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P Aaby

Publications and source records attributed to P Aaby.

At least 109 records · Page 6Linked to original sources
PubMed1996

Child mortality following standard, medium or high titre measles immunization in West Africa.

BACKGROUND: The World Health Organization (WHO) recommended the use of high titre measles vaccine in 1989. Subsequent long term follow-up of several trials yielded results suggesting higher mortality among children inoculated with medium and high titre vaccines compared to standard titre vaccines, although none of the individual trials found significant differences in mortality. METHODS: Long term survival after standard, medium and high titre measles vaccines has been investigated in a combined analysis of all West African trials with mortality data. In trials from Guinea-Bissau, The Gambia and Senegal, children received medium or high titre vaccines from 4 months of age and were compared to control groups recruited at the same time later receiving standard titre vaccine from 9 months of age. All children were followed up to at least 3 years old. RESULTS: Combining trials of high titre vaccines showed higher mortality among the high titre group compared to the standard group: mortality ratio (MR) = 1.33 (95% CI : 1.02-1. 73). Mortality among recipients of medium titre vaccines was not different from that in the standard vaccine group, MR = 1.11 (95% CI: 0.54-2.27). In a combined analysis by sex, the adjusted mortality ratios comparing high titre vaccine with standard vaccine were 1.86 (95% CI : 1.28-2.70) for females and 0.91 (95% CI : 0.61-1.35) for males. The trials were not designed to study long term mortality. Adjustments for several possible sources of bias did not alter the results. CONCLUSIONS: The combined analysis showed a decreased survival related to high titre measles vaccine compared with standard titre vaccines, though solely among females. As a result of these studies from West Africa and a study from Haiti, WHO has recommended that high titre measles vaccine no longer be used.

Age Distribution↗
PubMed1996

A community-based study of human immunodeficiency virus type 2 provirus load in rural village in West Africa.

A community-based study of provirus load in human immunodeficiency virus (HIV) type 2-infected subjects was done in a rural village in Guinea-Bissau. HIV-2 provirus load varied considerably, with a geometric mean of 124.3 (95% confidence interval, 86.0-179.6) copies/10(5) CD4 cells, which is a level similar to that found in HIV-1 infection. Neither malaria parasitemia, active syphilis, or human T cell leukemia virus coinfection significantly influenced provirus load, nor did age. Eleven of 104 HIV-2-infected subjects had died after 3 years of follow-up; 9 of those who died had a high provirus load of > or = 100 copies/10(5) CD4 cells and a relatively low CD4 cell percentage of < 29%.

Adult↗
PubMed1996

Age of wife as a major determinant of male-to-female transmission of HIV-2 infection: a community study from rural West Africa.

OBJECTIVE: To examine whether proviral load is important for transmission between spouses, since we have previously found that the proviral load of HIV-2 predicts the severity of infection. DESIGN: Proviral load was examined in 121 HIV-2-infected adults in a rural area of Guinea-Bissau. For the 68 subjects who had a spouse of known HIV status the risk of the spouse being infected was examined. METHODS: Statistical methods for dependent data were used, because several couples were polygamous. RESULTS: Twenty-seven HIV-2-infected men had 52 current wives of whom 17 (33%) were HIV-2-seropositive. Forty-one HIV-2-infected women had 36 current husbands of known HIV serostatus; nine (25%) were HIV-2-positive. In univariate analyses, concordance of female partners of HIV-2-infected men increased with a previous history of prostitution, age of wife, lack of age difference between the spouses, number of previous husbands, number of wives of the man, and the proviral load. The only significant predictor of concordance in multivariate analyses when wives with a history of prostitution were excluded was an age of 45 years or older [odds ratio (OR), 8.68; 95% confidence interval (CI), 2.34-32.22]. This tendency was not explained by the length of current marriage. Although husbands with a high proviral load were more likely to have concordant spouses than those with a low proviral load (< 20 copies/10(5) CD4 cells), this association was not statistically significant (OR, 2.59; 95% CI, 0.90-7.46). Among spouses of HIV-2-infected women, none of the examined factors, including previous prostitution or proviral load in the woman, predicted whether the husband was HIV-2-infected. CONCLUSIONS: Women appear to be more susceptible to HIV-2 infection after 40-45 years of age. The apparent change in susceptibility may be a major reason for the distinctive age pattern of HIV-2 infection observed in West Africa.

Adolescent↗
PubMed1996

No persistent T lymphocyte immunosuppression or increased mortality after measles infection: a community study from Guinea-Bissau.

BACKGROUND: Because measles immunization is reducing overall childhood mortality in addition to mortality from acute measles infection, it has been suggested that postmeasles cases have excess mortality, possibly related to persistent immunosuppression after measles infection. After an epidemic in 1988 in Guinea-Bissau, we therefore examined T lymphocyte subsets and long term survival among measles cases and controls. METHODS: We examined 69 children < 3 years of age with a median delay of 2 months after measles infection and 71 controls who did not contract measles. The immunoalkaline method was used to determine T lymphocyte subsets. The children were followed for 5 years. RESULTS: Compared with controls, there were no significant differences in white blood cell count, absolute lymphocyte count, CD4 percentage, CD8 percentage, total CD4 count and total CD8 count, although measles cases examined > 2 months after infection had slightly higher CD4 counts than controls (P = 0.06). Adjusted for age, sex and immunization status, postmeasles cases had a mortality rate ratio of 0.50 (95% confidence interval, 0.22 to 1.16) (P = 0.11) compared with controls. CONCLUSIONS: There is no indication of persistent suppression of T cell subsets after measles infection, and postmeasles cases did not have higher mortality than uninfected community controls.

Child, Preschool↗
PubMed1996

Maternal perception of cause, signs and severity of diarrhoea in a suburban west African community.

With the aim of investigating perceived morbidity and care seeking behaviour, a household survey was conducted, where 319 episodes of diarrhoea were followed by interviews every second day. The chance of consultation increased with the number of symptoms reported by the mother. The appearance of the eyes and how the child breastfed were early warnings that mothers recognized best. By contrast, there was an 80% reduction in the likelihood of seeking consultation when the mother perceived the diarrhoea as caused by teeth eruption (n = 96). Children with "teething diarrhoea" were, however, just as likely to develop signs of dehydration as children with non-teething diarrhoea. We conclude that health education concerning diarrhoea should emphasize early signs of dehydration and the discouragement of "teething" as an explanation of natural diarrhoea.

Africa, Western↗
PubMed1995

Role of immunizations in the recent decline in childhood mortality and the changes in the female/male mortality ratio in rural Senegal.

In early 1987, immunizations were introduced to an isolated area of eastern Senegal where there had previously been no regular immunizations. Since immunizations were the only change introduced in the area during this period, this allowed the authors to study the impact of immunizations of mortality in different age groups and the possible interaction with sex differences in mortality. They compared mortality rates for the 6 years before and the 6 years after the introduction of immunization. Neonatal mortality declined 31% (95% confidence interval (CI) 17 to 43); between 1 and 8 months of age, the reduction was 20% (95% CI -2 to 37); and between 9 and 59 months of age, mortality declined 48% (95% CI 39 to 56). Excluding acute measles deaths, the reduction was 16% (95% CI -8 to 35) between 1 and 8 months of age and 32% (95% CI 20 to 43) between 9 and 59 months of age. The decline was stronger in villages that maintained high coverage after the initial national campaign, whereas mortality increased again in the villages where the coverage declined. Since the reduction in mortality was most marked after 9 months of age, measles immunization is likely to have been the most important vaccination. Both female and male mortality declined but not equally quickly. The reduction in mortality in the neonatal period was significantly greater in males than in females, resulting in an increase in the female/male mortality ratio from 0.64 (95% CI 0.50 to 0.83) to 0.96 (95% CI 0.71 to 1.30), p = 0.04. After 9 months of age, the reduction in mortality was somewhat greater in females than in males, resulting in a decrease in the female/male mortality ratio from 1.04 (95% CI 0.85 to 1.28) to 0.79 (95% CI 0.62 to 1.02), p = 0.10.

Age Distribution↗
PubMed1995

Non-specific beneficial effect of measles immunisation: analysis of mortality studies from developing countries.

OBJECTIVE: To examine whether the reduction in mortality after standard titre measles immunisation in developing countries can be explained simply by the prevention of acute measles and its long term consequences. DESIGN: An analysis of all studies comparing mortality of unimmunised children and children immunised with standard titre measles vaccine in developing countries. STUDIES: 10 cohort and two case-control studies from Bangladesh, Benin, Burundi, Guinea-Bissau, Haiti, Senegal, and Zaire. MAIN OUTCOME MEASURES: Protective efficacy of standard titre measles immunisation against all cause mortality. Extent to which difference in mortality between immunised and unimmunised children could be explained by prevention of measles disease. RESULTS: Protective efficacy against death after measles immunisation ranged from 30% to 86%. Efficacy was highest in the studies with short follow up and when children were immunised in infancy (range 44-100%). Vaccine efficacy against death was much greater than the proportion of deaths attributed to acute measles disease. In four studies from Guinea-Bissau, Senegal, and Burundi vaccine efficacy against death remained almost unchanged when cases of measles were excluded from the analysis. Diphtheria-tetanus-pertussis and polio vaccinations were not associated with reduction in mortality. CONCLUSION: These observations suggest that standard titre measles vaccine may confer a beneficial effect which is unrelated to the specific protection against measles disease.

Bangladesh↗
PubMed1995

Assumptions and contradictions in measles and measles immunization research: is measles good for something?

Measles infection, the major cause of childhood mortality among infections preventable by immunization, has been considered to kill mainly young and malnourished children. Assuming that mainly 'weak' children are saved by immunizations, it has been speculated that the impact on survival of immunization is likely to be limited because the malnourished children are more prone to die of other infections. However, recent studies from developing countries have suggested that host factors may not be the most important determinants of acute and long-term mortality after measles infection. Instead, it was found that infection contracted after exposure at home infection contracted from someone outside the home. Furthermore, measles is particularly severe if contracted from someone of the opposite sex. Hence transmission factors, in particularly intensity of exposure and cross-sex transmission, may be more important determinants of measles mortality than the determinants of measles mortality than the host factors usually emphasized. Consistent with these observations and in contrast to assumptions about 'weak' children dying, immunization is associated with a major reduction in mortality. Since measles immunization is associated with a 30% reduction in mortality or more, the impact is much larger than should be expected from the proportion of all deaths attributed to measles. It has therefore been suggested that measles immunization may prevent the persistent immunosuppression and delayed mortality assumed to be associated with measles. However, several observations contradict the common understanding that the function of measles immunization is only to prevent the acute and long-term mortality associated with measles infection. Recently, the high-titre measles immunization recommended by WHO was found to be associated with reduced survival for female recipients compared with girls who have received the standard low-dose measles vaccine, and this difference in survival was not due to suboptimal protection against measles infection. Contrary to usual assumptions. against measles infection. Contrary to usual assumptions, standard low-dose measles vaccine reduces mortality even more when given before 9 months of age, the age currently recommended by WHO. The beneficial impact of standard vaccine is apparently temporary, lasting 1 to 2 years, whereas it should increase with the age of the child. The beneficial effect seems to be particularly strong for girls. The most likely interpretation of these observations, is that standard low-dose measles vaccine has a non-specific beneficial effect. Contrary to current assumptions, children who survive the acute phase of measles infection may have a survival advantage compared with unimmunized, uninfected children.(ABSTRACT TRUNCATED AT 400 WORDS)

Cause of Death↗
PubMed1995

Validity of measles mortality data using hospital registers and community surveys.

BACKGROUND: Case-fatality rates (CFR) for measles cases have previously been reported to be higher in hospital than in community studies. METHODS: Data on measles morbidity and mortality obtained in community investigations of measles outbreaks in two rural districts in Kenya were compared to data from the same time period on measles morbidity and mortality in children hospitalized with measles in the respective district hospitals. RESULTS: The CFR were found to be considerably lower in the respective district hospitals, 1.7 and 2.1%, than in the community surveys, 8.0% and 9.4%, respectively (relative risk [RR] 0.17, 95% confidence interval [CI] 0.10-0.30, and RR = 0.20, 95% CI: 0.05-0.81). CONCLUSIONS: Hospital-based studies of the CFR in measles infection are not representative of measles mortality in the community. It may be misleading to use hospital data in measles control surveillance systems. Further studies are needed of the mortality after discharge of hospitalized measles cases.

Age Factors↗
PubMed1995

Lower mortality for female-female twins than male-male and male-female twins in rural Senegal.

Twins have been registered prospectively for 12-22 years in 42 small villages in the Bandafassi area of Eastern Senegal. We studied 98 pairs of twins to test whether twins in opposite-sex pairs have higher postneonatal mortality than same-sex twins. Neonatal mortality for twins was 41.3%; mortality for infants and for children under age 5 years was 53.0% and 66.8%, respectively. Neonatal mortality was identical for same-sex and opposite-sex twin pairs, but much higher for boys than girls [relative risk = 1.8; 95% confidence interval (CI) = 1.2-2.6]. There was clustering of double neonatal deaths for all types of twins. In the postneonatal period, female-female twins had lower mortality than other twin types. Twins had higher post-neonatal mortality as long as the co-twin was alive [mortality rate ratio (MR) = 2.6; 95% CI = 1.0-6.7]. Girls had excess mortality when the co-twin was of the opposite sex (MR = 4.3; 95% CI = 1.2-15.3), whereas there was no difference for boys. In conclusion, contact with a co-twin of the opposite sex increased child mortality for female twins. Our data are not sufficient to determine whether this difference is specific for girls or applies to boys as well.

Child, Preschool↗
PubMed1995

Serologic status and measles attack rates among vaccinated and unvaccinated children in rural Senegal.

During a measles vaccine trial in a rural area of Senegal, antibody status was examined within 10 days of exposure for 228 previously vaccinated and 313 unvaccinated children more than 12 months old who were exposed to measles at home. Thirty-six percent of the children developed clinical measles, the clinical diagnosis being confirmed for 135 of the 137 children from whom 2 blood samples were collected. Vaccine efficacy was 90% (95% confidence interval, 83 to 94%). The hemagglutinin-inhibiting antibodies (HI) or plaque neutralizing antibodies (PN) assays were equally efficient in predicting susceptibility and protection against measles. Vaccinated children who had no detectable HI or PN antibodies at exposure had significant protection against measles compared with seronegative unvaccinated children (HI vaccine efficacy, 49% (95% confidence interval, 21 to 68%); PN vaccine efficacy, 43% (95% confidence interval, 12 to 62%)). The attack rate was high for children with a titer of 40 to 125 mIU) 67% (4 of 6) of those with a positive hemagglutinin-inhibiting antibody test and 36% (13 of 36) of those with a positive PN test developed measles. Attack rates among children with HI or PN titers above 125 mIU were 2% (6 of 295) and 3% (7 of 258), respectively. Because titers of < or = 120 mIU have been found to offer little protection in another study, this antibody level may be the best screening value for assessing susceptibility and protection against measles. However, it should be noted that many seronegative vaccinated children are protected against measles infection.

Adolescent↗
PubMed1995

Measles in infants: a review of studies on incidence, vaccine efficacy and mortality in east Africa.

Control of measles in developing countries is complicated by high incidence and mortality among infants. Hospital-based and community-based studies from East Africa were reviewed with respect to the reported incidence and mortality of measles and vaccine efficacy/seroconversion rates after the administration of measles vaccine to infants. The studies reviewed confirm that measles is particularly severe in infants, and some indicate that vaccination before 9 months with standard vaccine could be effective and have beneficial effects for children aged 6-9 months, while other studies refute this finding. Due to the high incidence and mortality of measles in infants, alternative control strategies are essential to reduce measles mortality. Further studies are needed on the effects of a two-dose schedule vaccinating at 6 and 9 months, which in mathematical modelling shows considerable benefit. Improved management of measles cases, including the administration of vitamin A could be considered as a complementary strategy for reducing measles mortality, especially in infants.

Age Distribution↗
PubMed1994

[Measles vaccination and age].

Recent studies have found administration of high-titre measles vaccine before 9 months of age to be associated with reduced survival. Since this suggests that early immunization could be unsafe, we examined the results of immunization campaigns with Schwarz standard measles vaccine carried out in 1980-1983 in three areas of Guinea-Bissau. Children were followed to death, migration or the age of five years. Children immunized at 4-8 months of age, of whom many were later re-immunized, had lower mortality between nine months and five years of age compared with children vaccinated at 9-11 months of age. The improved survival was unrelated to better protection against measles. There was no sign of socio-cultural differences between children immunized at different ages. Vaccination before 9 months of age is apparently safe and it may reduce childhood mortality compared with the currently recommended strategy of immunizing from nine months of age. Randomized trials are needed to confirm these observations which may have implications for the measles immunization strategy for developing countries.

Age Factors↗