Antifungal activity of four weedy plant extracts against selected mycotoxigenic fungi.

AIMS: To investigate the antifungal activity of aqueous and organic extracts of four weedy plant species viz. Tagetes minuta, Lippia javanica, Amaranthus spinosus and Vigna unguiculata against isolates of four agriculturally important fungi, i.e. Fusarium verticillioides, F. proliferatum, Aspergillus flavus and A. parasiticus. METHODS AND RESULTS: Dried powdered aerial parts of the plants were extracted sequentially with hexane, dichloromethane, methanol and water and tested for activity using a serial microdilution assay. Results were read every day over 120 h. All extracts except for the water extracts showed growth inhibitory activity against most isolates of the Fusarium spp. The most active were the methanol and hexane extracts of V. unguiculata and A. spinosus with minimum inhibitory concentration (MIC) values of <0.5 mg ml(-1) after 48 h against Fusarium spp. No inhibition of the Aspergillus spp. tested was observed, but conidium formation was stimulated on plates treated with plant extracts when visually compared to the growth controls. CONCLUSIONS: The results obtained from this study indicated that chemical constituents from these plant species may be developed as potential agrochemical fungicides. SIGNIFICANCE AND IMPACT OF THE RESEARCH: Food and feed are subject to infection by a variety of micro-organisms that can induce spoilage and/or produce metabolites that are toxic to humans and animals. Extracts of V. unguiculata and A. spinosus were most active and maybe developed into environmentally friendly fungicides, which are affordable to rural farmers in developing countries.

Low sale of antibiotics without prescription: a cross-sectional study in Zimbabwean private pharmacies.

OBJECTIVES: To assess the quality of private pharmacy practice with a focus on the extent of antibiotic sales without prescription in private pharmacies in four Zimbabwean cities in relation to two tracer infectious conditions-sexually transmitted infections (STIs) among females and males, and diarrhoea in a child. METHODS: A cross-sectional study including pharmacies in Harare and three other towns. Information about each pharmacy was collected through structured interviews. Staff were interviewed using a different structured interview guide and simulated clients were used to assess staff performance. Data were analysed statistically, and step models to evaluate pharmacist performance were developed. RESULTS: A majority (69%) stated that they would never sell an antibiotic without a prescription and very few actually did in spite of a high patient demand. Few respondents however performed acceptably regarding provision of information and advice in relation to guidelines: 8% for the STI male, 33% for the STI female and 22% for the diarrhoea scenario. CONCLUSIONS: The study revealed low sales of antibiotics without prescription, showing good adherence to the letter of the law. However, few respondents performed acceptably in relation to guidelines when considering information and advice for the tracer conditions.

Antibacterial activities of medicinal plants used for the treatment of diarrhoea in Limpopo Province, South Africa.

The ethnobotanical survey conducted in this study showed that 21 plant species belonging to 14 families are used in traditional medical practice in Limpopo Province, South Africa, for the treatment of diarrhoea. Methanol, ethanol, acetone and hot water extract from different plant parts (leaves, roots, bark and stem rhizome), of several of these plants (Indigofera daleoides, Punica granatum, Syzygium cordatum, Gymnosporia senegalensis, Ozoroa insignis, Elephantorrhiza elephantina, Elephantorrhiza burkei, Ximenia caffra, Schotia brachypetala and Spirostachys africana), were screened for antibacterial activity against Vibro cholera, Escherichia coli and Staphylococcus aureus, Shigella spp., Salmonella typhi. The antibacterial activity was determined by agar-well diffusion method and expressed as the average diameter of the zone of inhibition of bacterial growth around the wells. The minimum inhibitory concentration (MIC) of active extracts was determined by using the micro-plate dilution assay. Most of the extracts showed relatively high antibacterial activity against most of the tested microorganisms with the diameter of inhibition zones ranging between 10 and 31 mm. Of the plants studied, the most active extracts were those obtained from Punica granatum and Indigofera daleoides. All extracts from two plants, namely, Punica granatum and Ozoroa insignis, were active against all bacterial strains while only organic extracts of Indigofera daleoides inhibited the growth of all tested microorganisms. Water extract of Punica granatum were equally active as organic extracts against bacteria such as Staphylococcus aureus, Shigella sonnei and Shigella flexneri. All extracts of Elephantorrhiza elephantina, Elephantorrhiza burkei and Ximenia caffra and Schotia brachypetala were not active against Escherichia coli and Salmonella typhi. The MIC values for active extracts ranged between 0.039 and 0.6 mg/ml. The results obtained appeared to confirm the antibacterial potential of the plants investigated, and their usefulness in the treatment of diarrhoea.

Predictors and reference values of CD4 and CD8 T lymphocyte counts in pregnancy: a cross sectional study among HIV negative women in Zimbabwe.

OBJECTIVE: To identify predictors and define reference values for T lymphocyte subsets in HIV negative pregnant black women. DESIGN: Cross sectional study. SETTING: Edith Opperman Martenity Hospital, Harare, Zimbabwe. STUDY POPULATION: 1113 HIV negative women 22 to 35 weeks pregnant registering for routine antenatal care. METHODS: A questionnaire was used to collect demographic and obstetric data. CD4 and CD8 T lymphocyte counts were determined by manual immunocytochemistry. Concentrations in serum, of retinol, beta-carotene, ferritin, folate and 1-antichymotrypsin were also measured. Multiple linear regression analysis was employed to identify and estimate effects of potential predictors. MAIN OUTCOME MEASURES: CD4 and CD8 T lymphocyte levels, demographic, obstetric data and micronutrient status. RESULTS: Predictors of CD4 counts were gestational age, serum retinol and season. CD4 counts declined by 25 (95% confidence interval [CI]; 11 to 40; p = 0.001) cells/L for each week's increase in gestation among women with low serum retinol, while low serum retinol was independently associated with lower CD4 counts (-127; 95% CI, -233 to 20 cells/L; p = 0.02) at 35 weeks gestation. The late rainy season was associated with higher CD4 counts (137; 95% CI, 67 to 207 cells/L; p < 0.001). CD8 counts were higher in women with low serum folate (87; 95% CI, 6 to 166 cells/L; p = 0.036) and were slightly higher in gravida 4+ compared to gravida one to three. Reference values of CD4 but not CD8 count and percentage markedly differed from flow cytometry values of pregnant and non-pregnant women in developed and developing countries reported in the literature, even after controlling for the differences in methods of T lymphocyte subset immunophenotyping. CONCLUSION: Gestational age, gravidity, micronutrient status and season influence T lymphocyte subset levels and need to be considered when designing clinical management and intervention strategies for pregnant women. The data underscores the need for local reference values.

Does the first pregnancy precipitate age-related fat deposition?

Excessive accumulation of fat in women of childbearing age is a concern, since obesity is an important cause of morbidity and mortality. Deposition of fat during pregnancy, which is not metabolized during lactation, may contribute. However, the individual effects of age and gravidity on fat accumulation have not been disentangled. Based on multiple linear regression analysis of anthropometric data from 1113 pregnant women from Zimbabwe, we found evidence to suggest that fat deposition is an effect of age rather than gravidity that is precipitated by the first pregnancy.

The impact of repeated treatment with praziquantel of schistosomiasis in children under six years of age living in an endemic area for Schistosoma haematobium infection.

Praziquantel was given every eight weeks for two years to children aged under six years of age, living in a Schistosoma haematobium endemic area. Infection with S. haematobium and haematuria were examined in urine and antibody profiles (IgA, IgE, IgM, IgG1, IgG2, IgG3, and IgG4) against S. haematobium adult worm and egg antigens were determined from sera collected before each treatment. Chemotherapy reduced infection prevalence and mean intensity from 51.8% and 110 eggs per 10 ml urine, respectively, before starting re-treatment programme to very low levels thereafter. Praziquantel is not accumulated after periodic administration in children. Immunoglobulin levels change during the course of treatment with a shift towards 'protective' mechanisms. The significant changes noted in some individuals were the drop in 'blocking' IgG2 and IgG4 whereas the 'protecting' IgA and IgG1 levels increased. The antibody profiles in the rest of the children remained generally unchanged throughout the study and no haematuria was observed after the second treatment. The removal of worms before production of large number of eggs, prevented the children from developing morbidity.

The impact of repeated treatment with praziquantel of schistosomiasis in children under six years of age living in an endemic area for Schistosoma haematobium infection

Praziquantel was given every eight weeks for two years to children aged under six years of age, living in a Schistosoma haematobium endemic area. Infection with S. haematobium and haematuria were examined in urine and antibody profiles (IgA, IgE, IgM, IgG1, IgG2, IgG3, and IgG4) against S. haematobium adult worm and egg antigens were determined from sera collected before each treatment. Chemotherapy reduced infection prevalence and mean intensity from 51.8 percent and 110 eggs per 10 ml urine, respectively, before starting re-treatment programme to very low levels thereafter. Praziquantel is not accumulated after periodic administration in children. Immunoglobulin levels change during the course of treatment with a shift towards 'protective' mechanisms. The significant changes noted in some individuals were the drop in 'blocking' IgG2 and IgG4 whereas the 'protecting' IgA and IgG1 levels increased. The antibody profiles in the rest of the children remained generally unchanged throughout the study and no haematuria was observed after the second treatment. The removal of worms before production of large number of eggs, prevented the children from developing morbidity

HIV and other predictors of serum beta-carotene and retinol in pregnancy: a cross-sectional study in Zimbabwe.

BACKGROUND: Vitamin A status during pregnancy is important to maternal and infant health. OBJECTIVE: Our goal was to identify predictors of serum beta-carotene and retinol. DESIGN: This was a cross-sectional study of 1669 women (22-35 wk of gestation) in Harare, Zimbabwe, who were receiving prenatal care. The statistical effects of age, season, gestational age, gravidity, HIV-1 infection, malaria parasitemia, and serum alpha1-antichymotrypsin (ACT) on serum beta-carotene (log10 transformed) and retinol were estimated by using multiple linear regression analyses. RESULTS: HIV infection was found in 31.5% of the women; 0.4% had malaria. Serum beta-carotene concentrations (geometric x: 0.19 micromol/L) were lower in HIV-infected women than in uninfected women (10beta = 0.78; 95% CI: 0.72, 0.84) and increased with age (10beta = 1.05; 1.02, 1.07) in gravida 1 but not in gravida > or =2 (P for interaction = 0.00002). Serum retinol (x: 0.92 micromol/L) increased with age (beta = 0.004; 0.0001, 0.008) in uninfected women but not in HIV-infected women (P for interaction = 0.02) and was 0.05-micromol/L (0.02, 0.09) lower in HIV-infected women than in uninfected women at 24 y of age. Furthermore, gestational age, season, use of prenatal supplements, and malaria were predictors of serum beta-carotene. Serum retinol was lower in women carrying male (beta = -0.04; -0.08, -0.00005) and multiple (beta = -0.21; -0.35, -0.08) fetuses. Serum ACT concentrations of 0.3-0.4, 0.4-0.5, and >0.5 g/L were associated with 3%, 11%, and 44% lower serum beta-carotene and 0.04-, 0.15-, and 0.41-micromol/L lower serum retinol. Serum ACT (g/L) was higher in women with malaria than in those without (beta = 0.10; 0.03, 0.16) and in gravida 1 than in gravida > or =2 (beta = 0.012; 0.003, 0.021), but was not higher in HIV-infected women than in uninfected women (beta = 0.001; -0.008, 0.011). CONCLUSIONS: HIV infection, malaria, gravidity, and gestational age were predictors of serum beta-carotene and retinol. Serum ACT was an important predictor of both and was associated with gravidity and gestational age.

HIV and other predictors of serum folate, serum ferritin, and hemoglobin in pregnancy: a cross-sectional study in Zimbabwe.

BACKGROUND: Folate and iron status and hemoglobin concentrations are important to maternal and infant health. OBJECTIVE: Our goal was to identify predictors of serum folate, serum ferritin, and hemoglobin. DESIGN: This was a cross-sectional study of 1669 pregnant women (22-35 wk of gestation) in Harare, Zimbabwe, who were receiving prenatal care. The statistical effects of age, season, gestational age, gravidity, HIV-1 infection, malaria parasitemia, and serum alpha1-antichymotrypsin (ACT) on serum folate, serum ferritin (log10 transformed), and hemoglobin were estimated by using multiple linear regression analyses. RESULTS: Serum folate (x: 11.4 micromol/L) was 0.52-nmol/L (95% CI: 0.04, 1.0) lower in HIV-infected women than in uninfected women and 0.65-nmol/L (0.014, 1.28) lower in weeks 25-35 than in weeks 22-25. Serum ferritin (geometric x: 11.6 microg/L) was 0.93 times (0.86, 0.99) lower in HIV-infected women and 2.25 times (1.41, 3.61) higher in women with malaria parasitemia than in uninfected women. Similarly, serum ferritin was 0.71 times (0.63, 0.79) higher in weeks 32-35 than in weeks 22-25 and 1.21 times (1.12, 1.29) higher in gravida > or =3 than in gravida 1. Elevated serum ACT was a strong predictor of serum folate, serum ferritin, and hemoglobin. HIV infection was associated with a 12.9-g/L (8.9, 16.8) lower hemoglobin concentration in women with nondepleted iron stores but low serum retinol and a 7-8-g/L lower hemoglobin concentration in women with other combinations of serum ferritin and retinol (P for interaction = 0.038). Season, age, gestational age, and gravidity were not significant predictors of hemoglobin. Low serum folate, ferritin, and retinol were associated with low hemoglobin. CONCLUSIONS: HIV was associated with lower serum folate, serum ferritin, and hemoglobin. HIV infection was also associated with lower hemoglobin, particularly in women with stored iron and low serum retinol. Low serum folate, ferritin, and retinol were associated with low hemoglobin.

General practitioners and clinical guidelines.

OBJECTIVE: To assess the attitudes of general practitioners in Harare, Zimbabwe, towards the use of clinical practice guidelines (CPG's). DESIGN: Cross sectional survey. SETTING: General practitioners in private practice within the urban Harare (Zimbabwe) environs. SUBJECTS: Two hundred and thirty two general practitioners in Harare, Zimbabwe. MAIN OUTCOME MEASURES: The response to a questionnaire enlisting attitudes to CPGs. RESULTS: Questionnaires were sent to 232 general practitioners. Of these, 137 (59.1%) returned a completed questionnaire. Among the respondents, 95.6% felt that general practitioners should be involved in the development of guidelines, 72.6% had read at least one guideline, 65.9% were prepared to use guidelines in their practice, 61.6% thought that guidelines would improve their treatment ability, and 59.7% thought that guidelines would improve their knowledge of disease. 76.5% felt that the government should not legislate, 66.2% felt that guidelines reduce practitioners' flexibility and 57.9% felt that guidelines would not improve their diagnostic ability. CONCLUSION: The respondents were, in general, favourably disposed towards CPGs. Most had already read some guidelines, and about two thirds were prepared to use them. Almost all respondents felt that general practitioners should be involved in the development of guidelines for use in general practice. These general practitioners felt that guidelines were likely to help them treat patients than to make a diagnosis. Despite these favourable attitudes, many practitioners felt that guidelines would limit their personal flexibility in caring for patients. Organisations developing or implementing CPGs in general practice should address these concerns.

Enumeration of CD4 and CD8 T-cells in HIV infection in Zimbabwe using a manual immunocytochemical method.

OBJECTIVES: To enumerate CD4 and CD8 T-cells using the simple and cheap immuno-alkaline phosphatase (IA) method and to compare it with flow cytometry (FC); and to study the effects of duration of sample storage on the IA method results. DESIGN: Method comparison study. SETTING: Blair Research Laboratory, Harare, Zimbabwe. SUBJECTS: 41 HIV positive and 11 HIV negative men and women from Harare participating in HIV studies at Blair Research Laboratory, Zimbabwe. MAIN OUTCOME MEASURES: CD4 and CD8 T-cell counts by FC and the IA method. RESULTS: The IA method and FC were highly correlated for CD4 counts (Spearman rs = 0.91), CD4 percentage (rs = 0.84), CD8 count (rs = 0.83), CD8 percentage (rs = 0.96) and CD4/CD8 ratio (rs = 0.89). However, CD4 cell counts and percentage measured by the IA method were (mean difference +/- SE) 133 +/- 24 cells/microL [corrected] and 6.7 +/- 1.1% higher than those measured by the FC method (p < 0.0001) respectively. CD8 counts and percentages by the IA method were lower than those by the FC method (p < 0.01). Accordingly, the IA method gave a higher CD4/CD8 ratio (p < 0.01). IA method CD4 counts < 300/mL best predicted FC CD4 counts < 200/mL while IA CD4% < 25 best predicted FC CD4% < 14%. IA method CD4/CD8 ratio < 0.8 best predicted FC CD4/CD8 ratio < 0.5. Smears stored for up to 18 months gave results similar to fresh smears. CONCLUSION: The IA method correlates well with but gives CD4 counts and percentages that are higher than those determined by FC. On the contrary, the IA method gives CD8 counts and percentage that are lower than FC values. The method is a cheap and reliable alternative to FC and allows storage of samples for extended periods before analysis, making it an appropriate technology for resource poor countries.

Ethics and HIV research in Zimbabwe.

A plethora of articles are now being published in both local and international journals on research activities conducted on the human immunodeficiency virus (HIV) in Zimbabwe. Some of the bioethical issues they raise, however, are neither unique to HIV nor unique to developing countries. In this article we discuss several of these issues, including the failure to provide interventions of known efficacy, ethical relevance of study design, informed consent, and exploitation. A challenge raised by much of the research in HIV/AIDS is whether, or under what conditions, it is ethical in research to fail to provide an intervention of known efficacy. The further we diverge from this situation, in which an effective, easy to implement intervention is available, to situations that resemble the controversial international clinical trials to prevent perinatal transmission of HIV the less clear the ethical mandate becomes. In relation to clinical trials the debate has focused on whether the standard of care in the United States--an expensive and complex regimen of Zidovudine--must be provided to all HIV infected pregnant women who join a research study in developing countries. Different scientists and scholars in bioethics have drawn the line differently in terms of what interventions routinely available in the developed world must be provided to research participants in developing countries. At an extreme, no one suggests that the most expensive and complex of Western tertiary care, for example, renal dialysis or coronary bypass, must be provided in research conducted in Zimbabwe. Indeed, public debates about the HIV perinatal transmission trials have not even focused on whether the women in the trials should be provided with HIV combination therapy as they would be in the West or whether they should even have the Zidovudine continued post partum.

Antiretrovial (ARV) drug utilisation in Harare.

OBJECTIVE: To investigate ARV utilisation in Harare in order to gather necessary data to help in the formulation of treatment guidelines to be used in Zimbabwe. DESIGN: A cross sectional study. SETTING: Doctors' rooms and retail pharmacy outlets. SUBJECTS: 68 primary care physicians, 80 pharmacists and 92 patients. MAIN OUTCOME MEASURES: Number of physicians prescribing antiretroviral agents (ARVs) and pharmacists stocking ARVs. Type of ARV utilised, cost to the patient and information on ARV available. RESULTS: Out of the 68 private practitioners interviewed 18 were prescribing ARVs during the period of study. There were 92 patients on ARVs whose mean age was 35 +/- 5 years and consuming an average total of 17 tablets daily. Thirteen out of the 18 doctors had access to laboratory facilities to determine CD4 counts and viral load. The rest were using other approaches to treat and manage HIV/AIDS patients. About a quarter, 27.0%, of the retail pharmacists stocked ARVs. The majority, 82.0%, of the patients appeared to be on Zidovudine (AZT) mainly in combination with other drugs. The most popular combination was that of AZT, Lamivudine (3TC) and Indinavir prescribed to 29.0% of the patients, followed by that of Didanosine (DDI) and hydroxyurea prescribed to 17% of patients. At least 17% of the patients were on AZT monotherapy. There was no significant difference (p = 0.06) in the number of tablets consumed by patients who had other conditions secondary to HIV infection. Only 39 out of the 92 patients reported untoward experiences with ARVs. The major problem being associated gastro-intestinal disturbance which accounted for 56% of the reports. It was not possible to ascertain adherence. CONCLUSION: There appeared to be therapeutic anarchy in the private sector in Harare in the way ARVs were being used. Patients need to be told that deciding to take one of the combinations means making a serious commitment to the drugs on schedule if they want to enjoy the benefit. At the same time there is need to develop and publicize HIV/AIDS treatment guidelines and effective Information, Education and Communication (IEC) materials specific to Zimbabwe.

People's perceptions about malaria transmission and control using mosquito repellent plants in a locality in Zimbabwe.

OBJECTIVE: To assess peoples' perceptions and knowledge about malaria transmission and control with special reference to the use of plants as mosquito repellents. DESIGN: Cross sectional study. SETTING: Mandeya ward "A" (33 degrees E and 18 degrees 30' S), Honde Valley, Zimbabwe. SUBJECTS: 226 household heads present when interview was conducted. MAIN OUTCOME MEASURES: Mosquito control methods, spraying coverage, plants used to repel mosquitoes and reasons for using them. RESULTS: 215 (95.0%) of the respondents' homes had been sprayed and their understanding of malaria transmission was not related to compliance with the National Malaria Control Programme (NMCP). Taking mosquito control measures was related to knowledge of malaria transmission, with 24 (75.0%) of those who did not know, taking no measures of their own. The use of plants was mentioned by 50 (23.5%) of the respondents and the reasons given were that they were cheap 43 (86.0%), effective five (10.0%) and locally available two (4.0%). The plant which was mentioned as being used by all age groups was L. javanica 25 (50.0%) and the other plants were used to a lesser extent. Forty six (92.0%) of the people said that they had used plants for mosquito control. The leafy part of the plant was used by 43 (86.0%) and a fresh preparation 43 (86.2%) gave better protection than a dry one. The plants were crushed and applied on the skin by eight people (14.6%), burnt by 36 people (72.8%) and used in their original form by six people (12.6%) and used once per by day 42 people (84.0%). CONCLUSIONS: One of the important points to emerge from this study is that, despite widespread knowledge about the morbidity of malaria, understanding about its prevention was generally low and this has negative implications on an integrated control programme.

The impact of health education on the knowledge, attitudes and practices of a rural community with regards to schistosomiasis control using a plant molluscicide, Phytolacca dodecandra.

OBJECTIVE: To determine the impact of health education on knowledge, attitudes and practices (KAP) with regards to use of a plant molluscicide in snail control. DESIGN: Repeat cross sectional survey. SETTING: Chiweshe communal lands. SUBJECTS: Males and females--age range 13 to 87 years. MAIN OUTCOME MEASURES: Changes in: KAP after health education, water usage pattern, water contact behaviour, willingness to participate in use of P. dodecandra. RESULTS: A high proportion of the community indicated prior knowledge of schistosomiasis during both knowledge, attitudes and practices (KAP) surveys. In the follow up KAP survey changes in the community's water contact behaviour as well as their practices in relation to sanitation were reported. The involvement of the community in the application of P. dodecandra during the course of the study ensured continued support and participation of the community. This was evidenced in the follow up survey when it was apparent that the community's attitude towards schistosomiasis had been influenced by the different activities that had taken place. CONCLUSION: Changes in the community's KAP with regards to schistosomiasis control, can be interpreted as an indication of the impact of the health education delivered during the course of the study. Health education should, therefore, precede programmes that require full participation of the community, as this enables the community to make informed decisions regarding their participation.

Bioavailability of rifampicin in a separate formulation and fixed dose combination with isoniazid NIH: a case for a fixed dose combination (FDC) for the treatment of tuberculosis.

OBJECTIVES: To study and compare the bioavailability of rifampicin (RIF), in two locally manufactured formulations; an FDC and a separate formulation and an imported FDC formulation. DESIGN: Open within subjects, single blind cross over study. INTERVENTIONS: Each volunteer subject, acting as their own control, received the two fixed dose combinations and the separate formulation with the same amount of 450 mg RIF. MAIN OUTCOME MEASURES: Cmax (peak drug concentration achieved), Tmax (time at which peak drug concentration is achieved), T1/2el (biological half-life of elimination) and area under the curve (AUC) for zero to 10 hours and zero to infinity. These are obtained from plotting plasma concentration against time. RESULTS: There was a significant difference in the Cmax between free and RIF combined with INH (6.1 and 7.6 mg/l respectively) and no significant difference in the other parameters measured, of the local products. Comparison of the local products and imported product showed no significant difference in AUC but significant differences in T1/2el, C max and Tmax (p = 0.003, 0.041 and 0.025 respectively). CONCLUSION: The Zimbabwe manufactured and the German products had "demonstrable bioavailability" as defined by the International Union Against Tuberculosis and Lung Diseases (IUATLD). The local manufacturer appeared to have the technological capability to produce a registrable combined RIF/INH table to be used in the treatment of tuberculosis and to prevent the irrational use of RIF.

TB infection: an exploratory study of BCG protective properties and the possible role of environmental mycobacteria.

OBJECTIVE: To evaluate the presence of environmental mycobacterial strains and explore the implications for BCG vaccination against TB. DESIGN: Multimethod approach which included structured interviews and medical records examination. Soil and water samples were analysed using standard microbiology methods. SETTING: Beatrice Infectious Diseases Hospital, Public Health laboratories, University of Zimbabwe Medical School and several residential areas in Harare. SUBJECTS: 129 tuberculosis inpatients at Beatrice Infectious Diseases Hospital, 26 Public Health Laboratory technicians handling TB specimens and 51 fourth year medical students. MAIN OUTCOME MEASURES: Vaccination status of TB inpatients, medical students and laboratory technicians, protective efficacy of BCG in all subjects, presence of environmental mycobacterium in the environment. RESULTS: The type of tuberculosis did not differ significantly between vaccinated and non-vaccinated TB patients x2(df = 1) = 0.171 p > 0.05. There was no apparent difference between the revaccinated and non-vaccinated laboratory technicians. One respondent out of each of the revaccinated and non-vaccinated laboratory technicians had developed pulmonary tuberculosis. Among the fourth year medical students, four had positive tuberculin test results, even though they had not been vaccinated at the University clinic. Environmental mycobacteria presumptively identified as Mycobacterium scrofulaceum and Mycobacterium intracellulare were isolated from both the water and soil samples taken from a few selected areas in Harare. Of the 129 TB in-patients, 88 (68.2%) had previously been vaccinated against TB. Similarly among the 51 medical students 44(86.3%) had been vaccinated. Laboratory technicians re-vaccinated on the job were nine out of 26. CONCLUSION: The results obtained seemed to indicate that BCG protective efficacy did wane with time and revaccination appeared not to be useful. Environmental mycobacterium that could influence the BCG efficacy do exist in our environment.