Biomedical subjects

Peter Aaby

Publications and source records attributed to Peter Aaby.

At least 37 records · Page 2Linked to original sources

PubMed2006

The sequence of vaccinations and increased female mortality after high-titre measles vaccine: trials from rural Sudan and Kinshasa.

OBJECTIVE: West African studies have hypothesized that increased female mortality after high-titre measles vaccine (HTMV) was due to subsequent diphtheria-tetanus-pertussis (DTP) and inactivated polio vaccine (IPV) vaccinations. We tested two deductions from this hypothesis in HTMV studies from rural Sudan and Kinshasa; first, there should be no excess female mortality for HTMV recipients when DTP was not given after HTMV and second, excess female mortality should only be found among those children who received DTP after HTMV. STUDIES: The Sudanese trial randomised 510 children to Edmonston-Zagreb (EZ) HTMV, Connaught HTMV or a control vaccine (meningococcal). Both the Connaught HTMV and the control group received standard measles vaccine at 9 months. In the Kinshasa study 1023 children received one dose of HTMV at 6 months or two doses at 312 and 912 months of age. FINDINGS: First, the Sudan trial is one of the few randomised studies of measles vaccine; the EZ HTMV group had lower mortality between 5 and 9 months of age than controls, the mortality ratio (MR) being 0.00 (p = 0.030). This effect was not due to prevention of measles infection. Second, both studies provided evidence that HTMV per se was associated with low mortality. In a combined analysis comparing both HTMV groups with controls, the HTMV groups had a MR of 0.09 (0.01-0.71) between 5 and 9 months of age. In Kinshasa, the HTMV recipients who did not receive simultaneous DTP had an annual mortality rate of only 1.0% between 6 months and 3 years of age. Third, the female-male MR was related to subsequent DTP vaccinations. In Kinshasa, the female-male MR was only 0.40 (0.13-1.27) among the HTMV recipients who did not receive further doses of DTP. In Sudan, the female-male mortality ratio in the EZ group was 3.89 (95% CI 1.02-14.83) and the female-male MR increased with number of doses of DTP likely to have been given during follow-up (trend, p = 0.043). Fourth, in Kinshasa, mortality was higher among children who had received HTMV and DTP simultaneously than among children who had received HTMV alone (MR = 5.38 (1.37-21.2)). CONCLUSIONS: Measles vaccine is associated with non-specific beneficial effects. When not given with DTP, HTMV per se was associated with low mortality. Increased female mortality was not found among children who did not receive DTP after HTMV. Hence, our deductions were supported and the sequence or combination of vaccinations may have an effect on sex-specific mortality patterns in low-income countries.

Age Factors↗

PubMed2006

Tuberculin reaction, BCG scar, and lower female mortality.

BACKGROUND: Recent studies have suggested that bacille Calmette-Guérin (BCG) immunization may have a nonspecific beneficial effect on infant survival and that the effect may be more pronounced among girls. In a prospective birth cohort, we examine whether a positive tuberculin skin test and BCG scar in response to BCG immunization were related to better overall survival in Guinea-Bissau and, if so, whether the effect was sex-specific. METHODS: Skin tests and BCG scarring were monitored at ages 2 months (n = 2332) and 6 months (n = 1817) in children born from March 2000 to July 2002. A tuberculosis (TB) surveillance system allowed us to exclude from the analysis children with likely TB exposure. The children were followed for survival until 18 months of age. RESULTS: Among children with a tuberculin skin test at 2 and 6 months of age, the mortality rate ratio for skin test reactors (>1 mm) versus nonreactors (0-1 mm) was 0.54 (95% confidence interval = 0.30-0.99). Comparing children with and without a BCG scar, the ratio was 0.55 (0.31-0.96). The effect of a skin test reaction or a BCG scar seemed stronger among girls; for those with positive reaction, the mortality ratio was 0.31 (0.11-0.88) among girls and 0.84 (0.39-1.82) among boys; and for BCG scar, the results were 0.41 (0.21-0.82) and 0.88 (0.34-2.30), respectively. CONCLUSIONS: A good response to BCG vaccination is related to lower child mortality. The effect seems most pronounced among girls. The findings may have implications for future vaccine trials and policy.

BCG Vaccine↗

PubMed2006

Sex differential effects of routine immunizations and childhood survival in rural Malawi.

BACKGROUND: Recent studies from West Africa suggest that routine vaccinations may have sex differential nontargeted effects. To answer whether these patterns are found elsewhere, we reanalyzed data about vaccinations and mortality in a Malawian cohort. METHODS: Children were followed from birth with monthly home visits until 18 months of age. Anthropometric measurements and vaccination information were obtained at these visits. We investigated survival in relation to vaccination status using 2 different methods. First, we included all children updating vaccination information retrospectively. Second, we included only those present at monthly home visits for whom prospective vaccination information was likely to be most complete. SUBJECTS: This study included 751 children surviving the first week of life. MAIN OUTCOME MEASURES: Main outcome measures consisted of mortality rate ratios (MR) for BCG, diphtheria-tetanus-pertussis (DTP) and measles-vaccinated children compared with children who had not received these vaccines and female-male MRs among children who had received the same vaccine. RESULTS: In all analyses, BCG and MV were associated with lower mortality. Children with better nutritional status received DTP1 significantly earlier (P = 0.02). However, DTP1-vaccinated children did not have lower mortality, the MR being 0.99 (0.45-2.19) and 3.19 (0.80-12.8), respectively, using the 2 analyses with retrospective updating or with prospective determination of vaccination status. The female-male MR varied significantly with age, being increased at 3 to 8 months of age, the age of DTP vaccination, and reduced between 9 and 17 months of age, the age of measles vaccination (MV). Using prospective vaccination information, the MR for girls declined after BCG vaccination of unvaccinated girls but increased after DTP1 (P = 0.10) and declined after MV (P = 0.01). Children who received DTP and MV simultaneously had a MR of 5.27 (1.11-25.0) compared with children who received MV only. CONCLUSION: The female-male mortality ratio varied with age. The mode of analysis was important. Using prospective vaccination information like in previous studies from West Africa, BCG, DTP1 and MV had differential effects for girls and boys.

Diphtheria-Tetanus-Pertussis Vaccine↗

PubMed2006

Long-term consequences of respiratory syncytial virus acute lower respiratory tract infection in early childhood in Guinea-bissau.

AIM: The study aimed to investigate long-term consequences of respiratory syncytial virus (RSV) positive acute lower respiratory tract infection (ALRI) in a low-income country according to severity of the initial infection. DESIGN: The study was a 1:1 matched case-control study of 335 RSV case children and 335 control children. The mean age of RSV ALRI was 0.9 year and at follow-up, 6.8 years. Case children were identified at the hospital and in the community with an antigen and an IgM test to diagnose RSV. Severe RSV infection was defined when a child was treated at the hospital, whereas disease was assumed less severe when a child was diagnosed at home and received no care in the hospital. RESULTS: At follow-up, forced expiratory volume in 1 second (FEV1) and peak flow were significantly lower in case children (odds ratio [OR] = 0.28; 95% confidence interval [CI] 0.10-0.79), the effect being particularly marked for children with severe RSV. Bronchitis at follow-up was reported more frequently among the case children with severe disease. Fewer case children had a positive skin-prick test for local allergens than control children (OR 0.64; 95% CI = 0.44-0.94). Specific IgE for dust mites and cockroach was elevated (52%) in both case and control children. However, specific IgE to peppertree was higher in the case children (OR 2.18; 95% CI = 1.17-4.07). All identified differences were particularly marked for children with severe RSV. CONCLUSION: Severe RSV infection in infancy was associated with decreased lung function in preschool age in Guinea-Bissau. Children with severe RSV disease had more long-term health problems than children with less severe disease.

Case-Control Studies↗

PubMed2006

Breast milk reduces the risk of illness in children of mothers with cholera: observations from an epidemic of cholera in Guinea-Bissau.

BACKGROUND: A protective effect of breastfeeding against cholera has been demonstrated in areas endemic of cholera. To assess the protection offered by breast milk from mothers living in an area that had been free from cholera for 7 years, we investigated mothers with cholera and their children during an epidemic with Vibrio cholerae El Tor in the capital of Guinea-Bissau. METHODS: Eighty mothers with clinical cholera and their children were identified, and interviewed. Blood samples for vibriocidal and antitoxin antibodies were collected from mother-and-child pairs. Breast milk samples were collected from lactating mothers. Cholera was defined as acute watery diarrhea during the epidemic and a vibriocidal reciprocal titer of 20 or above. RESULTS: Three (7%) of 42 breastfed children had cholera as defined above compared with 9 (24%) of 38 nonbreastfed children (RR for breastfed children, 0.19; 95% CI, 0.04-0.91, adjusted for age). The 3 breastfed children who developed cholera received milk containing lower concentrations of anticholera toxin IgA/total IgA (median, 2.0 units/mL) than 14 children who had serologic signs of colonization but did not develop the disease (median, 17.4 units/mL). CONCLUSIONS: The protective effect of breast milk against cholera is not confined to endemic areas. Lactating mothers with cholera should receive supportive care to continue breastfeeding.

Adolescent↗

PubMed2006

Atopic disposition, wheezing, and subsequent respiratory syncytial virus hospitalization in Danish children younger than 18 months: a nested case-control study.

OBJECTIVES: This study examined whether atopic disposition, wheezing, and atopic disorders increased the risk of hospitalizations because of respiratory syncytial virus in children between birth and 18 months of age. PATIENTS AND METHODS: Relative risks for respiratory syncytial virus hospitalization were studied in a nested 1:5 case-control design using exposure information obtained from interviews with mothers of 2564 case and 12,816 control children who had been followed prospectively from birth and until 18 months of age as participants in the Danish National Birth Cohort. Information on the children's ages at respiratory syncytial virus hospitalization, presentation of infrequent wheezing, recurrent wheezing, and atopic dermatitis were used to study these associations chronologically. RESULTS: The adjusted relative risk of respiratory syncytial virus hospitalization in the offspring was 1.11 for maternal atopic dermatitis, 1.72 for maternal asthma, and 1.23 for paternal asthma. Atopic dermatitis in the child was associated with an increased risk of subsequent respiratory syncytial virus hospitalization among infants <6 months of age. Infrequent wheezing was associated with a relative risk of subsequent respiratory syncytial virus hospitalization of 2.98 and recurrent wheezing with a relative risk of 5.90. These associations were present also if infants with medical risk factors were excluded from the analysis. CONCLUSIONS: Asthmatic disposition and wheezing were strong determinants of subsequent respiratory syncytial virus hospitalization in Danish children <18 months of age.

Case-Control Studies↗

PubMed2005

Mortality patterns during a war in Guinea-Bissau 1998-99: changes in risk factors?

BACKGROUND: The crude mortality rate of the whole population and the mortality of children <5 years of age are the common indicators of the severity of a complex emergency situation. However, these indicators rarely take account of differences in socioeconomic conditions and vulnerability. METHODS: We followed a population in Guinea-Bissau, which fled when fighting took place in the capital during the war in 1998-99. The population stayed close to the area of conflict and returned as soon as a cease-fire was negotiated. A peace treaty was signed after half-a-year. The following 6 months was a period of returning and re-settlement, even though two outbreaks of fighting occurred. RESULTS: In the first half-year the mortality rate was 78% [mortality ratio (MR) = 1.78; 95% CI 1.61-1.97] increased and mortality for children <5 years of age doubled (MR = 2.07; 95% CI 1.79-2.38). In the last 6 months of the war, mortality was slightly increased for children and not at all for the total population. In the first half-year, households living in better houses and having members with schooling were less affected. In the 're-settlement' period two inequalities emerged; the largest ethnic group, Pepel, continued to have high mortality when the mortality of other groups declined; likewise girls continued to have an elevated mortality whereas mortality of boys declined. CONCLUSION: Whereas specific 'free' interventions reduced social inequalities for the groups affected, for the total population health-inequalities were slightly amplified during the war. Once the population returned to their urban homes, mortality fell to pre-war levels even though some fighting continued, limited humanitarian aid was available and the pre-war infra-structure had not been re-established.

Child, Preschool↗

PubMed2005

Randomised study of effect of different doses of vitamin A on childhood morbidity and mortality.

OBJECTIVES: To determine whether the dose of vitamin A currently recommended by the World Health Organization or half this dose gives better protection against childhood morbidity and mortality. DESIGN: Randomised study. SETTING: A combined oral polio vaccine and vitamin A supplementation campaign in Guinea-Bissau, Africa. PARTICIPANTS: 4983 children aged 6 months to 5 years. INTERVENTIONS: One of two doses of vitamin A (recommended and half); oral polio vaccine. MAIN OUTCOME MEASURES: Mortality and morbidity at six and nine months. RESULTS: Mortality was lower in the children who took half the recommended dose of vitamin A compared with the full dose at both six months (mortality rate ratio 0.69, 95% confidence interval 0.36 to 1.35) and nine months (0.62, 0.36 to 1.06) of follow-up. There was a significant interaction between sex and dose, the lower dose being associated with significantly reduced mortality in girls (0.19, 0.06 to 0.66) but not in boys (1.98, 0.74 to 5.29). The lower dose of vitamin A was consistently associated with lower hospital case fatality in girls (0.19, 0.02 to 1.45). Paradoxically, in children aged 6-18 months, the low dose was associated with slightly higher morbidity. CONCLUSIONS: Half the dose of vitamin A currently recommended by WHO may provide equally good or better protection against mortality but not against morbidity.

Adult↗

PubMed2005

Effect of sublingual misoprostol on severe postpartum haemorrhage in a primary health centre in Guinea-Bissau: randomised double blind clinical trial.

OBJECTIVE: To evaluate whether routine administration of sublingual misoprostol 600 microg after delivery reduces postpartum haemorrhage. DESIGN: Randomised double blind placebo controlled trial. SETTING: Primary health centre in Bissau, Guinea-Bissau, West Africa. PARTICIPANTS: 661 women undergoing vaginal delivery. INTERVENTION: Misoprostol 600 mug or placebo administered sublingually immediately after delivery. MAIN OUTCOME MEASURES: Postpartum haemorrhage, defined as a loss of > or = 500 ml and decrease in haemoglobin concentration after delivery. RESULTS: The incidence of postpartum haemorrhage was not significantly different between the two groups, the relative risk being 0.89 (95% confidence interval 0.76 to 1.04) in the misoprostol group compared with the placebo group. Mean blood loss was 10.5% (-0.5% to 20.4%) lower in the misoprostol group than in the control group. Severe postpartum haemorrhage of > or = 1000 ml or > or = 1500 ml occurred in 17% (56) and 8% (25) in the placebo group and 11% (37) and 2% (7) in the misoprostol group. Significantly fewer women in the misoprostol group experienced a loss of > or = 1000 ml (0.66, 0.45 to 0.98) or > or = 1500 ml (0.28, 0.12 to 0.64). The decrease in haemoglobin concentration tended to be less in the misoprostol group, the mean difference between the two groups being 0.16 mmol/l (-0.01 mmol/l to 0.32 mmol/l). CONCLUSION: Sublingual misoprostol reduces the frequency of severe postpartum haemorrhage.

Administration, Sublingual↗

PubMed2005

Sibship characteristics and risk of allergic rhinitis and asthma.

Studying associations between sibship characteristics and allergic diseases in detail may contribute clues to their etiology. The authors studied associations between sibship characteristics and risk of self-reported allergic rhinitis and asthma among 31,145 pregnant women participating in a nationwide study in Denmark during 1997-2000. Increasing sibship size was associated with a decreased risk of allergic rhinitis and asthma with allergic rhinitis but not with asthma without allergic rhinitis. The protective effect of having older siblings was stronger than the protective effect of having younger siblings for both allergic rhinitis and asthma with allergic rhinitis. There was no association between interval to closest older or younger sibling and risk of allergic rhinitis or asthma with allergic rhinitis, while the risk of asthma without allergic rhinitis increased with intervals of 2 or more years compared with less than 2 years to the nearest older sibling. The protective effect of having siblings on the risk of asthma with allergic rhinitis could be explained by a protective effect of siblings on the risk of allergic rhinitis alone. In conclusion, our findings suggest that different etiologic mechanisms are involved for allergic rhinitis and asthma with respect to the effect of sibship characteristics. Furthermore, the findings that allergic rhinitis was associated with the number of younger siblings but not with the age interval to younger siblings support the hypothesis of an influence of postnatal mechanisms and suggest that these mechanisms may not necessarily be operating only in early life.

Adolescent↗

PubMed2005