically cross-reacting and non-pathogenic members of the filovirus family are active in equatorial Africa.

Prospective longitudinal study of rotavirus infections in children from birth to two years of age in Central Africa.

A cohort of 111 children born in Bangui (Central African Republic) was followed from birth to two years of age for rotavirus infections by biweekly stool investigations until six months of age, as well as at each diarrhoeic episode. Thirty-eight children (34.2%) exhibited at least one rotavirus infection by the age of 6 months. Thirty children (27%) presented with rotavirus-associated diarrhoea before 2 years of age. Until the children reached the age of 12 months, rotavirus was identified significantly more frequently in diarrhoeic stools than in non-diarrhoeic stools (p less than 0.001). A low diversity of characterized rotavirus strains was found; only two electrophoretypes were identified, and 91% of the strains belonged to subgroup II, serotype 1, with no special strain identified in newborns. A total of 38 children had a rotavirus infection before the age of six months, while 73 did not: only 2.6% of the first group had diarrhoea associated with rotavirus between 6 and 24 months, versus 20.5% in the second group (p less than 0.05). In two-thirds of the cases of infection, the presence of rotavirus in stools was detected only once; repetitive isolations were more frequent in diarrhoeic than in asymptomatic infections. The isolation rate of rotavirus in the general populations was found to be very low (0.2%).

A cohort study of enteric campylobacter infection in children from birth to two years in Bangui (Central African Republic).

A cohort of 111 children from Bangui, Central African Republic, was followed for enteric campylobacter infection from birth until the age of 2 years. Stools were examined at each episode of diarrhoea, and bi-weekly up to the age of 6 months irrespective of the presence of diarrhoea. 349 episodes of diarrhoeal illness were recorded (1.6 per child-year). Campylobacters were isolated from 41 (11.7%) of the 349 episodes, but in half of them another enteric pathogen was also isolated. Campylobacters were statistically associated with diarrhoea only before the age of 6 months. Bi-weekly sampling up to this age detected 75 infections (1.3 per child-year), yet only 12 (16%) were associated with diarrhoea. Campylobacter coli was isolated slightly more often (51%) than C jejuni (49%); biotyping and serogrouping showed that no strain was especially associated with disease. Fewer children who had campylobacter infection before the age of 6 months suffered campylobacter diarrhoea between 6 and 24 months of age than those who did not, but the difference did not reach statistical significance. A significantly higher rate of isolation was found in the homes of infected children (human and animal contacts) than of non-infected children. Campylobacter infections were statistically associated with the presence of live poultry and the lack of piped water in homes.

Premier isolement du virus Mokola à partir d'un rongeur (Lophuromys sikapusi)

Summary An isolate of Mokola virus (AnRB3247) was obtained from the brain of a wild rodent Lophuromys sikapusi caught in the Central African Republic. This was the first isolation of Mokola virus from a rodent and the first isolation of this virus in the Central African Republic. This isolate was identified with Mokola virus by complement fixation and seroneutralization tests. The antigenic pattern of this isolate was determined with a panel of monoclonal antibodies, and was compared to those of Mokola isolates from Nigeria and Cameroun, of Lagos bat virus and of Duvenhage virus.