Biomedical subjects

Peter Aaby

Publications and source records attributed to Peter Aaby.

At least 91 records · Page 5Linked to original sources

PubMed2003

BCG scar and positive tuberculin reaction associated with reduced child mortality in West Africa. A non-specific beneficial effect of BCG?

Previous studies have suggested that the bacille Calmette-Guérin (BCG) vaccine may have a non-specific beneficial effect on childhood survival in areas with high mortality. We examined whether BCG-vaccinated children with a BCG scar or a positive tuberculin reaction had better survival than children without such reactions. As part of an ongoing two-dose measles vaccine trial for which children were recruited at 6 months of age, we examined 1813 children for BCG scar at 6 months of age and 813 BCG-vaccinated children were skin-tested for delayed hypersensitivity to tuberculin, tetanus and diphtheria. We found that BCG-vaccinated children with a BCG scar had significantly lower mortality compared with BCG scar-negative children, the mortality ratio in the first 12 months of follow-up being 0.41 (0.25-0.67). BCG-vaccinated children with a positive tuberculin test had a mortality ratio of 0.45 (0.24-0.85) compared with tuberculin negative children. These results were unchanged by control for potential confounders or using different cut-off points for a tuberculin-positive response. Exclusion of dead children who had HIV antibodies did not modify the estimate (mortality rate (MR)=0.46 (0.23-0.94)). After censoring for tuberculosis (TB) exposure at home, the mortality ratios for having a scar and being tuberculin-positive were 0.46 (0.27-0.79) or 0.42 (0.21-0.84), respectively. Children positive to tetanus or diphtheria in the skin test had the same mortality as children not responding to these vaccine-related antigens. Thus, BCG scar and a positive tuberculin reaction were associated with better survival in early childhood in an area with high mortality. Since nothing similar was found for responders to diphtheria-tetanus-pertussis (DTP) vaccine, and the effect could not be explained by protection against tuberculosis, the effect of BCG vaccination could be due to non-specific immune-stimulation protecting against other infections.

Adjuvants, Immunologic↗

PubMed2003

Dual infections with HIV-1, HIV-2 and HTLV-I are more common in older women than in men in Guinea-Bissau.

OBJECTIVES: To investigate the association between the three human retroviruses, HIV-1, HIV-2 and HTLV-I. DESIGN: Community-based follow-up studies of retrovirus infections in two cohorts. METHODS: A total of 2057 individuals aged 35 years and over were eligible for inclusion. Participants were interviewed and had a blood sample drawn. Samples were analysed for HIV-1, HIV-2 and HTLV infections. Uni- and multivariate analyses that included behavioural and socio-economic factors were performed using logistic regression and Poisson regression models. RESULTS: A total of 1686 individuals participated with a blood sample in the HIV prevalence analyses and 1581 individuals participated in the HTLV-I prevalence analyses. The overall prevalence was 2.1% for HIV-1, 13.5% for HIV-2 and 7.1% for HTLV-I. Comparing the < 45 year age group with 45+ year age groups, the female : male (F : M) prevalence ratio increased with age for all three retroviruses. Dual infections were more common in women than in men. Assuming independent distribution of the viruses, the observed prevalence of dual infections in women was significantly higher than expected, while the prevalence was not increased in men. The prevalence of dual infections increased with age in women, the odds ratio (OR) being 3.4 [95% confidence interval (CI), 1.0-11.3] for any combination of dual infection, while the prevalence decreased with age in men (OR, 0.3; 95% CI, 0.1-2.0) (test of interaction, P = 0.033). Control for behavioural factors did not modify these patterns. CONCLUSIONS: The pattern of increased prevalence among older women could have public health implications; women of older age groups should be regarded as a potential vulnerable group and included in HIV/AIDS prevention programmes.

Adult↗

PubMed2003

The challenge of improving the efficacy of measles vaccine.

Despite a safe and effective measles vaccine, measles still claims an estimated 800,000 lives per year mostly among children in developing countries. This paper deals with strategies to improve vaccine efficacy and prevent unnecessary deaths, including considerations of one dose at 9 months strategy for developing countries, strain of vaccine, potency and number of doses of measles vaccine. After more than 20 years of measles immunisation in the developing world, the epidemiology of measles is radically changed, and the absence of measles epidemics might lead to waning immunity due to less clinical and subclinical infections boosting the antibody level. An increasing proportion of mothers are vaccinated, thus transferring a lower maternal antibody level to their infants who will be susceptible to measles at a younger age. The strategies to limit nosocomial measles infection and spread of measles epidemics are reviewed. Though the measles elimination programmes have been very effective in the Americas, it seems unlikely that they will be equally effective in the rest of the world. Even if eradication should be possible, it might be unwise to stop measles vaccination because the vaccine apparently has beneficial effects and because it would make measles a likely weapon for bio-terrorism. If we are unlikely to get rid of measles and measles vaccine, it might be wise to study further some of the many unanswered questions regarding the long-term effects of measles and measles vaccination.

Age Factors↗

PubMed2003

Can mothers be trusted to give malaria treatment to their children at home?

Children with symptomatic malaria in Bissau were randomly assigned to treatment with chloroquine 25 mg base/kg given supervised at a health centre or unsupervised by the mothers at home. On day 7, a blood sample for drug analyses was drawn and the children were then followed once weekly for 5 weeks. The data were analysed on an intention to treat basis. No differences were seen in the outcome of treatment nor in the blood drug concentrations on day 7 between the two groups. Mothers in Bissau can be trusted to give adequate anti-malarial medication to their children at home.

Adolescent↗

PubMed2003

High-titer measles vaccination before 9 months of age and increased female mortality: do we have an explanation?

In 1989, high-titer (HT) Edmonston-Zagreb measles vaccine with a titer more than 10(4.7) plaque-forming-units was recommended by the World Health Organization for use in areas with a high incidence of measles in children younger than 9 months. In 1992, the recommendation was rescinded following reports from Guinea-Bissau, Senegal, and Haiti showing an increased incidence of female mortality occurring after administration of HT Edmonston-Zagreb vaccination. We reviewed 9 studies of HT measles vaccines that reported data on mortality. These reports included 4 randomized trials comparing HT vaccine administered to children younger than 9 months with standard-titer (ST) vaccines (10(3.0) to 10(4.0) plaque-forming-units) given at 9 months of age. Five studies from Zaire, Haiti, Senegal, Rwanda, and Zaire had no control group receiving ST vaccine at 9 months of age, but investigators were able to examine the female-to-male mortality ratio within these HT studies. Investigators have hypothesized that HT vaccine had caused immune suppression similar to that of measles infection. The present review suggests first that the HT vaccine itself is unlikely to be the cause because the effect was not found in all studies. Second, the increased mortality started only after 9 to 10 months of age when controls received ST measles vaccine, and HT groups received the "control vaccine." It was not found in the studies that provided another measles vaccine instead of control vaccine. Third, because the HT studies with excess mortality rates showed increased female mortality rates, we need to find environmental or contextual conditions associated with increased female mortality rates in some studies to explain the problem associated with HT measles vaccination.

Africa South of the Sahara↗

PubMed2003

Maternal mortality: only 42 days?

OBJECTIVE: A maternal death is defined by WHO as 'the death of a woman while pregnant or within 42 days of termination of pregnancy em leader '. The origin of the 42 days is no longer clear. In developing countries, the burden imposed by pregnancy and birth on a woman's body may extend beyond 42 days as pregnancy-related anaemia can persist for longer and vaginal haemorrhaging and risk of infections are not necessarily over after six weeks. We therefore examined duration of excess mortality after delivery in rural Guinea-Bissau. DESIGN: In a prospective cohort study, we followed 15,844 women of childbearing age with biannual visits over a period of six years, resulting in a total of 60,192 person-years-at-risk. To establish cause and timing in relation to termination of pregnancy, verbal autopsy was carried out for all deaths. Mortality rates were calculated for short time intervals after each delivery or miscarriage. RESULTS: During the observation period we registered 14,257 pregnancies and 350 deaths. One hundred and ninety-four deaths followed termination of a registered pregnancy and thus were eligible for the analysis. Eighty-two deaths occurred during the first 42 days after delivery/miscarriage. A further 16 women died in the period from 43 to 91 days after parturition, 16 between 92 and 182 days and 18 between 183 and 365 days after delivery. Compared with baseline mortality 7-12 months after delivery, women who had recently delivered had 15.9 times higher mortality (95% CI 9.8-27.4). From days 43 to 91 the mortality was still significantly elevated (RR = 2.8 [1.4-5.4]). CONCLUSION: Where living conditions are harsh, pregnancy and delivery affect the health of the woman for more than 42 days. Using the WHO definition may result in an under-estimation of the pregnancy-related part of the reproductive age mortality. Extending the definition of maternal death to include all deaths within three months of delivery may increase current estimates of maternal mortality by 10-15%.

Abortion, Spontaneous↗

PubMed2003

Breastfeeding status as a predictor of mortality among refugee children in an emergency situation in Guinea-Bissau.

OBJECTIVE: To identify the population risk factors in emergency situations, we studied breastfeeding status as a predictor for child mortality during a war in Guinea-Bissau. METHODS: Data on breastfeeding status are routinely collected by the surveillance system of the Bandim Health Project in Bissau. We used data collected during a 3-month period prior to the war in Guinea-Bissau in June 1998 to assess the impact of breastfeeding status on mortality in an emergency. We compared the war cohort with two cohorts of children who had had their breastfeeding status assessed in a similar way by the surveillance system in the 3 months prior to June 1996 and June 1997. As very few are weaned prior to 9 months of age and the median age of weaning is 22 months, we assessed the risk of dying over a 3-month period for breastfed and weaned children aged 9-20 months. RESULTS: Controlling for age, weaned children experienced a sixfold higher mortality [mortality rate (MR) = 5.73 (95% CI 2.40-13.71)] during the first 3 months of the war compared with children still breastfeeding. In the two control cohorts from 1996 and 1997, weaned children did not have higher mortality than the breastfed children over a similar 3-month period. Mortality in weaned children was five times higher [MR = 4.96 (1.44-16.63)] during the first 3 months of the conflict than in a similar group of weaned children from early June 1996 and June 1997, whereas there was no significant difference in mortality between breastfed children during the conflict and the preceding years [MR = 1.46 (0.84-2.55)]. Control for other background factors, including living with mother, gender, ethnic group, mother's schooling and district, did not change these differences. CONCLUSION: The protective effect of breastfeeding against infections may be particularly important in emergencies. Continuing or recommencing breastfeeding should be emphasized in emergency situations.

Arm↗

PubMed2003

Smallpox vaccination and risk of allergy and asthma.

BACKGROUND: It has been proposed that childhood vaccinations may influence the development of allergy. Atopy and allergic diseases have increased after routine smallpox vaccination was stopped in the 1970s. OBJECTIVE: We examined whether administration of smallpox vaccination during childhood was associated with a decreased risk of atopy, allergic rhinitis, and asthma. METHODS: The occurrence of atopy, allergic rhinitis, and asthma was studied in nearly 2000 women participating in a national birth cohort study. Detailed information on smallpox vaccination was available from school health records. Atopic status was assessed serologically by a specific response to 11 common inhalant allergens by using serum samples obtained from the women during the period 1997 to 2001. Information on allergic rhinitis and asthma was available from telephone interviews. RESULTS: We found no association between having been vaccinated against smallpox in childhood and risk of atopy or allergic rhinitis. Smallpox vaccination was associated with a slightly decreased risk of asthma. There was no association between age at smallpox vaccination and risk of atopy, allergic rhinitis, or asthma. Adjusting for birth cohort, sibship size, age of the woman's mother at birth, and social class in childhood did not change these results. CONCLUSION: Our findings do not suggest that childhood vaccination against smallpox, even if given early in life, influences the development of atopy or allergic rhinitis. The association with asthma should be interpreted with caution and needs further study.

Adolescent↗

PubMed2003

The survival benefit of measles immunization may not be explained entirely by the prevention of measles disease: a community study from rural Bangladesh.

OBJECTIVE: To examine whether the reduction in childhood mortality after immunization can be explained by the prevention of measles and its long-term effects. METHODS: and Data We re-analysed an existing data set from Matlab, Bangladesh. During 1982-1985, measles immunization was used from 9 months of age in half of the study area, and the other half was used as an unvaccinated control area. A total of 8134 immunized children had been matched by age with 8134 non-immunized children; 578 children died during the follow-up period of 3 years. Using these data, we calculated the vaccine effectiveness against death (VED) controlling for significant factors in a matched analysis. In the absence of measles, there should be no difference in mortality between immunized, uninfected children and non-immunized, uninfected children. We therefore calculated VED after the exclusion of all measles cases in the survival analysis. To assess the long-term effects of measles, we compared survival of unvaccinated children after measles disease with children who had not yet contracted measles. RESULTS: Prior to immunization and again after 1985, childhood mortality rates were 10% lower in the area that had received immunization. Though measles deaths only constituted 12.4% of the non-accidental deaths, the VED controlling for significant factors was 49% (95% CI: 38-58%). The vaccine was protective against measles death throughout the study, but it also had a marked effect against other causes of death, particularly diarrhoea and oedema. This effect may have been particularly strong in the first 6 months after immunization (VED = 74, 95% CI: 57-84%). The VED was only reduced from 49% to 43% (95% CI: 31-54%) when measles cases were excluded in the survival analysis. Controlling for background factors, mortality among measles cases was increased during the acute phase (0-45 days) (mortality ratio [MR] = 17.35, 95% CI: 11.9-25.3) and in the following 1(1/2) months (MR = 2.35, 95% CI: 0.95-5.84). However, post-measles cases had significantly lower mortality than uninfected, non-immunized children in the following 9 months (MR = 0.40, 95% CI: 0.16, 0.98). CONCLUSIONS: The non-randomized character of the original study and the possibility of uncontrolled confounding between the two areas prevent a precise estimate of the effectiveness of measles vaccine, but it is likely to have been substantial. Though there may have been some underreporting of cases of measles, the prevention of measles infection can only explain a limited part of the observed impact of measles immunization in Bangladesh. Furthermore, mortality may be reduced after the acute phase of measles infection. The observations from Bangladesh are consistent with recent research from Africa suggesting that measles immunization may have non-specific beneficial effects on survival.

Bangladesh↗

PubMed2003

Hypothesis: Vitamin A supplementation and childhood mortality: amplification of the non-specific effects of vaccines?

Most areas of health research will have accepted data and a dominating interpretation. If the interpretation is not correct, contradictions will accumulate, and it will eventually become clear that the current interpretation is untenable. In this situation, the best hypothesis is the one that accounts for all of the known data as well as the apparent contradictions. The area of vitamin A supplementation and childhood mortality in developing countries is afflicted with many contradictions and there is a need for a new hypothesis. We propose that the effect of vitamin A supplementation may depend on the amplification of non-specific effects of vaccines on childhood mortality.

Adjuvants, Immunologic↗

PubMed2003

Survival of previously measles-vaccinated and measles-unvaccinated children in an emergency situation: an unplanned study.

BACKGROUND: Previous studies have suggested that standard measles vaccine may reduce mortality by more than the number of deaths thought to be caused by measles infection in areas with high mortality. However, these observations have not been based on randomized trials. METHODS: During the recent war in Guinea-Bissau, most children fled from the city of Bissau and immunization services in the country broke down for several months. We were performing a trial in which children were randomized at 6 months of age to receive either measles vaccine or inactivated polio vaccine. Because of the war many children did not receive the dose of measles vaccine planned for 9 months of age. We were able to monitor mortality during the war and after. RESULTS: Included in the study were 433 children 6 to 11 months of age. Fifteen children died (3.6%) during the first 3 months of the war before vaccination programs were resumed, 4 of 214 measles-vaccinated children and 11 of 219 children who had received inactivated polio vaccine. The effect of measles vaccine was marked for girls [mortality rate ratio (MR), 0.00; 95% confidence limits, 0.0 to 0.37], whereas there was no difference for boys (MR = 1.02; 95% confidence limits, 0.25 to 3.88). In a combined analysis controlling for factors that differed between the two groups, the MR for measles-vaccinated children was 0.30 (95% confidence limits, 0.08 to 0.87). Prolonging the period of observation to the end of 1998 or including the prewar period did not modify the significant beneficial effect of measles vaccine for girls. Twenty-two of the children in the cohort were reported to have had measles, 8 cases occurring during the 3 months of the war. Exclusion of measles cases in the analysis did not change the results; children who had received measles vaccine had a MR of 0.28 (95% confidence limits, 0.06 to 0.89) during the first 3 months of the war. CONCLUSIONS: Consistent with previous observational studies, measles vaccination was associated with a reduction in mortality that cannot be explained by the prevention of measles infection. This nonspecific beneficial effect was particularly strong for girls. Further studies are needed to examine the extent of nonspecific effects in settings with high mortality.

Cause of Death↗

PubMed2003

Cohort study of Guinean children: incidence, pathogenicity, conferred protection, and attributable risk for enteropathogens during the first 2 years of life.

We recruited 200 children shortly after birth and collected stool specimens weekly, irrespective of whether the children had diarrhea, until up to 2 years of age. All children were recruited during the first year of the study and were monitored for a median of 18.4 months. To measure pathogenicity, the odds ratio for diarrhea, adjusted for age, sex, and coinfections with other enteropathogens, was determined by logistic regression. Standard estimation of the population attributable risk indicated that rotavirus, enterotoxigenic Escherichia coli that produced only the heat-stable toxin ST, Isospora spp., Cryptosporidium parvum, Shiga toxin (Stx)-producing E. coli (STEC), and Shigella spp. or enteroinvasive E. coli were the most important contributors to diarrhea in this population. Stx2- but not Stx1-producing STEC strains were pathogenic. Enteroaggregative E. coli, diffusely adherent E. coli, and attaching-and-effacing E. coli strains, which were the most commonly isolated microorganisms, were not associated with diarrhea. For most of the microorganisms, primary infections did not confer protection against reinfection with the same organism, but some conferred protection against diarrhea from reinfection.

Age Factors↗

PubMed2003

Long-term mortality after poliomyelitis.

BACKGROUND: Few studies have described mortality and cause of death among persons with a history of polio. METHODS: We identified a group of patients diagnosed with poliomyelitis in Copenhagen between 1919 and 1954. We obtained information on vital status through May 1997 and on cause of death by linkage with the Danish Civil Registration System and the Danish Cause-of-Death Register. Overall and cause-specific standardized mortality ratios served as the measure of mortality risk relative to that of the general population. RESULTS: We observed 1295 deaths among 5977 polio patients compared with an expected 1141 deaths (standardized mortality ratio = 1.14; 95% confidence interval = 1.07-1.20). Excess mortality was restricted to polio patients with a history of severe paralysis of the extremities (1.69; 1.32-2.15) or patients who had been treated for respiratory failure during the epidemics (2.71; 2.18-3.37). Apart from polio patients with respiratory failure, long-term mortality did not appear to increase until 20 years after discharge. Contracting severe paralytic poliomyelitis at a young age seemed to increase long-term mortality. The most common causes of death were polio sequelae (standardized mortality ratio = 141; 95% confidence interval = 98-203), respiratory tract diseases (1.38; 1.13-1.69), breast cancer (1.40; 1.06-1.85), gastrointestinal diseases (1.44; 1.14-1.82) and suicide (1.53; 1.25-1.86). Except for polio sequelae, causes of death did not differ between paralytic and nonparalytic polio patients. CONCLUSIONS: Survivors of poliomyelitis, especially severely paralyzed polio patients, have an increased long-term mortality.

Adolescent↗

PubMed2002

Low mortality after mild measles infection compared to uninfected children in rural West Africa.

BACKGROUND: It has been assumed that measles infection may be associated with persistent immune suppression and long-term excess mortality. However, few community studies of mortality after measles infection have been carried out. We examined long-term mortality for measles cases, sub-clinical measles cases, and uninfected contacts after an epidemic in rural Senegal. METHODS: The study was carried out in Niakhar, a rural area of Senegal. Index cases of measles were identified and children less than 7 years of age exposed to measles in the same compound had acute and convalescent blood samples collected. Clinically diagnosed measles cases were serologically confirmed. Children without clinical symptoms were classified as sub-clinical cases if they had a four-fold or greater change in antibody levels between samples collected at exposure and 1 month later and as uninfected if there was no or a two-fold change in antibody levels. RESULTS: There were 31 index cases, and among 184 exposed contacts, 35 (19%) children developed clinical measles. Among contacts that did not develop clinical measles, 45% had sub-clinical infection. Measles cases, sub-clinical cases, and uninfected contacts did not differ with respect to nutritional status. However, uninfected children without clinical symptoms and change in antibody level had higher initial measles specific IgG antibody levels and less intensive exposure to the index case. No index or secondary case of measles died in the acute phase of infection nor did any of the children exposed to measles die in the first 2 months after exposure. Exposed children developing clinical measles had lower age-adjusted mortality over the next 4 years than exposed children who did not develop clinical measles (P<0.05). Sub-clinical measles cases tended to have low mortality and compared with uninfected children, exposed children with clinical or sub-clinical measles had lower age-adjusted mortality (mortality ratio (MR)=0.20 (0.06-0.74)). Controlling for background factors had no impact of the estimates. CONCLUSIONS: When measles infection is mild, clinical measles has no long-term excess mortality and may be associated with better overall survival than no clinical measles infection. Sub-clinical measles is common among immunised children and is not associated with excess mortality.

Child↗

PubMed2002

Routine vaccinations and child survival in a war situation with high mortality: effect of gender.

Non-specific effects of vaccination may be different for boys and girls. Due to the sequential administration of vaccines, it is difficult to separate the effect of different vaccines. We tested sex-specific effects of diphtheria, tetanus, pertussis (DTP) and polio vaccines and measles vaccines during the recent war (1998) in Guinea-Bissau when there was no functioning immunisation programme in the country. The study included 1491 children aged 1-17 months in four urban districts in Bissau. Vaccination status had been assessed in the study area in the 3 months before the war. The effect of DTP and polio vaccines was assessed for children who had not received measles vaccine. The effect of measles vaccine was evaluated for children aged 6-17 months. Compared with measles-unvaccinated children, measles-vaccinated children had lower mortality (mortality ratio (MR)=0.44 (95% CI 0.20-1.00)), the difference being marked for girls (0.25 (0.09-0.71)) but not for boys (0.84 (0.26-2.75)) (test of homogeneity, P=0.095). If measles cases were censored in the analysis, the mortality ratio for vaccinated and unvaccinated children was 0.38 (0.16-0.89). DTP and polio-vaccinated children did not have lower mortality than unvaccinated children. The female-male mortality ratio for DTP and polio-vaccinated children was 3.08 (1.11-8.56) and 0.63 (0.28-1.40) for measles-vaccinated children, a significant inversion of the ratios (test of homogeneity, P=0.013). The divergent female-male mortality ratios are unlikely to be explained by a selection bias going in different directions for different vaccines. The reduction associated with measles vaccination was unrelated to prevention against measles infection. Non-specific effects of vaccination should be assessed separately for boys and girls. Taking these effects into consideration may have implications for child mortality patterns in developing countries.

Diphtheria-Tetanus-Pertussis Vaccine↗

PubMed2002

Enterotoxigenic Escherichia coli infections and diarrhea in a cohort of young children in Guinea-Bissau.

In an effort to describe the natural history of enterotoxigenic Escherichia coli (ETEC) infection and diarrhea, 200 children in Guinea-Bissau, West Africa, were followed up from birth until up to age 2 years with weekly stool specimen collection, regardless of whether the children had diarrhea. ETEC isolates were tested for the presence of the porcine and human heat-stable toxins (STp and STh), the heat-labile toxin (LT), and 18 of 21 known colonization factors (CFs). The rate of primary infections increased substantially after age 3 or 6 months (depending on the type of ETEC causing the infection). The pathogenicity of STh-containing ETEC was substantially higher than that of STp-containing ETEC, and STp and STh were associated with separate sets of CFs. Small epidemics were observed, mainly caused by STh-containing ETEC. The difference in epidemic propensity, CF association, and pathogenicity suggests that STh- and STp-containing ETEC represent 2 different groups of human ETEC. Vaccines should primarily target STh-containing ETEC.

Cohort Studies↗

PubMed2002

Low level viremia and high CD4% predict normal survival in a cohort of HIV type-2-infected villagers.

A community-based study of human immunodeficiency virus type 2 (HIV-2) infection was conducted in a rural village in northern Guinea Bissau, West Africa to assess the relationship between plasma HIV-2 RNA levels, CD4 lymphocyte percentage, and survival over an 8-year period. The cohort of 133 HIV-2-infected individuals and 160 HIV-uninfected controls enrolled in 1991 were followed up at home until 1998. Thirty-one (23%) HIV-2-infected and 24 (16%) HIV-uninfected individuals died over the follow-up period (mortality hazard ratio 1.7, 95% CI 1.0, 2.9; p= 0.06). In HIV-2-infected individuals, the median HIV-2 RNA level was 347 copies/ml and the mean CD4% was 28.6. Both plasma viremia and CD4% were independent predictors of survival, with hazard ratios increasing by 1.6 (95% CI, 1.1, 2.3) for each log(10) increase of plasma viremia and 1.7 (1.1, 2.6) for each 10% decrease of CD4%. Infected subjects with a plasma viral load >or= the median (347 copies/ml) and a CD4% <or= the mean (28.6%) had a mortality hazard ratio of 3.1 (95% CI 1.7, 5.8) compared to uninfected controls, whereas the remaining infected subjects had a mortality rate similar to uninfected controls, the mortality hazard ratio being 1.0 (95% CI, 0.5, 2.1.) In those who survived between 1991 and 1996, HIV-2 RNA levels were unchanged overall and CD4 lymphocyte counts remained high. In conclusion, baseline HIV-2 RNA levels predicted a normal survival for the majority, with low and stable levels of plasma viremia characterizing HIV-2 infections in this rural West African community.

Adult↗

PubMed2002

The molecular epidemiology of varicella-zoster virus: evidence for geographic segregation.

Of 75 varicella-zoster virus (VZV) isolates obtained from patients in Africa, Asia, and the Far East, 74 (98.6%) were found to be positive for a BglI restriction site in gene 54. By contrast, <22% of strains from patients in the United Kingdom and in North and South America were positive for the BglI restriction site. Viruses positive for BglI were significantly more common in zoster occurring in patients of nonwhite origin (P<.05). Irrespective of the country in which the sample was obtained, 98% of strains positive for BglI clustered within a single phylogenetic group, which we termed "group A"; the exception was 1 strain that appeared to be recombinant genotype C/A. We used the BglI site to examine both the spread of type A viruses in the United Kingdom and the patterns of VZV infections within persons from different ethnic groups who grew up in the United Kingdom or abroad.

Adult↗