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Biomedical subjects

P Byass

Publications and source records attributed to P Byass.

At least 73 records · Page 4Linked to original sources
PubMed1987

Trial of an attenuated bovine rotavirus vaccine (RIT 4237) in Gambian infants.

A randomised, controlled trial of bovine rotavirus vaccine was undertaken in Gambian infants. Three doses were administered, from the age of ten weeks, concurrently with oral or killed polio vaccine. Prevaccination rotavirus neutralising antibody levels were high. 84/185 infants (45%) showed an increase in neutralising antibody titre after receiving rotavirus vaccine, compared with 20/91 (22%) unvaccinated infants. Clinical rotavirus infection was detected in 24/78 (31%) children in the rotavirus/oral polio group, 34/83 (41%) children in the placebo/oral polio group, and 23/92 (25%) children in the rotavirus/killed polio group, giving an overall vaccine efficacy of 33% (95% CI 4-53%). RIT 4237 did not appear to reduce the severity of clinical infections. Most cases (92%) were caused by rotaviruses with short RNA electropherotypes. Serological responses to rotavirus vaccination appeared unaffected by the concurrent administration of oral polio vaccine. Lower types 1 and 3 polio antibody levels were found in children who received oral polio and rotavirus vaccines but the differences were not statistically significant.

Animals↗
PubMed1987

Mortality and morbidity from malaria among children in a rural area of The Gambia, West Africa.

Mortality and morbidity from malaria were measured among 3000 children under the age of 7 years in a rural area of The Gambia, West Africa. Using a post-mortem questionnaire technique, malaria was identified as the probable cause of 4% of infant deaths and of 25% of deaths in children aged 1 to 4 years. The malaria mortality rate was 6.3 per 1000 per year in infants and 10.7 per 1000 per year in children aged 1 to 4 years. Morbidity surveys suggested that children under the age of 7 years experienced about one clinical episode of malaria per year. Calculation of attributable fractions showed that malaria may be responsible for about 40% of episodes of fever in children. Although the overall level of parasitaemia showed little seasonal variation, the clinical impact of malaria was highly seasonal; all malaria deaths and a high proportion of febrile episodes were recorded during a limited period at the end of the rainy season.

Age Factors↗
PubMed1987

Epidemiology of rotavirus in a periurban Gambian community.

Short, well demarcated epidemics of rotavirus diarrhoea were observed during two consecutive cool, dry seasons in The Gambia. This seasonal pattern has now been documented for 4 consecutive years. During the 1985/86 epidemic, transmission was intense, with a clinical attack rate for infants of 36%. During this outbreak it was estimated that asymptomatic virus-shedding was two-thirds as common as symptomatic infection. Rotavirus diarrhoea was more severe than diarrhoea due to all other causes and clinical rotavirus infection was associated with weight loss in the post-infection period. Non-epidemic periods were characterized by very occasional mild cases and asymptomatic virus-shedding in neonates. There was a change in RNA electropherotypes from a predominantly long pattern in 1983/84 and 1984/85 to short patterns in 1985/86.

Child, Preschool↗
PubMed1986

Bed-nets (mosquito-nets) and morbidity from malaria.

A study was undertaken in the Farafenni area of The Gambia to determine the relation between morbidity from malaria in children and the use of bed-nets (mosquito-nets). From comparisons of parasite and spleen rates in bed-net users and in non-users it seemed that bed-nets had a strong protective effect. However, the prevalence of malaria in the study population was also influenced by ethnic group and place of residence, and the association of bed-net use with these two confounding factors accounted for some of the differences observed between bed-net users and non-users. Nevertheless, a significant inverse correlation between splenomegaly and the use of bed-nets remained. This suggests that bed-nets give Gambian children some protection against malaria and that the use of bed-nets, either untreated or treated with an insecticide such as permethrin, should be investigated further as a means of malaria control in Africa.

Adolescent↗
PubMedDate not supplied

Cellular immune responses to Plasmodium falciparum antigens in children receiving long term anti-malarial chemoprophylaxis.

Fifty-two Gambian children who had received fortnightly chemoprophylaxis with maloprim, (pyrimethamine and dapsone), and 45 receiving placebo, were studied. Cellular immune responses to malaria antigens, measured by lymphoproliferative responses and interferon production, were higher in children who had received prophylaxis than in controls, although the anti-malarial antibody levels were lower. During a one-year period after termination of prophylaxis, there was no increase in the frequency of clinical episodes of malaria in the children who had received Maloprim. These results suggest that chemoprophylaxis for 3 years may lower malaria antibody levels, but does not interfere with the development of protective immunity, perhaps by enhancing cell-mediated immune responses to malaria in protected children.

Animals↗
PubMedDate not supplied

The effects of malaria chemoprophylaxis given by traditional birth attendants on the course and outcome of pregnancy.

A trial of malaria chemoprophylaxis given by traditional birth attendants was undertaken in a rural area of The Gambia where access to antenatal clinics is difficult. Women received one or more doses of Maloprim or placebo from a traditional birth attendant during 1049 of 1208 pregnancies (87%) recorded in 16 villages over a 3-year period. Primigravidae who received Maloprim had a lower parasite rate and a significantly higher mean packed cell volume than primigravidae who received placebo, and their babies were significantly heavier (6% low birth weight vs 22%). In multigravidae chemoprophylaxis reduced malaria parasitaemia but it had no beneficial effect on haemoglobin level and much less effect on birth weight than was observed in primigravidae. However, the mean birth weight of babies born to grandemultigravidae who received chemoprophylaxis was significantly higher than that of babies born to grandemultigravidae who did not.

Antimalarials↗
PubMedDate not supplied

Lack of an association between acute gastroenteritis, acute respiratory infections and malaria in young Gambian children.

The incidence of acute gastrointestinal and acute respiratory infections was measured in 2 groups of approximately 750 Gambian children aged 3-59 months during a 3-year period. One group of children was partially protected against malaria by fortnightly chemoprophylaxis with Maloprim whilst children in the other group were infected much more frequently. Mortality from acute gastroenteritis and from acute respiratory infections was similar in the 2 groups. The proportions of children in each group who complained of gastrointestinal or severe respiratory symptoms on morbidity surveillance were also similar. Thus, no evidence was found to suggest that malaria plays either a direct or indirect role in causing acute gastrointestinal or respiratory infections in young children in The Gambia.

Acute Disease↗
PubMedDate not supplied

Sustained protection against mortality and morbidity from malaria in rural Gambian children by chemoprophylaxis given by village health workers.

Mortality and morbidity from malaria were measured in children for a one-year period in a rural area of The Gambia 3-4 years after the introduction of a primary health care programme into some villages in the study area. Among children resident in primary health care villages who received treatment for febrile illnesses from a village health worker resident in their village there was no reduction in overall mortality or in morbidity from malaria compared with levels found in villages without a primary health care worker. However, among children aged 3-59 months who received malaria chemoprophylaxis from a village health worker in addition to treatment there was a 49% reduction in mortality and a 73% reduction in attacks of clinical malaria. The level of protection against malaria achieved by chemoprophylaxis given by village health workers 3-4 years after the chemoprophylaxis programme was started was as high as that obtained shortly after the introduction of the primary health care programme.

Antimalarials↗
PubMedDate not supplied

The relationship between anthropometric measurements and measurements of iron status and susceptibility to malaria in Gambian children.

Anthropometric measurements were made and serum iron and ferritin levels determined in a group of Gambian children at the beginning of the rainy season and these findings were related to the malaria experience of the children during the following malaria transmission season. Susceptibility to malaria was not correlated with prior weight-for-age, height-for-age, weight-for-height or serum albumin, or with serum iron, serum iron binding capacity nor serum ferritin. Thus, our findings do not provide any support for the view that poor nutritional status, as assessed by anthropometric measurements, or iron deficiency protect against malaria infection. Children who developed a clinical attack of malaria accompanied by a high level of parasitaemia tended to have a higher mean weight-for-age at the beginning of the rainy season than did children who had a clinical attack accompanied by a low level of parasitaemia, but the difference between groups was not statistically significant. However, they had a significantly higher mean serum ferritin level (P less than 0.01).

Anthropometry↗
PubMedDate not supplied

Malaria chemoprophylaxis, birth weight and child survival.

Study of the effects of malaria chemoprophylaxis given during pregnancy on birthweight and investigation of the influence of birthweight on child survival suggest that, in a rural area of The Gambia, chemoprophylaxis given during pregnancy might reduce infant mortality by about one-fifth in the children of primigravidae but by less than 5% in the children of multigravidae. In malaria endemic areas, primigravidae should be protected against malaria not only for their own sake but also for that of their infants.

Antimalarials↗
PubMedDate not supplied

Measurement of serum haptoglobin as an indicator of the efficacy of malaria intervention trials.

Serum haptoglobin levels were measured by an enzyme-linked immunosorbent assay in Gambian children who participated in 3 malaria intervention trials with untreated or impregnated bed nets. In one study, in which a significant effect on clinical malaria was observed, the mean serum haptoglobin level was significantly higher in the intervention than in the control group. In the other 2 studies, in which no significant protection was observed, mean haptoglobin levels were similar in intervention and control groups. Measurement of serum haptoglobin may provide a useful indirect measure of the effectiveness of malaria control programmes.

Bedding and Linens↗
PubMedDate not supplied

Mortality and morbidity from malaria after stopping malaria chemoprophylaxis.

Gambian children who had received malaria chemoprophylaxis for a variable period of time during their first 5 years of life were followed to determine whether they experienced a rebound in mortality or in morbidity from malaria during the period after chemoprophylaxis was stopped. The risk of dying between the ages of 5 years, when chemoprophylaxis was stopped, and 10 years was no higher among children who had received chemoprophylaxis with Maloprim (pyrimethamine plus dapsone) for some period during their first 5 years of life than among children who had received placebo (21 vs. 24 deaths) and the beneficial effect of chemoprophylaxis on mortality observed during the first 5 years of life was sustained. The incidence of clinical attacks of malaria during the year after medication was stopped was significantly higher among children who had previously received Maloprim for several years than among children who had previously received placebo. However, at the end of this year, there was no significant difference in spleen rate, parasite rate or packed cell volume between the 2 groups of children. Thus, stopping chemoprophylaxis after a period of several years increased the risk of clinical malaria but did not result in a rebound in mortality in Gambian children. However, the number of deaths recorded was small, so a modest effect on mortality cannot be excluded.

Animals↗