Antiviral activity of carrageenan on hepatitis A virus replication in cell culture.

Sulphated polysaccharides such as iota-, lambda- and kappa-carrageenans showed a potent inhibitory effect on the replication of hepatitis A virus (HAV) in the human hepatoma cell line PLC/PRF/5. No cytotoxic effects were detected with concentrations of carrageenans up to 200 micrograms/ml. The selectivity indices of these substances, calculated as the ratio of the dose that reduced the number of viable cells to 50% (CD50) to the effective dose that inhibited 50% of viral antigen expression (ED50), were greater than 400 with iota-carrageenan, greater than 222 with lambda-carrageenan and greater than 10 with kappa-carrageenan. The selectivity index of ribavirin (reference substance) was only 5. The 3 types of carrageenans resulted in concentration-dependent reduction of HAV-antigen expression and HAV infectivity. lota-and lambda-carrageenan emerged, from the present study, as promising candidates for chemotherapy of acute hepatitis A.

[Role of E. coli enterotoxins in the etiology of infantile diarrhea. Comparison of an African country Yaoundé (Cameroon) and France (Grenoble)]. / Place des E. coli entérotoxigènes dans l'étiologie des diarrhées infantiles. Comparaison entre un pays africain Yaoundé (Cameroun) et la France (Grenoble).

The detection of heat-labile enterotoxin by two tests (culture on Y1 cells and GM1-ELISA) has been carried out on strains of E. coli isolated in stools of children with diarrheal disease (220 strains isolated in the Pasteur Institute in Yaoundé, Cameroon, and 133 stool specimens selected in Grenoble). This work was undertaken to determine the frequency of enterotoxigenic E. coli in two different populations. In Yaoundé the isolation rate (6%) is not very high in comparison with other developing countries. It should be observed that some strains belong to enteropathogenic serogroups. In Grenoble results confirm the very low frequency of enterotoxigenic E. coli in industrialized countries.

[Bacteriological evaluation of a new system for transport and storage of urine: the UC and S Vacutainer system]. / Evaluation bactériologique d'un nouveau système de transport et de conservation de l'urine: le système Vacutainer UC et S.

A study realized on 360 clinical urine specimens compared results of the cytobacteriological examination obtained from freshly voided urines and from the same urines preserved during 24 hours at room temperature (20-22 degrees). A new system (UC & S Vacutainer system--Becton-Dickinson) was used for preservation. Urine preservation induced no change in count of leukocytes and erythrocytes present in urine and in bacterial count (agreement between the two numerations: 98.8 p. cent). Bacterial identification and determination of antibacterial activity of antibiotics remained also unchanged. Soluble antigens eventually present in urine were not altered by preservation on UC & S tubes. This study showed that UC & S Vacutainer system was very effective for preservation of urine clinical specimens.

Seroepidemiologic studies of acute hemorrhagic conjunctivitis virus (enterovirus type 70) in West Africa. III. Studies with animal sera from Ghana and Senegal.

One hundred and thirty-nine bovine sera collected in Senegal in 1968 and 1969, before the human pandemic of acute hemorrhagic conjunctivitis (AHC), and 145 sera collected in 1977, seven years after the introduction of AHC, were tested for virus neutralizing (VN) titers against enterovirus 70 (EV70) in neutralization tests. Positive rates of VN titers (1:16) were fairly constant (about 40%) in 1968 and 1969 but the proportion of positives from the 1977 collection was significantly higher (61%). The proportion of Ghanaian bovine sera positive in 1977 (39%) was comparable with those collected earlier in Senegal but the proportion was lower in sera of calves (7%). Similar studies were performed on sheep sera collected in 1966, 1967, 1968, and 1969 in Senegal. The proportions positive and the geometric mean titers (GMTs) peaked in alternate years: the proportions were 43% and 54% in 1966 and 1968 but dropped to 12% and 5% in 1967 and 1969, respectively. The prevalence rate for Ghanaian sheep sera in 1977 was comparable to the earlier figures in Senegal. The prevalence of VN (83%) and the GMT (1:27.28) in swine sera in Ghana in 1977 were much higher than those seen in chickens and dogs. However, 87 sera of wild monkeys caught in Senegal after 1970 were negative in neutralization tests. The VN substance detected in these domestic animals was found to be 2-mercaptoethanol sensitive; hence it is considered to belong to IgM. The results seem to favor the hypothesis that enterovirus type 70 (EV70) evolved from an animal enterovirus which shares a common antigen with EV70.

Seroepidemiologic studies of acute hemorrhagic conjunctivitis virus (enterovirus type 70) in West Africa. II. Studies with human sera collected in West African countries other than Ghana.

Human sera were collected in Senegal, Nigeria, Ivory Coast, Dahomey, Liberia, Gabon and Togo during the pre-epidemic period of acute hemorrhagic conjunctivitis (AHC) from 1965 to 1969, and tested for virus neutralizing (VN) antibody to enterovirus type 70 (EV70). Of these, 1109 (91%) were antibody negative (less than equal to 1:4), 116 (9%) neutralized at a dilution of 1:8 or over, and 45 (4%) at dilutions of at least 1:16. The distribution pattern is not significantly different from that of sera collected from Kenya in 1967 or from army recruits in the United States, Argentina, Brazil and Colombia in the 1960s. Sera collected during the post-epidemic period (1970 to 1977) in Senegal, Sierra Leone, Mali, Upper Volta, Chad, Niger and Gabon were also examined; 1573 (68%) were VN antibody negative (less than or equal to 1:4), while 733 (32%) and 433 (19%) had titers of 1:8 or greater and 1:16 or over, respectively. There is a significant difference in distribution between pre- and post-epidemic antibody titers (p less than 0.001), although the incidence of AHC was lower in these countries than in Ghana and Southeast Asia. The prevalence of VN antibodies tends to be lower in the dry, hot inland areas and thus humid coastal monsoonal climates and dense populations seem to favor the spread of AHC.

Yellow fever in the Gambia, 1978--1979: entomological aspects and epidemiological correlations.

An entomological survey was conducted in the Gambia in January 1979, during the last phase of a yellow fever (YF) outbreak which began during the previous rainy season. In the dry conditions which prevailed in January, Aedes aegypti was the only YF vector present. Two YF virus strains were isolated from females of this mosquito species caught in a village of western Gambia, where active human cases were documented. The ae. aegypti breeding sites were exclusively of the domestic type. Larval indices varied greatly from place to place, but generally appeared to correlate with the incidence of disease. A better understanding of the conditions that prevailed at the onset and during the early phase of the epidemic will require further entomological investigations. Nevertheless, it appears probable that initial transmission as by sylvatic vectors such as the Ae. furcifer-taylori group and possibly others such as Ae. luteocephalus, Ae. metallicus, and Ae. vittatus. As the outbreak progressed, interhuman transmission by Ae. aegypti also occurred, and this mixed epidemiological pattern later gave way to transmission by Ae. aegypti only when sylvatic vector populations declined in the dry season. We speculate that a prolongation of the rainy season during 1976--1978 was important in the origin of the outbreak. The relationship of this epidemic to the established focus of sylvatic YF in southeastern Senegal is discussed. The Gambian outbreak is considered the result of a recent northwesterly extension of the YF Emergence Zone.

[A serological survey of arboviruses in Gabon]. / Enquête sérologique pour les arbovirus au gabon.

Serological studies for arbovirus antibodies were carried out on 1.279 human serum specimens collected from adults in south-eastern part of Gabon from June to September 1975 during a multipurpose epidemiological survey. More than 80% of the population surveyed have neutralizing antibodies for yellow fever virus as consequence of mass vaccination campaign. Chikungunya, Zika, Wesselsbron and Koutango virus showed some activity, especially in woodland savannahs.

[A serological survey of arboviruses in the human population of Senegal]. / Enquête sérologique pour les arbovirus dans la population humaine du sénégal.

2,457 serum samples collected during an epidemiological survey on treponematosis in Senegal by the W. H. O. IR051 team in five areas of Senegal between 1972 and 1975 were studied for arbovirus antibodies using hemagglutination inhibition test. In addition 998 were studied using CF test and 1012 in neutralization test with yellow fever virus. The prevalence of arbovirus antibodies is important in all the country and does not vary basically between the different areas. In group A, chikungunya antibody is the most frequent and Sindbis antibody was found only in areas where migrant birds are resting. There is evidence of recent yellow fever infection in Upper Casamance and in Eastern Senegal. Most of the children are not immune and have to be immunized. Zika and Wesselsbron viruses show activity in all the areas and West-Nile, as Sindbis, is related to areas where birds are numerous. Bunyamwera virus activity is low.

[Controlled tests of anti-meningococcal polysaccharide A vaccine in the African Sahel area (Upper Volta and Mali) ]. / Essais controles du vaccin anti-meningococcique polysaccharidique a en Afrique de l'ouest Sahelienne (Haute Volta et Mali).

After the first tests of this vaccine in Egypt (1972) and in the Sudan (1973), two controlled tests in the field were performed in two high-risk areas for meningitis: --firstly, in the region of Koudougou (Upper-Volta), in November-December 1973 (17,300 vaccines). Its major aim was to solve operational and logistical problems; --secondly, in the Koutiala (Mali) area, according to a very strict schedule, in November-December 1975 and December 1975 (37,979 vaccines). The complete innocuousness of the vaccine was proven and excellent seroconversion was observed after its administration. On the individual level, it was confirmed that the vaccine ensures excellent protection for a period of at least three years. This new prophylactic weapon inspires the authors to suggest a new strategy in the fight against meningitis epidemics caused by meningococcus in the African Sahel area, taking into account the current increase there in serogroup C, against which there is also a vaccine whose efficacy has already been demonstrated.