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Biomedical subjects

P Aaby

Publications and source records attributed to P Aaby.

At least 163 records · Page 9Linked to original sources
PubMed1990

Increased postperinatal child mortality among children of mothers exposed to measles during pregnancy.

Previous studies of an urban and a rural epidemic in Guinea-Bissau have shown perinatal mortality to be statistically significantly higher among children whose mothers have been exposed to measles during pregnancy. After the epidemic in 1970 in Bandim, a district in the capital of Guinea-Bissau, such children also had a postperinatal childhood mortality risk (7 days to 5 years of age) of 0.229, compared with 0.134 for other children in the community. None of the mothers had developed clinical measles. In a Cox regression analysis adjusting for known background factors, the mortality hazard ratio between the exposed and the controls was found to be 2.0 (95% confidence interval 1.1-3.8). After a small rural measles epidemic in Quinhamel in 1983, the mortality hazard ratio for children of mothers exposed during pregnancy compared with controls was 1.7 (95% confidence interval 0.6-4.6). Exposure to measles or some concomitantly transmitted pathogen during fetal life may contribute to the high childhood mortality found in many developing countries.

Child, Preschool↗
PubMed1990

An epidemic outbreak of cryptosporidiosis: a prospective community study from Guinea Bissau.

In the first year of a prospective community study of childhood diarrhea conducted in a semiurban area in the capital of Guinea Bissau, Cryptosporidium sp. was found in 73 (6.0%) of 1216 episodes of diarrhea. The parasite was the second most prevalent intestinal parasite, and the only one significantly associated with diarrhea (OR = 2.79, P = 0.0006). The seasonal distribution was striking, with a peak prevalence in the beginning of the rainy season (May 17.6%) when an epidemic outbreak of diarrhea started. The prevalence was highest in children younger than 18 months, an age at which prevalences of other intestinal parasites were low. This reverse age pattern may possibly be explained by the small infective dose needed to create severe infections, by air-borne transmission and by the development of protective immunity.

Cryptosporidiosis↗
PubMed1990

Immunodeficiency in HIV-2 infection: a community study from Guinea-Bissau.

In a community study in Guinea-Bissau, West Africa, 47 HIV-2-seropositive cases and 87 matched controls were evaluated immunologically using immuno-alkaline phosphatase linked to avidin-biotin complex for the assessment of CD4 and CD8 status. HIV-2-seropositive individuals had significantly lower total numbers of CD4 cells and CD4/CD8 ratios, 38% having a total number of CD4 cells less than or equal to 0.5 x 10(9)/l and 36% having a CD4/CD8 ratio less than or equal to 0.8. Total numbers of CD4 cells less than or equal to 0.5 x 10(9)/l or CD4/CD8 ratio less than or equal to 0.8 were found in 53% of the HIV-2 seropositives compared with 11% among controls [odds ratio (OR) = 7.3; 95% confidence interval (CI): 3.1-17.1]. Lymphadenopathy was significantly more frequent among HIV-2 seropositives than among controls (OR = 3.4; 95% Cl: 1.5-7.6). HIV-2 seropositives with lymphadenopathy had significantly fewer lymphocytes (P = 0.008) and lower total CD4 (P = 0.029) and total CD8 number (P = 0.011) than HIV-2 seropositives without lymphadenopathy. This study indicates that HIV-2 has a significant immunosuppressive effect.

Adult↗
PubMed1989

Prevalence of and mortality from human immunodeficiency virus type 2 in Bissau, West Africa.

In a community based prevalence study of HIV infection in Bissau, West Africa, 1987, the population in 100 randomly selected "houses" was asked to participate. 89% (1329/1499) were examined and had a blood sample taken. None was HIV-1 seropositive but 4.7% were seropositive for HIV-2 (0.6% in children, 8.9% in those aged 15 years and over, and 20% in those aged 40 years and over). There was no significant difference in seroprevalence between areas or ethnic groups or between individuals of different civil status when age was taken into account. Sexual contact and blood transfusions were the dominant transmission routes, and no case of vertical transmission was identified. The HIV-2 seroprevalence in spouses of HIV-2 seropositive index persons was 40%. For a history of blood transfusion the relative risk of being HIV-2 seropositive was 103.6 in children and 2.4 for adults. After exclusion of spouses, no clustering of HIV-2 seropositivity was seen. At follow-up, after a mean observation time of 325 days, there was an excess mortality for HIV-2 seropositives. The relative risk of dying for HIV-2 seropositive children was 60.8 and for adults 5.0.

Adolescent↗
PubMed1989

Measles immunization research: a review.

Most global estimates indicate that more than 1 million children a year die from acute measles. The actual number of deaths may, however, be considerably higher than this. In addition, the impact of delayed mortality as a result of measles infection is only now being realized. Many months after they contract measles, children continue to experience higher levels of mortality and morbidity than those who do not. Immunization of children against measles therefore prevents mortality and morbidity not only during the acute phase but also during subsequent months. The impact of measles immunization programmes may therefore have generally been underestimated. The effects of measles infection on children during the early months of life are more damaging than those experienced by older children. Children should therefore be immunized against measles as early in life as possible, given the limitations of existing vaccines.

Child↗
PubMed1989

Child mortality related to seroconversion or lack of seroconversion after measles vaccination.

When blood samples were analyzed for seroconversion after measles vaccination, it was discovered that the vaccine had been ineffective for a certain period. During the 2 years between vaccination and the time of seroanalysis, nonseroconverters had a significantly higher mortality than seroconverters (P less than 0.05). The incidence of measles among nonseroconverters was 30% during the period. Between 9 months and 3 years of age, cumulative mortality was 15.1% for nonseroconverters and 4.5% for seroconverters. The difference in mortality was larger when high risk groups (twins, motherless children) were excluded from the analysis (P less than 0.01). The difference in mortality was particularly marked among children vaccinated in the age group 9 to 11 months. This as well as other community studies suggest that measles vaccination reduces child mortality from the age of vaccination by at least 30%.

Antibody Formation↗
PubMed1988

Trial of high-dose Edmonston-Zagreb measles vaccine in Guinea-Bissau: protective efficacy.

In a randomised study of 558 children in an urban African community, the protective effect of the Edmonston-Zagreb (EZ) measles vaccine given in a dose of 40,000 plaque forming units from the age of 4 months was compared with the effects of a standard dose (6000 tissue culture infectious units) of Schwarz measles vaccine given from the age of 9 months. During two years of follow-up, all 14 clinical cases of measles occurred in the Schwarz group; 10 of the children contracted measles before vaccination and 4 after measles vaccination. Thus the EZ vaccine provided significant protection against measles both before and after the usual age of vaccination. Among the children who were exposed to measles at home, those given EZ vaccine were better protected than either unvaccinated children or those given the Schwarz vaccine.

Age Factors↗
PubMed1988

Trial of high-dose Edmonston-Zagreb measles vaccine in the Gambia: antibody response and side-effects.

In a randomised trial, infants living in a large village in The Gambia were immunised either at 4 months of age with 40,000 plaque forming units (PFU) of the Edmonston-Zagreb (EZ) measles vaccine or at the usual age of 9 months with 6000 TCID50 of a conventional Schwarz measles vaccine. Measles developed in 2 of 119 children who received the EZ vaccine, in 1 before and in the other after 9 months of age. In the Schwarz group measles developed in 7 of 120 children--in 5 before and in 2 after 9 months of age. Serological responses measured at 5 months after vaccination and at 18 months of age were satisfactory in both groups although in the Schwarz group levels were on average 2-fold higher than in the EZ group. The frequencies of fever, cough, vomiting, and diarrhoea were no higher in the EZ vaccinees in the 3 weeks following vaccination than in age-matched non-immunised controls. Long-term morbidity as assessed by clinic attendances and weight at 18 months of age was much the same in the two groups. The EZ measles vaccine is thus safe and clinically and serologically effective when used in a high dose to immunise young Gambian infants.

Age Factors↗
PubMed1988

Decline in measles mortality: nutrition, age at infection, or exposure?

The mortality from measles was studied in an urban area of Guinea-Bissau one year before and five years after the introduction of a vaccination programme. The years after the introduction of immunisation saw a decline in mortality among unvaccinated children with measles. This decline occurred despite a lower age at infection and an increasing prevalence of malnourished children. State of nutrition (weight for age) did not affect the outcome of measles infection. The incidence of isolated cases, however, increased in the period after the introduction of measles vaccination. As mortality was lower among these cases, diminished clustering explained some of the reduction in mortality. Comparison between the urban district and a rural area inhabited by the same ethnic group showed a lower age at infection, less clustering of cases, and lower case fatality ratios in the urban area. Endemic transmission of measles in urban districts leads to less clustering of cases, which may help explain the usually lower case fatality ratios in these areas. As measles vaccination increases herd immunity and diminishes clustering of cases, it may reduce mortality even among unvaccinated children who contract the disease.

Age Factors↗
PubMed1988

Increased perinatal mortality among children of mothers exposed to measles during pregnancy.

A survey done after a severe epidemic of measles in an urban area of Guinea-Bissau has shown that children born to women exposed to measles during pregnancy had a perinatal mortality rate of 15%, compared with only 4% for other children in the community (OR = 4.2; 95% CI 2.1-8.5). None of the women had clinical evidence of measles. Adjusting for background variables, logistic regression analysis showed no tendency towards reduced risk of perinatal mortality among children of women exposed during pregnancy relative to controls. Both stillbirth and early neonatal mortality rates were increased. A similar tendency was found in a rural epidemic (OR = 9.5; 95% CI 2.6-35.1). Exposure during any trimester of fetal life increased the rate of perinatal mortality. The results suggest that exposure to measles virus or some concomitantly transmitted pathogen may contribute to the high perinatal mortality risk found in many developing countries. The possible long-term health consequences of exposure to measles virus should be considered when assessing the value of measles control programmes.

Disease Outbreaks↗
PubMed1987

Humoral immunity in measles infection: a critical factor?

Cell-mediated immunity is generally regarded as the essential factor in recovery from measles infection. In other viral infections humoral immunity has been considered a critical factor when antibody titres were correlated with outcome or when serum therapy proved protective. A review of available studies of severe-to-fatal cases of measles infection having non-neurological symptoms indicate that the antibody response is depressed in virtually all cases. The current view of immune globulin being an ineffective therapeutic agent is based on treatment of measles encephalitis; in fact, the least effect should be expected among encephalitis cases since some already have antibodies from the onset of symptoms. Larger examinations of measles with other than neurological symptoms suggest that immune globulin has a beneficial impact on the clinical course of infection. There are indications that hyperimmune globulin increases the efficacy of this form of treatment. Since measles is still a major cause of hospitalization and mortality, further studies of the therapeutic effect of specific immune globulin are warranted. From our current knowledge, both the humoral and cell-mediated immunity seem to be critical factors in recovery from measles infection.

Antibody Formation↗
PubMed1986

High measles mortality in infancy related to intensity of exposure.

In a West African urban community, measles infection in infants was examined over 5 years (1979-1983). In the age group 0 to 11 months, measles mortality was higher among secondary cases (infected in the house) than among index cases (infected outside the house), and the proportion of secondary cases was significantly higher for this age group than for older children. Intensive exposure related to the social pattern of disease transmission may be important in explaining the high infant mortality observed with measles in developing countries. Mortality during the first 12 months of life increased with age, presumably because of the decrease of maternally derived measles antibodies. In children younger than 6 months of age, who are usually considered to be protected by maternal antibody, intensive exposure may lead to infection, as demonstrated by a high level of measles-specific antibodies in some children exposed to an older sibling with measles. The aim of public health policies should be to change conditions of exposure.

Antibodies, Viral↗
PubMed1986

Survival 0-6 years of age in a periurban community in Guinea-Bissau: a longitudinal assessment.

In the preparation of a child health-care project in a periurban settlement area with a population of 6200, a census identified 1464 children below 6 years of age. One thousand, one hundred and eighty-eight of these children were examined. They were followed up 12 months later, during which interval there was a current registration of the pregnancies, births and deaths in the area. The 360 newborns in the period were successively included in the follow-up. One hundred and forty-four deaths were documented, including the symptoms preceding their occurrence. Sixty-two of the deaths were due to epidemic measles. The probability of survival through the neonatal period was 0.941, to 12 months of age 0.803, and to 60 months 0.546. The health-work that ensued upon this study emphasizes intra-pregnancy care and immunizations to the young children.

Child↗
PubMed1986

Severe measles in Sunderland, 1885: a European-African comparison of causes of severe infection.

On the basis of research in Guinea-Bissau, this paper re-analyses a severe measles epidemic which occurred in 1885 in Sunderland (England). In both England and Guinea-Bissau, acute measles mortality was higher in households with multiple cases than in families with only a single case of measles. Secondary cases (infected in the house) had higher mortality and higher frequency of severe complications than index and single cases. In Sunderland, severe complications were associated with a history of previous respiratory infection and with greater number of siblings. Since cases with severe complications had significantly prolonged prodromal symptoms and shorter periods of incubation, it is suggested that high dose of infection may be an essential mechanism in the pathogenesis of severe disease. Overcrowding may be a major determinant of severe measles because it increases the risks of intensive exposure, intercurrent infections, and previous respiratory infection.

Adolescent↗
PubMed1986

Vaccinated children get milder measles infection: a community study from Guinea-Bissau.

We studied the occurrence of measles in vaccinated children from an urban area of Guinea-Bissau where measles causes high mortality. Vaccinated children who developed measles required more-intense exposure to become infected (they had a higher ratio of secondary cases [infected in the house] to index cases [infected outside the house]), had a lower mortality among secondary cases, and were less infectious (they generated fewer secondary cases than did unvaccinated children with measles). The attack rate among vaccinated children was significantly higher in households in which someone died of measles. Both severity of infection and development of measles in vaccinated children were related to intensity of exposure. Vaccine efficacy was 72%, and 33% of cases occurred among vaccinated children; however, most mothers remained confident that vaccinated children get milder measles. Moreover, there was significantly greater vaccination coverage among younger siblings of vaccinated children who had contracted measles than among other children in the community.

Age Factors↗