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.

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.

Cellular profiles in bronchoalveolar lavage fluid of HIV-infected patients with pulmonary symptoms: relation to diagnosis and prognosis.

Bronchoalveolar lavage (BAL) cell differentials and T-lymphocyte subpopulations were analysed in 95 HIV-infected patients with pulmonary symptoms to determine whether the type of cellular inflammatory response could be useful in diagnosis or as a prognostic marker. Patients with Pneumocystis carinii pneumonia (PCP) had more BAL fluid lymphocytes, mainly comprising CD8+ cells, and patients with bacterial infection had more neutrophils than other patients. Neither of these changes were mirrored in peripheral blood. Seven patients who died after their acute episode of PCP had significantly higher BAL fluid neutrophils than 53 patients with PCP who survived (P = 0.002). There seems to be correlation between BAL fluid neutrophilia, PCP and concomitant bacterial infection since four out of seven patients with a fatal outcome had coinfection with bacteria, whereas only one patient with PCP and bacterial coinfection survived (P = 0.0007).

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.

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

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

Lack of evidence of vertical transmission of human immunodeficiency virus type 2 in a sample of the general population in Bissau.

Twenty-nine human immunodeficiency virus type 2 (HIV-2) seropositive women identified in a cross-sectional study in Bissau in 1987 participated in a follow-up study in 1988, where each was matched for age and marital status with two HIV-2 seronegative women. Detailed information about all pregnancies was obtained. The HIV-2 seropositive women and their controls had similar mean numbers of pregnancies, live children, children who died, and abortions. The HIV-2 seropositive women did not have a greater risk of having had an abortion or a child who died than did the HIV-2 seronegative women. No difference in survival was seen between children born to HIV-2 seropositive and HIV-2 seronegative women. The H/S-ratios and CD4 numbers were lower in the seropositive group, but none had values lower than 0.4 and 0.4 x 10(9)/L, respectively. Seven prospectively observed children born to HIV-2 seropositive mothers showed no sign of infection. The lack of evidence of transmission of HIV-2 from mother to child is suggested to be due to the absence of marked immunodeficiency in this random sample of the general population.

HIV-associated lymphoma: histopathology and association with Epstein-Barr virus genome related to clinical, immunological and prognostic features.

All 51 cases of HIV-related malignant lymphoma in Denmark diagnosed from 1983 to 1989 were reviewed. There were 12 Burkitt-type lymphomas, 30 immunoblast-rich lymphomas and 9 other lymphomas. Patients with immunoblast-rich lymphomas had significantly lower CD4 cell counts (median 60 vs. 188 x 10(6)/l, P less than 0.05), and more often a history of previous AIDS-defining illnesses (50% vs. 0%, P less than 0.005), compared with patients with Burkitt-type lymphomas. Epstein-Barr virus (EBV) DNA was demonstrated in 14 of 19 immunoblast-rich tumours, and in 2 of 7 Burkitt-type lymphomas (P = 0.10). Compared with EBV DNA-negative tumours EBV DNA-positive tumours were associated with lower CD4 cell counts (median 39 vs. 188 x 10(6)/l, P = 0.01). It is concluded that two main types of HIV-related malignant lymphoma exist. One is associated with severe immunosuppression, is often of immunoblast-rich morphology, and may be linked to EBV, whereas the other may occur in the absence of immunosuppression, is often of Burkitt-type morphology, and is probably not linked to EBV. In addition to these two main types, other non-Hodgkin lymphomas and Hodgkin's disease do occur.

Labelling of T cell subsets under field conditions in tropical countries. Adaptation of the immuno-alkaline phosphatase staining method for blood smears.

Immuno-alkaline phosphatase (AP) staining for T cell subsets (CD4 and CD8) of smears from fingerprick blood functioned well under tropical climatic conditions when smears were stored frozen with silica gel before being labelled. Unlabelled smears were stored for up to 12 months and could be transferred abroad without antigenic damage. Identical total CD4 and CD8 counts were obtained on venous and capillary blood, when compared using a FACS analyser. Although the AP method gave somewhat higher total CD4 and CD8 counts, the ratio remained the same. The major advantages of the method are: (i) no expensive equipment is required, (ii) only minute amounts of blood are needed, and (iii) slides can be stored for long periods before labelling and can be preserved for later reading. The method is suitable for community studies where there is a need for assessing the immune status of the population.

Bone marrow stroma in idiopathic myelofibrosis and other haematological diseases. An immunohistochemical study.

Bone marrow stroma was investigated immunohistochemically in 31 patients with haematological diseases, mainly idiopathic myelofibrosis (n = 8) and related chronic myeloproliferative disorders (n = 14). The bone marrow from patients with idiopathic myelofibrosis and some CML patients showed marked staining reactions with antibodies against type III procollagen (pN collagen), type IV collagen, fragment P1 of laminin and factor VIII. Patients with osteomyelosclerosis had particularly increased collagen content, including both newly deposited type III collagen (pN collagen) and mature collagen fibres. As in normal bone marrow, argyrophilic fibres and type III collagen displayed a close co-distribution, which was also demonstrated for type IV collagen and laminin. While normal bone marrow sinusoids had discontinuous basement membranes, fibrosing bone marrow was characterized by endothelial cell proliferation and capillarization, with the development of continuous sheets of basement membrane material beneath endothelial cells.

Long term impact of high titer Edmonston-Zagreb measles vaccine on T lymphocyte subsets.

Several trials of high titer measles vaccine (> 10(4.7) plaque-forming unit) have found female recipients of Edmonston-Zagreb (EZ) vaccine to have lower survival than female recipients of standard measles vaccine. Two trials with medium and high titer EZ vaccine from the age of 4 months were conducted in Guinea-Bissau. To test for possible long term impact on the immune system, an investigation of T cell subsets was conducted among all children still residing in the community at 3 to 5 years of age. No differences were found between recipients of medium titer vaccine and controls. In the second trial, however, recipients of high titer had lower CD4:CD8 ratios than controls and had significantly higher CD8 percentages and lower CD4:CD8 ratios than recipients of medium titer EZ. When analyzed by sex, differences were found only among the girls. However, these differences were small and seemed unlikely to explain the reduced survival which has been associated with high titer EZ measles vaccination. In the 2 years after the investigation of T cell subsets, there was no increased mortality for recipients of EZ vaccine. Hence it is unlikely that high titer vaccine has an persistent adverse effect on survival after 3 years of age.

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.

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

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

Occurrence and type of chromosomal abnormalities in consecutive malignant monoclonal gammopathies: correlation with survival.

Chromosome studies were done on 73 patients with multiple myeloma and three patients with plasma cell leukemia. Eighteen of 76 patients (24%) had chromosomally abnormal clones, including all three patients with PCL. The most common anomalous chromosomes were #1, #14, and #12. In addition, i(17q) was found in two patients with plasma cell leukemia. Among newly diagnosed patients there was no difference in survival for those with abnormal karyotypes and those with normal karyotypes. Among previously diagnosed patients receiving treatment, however, individuals with an abnormal clone had a significantly higher mortality during the first 2 years compared to those with a normal clone. Patients with no growth of metaphases in their bone marrow aspirate had a significantly lower mortality than other patients (p less than 0.05).

Demonstrated Benefit of Continuous Interferon-Alpha-2b Therapy in Hairy Cell Leukemia. A Two-Year Follow-Up.

Interferon-alpha-2b (IFN) was given to a series of 50 patients with hairy cell leukemia (HCL). The IFN dose for both induction and maintenance was 2.0 × 10(6) IU/m(2) s.c. three times weekly. At 24 months 38 patients remained in the study. The proportion of complete responders (CR) increased during the follow-up, and had at 24 months reached 58%, while 28% at the same time had a partial (PR) and 14% a minor response (MR). During the two years of continuous IFN treatment none of the 38 patients showed any signs of relapse. The response rate was similar between splenectomized (n = 15) and non-splenectomized (n = 23) patients, but the rise in platelets was much steeper and reached a significantly higher plateau in patients, who previously had undergone splenectomy. The IFN therapy was generally well tolerated, but when evaluated at 24 months at least some (mostly mild) toxicity was noted in 76% of the patients. None of the patients developed neutralizing antibodies to IFN.

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.

Introduction of measles into a highly immunised West African community: the role of health care institutions.

In an urban area of Guinea-Bissau, where more than 80% of the children have been vaccinated, measles continues to be a major cause of child mortality. Compared with the period before the introduction of vaccination, more cases occur outside the community, while more cases within the district are now guests and newcomers. Half of the new introductions of measles into the community and 30% of the measles deaths can be traced back to the paediatric ward. Contact with health care institutions plays an important role in the transmission of measles, particularly among the youngest children. This consequence of health care may be avoidable, however, since several studies suggest that sick children can be vaccinated safely and effectively.

A community study of T lymphocyte subsets and malaria parasitaemia.

In a community survey of 312 children aged 3-6 years in urban Guinea-Bissau, we examined Plasmodium falciparum parasitaemia and T cell subsets. 183 children (59%) had parasites in their blood, 13 had fever > or = 37.5 degrees C, and 9 (3%) had fever and a parasite density > 5000/microL (clinical malaria). Compared with children with no parasitaemia or asymptomatic parasitaemia, children with acute malaria had lymphopenia and significantly lower total CD4 and CD8 cell counts, but there was no significant difference in white blood cell count percentages of CD4 and CD8 cells, or the CD4/CD8 ratio. Children with parasitaemia but without fever had a significantly lower percentage of CD4 cells than children without parasites (P = 0.031), but did not differ in any other haematological index. Controlling for other factors, the CD4 cell percentage was inversely correlated with the density of malaria parasites (P = 0.024), whereas there was no association with CD8 cell percentage or the CD4/CD8 ratio. Asymptomatic parasitaemia may be an important confounder in general community studies of T cell subsets in the tropics.

Simultaneous meningeal and testicular lymphoblastic transformation of Ph1-positive chronic myelocytic leukaemia in a three-year-old boy.

A three-and-a-half-year-old boy presented in the blastic phase of chronic myelocytic leukaemia (CML) with lymphoblastic infiltration of CNS and testes. The clinical signs and symptoms and also blood and bone marrow findings were otherwise compatible with the chronic phase of the disease, and none of the factors predictive of early transformation were present. Cytogenetic analysis revealed that the Ph1 chromosome, with no additional chromosomal abnormalities, was present in 85% of the bone marrow cells. Meningeal leukaemia is almost unknown in the chronic phase of CML. However, the incidence in the blastic phase may resemble the incidence of CNS leukaemia at diagnosis in children with acute leukaemias. Testicular involvement appears to be extremely rare even in the blastic phase of CML; the "true" incidence may, however, also resemble that of acute leukaemias. This raises the question of the need for testicular and meningeal surveillance and prophylaxis, at least during the blastic phase of CML. One should consider whether the simultaneous meningeal and testicular lymphoblastic leukaemia in this patient was the result of blastic transformation at two independent sites, or whether the testes were seeded from the meninges without identifiable spread to blood and bone marrow.

Measles vaccination and reduction in child mortality: a community study from Guinea-Bissau.

Earlier studies have suggested that general measles vaccination programmes should not be made a priority in developing countries because the presumably malnourished children saved from measles are likely to die from something else. Recent community studies indicate, however, that malnutrition is not the cause of high measles mortality. In an urban community in Guinea-Bissau, child mortality has been registered for a period of 3 years; 1 year before and 2 years after the introduction of a general measles vaccination program. In the years following the introduction of measles vaccination, mortality for children aged 6 to 35 months has significantly diminished. Though this is not a controlled study of vaccinated and unvaccinated children, much of the reduced mortality can apparently be attributed to the protective effect of measles vaccination. Children with a history of earlier measles infection had a significantly higher mortality rate than children vaccinated against measles. Rather than being a mechanism of natural selection taking the weakest children, measles apparently aggravates the condition of many children, leading to delayed excess mortality. In areas where the case fatality rate is high, vaccination against measles should be made an indispensable part of primary health care.

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.