Clinical predictors for death in HIV-positive and HIV-negative tuberculosis patients in Guinea-Bissau.

OBJECT: To assess easily monitored predictors for tuberculosis mortality. DESIGN: Risk factors for tuberculosis mortality were assessed during the 8-month treatment in 440 men and 269 women diagnosed with confirmed or presumed intrathoracic tuberculosis included prospectively in Guinea-Bissau from May 1996 to April 2001. A civil war occurred in the study area from June 1998 to May 1999. RESULTS: 12% were HIV-1 positive, 16% HIV-2 positive and 7% were HIV dually infected. Case fatality rates for HIV positive were higher during (35% [22/63]) and after the war (29% [27/92]) compared to before the war (17% [15/88]). The war did not have an effect on the case fatality rate in HIV negative (10% [13/135] before the war). HIV-1-infected patients had higher mortality than HIV-2 infected, mortality rate ratio (MRR) = 2.28 (95% confidence interval 1.17-4.46). Men had higher mortality than women but only among the HIV negative (MRR = 2.09 [0.95-4.59]). Hence, the negative impact of HIV infection on mortality was stronger in women (MRR = 6.51 [2.98-14.2]) than in men (MRR = 2.64 [1.67-4.17]) (test of homogeneity, p = 0.051). Anergy to tuberculin was associated with death in HIV positive (MRR = 2.77 [1.38-5.54]) but not in HIV negative (MRR = 1.14 [0.52-2.53]). Signs of immune deficiency, such as oral candida infection or leukoplakia (MRR = 4.25 [1.92-9.44]) and diarrhea (MRR = 2.15 [1.29-3.58] was associated with mortality in HIV positive. Tendencies were similar among HIV negative. HIV-positive relapse cases were at increased risk of dying (MRR = 2.42 [1.10-5.34]). Malnutrition, measured through mid-upper arm circumference (MUAC), increased the risk of death. CONCLUSION: Easily monitored predictors for mortality in tuberculosis patients include clinical signs of immune deficiency and low MUAC.

Predictive value of soluble haemoglobin scavenger receptor CD163 serum levels for survival in verified tuberculosis patients.

Pre-treatment serum levels of sCD163 were measured in a cohort of 236 suspected tuberculosis (TB) cases from Guinea-Bissau, with a median follow-up period of 3.3 years (range 0-6.4 years). In 113 cases, the diagnosis of TB was verified by positive sputum microscopy and/or culture. Among the verified TB cases, a decreased survival rate was found in 27 patients with sCD163 levels above the upper reference limit (3.95 microg/mL). The difference in survival was significant during TB treatment (log rank, p<0.02) and after long-term follow-up (log rank, p<0.001). The decrease in survival rate during TB treatment remained significant in a multivariate Cox model controlling for human immunodeficiency virus (HIV) status, age and gender, with a mortality increase of 1.19 (95% CI, 1.04-1.36) per microg of sCD163, and a hazard ratio (HR) for sCD163 levels above the upper reference limit of 4.18 (95% CI, 1.06-16.4). The difference was not significant after excluding patients with concomitant HIV-1 and HIV-2 infection in Kaplan-Meier analyses (log rank, p 0.11). In contrast, the difference in survival remained significant in Kaplan-Meier analyses after long-term follow-up, even after excluding patients with concomitant HIV-1 and HIV-2 infection (log rank, p 0.002). In the Cox model, the mortality increase per microg of sCD163 was 1.27 (95% CI, 1.14-1.40), with an HR for elevated sCD163 levels of 2.85 (95% CI, 1.44-5.63). The HRs for concomitant HIV-1 and HIV-2 infection were 6.92 (95% CI, 3.28-14.58) and 2.48 (95% CI, 1.09-5.67), respectively. Thus, sCD163 levels appeared to be an independent predictor of survival in verified TB patients.

Investigation of the risk factors for tuberculosis: a case-control study in three countries in West Africa.

BACKGROUND: Host-related and environment-related factors have been shown to play a role in the development of tuberculosis (TB), but few studies were carried out to identify their respective roles in resource-poor countries. METHODS: A multicentre case-control study was conducted in Guinée, Guinea Bissau, and The Gambia, from January 1999 to March 2001. Cases were newly detected smear positive TB patients. Two controls were recruited for each case, one within the household of the case, and one in the community. RESULTS: Regarding host-related factors, univariate analysis by conditional logistic regression of 687 matched pairs of cases and household controls showed that TB was associated with male sex, family history of TB, absence of a BCG scar, smoking, alcohol, anaemia, HIV infection, and history and treatment of worm infection. In a multivariable model based on 601 matched pairs, male sex, family history of TB, smoking, and HIV infection were independent risk factors of TB. The investigation of environmental factors based on the comparison of 816 cases/community control pairs showed that the risk of TB was associated with single marital status, family history of TB, adult crowding, and renting the house. In a final model assessing the combined effect of host and environmental factors, TB was associated with male sex, HIV infection, smoking (with a dose-effect relationship), history of asthma, family history of TB, marital status, adult crowding, and renting the house. CONCLUSION: TB is a multifactorial disorder, in which environment interacts with host-related factors. This study provided useful information for the assessment of host and environmental factors of TB for the improvement of TB control activities in developing countries.

A household study of chickenpox in Guinea-Bissau: intensity of exposure is a determinant of severity.

OBJECTIVE: To determinate the relative importance of state of nutrition and intensity of exposure for clinical severity of chickenpox in a developing country. METHODS: A prospective household study was performed in a semi-urban area in Bissau, the capital of Guinea-Bissau, between December 1994 and June 1995. Antibodies were measured in the acute and the convalescence phase to assess validity of clinical diagnoses. The clinical severity of infection was assessed by number of pox, fever response and skin infections. Severity was compared for index cases, i.e. the first case in the house, and secondary and tertiary cases infected following exposure at home. RESULT: Chickenpox was diagnosed in 165 persons. The clinician's and the mothers' diagnoses corresponded well with the serological results. Median age was 36 months (range 3 months to 30.3 years). There was no correlation between nutritional status measured by arm-circumference and severity of infection. The number of pox was higher for secondary cases than for index cases (median 106 vs. 89, P<0.01), the difference being more pronounced for girls (P=0.018) than for boys (P=0.575). The risk of skin infection as a complication was correlated with the number of pox (P<0.001). CONCLUSION: Chickenpox was recognised correctly by Guinean mothers. The age distribution in Guinea-Bissau resembled the pattern in developed countries. The intensity of exposure was a major determinant of severity, especially for girls.

The serum level of soluble urokinase receptor is elevated in tuberculosis patients and predicts mortality during treatment: a community study from Guinea-Bissau.

OBJECTIVE: To investigate whether the serum level of soluble urokinase plasminogen activator receptor (suPAR) carries prognostic information in individuals infected with Mycobacterium tuberculosis. DESIGN: suPAR was measured by ELISA in 262 individuals at the time of enrolment into a cohort based on suspicion of active tuberculosis and in 101 individuals after 8 months of follow-up. RESULTS: The suPAR levels were elevated in patients with active TB compared to TB-negative individuals (P < 0.001). suPAR levels were highest in patients positive for TB on direct microscopy (n = 84, median suPAR 3.17 ng/ml, P < 0.001), followed by patients negative on direct microscopy but culture positive (n = 35, median suPAR 2.41 ng/ml, P = 0.005) and by patients diagnosed on clinical grounds (n = 63, median suPAR 2.13 ng/ml, P = 0.06) compared to 64 TB-negative individuals (median suPAR 1.73 ng/ml). During the 8-month treatment period, 23 TB cases died. In a multivariate Cox model controlling for HIV status, age, sex, CD4 count and type of TB diagnosis, the mortality increase per ng suPAR was 1.25 (95%CI 1.12-1.40). After treatment, suPAR levels had decreased to the levels of TB-negative individuals. CONCLUSIONS: suPAR levels are elevated in TB patients and associated with mortality. Furthermore, suPAR may be a potential marker of treatment efficacy.

Thymus size at birth is associated with infant mortality: a community study from Guinea-Bissau.

UNLABELLED: A few studies have suggested that thymus atrophy is associated with severe malnutrition and increased morbidity; however, no study of thymus size has been undertaken in countries with high mortality. This study examined the relation between thymus size at birth and subsequent mortality in an urban West African community. The size of the thymus was assessed by sonography as a volume estimate, the thymus index. A total of 278 children born at the local health centre in Bandim in Bissau, Guinea-Bissau, was enrolled in the study. Children were followed to the age of 2 y. Thymus size at birth was associated with most strongly weight, as well as with length and arm circumference. Controlling for weight and other risk factors, boys had larger thymus indices than girls [means ratio (MR) = 1.07, 95% confidence interval (95% CI) 1.01-1.14)]. Thymus size was also associated with prematurity, ethnic group, season and investigator, but not with birth order, mother's age, socioeconomic factors or the use of health services. Infant mortality was 117/1000. In a multivariate analysis, excluding premature infants and adjusting for age, gender, ethnic group, season of birth and investigator, higher birthweight (MR = 0.35, 95% CI 0.16-0.74) and larger thymus size (MR = 0.17, 95% CI 0.06-0.48) were independently associated with lower infant mortality. When both indices were estimated in the same model, the thymus index was associated with infant mortality (MR = 0.27, 95% CI 0.07-1.00), whereas birthweight had a non-significant effect (MR = 0.59, 95% CI 0.24-1.47). After 1 y of age neither birthweight nor thymus size at birth was associated with mortality. CONCLUSION: As all deaths were due to infectious diseases, thymus size at birth may be an important predictor of immune competence. Future studies should examine the determinants of thymus growth.

Thymus size and head circumference at birth and the development of allergic diseases.

BACKGROUND: The positive association between a large head circumference at birth and total serum IgE levels has been suggested to be due to negative associations between head circumference at birth and thymus development and between thymus development and total serum IgE levels. OBJECTIVES: To examine the associations between head circumference and thymus size at birth and the development of allergic disease. METHODS: The size of the thymus was assessed by sonography during the first week of life in 149 healthy term infants. Information on birth characteristics and mode of delivery was collected at delivery. The presence of allergic disease was assessed 5 years later by mailed questionnaires, which were returned by 85% of the eligible families. RESULTS: At birth, head circumference was positively associated with thymus size (P < 0.001). In all, 27 (23%) of the children had developed at least one allergic disease. Multivariate analysis revealed that both parental allergy (Prevalence Ratio and 95% CI) = 3.18 (1.49-6.78)) and caesarean delivery (2.62 (1.48-4.64)) were independently correlated with allergic disease, whereas thymus size was not. CONCLUSIONS: Our study does not support that a large head circumference is associated with a small thymus size, nor that a small thymus size is associated with allergic disease. Whether thymus size at birth is related to total serum IgE levels still remains to be elucidated.

Long-term effect of preventive therapy for tuberculosis in a cohort of HIV-infected Zambian adults.

OBJECTIVE: To determine the long-term effect of preventive therapy (PT) for tuberculosis on the rates of tuberculosis, mortality and HIV progression. METHODS: In a randomized controlled trial, 1053 HIV-positive Zambian adults received isoniazid (H) for 6 months, rifampicin plus pyrazinamide (RZ) for 3 months, or a placebo. CD4 percentage, neopterin, absolute lymphocyte count and haemoglobin were measured from enrolment (absolute CD4 cell counts from 12 months after enrolment). Because PT reduced the incidence of tuberculosis, eligible placebo subjects were offered H. Here, tuberculosis and mortality rates are compared in the three original arms (intention to treat) using data beyond the end of the trial (average follow-up 3 years; maximum 7 years). RESULTS: There were 102 cases of tuberculosis and 281 deaths (rates 3.6 and 9.0/100 person-years, respectively). There was no significant difference between the tuberculosis rates in the H and RZ groups at any time. The effect of H/RZ on tuberculosis diminished over time (P = 0.011) but the cumulative risk of tuberculosis in the first 2.5 years was significantly lower in the H/RZ group than the placebo group (rate ratio 0.55; 95% confidence interval 0.32-0.93; P = 0.028). There was no significant effect of PT on mortality or progression markers. Tuberculosis was associated with an increased mortality (adjusted rate ratio 1.96; 95% confidence interval 1.21-3.18; P = 0.006). CONCLUSIONS: Both PT regimens protect against tuberculosis for at least 2.5 years but appear to have no effect on HIV progression or mortality. These results may be used in cost-effectiveness models of PT.

Human immunodeficiency virus-associated malignant lymphoma in eastern Denmark diagnosed from 1990-1996: clinical features, histopathology, and association with Epstein-Barr virus and human herpesvirus-8.

The clinicopathological features of human immunodeficiency virus (HIV)-associated lymphoma were investigated in a retrospective study of 85 adult patients in eastern Denmark diagnosed during the period 1990-1996. The possible pathogenetic role of Epstein-Barr virus (EBV) and human herpesvirus 8 (HHV-8) in these tumours was also studied. Seventy patients (82%) presented with extranodal disease and 26 (31%) had CNS involvement at diagnosis. Diffuse large cell B-cell lymphoma was the most frequent histological subtype, comprising 65 of 79 cases available for microscopic re-evaluation (82%) and including 20 of 23 evaluable patients with CNS lymphoma (87%). EBV RNA was demonstrated by in situ hybridization in 51 of 65 evaluable tumours (79%) and in 14 of 16 cases (88%) with CNS-lymphoma. Three cases showed a T-cell phenotype. The presence of HHV-8 DNA was analysed by PCR in 32 cases. A strong band consistent with tumour cell infection was detected in only one case, weaker bands being seen in 4 cases. None of these patients had primary effusion lymphomas. In conclusion, Danish AIDS-related lymphomas are of predominantly high-grade B-cell type with extranodal localization and atypical presentation. Our results provide further evidence that EBV plays a major role in the pathogenesis of large cell AIDS-related lymphoma, whereas HHV-8 does not appear to contribute significantly to the development of solid lymphomas in this group of patients.

No strong long-term effect of vitamin A supplementation in infancy on CD4 and CD8 T-cell subsets. A community study from Guinea-Bissau, West Africa.

The World Health Organization recommends that 100,000 IU of vitamin A be given to infants between 6 and 12 months of age at the same time as measles vaccination in order to prevent vitamin A deficiency. In the present study, our aim was to assess the effect of vitamin A supplementation on T-cell subsets in a randomized factorial design, seeking a possible modifying effect of measles vaccination. Three hundred children were allocated either to two doses of measles vaccine at 6 and 9 months of age or to poliomyelitis vaccine at age 6 months and measles vaccine at age 9 months. Within each group, infants were to receive two doses of vitamin A or two doses of placebo at 6 and 9 months of age. We found no significant effect of vitamin A supplementation on CD4 and CD8 T-cell subsets at 3 and 9 months after supplementation. We found no effect of measles vaccine and no interaction between vitamin A supplementation and measles vaccine. Based on these observations, vitamin A supplementation does not seem to have a strong long-term effect on CD4 and CD8 T-cell subsets in infants without clinical vitamin A deficiency.

Increased prevalence of retrovirus infections among older women in Africa.

Recent studies of HIV-2 have suggested an increased incidence and prevalence among women older than 45 y compared with younger women. We therefore examined whether this phenomenon applied generally to all 3 major retroviruses, HIV-1, HIV-2 and HTLV-I, among women in Africa. We conducted a MedLine search from 1987 to 1997, using the keywords Africa and HIV-1, HIV-2 or HTLV, respectively. Community studies, national surveys and studies on professional cohorts were selected. Age groups > 45/50 y were compared with the age group with the lowest female/male prevalence ratio between 20 and 44 y of age. Thirty-one studies had sufficient data to be included. The female/male odds ratio (OR) for seropositivity was calculated for the old and the young age groups, respectively, providing the ratio of odds ratios: OR (old)/OR (young). Summary ratios for studies of all 3 retroviruses were estimated. In general we found a higher female/male prevalence ratio in the age group over 45/50 y than in the younger age group. For HIV-1 the odds ratio was 1.82 times [95% confidence interval (CI) 1.19-2.79] higher in the old age group than in the young group. For HIV-2 it was 1.97 [95% CI 0.95-4.08], and for HTLV-I it was 2.02 [95% CI 0.99-4.14] times higher. For all 3 viruses combined, the ratio was 1.88 [95% CI 1.36-2.61]. The few incidence studies of HIV-1 and HIV-2 indicated a similar tendency. Since differential mortality is unlikely to explain the pattern, the increase in the HIV-1, HIV-2 and HTLV-I female/male prevalence ratio suggests that older women may have increased exposure or susceptibility to all 3 retrovirus infections.

Nutritional status and mortality of refugee and resident children in a non-camp setting during conflict: follow up study in Guinea-Bissau.

OBJECTIVE: To study the effects on children of humanitarian aid agencies restricting help to refugee families (internally displaced people). DESIGN: Follow up study of 3 months. SETTING: Prabis peninsular outside Bissau, the capital of Guinea-Bissau, which has functioned as a refugee area for internally displaced people in the ongoing war, and the study area of the Bandim health project in Bissau. PARTICIPANTS: 422 children aged 9-23 months in 30 clusters. MAIN OUTCOME MEASURES: Mid-upper arm circumference and survival in relation to residence status. RESULTS: During the refugee situation all children deteriorated nutritionally, and mortality was high (3.0% in a 6 week period). Rice consumption was higher in families resident in Prabis than in refugees from Bissau but there was no difference in food expenditure. Nutritional status, measured by mid- upper arm circumference, was not associated with rice consumption levels in the family, and the decline in circumference was significantly worse for resident than for refugee children; the mid-upper arm circumference of refugee children increased faster than that of resident children. For resident children, mortality was 4.5 times higher (95% confidence interval 1.1 to 30.0) than for refugee children. Mortality for both resident and refugee children was 7.2 times higher (1.3 to 133.9) during the refugee's stay in Prabis compared with the period after the departure of the refugees. CONCLUSION: In a non-camp setting, residents may be more malnourished and have higher mortality than refugees. Major improvements in nutritional status and a reduction in mortality occurred in resident and refugee children as soon as refugees returned home despite the fact that there was no improvement in food availability.

PIP: This paper examines the nutritional status and mortality of refugee and resident children in a non-camp setting during the war in Guinea-Bissau. Subjects included 422 children aged 9-23 months in 30 clusters. Results showed that, during the refugee situation, all the children deteriorated nutritionally and mortality was high (3.0% in a 6-week period). Rice consumption was higher in families residing in Prabis than in refugees from Guinea-Bissau, but there was no difference in food expenditure. Nutritional status, measured by mid-upper-arm circumference, was not associated with rice consumption levels in the family, and the decline in circumference was significantly worse for resident than for refugee children; the mid-upper-arm circumference increased faster than that of resident children. For resident children, mortality was 4.5 times higher than for refugee children. Mortality for both resident and refugee children was 7.2 times higher during the refugee's stay in Prabis compared with the period after the departure of the refugees. Finally, major improvements in nutritional status and reduction in mortality occurred in resident and refugee children as soon as refugees returned home despite the fact that there were no improvements in food availability.

Acute and long-term changes in T-lymphocyte subsets in response to clinical and subclinical measles. A community study from rural Senegal.

To investigate the possibility of long-term suppression of T-lymphocyte subsets, we examined children exposed to measles at home during an epidemic in rural Senegal, at time of exposure and 1 and 6 months later. The measles case fatality ratio was 1%. Subclinical measles was common among vaccinated children exposed to measles (45%). Both clinical and subclinical cases of measles showed a significant rise in absolute CD4 count in the incubation period. In the prodromal phase and the first week after the rash, the lymphocyte percentage, the white blood cell count and the absolute CD4 cell numbers were significantly reduced. There was no persistent decrease of absolute CD4 or CD8 numbers at 1 or 6 months after exposure. Measles infection was followed by significant changes in the subset composition, both CD4 and CD8 percentages being significantly higher in the second month after measles than among non-seroresponders. These changes were more marked among girls, since they had significantly higher CD4 percentages and CD4/CD8 ratios than boys in the convalescence phase. In conclusion, measles infection is not associated with a long-term suppression of CD4+ or CD8+ T-lymphocytes.

Evaluation of T cell subsets by an immunocytochemical method compared to flow cytometry in four countries.

The authors tested an alternative method for CD4 and CD8 T lymphocytes enumeration, the immunoalkaline phosphatase method (IA), in three African countries and in Denmark. The IA determinations from 136 HIV antibody positive and 105 HIV antibody negative individuals were compared to the corresponding results obtained by flow cytometry (FC) performed in the respective countries. The authors found good correspondence between the two methods for measurements of CD4 and CD8 T lymphocytes independent of serological status and geographical site. However, the CD4 and CD8 T lymphocytes values obtained by the two methods are not interchangeable as IA compared to FC consistently gives higher percentage of CD4 T lymphocytes, and lower percentage of CD8 T lymphocytes. Mean differences between the two methods did not differ between the three African countries indicating that the IA method provides systematic results. Replicate measurements suggested good correspondence between results obtained by IA. By using an IA level of < 300 CD4 T lymphocytes/microliter, the sensitivity was 81% and specificity 96% for detecting an FC level of < 200 CD4 T lymphocytes/microliter. Using an IA level of < 20% CD4 T lymphocytes, the sensitivity was 89% and specificity 95% for detecting an FC level of < 14% CD4 T lymphocytes. The FC and IA methods had the same internal correspondence between low absolute CD4 T cell count and low CD4 percentages; the sensitivity and specificity for detecting a low absolute CD4 T cell counts with a low CD4 percentage was 92% and 68% for FC and 91% and 73% for IA, respectively. The IA method is 10-fold cheaper than FC, is independent of advanced laboratory facilities, and does not need immediate processing of samples as blood smears can be stored for long periods. The IA method is therefore suitable for use in areas with limited resources and laboratory facilities where there is a need for immunological surveillance in hospital or community studies.

9-year HIV-2-associated mortality in an urban community in Bissau, west Africa.

BACKGROUND: Community studies with 1-3 years of follow-up have reported four to five times higher mortality in HIV-2-infected than in uninfected adults. In a cohort study of HIV-1, an increasing difference in mortality rates of HIV-1-infected and uninfected individuals is expected over time, because of rising mortality with advancing HIV-1 infection. We therefore investigated long-term survival of HIV-2-infected adults. METHODS: Adults enrolled in 1987 in a community study of HIV-2 infection in Guinea-Bissau were followed up with serological surveys in 1989 and 1992. Survival was assessed in 1995, 9 years after enrollment. FINDINGS: The annual incidence of HIV-2 was 0.7% for adults and tended to be higher for older individuals than for participants aged 15-44 years (relative risk 3.21 [95% CI 0.91-11.37]). With control for age, HIV-2-infected adults had twice as high mortality as uninfected individuals (mortality ratio 2.32 [1.18-4.57]); the mortality ratio was highest in the first year of the study (4.50 [1.31-15.43]). The difference between infected and uninfected individuals was stronger for adults under 45 years of age (mortality ratio 4.72 [1.86-11.97]) than for older people (1.35 [0.51-3.56]). HIV-2-infected individuals living with an infected spouse had significantly higher mortality than HIV-2-infected individuals living with an uninfected spouse (p = 0.027). INTERPRETATION: HIV-2-associated mortality is not increasing with length of follow-up. Mortality in HIV-2-infected adults is only twice as high as that in uninfected individuals. In the majority of adults, HIV-2 has no effect on survival.

PIP: While HIV-2 infection can lead to AIDS, it takes longer than HIV-1 to induce immunosuppression and AIDS, it is less transmissible, and it is associated with lower mortality than HIV-1 infection. 1329 people from among 100 houses in Guinea-Bissau participated in a 1987 study of HIV seroprevalence in their community. 8.9% of the family members older than age 14 years were infected with HIV-2, as well as 0.6% of the 677 children, but no one was infected with HIV-1. All subjects enrolled in the 1987 study over age 14 were followed up with serological surveys in 1989 and 1992, with their survival assessed in 1995. HIV-2 associated mortality did not increase over time and mortality in HIV-2-infected adults was only twice as high as that among uninfected individuals. In the majority of adults, HIV-2 has no effect upon survival. The difference in mortality between the infected and the uninfected was greater for adults under age 45 years than for older people. Furthermore, HIV-2-infected individuals living with an infected spouse had significantly higher mortality than those living with an uninfected spouse.

T-lymphocyte subsets in West African children: impact of age, sex, and season.

OBJECTIVE: There has been no reference material for T-lymphocyte subsets for normal children in developing countries. We therefore used T-lymphocyte subset determinations among children in three different studies in Guinea-Bissau to construct age-related reference material and to examine possible determinants of T-lymphocyte subset levels. METHODS: A total of 803 healthy West African children younger than 6 years were included in the three community studies of T-lymphocyte subsets among twins and singletons, after measles infection and after measles immunization. We used the immunoalkaline phosphatase method to determine T-lymphocyte subsets. RESULTS: We found differences by age, sex, and season, whereas there were no significant differences by birth order, twinning, or ethnic group. The CD4+ percentage declined from birth to age 2 years, at which time it started to increase to higher levels at age 4 to 5 years. The CD8+ percentage increased gradually from early infancy to age 2 to 4 years. The leukocyte count peaked at age 12 to 23 months and declined thereafter, whereas the lymphocyte percentage peaked at age 1 to 5 months and declined gradually thereafter. Compared with dry-season results, the lymphocyte percentage, the absolute lymphocyte count, the absolute CD4+ T-lymphocyte count, and the CD4+/CD8+ ratio were significantly lower during the rainy season, whereas the CD8+ percentage was increased during the rainy season. Girls had higher CD4+/CD8+ ratios and lower CD8+ percentages than did boys. CONCLUSIONS: Compared with the limited data on T-lymphocyte subsets available from healthy children in developed countries, Guinean children have markedly lower CD4+ percentages and CD4+/CD8+ ratios and higher lymphocyte percentages during the first 2 years of life, when the pressure of infections is particularly high in Africa.

Sonographic measurement of thymic size in healthy neonates. Relation to clinical variables.

PURPOSE: To assess the variation in thymic size in healthy neonates by sonography and to study the possible correlation to clinical variables. MATERIAL AND METHODS: A study was made of 149 healthy term infants, at less than one week of age. The size of the thymus was assessed by sonography as a volume estimate, the thymic index. This index was compared to sex, weight, length, gestational age, and level of perinatal asphyxia of the infant. T-cell subsets (percentages of CD4 and CD8 receptor-positive T-lymphocytes in peripheral blood) were determined in 83 of the infants and compared to the sonographic thymic index. RESULTS: The thymic index varied between 4 and 29, and was positively correlated to the weight of the infant (p = 0.0003). There was no correlation to sex, length, gestational age or slight perinatal asphyxia. We found no correlation between the size of the thymus and the CD4 percentage, the CD8 percentage, or the CD4/CD8 ratio. CONCLUSION: The size of the thymus in healthy neonates as measured by sonography is significantly correlated to the weight of the infant. For a given weight of an infant it is possible to predict the normal range of thymic size.