Safety and immunogenicity of three doses of a Neisseria meningitidis A + C diphtheria conjugate vaccine in infants from Niger.

BACKGROUND: High rates of endemic disease and recurrent epidemics of serogroup A and C meningococcal meningitis continue to occur in sub-Saharan Africa. A meningococcal A + C polysaccharide diphtheria-toxoid-conjugated vaccine may address this issue. METHODS: In Niger three doses of a bivalent meningococcal A + C diphtheria-toxoid-conjugated vaccine (MenD), containing 1, 4 or 16 microg of each polysaccharide per dose, administered at 6, 10 and 14 weeks of age, were compared with Haemophilus influenzae type b-tetanus toxoid-conjugated (PRP-T) vaccine given with the same schedule or with a meningococcal A + C polysaccharide vaccine (MenPS) given at 10 and 14 weeks of age. One blood sample was taken at the time of enrollment (6 weeks of age) and another was taken 4 weeks after the primary series. RESULTS: All doses of MenD were well-tolerated. After the primary series a higher proportion of infants had detectable serum bactericidal activity against serogroup A for each dose of MenD (from 94% to 100%) than for MenPS (31%) or H. influenzae type b-tetanus toxoid-conjugated vaccine (18.9%); P < or = 0.05. Significant differences were also observed for serogroup C MenD 4 microg or MenD 16 microg (100%) vs. MenPS (69.7%) or Haemophilus influenzae type b-tetanus toxoid-conjugated vaccine (24.3%); P < or = 0.05. When MenPS vaccine was given to 11-month-old children, the immune response measured by both enzyme-linked immunosorbent assay and serum bactericidal assay was greater in those previously immunized with MenD than in those immunized with MenPS vaccine. CONCLUSION: MenD was safe among infants in Niger, and immunization led to significantly greater functional antibody activity than with MenPS. The 4-microg dose of MenD for both the A and C serogroups has been selected for further studies.

Chlamydial antibodies and tubal infertility.

Prevalence of Chlamydia trachomatis antibodies was studied in infertile women with and without tubal obstruction, and in a control group of pregnant women in a Central-African country with a high infertility rate. In comparison with the control group, tubal infertility patients were significantly more likely to have serum antibodies of 1:64 or greater with an age-adjusted odds ratio of 7.8 (95% confidence interval (CI) 3.2-19.1). Infertile women without tubal obstruction had antibody titres similar to the control group with an odds ratio of 1.1 (95% CI: 0.6-1.9). In the tubal infertility group there was a kind of dose-response relationship between chlamydial antibodies and the severity of tubal damage and pelvic adhesions on laparoscopy, with odds ratios of 3.2 (95% CI: 0.7-14.8), 6.2 (95% CI: 1.9-21.6) and 18.1 (95% CI: 6.0-68.5) in the group with mild, moderate and severe pelvic adhesions respectively. This survey adds more evidence to the hypothesis that C. trachomatis is a major agent responsible for tubal infertility in Central Africa.

A rapid, simple method for isolation of viable microfilariae.

We describe a rapid, efficient method for purifying Loa loa microfilariae from blood that does not affect their longterm motility. It is based on the separation of microfilariae on a performed discontinuous Percoll gradient, followed by filtration on cellulose ester membranes. The parasite population, after isolation, is close to 100% pure, 100% viable and remains motile for at least 20 days. Recovery from original blood samples is typically around 90%. The method, because of its simplicity and minimal material requirements, could be used with up to 210 ml of blood. It also allows the isolation of Mansonella perstans microfilariae.

Considerations regarding mass vaccination against typhoid fever as an adjunct to sanitation and public health measures: potential use in an epidemic in Tajikistan.

We report on the ongoing epidemic of typhoid fever in Tajikistan that started in 1996. It has involved more than 24,000 cases to date, and is characterized by multiple point sources, overflow of sewage, contaminated municipal water, and person-to-person spread. Of the Salmonella typhi isolates available for testing in western laboratories, more than 90% are multidrug-resistant (MDR). Most recently, 28 (82%) of 34 isolates are resistant to ciprofloxacin, representing the first reported epidemic of quinolone-resistant typhoid fever. In the past, mass immunization during typhoid fever epidemics has been discouraged. A review of this policy is recommended in light of the alarming emergence of quinolone-resistant strains of S. typhi, the availability of improved vaccines, and the ongoing epidemic in Tajikistan. Mass immunization may be a useful measure for the control of prolonged MDR typhoid fever epidemics, as an adjunct to correction of municipal infrastructure and public health intervention.

Loa loa: a simple method for isolation of microfilariae from blood with production of antigen in extraction medium.

A simple method for isolating Loa loa microfilariae from the blood of patients is described. This involves sedimentation on Ficoll followed by migration of the microfilariae into an extraction medium. During migration the microfilariae release antigen-rich excretory or secretory products. The procedure thus yields two products: pure microfilariae and large amounts of antigen in the extraction medium.

Filariasis due to Loa loa and Mansonella perstans: distribution in the region of Okondja, Haut-Ogooué Province, Gabon, with parasitological and serological follow-up over one year.

The prevalence of Loa loa and Mansonella perstans filariasis has been determined in 6 rural villages in eastern Gabon. Between 18.9 and 27.2% of people carry L. loa microfilariae with an overall microfilarial rate of 25.1%. The microfilarial rate for M. perstans was more variable, between 33.3 and 62.2% (average 49.1%). No significant difference was seen in the microfilarial rate with age over 15 years for either parasite, but men were infected more frequently than women. Anti-L. loa antibody titres were measured, using a homologous microfilarial antigen in ELISA. Taking the parasitological and immunological evaluations together, only 10% of the sample population appear to be free of these filarial infections. L. loa and M. perstans microfilaraemia and corresponding serology were also investigated twice in 150 people at a one-year interval. 99.1% of the cases who had no circulating L. loa microfilaria in March 1984 still did not show any 12 months later. Similarly, 97.1% of the untreated, microfilaraemic cases still harboured this parasite a year later. The same was not observed for M. perstans, since microfilariae appeared or disappeared in 26.7% of the cases. This suggests different dynamics for the two filarial infections. Variation in individual anti-L. loa antibody titres was low. The possibility of a genetic influence on the expression of loiasis is discussed.

Ophthalmia neonatorum in a semi-rural African community.

The incidence and aetiology of ophthalmia neonatorum have been estimated over a 7-month period in Franceville, a semi-rural community in south-eastern Gabon. Chlamydia trachomatis was the most frequently observed pathogen, being isolated from 17 babies (2.7% of births), and Neisseria gonorrhoeae was recovered from 12 (1.6% of births). 5 of 17 cases of chlamydial conjunctivitis were in infants less than 5 d old as opposed to 9 in the typical 5 to 10-days-old group. As expected, most cases of gonococcal ophthalmia neonatorum occurred in the first 5 d of life with cases in older infants often not accompanied by a granulocytic response. Chlamydial conjunctivitis was usually unilateral whereas other cases were most frequently bilateral.

Haemorrhagic fever in Gabon. I. Incidence of Lassa, Ebola and Marburg viruses in Haut-Ogooué.

A serological enquiry aimed at determining the incidence of infection with Lassa, Ebola and Marburg viruses was conducted on the human population of the region of Haut-Ogooué (Gabon) and on primates. The results, obtained by the indirect immunofluorescence technique, showed that more than 6% of the human population had had contact with Ebola virus but no antibodies against Marburg or Lassa viruses were found. Most sera reacted to an Ebola antigen from a Zairian strain, but showed little or no reaction to an antigen from a Sudanese strain.

Infertility in Central Africa: infection is the cause.

Determinants of infertility were studied in 340 women in Eastern Gabon, an area situated in the "infertility belt" of Central Africa. Fallopian tube occlusion was diagnosed in 82.8% of cases, showing the importance of infection-related causes. Women with tubal occlusion did not differ significantly from women with normal tubes in obstetrical history or prevalence of Neisseria gonorrhoeae or Chlamydia trachomatis on endocervical culture. Antecedents of pelvic inflammatory disease or a pelvic mass were significantly more common in the group with tubal occlusion. This group also had a significantly higher prevalence of serum chlamydial antibodies at a titer of 1/64 or higher. Hormonal factors were found in 31.7% of women, a cervical factor in 29.0% and mechanical factors in 5.6%. No diagnosis could be made in 12.2% of cases. During the investigation, 4.4% of women became pregnant. The predominance of infectious related causes of infertility makes it imperative to focus resources on prevention programs of upper genital tract infections in women.

PIP: Determinants of infertility were studied in 340 women in Eastern Gabon, an area situated in the "infertility belt" of Central Africa. Fallopian tube occlusion was diagnosed in 82.8% of cases, showing the importance of infection-related causes. Women with tubal occlusion did not differ significantly from women with normal tubes in obstetrical history or prevalence of Neisseria gonorrhea or Chlamydia trachomatis on endocervical culture. Antecedents of pelvic inflammatory disease or a pelvic mass were significantly more common in the group with tubal occlusion. This group also had a significantly higher prevalence of serum chlamydial antibodies at a titer of 1/64 or higher. Hormonal factors were found in 31.7% of women, a cervical factor in 29.0% and mechanical factors in 5.6%. No diagnosis could be made in 12.2% of cases. During the investigation, 4.4% of women became pregnant. The predominance of infectious related causes of infertility makes it imperative to focus resources on prevention programs of upper genital tract infections in women. The study sample is from a small semi-urban center of 25,000 inhabitants and consisted of all women consulting for infertility at the gynecology department of the Franceville hospital from January 1983 until December 1984.

[Traveller's diarrhea: which vaccines?]. / Diarrhées du voyageur: quels vaccins?

Diarrheal diseases are a major cause of child morbidity and mortality, particularly in developing countries. It is estimated that diarrheal diseases and typhoid fever cause around 2.5 million deaths per year in the world. Four bacteria and one virus share this responsibility: Shigella spp, Escherichia coli ETEC, Vibrio cholerae, Salmonella typhi and rotavirus. People travelling in countries with high endemicity of diarrhoeal diseases risk facing these four bacteria or the less common rotavirus, which is usually active in infants, even though some cases of diarrhoea due to rotavirus have already been reported in adults. The usual recommendations concerning basic measures of hygiene are most of the time quickly forgotten and followed only by a small number of travellers (12). Therefore, apart these useful recommendations, it is therefore necessary to consider complementary actions for controlling these diseases which are mainly transmitted by contaminated water and food. This article aims at giving an overview of currently available and future vaccines for preventing travellers' diarrheas.

[Anticholera vaccines and vaccination]. / Vaccins et vaccination anticholériques.

Cholera is still an important diarrhoeal disease in developing countries. The impact of cholera out-break is tremendous for a country at human and economic level. WHO estimates that diarrhoeal diseases cause about 2.8 million deaths per year in developing countries. Officially, cholera is causing around 120,000 deaths per year. The poorest population (from slums and refugee camps) are the most vulnerable target for cholera infection. Development of simple cheap and effective vaccine is highly recommended. This article aims at giving an update on the currently available and future vaccines for the prevention of diarrhoea due to Vibrio cholerae O1 and O139.

[The placenta of premature and hypotrophic Gabonese infants]. / Le placenta de l'enfant gabonais, prématuré et hypotrophique.

494 placentae coming from two different geographical parts of Gabon were studied. They were grouped into control, premature, small-for-dates and stillborn. The urban population gives rise to most mothers of about 26 years of age, who deliver normally at 38 weeks of babies weighing 3,300 g and 50 cm long, with placentae weighing 550 g, as well as premature babies and those in which there is white cell infiltration of the membranes, signs of toxaemia and normal placentae. On the eastern plateaux of Gabon there are more mothers around the age of 23, who deliver normally at 37 weeks of pregnancy of babies weighing 3,100 g and 48 cm long, with placentae weighing 450 g, with small-for-dates babies and inflammation of the placenta. Malaria is the cause of many premature deliveries and of small-for-dates and stillborn, especially in the plateaux.

[Three successive cases of salmonella meningitis in Gabon]. / A propos de trois cas successifs de méningites à Salmonella au Gabon.

In a two months period Salmonella ajiobo and S. typhimurium (twice) were isolated from cloudy cerebrospinal fluids (CSF) of children less than one year old. No other cases of Salmonella meningitis occurred in a 2 year survey of meningitis in Franceville, a semi-rural community in southeastern Gabon. One case was fatal and the case with S. ajiobo needed a prolonged course since the CSF was not sterilized even after 6 days of therapy.

[Acute gastroenteritis and breast feeding in Gabon. Preliminary results]. / Gastroentérites aiguës et allaitement maternel au Gabon. Résultats préliminaires.

76 diarrheic infants (from 15 days to 2 years) had a stool examination for rotavirus (ELISA method) and a stool culture and were classified according to breast feeding or not. This study was performed in a semi-urban region (Haut-Ogooué, Gabon). The preliminary results suggest a protection by breast feeding against rotavirus and enteropathogenic bacteria, rapid elimination of diarrheic agents may be facilitated by human milk.

[Cholera update at the dawn of the millenium]. / Actualités du choléra a l'aube du millénaire.

Cholera is an ancestral disease belonging to the mythology of numerous societies. In the last two centuries, seven pandemias have been recorded, in which the spatial and temporal modalities of disease transmission are related to the major technical revolutions of the period. The now ongoing seventh pandemia is by far the longest and most widespread with specific features that raise new challenges and hopes. The authors present the situation at the dawn of the third millennium based on a review of current epidemiological, clinical, therapeutic, diagnostic and vaccinal data. This update shows that the field is progressing and may indeed be standing on the verge of significant breakthroughs for management of the disease and vibrion endemicity.