Evidence of sexual recombination among Cryptococcus neoformans serotype A isolates in sub-Saharan Africa. (25/208)

The most common cause of fungal meningitis in humans, Cryptococcus neoformans serotype A, is a basidiomycetous yeast with a bipolar mating system. However, the vast majority (>99.9%) of C. neoformans serotype A isolates possess only one of the two mating type alleles (MATalpha). Isolates with the other allele (MATa) were recently discovered and proven to mate in the laboratory. It has been a mystery whether and where C. neoformans strains undergo sexual reproduction. Here, we applied population genetic approaches to demonstrate that a population of C. neoformans serotype A clinical isolates from Botswana contains an unprecedented proportion of fertile MATa isolates and exhibits evidence of both clonal expansion and recombination within two partially genetically isolated subgroups. Our findings provide evidence for sexual recombination among some populations of C. neoformans serotype A from sub-Saharan Africa, which may have a direct impact on their evolution.  (+info)

Genotypic characterization of Kaposi's sarcoma-associated herpesvirus in asymptomatic infected subjects from isolated populations. (26/208)

Molecular epidemiological studies of Kaposi's sarcoma-associated herpesvirus (KSHV) have concentrated on characterization of viral strains in tumour biopsy samples from Kaposi's sarcoma (KS) patients, mostly obtained in the United States and Europe. Tumour biopsies are a convenient source of viral DNA, as they have a high viral load compared to peripheral blood. However, sequences obtained from biopsies may not be representative of viral strains in asymptomatic subjects and information on ethnicity is often not available. Here, a population-based approach has been used to study the molecular and seroepidemiology of KSHV in isolated populations in Ecuador and Botswana. Amerindians in Ecuador had a variable prevalence of KSHV and all strains characterized were of subtype E, based on K1 sequencing. All Amerindian strains had predominant (P)-type K15 alleles and had sequences in both T0.7 and ORF 75 that appeared to be characteristic of these strains. The prevalence of KSHV in two ethnic groups in Botswana was extremely high. K1 sequences from both Bantu and San subjects were mostly of subtypes B and A5, which are typical of African KSHV strains, but the sequence from one San subject did not cluster with any known subtype. Considerable heterogeneity was seen in the T0.7 and ORF 75 genes in the San subjects and one had a minor (M)-type K15 allele. The heterogeneity of the KSHV strains found in these subjects from Botswana contrasts with the homogeneity of KSHV strains in Amerindians, reflecting differences in the evolutionary history of these populations.  (+info)

Tuberculosis serodiagnosis in a predominantly HIV-infected population of hospitalized patients with cough, Botswana, 2002. (27/208)

A sensitive and accurate tuberculosis (TB) serodiagnostic test would aid in the control of TB, but results of current tests are relatively unreliable for persons infected with human immunodeficiency virus (HIV). We evaluated a new prototype immunochromatographic strip test and 5 commercially available serodiagnostic TB tests in a prospective study comprised of 465 consecutively enrolled patients with suspected TB from 2 hospitals in Botswana. Consenting adults underwent HIV testing, >/=2 sputum smears and cultures, and mycobacterial blood culture. Patients were defined as having TB on the basis of any positive smear or culture. Between January and September 2002, 465 of 498 consecutive patients consented to enrollment. A total of 384 patients (83%) were infected with HIV, and 175 (38%) had TB; the mycobacterial blood culture was the sole source of diagnosis for 26 patients (15%) with TB. Among the tests evaluated, the sensitivity was 0%-63%, the specificity was 39%-99%, the positive predictive value was 0%-39%, and the negative predictive value was 63%-65%. We conclude that the serodiagnostic tests evaluated in this study lacked sufficient sensitivity as sole tests for TB in this population.  (+info)

The UNAIDS Estimation and Projection Package: a software package to estimate and project national HIV epidemics. (28/208)

This paper describes the Estimation and Projection Package (EPP) for estimating and projecting HIV prevalence levels in countries with generalised epidemics. The paper gives an overall summary of the software and interface. It describes the process of defining and modelling a national epidemic in terms of locally relevant sub-epidemics and the four epidemiological parameters used to fit a curve to produce the prevalence trends in the epidemic. It also provides an example of using the EPP in a country with a generalised epidemic. The paper discusses the strengths and weaknesses of the software and its envisaged future developments.  (+info)

Low CD4+ T-lymphocyte values in human immunodeficiency virus-negative adults in Botswana. (29/208)

CD4+-lymphocyte counts (LCs) play a crucial role in the management and monitoring of HIV infection. Variability in CD4+ LCs has been reported to occur as a result of measurement techniques and/or biological variations. We report on the CD4+ LCs of healthy human immunodeficiency virus (HIV)-seronegative adults in Botswana. Samples were obtained from HIV-seronegative blood donors. The median CD4+ LC was 726 cells/mm3 (for females, 782 cells/mm3; for males, 698 cells/mm3). The median CD8+ LC was 488 cells/mm3 (for females, 494 cells/mm3; for males, 485 cells/mm3). The median CD4+-to-CD8+ ratio was 1.57 (for females, 1.66; for males, 1.51). Our findings of low CD4+ LCs among HIV-negative adults in Botswana are significant and have important implications for the management of HIV disease in the population of this sub-Saharan African country.  (+info)

Chlamydia and gonorrhoea in pregnancy: effectiveness of diagnosis and treatment in Botswana. (30/208)

BACKGROUND: Millions of patients are prescribed drugs for sexually transmitted infections (STIs) in developing countries each year, yet the treatment effect of these prescriptions is largely unknown. OBJECTIVES: To determine if the prescribing of erythromycin and ceftriaxone to pregnant women with STI symptoms leads to a reduction in the prevalence among these women of chlamydia and gonorrhoea, respectively. METHODS: We compared the prevalence of chlamydia among 116 pregnant women who had been prescribed erythromycin for a history of STI symptoms in their current pregnancy with the prevalence in a control group of 557 pregnant women who had not been prescribed this drug. Similarly we compared the prevalence of gonorrhoea among 110 pregnant women who had and 561 women who had not been prescribed ceftriaxone. RESULTS: There was no significant difference in the prevalence of chlamydia among the women who had and the women who had not been prescribed erythromycin four times daily for 10 days (7% v 8%). Contrarily, none of the women who had been prescribed a single dose of ceftriaxone had gonorrhoea, whereas 4% of the women who had not had this drug prescribed did have gonorrhoea. CONCLUSIONS: The prescribing of erythromycin seems to have had a limited effect on chlamydia in this population, whereas the prescribing of ceftriaxone led to the curing of gonorrhoea. Ceftriaxone is provided as a single dose injection at the point of care, and the differential effectiveness between the two drugs may reflect low compliance with the complex erythromycin regimen. Interventions to increase compliance could improve cure rates. The use of a simpler drug regimen should be considered when low compliance is likely.  (+info)

Introduction of routine HIV testing in prenatal care--Botswana, 2004. (31/208)

In 2003, approximately 37% of pregnant women in Botswana (2001 population: 1.7 million; approximately 40,000 births per year) were infected with human immunodeficiency virus (HIV). Since 2001, all prenatal clinics in Botswana have offered HIV screening and interventions for prevention of mother-to-child transmission of HIV (PMTCT), which can decrease vertical transmission of HIV from 35%-40% to 5%-10%. Historically, HIV testing in Botswana has been performed after individual pretest counseling, with patients actively choosing whether to be tested (i.e., an "opt-in" approach). In 2003, 52% of pregnant women receiving prenatal care nationwide learned their HIV status. In 2004, to increase use of free national PMTCT and antiretroviral treatment (ARV) programs, Botswana began routine, noncompulsory (i.e., "opt-out") HIV screening in prenatal and other health-care settings. Concerns have been raised that routine testing in Africa might deter women from seeking prenatal care and might result in fewer women returning for their test results and HIV care after testing. To assess the early impact of routine testing on HIV-test acceptance and rates of return for care, the CDC Global AIDS Program and the PMTCT program in Botswana evaluated routine prenatal HIV testing at four clinics in Francistown, the second largest city in Botswana, where HIV prevalence has been > or =40% since 1995. This report describes the results of that assessment, which indicated that, during February-April 2004, the first 3 months of routine testing, 314 (90.5%) of 347 pregnant women were tested for HIV, compared with 381 (75.3%) of 506 women during October 2003-January 2004, the last 4 months of the opt-in testing period (p<0.001). However, many women who were tested never learned their HIV status because of logistical problems or not returning to the clinic. Substantial increases in HIV testing of pregnant women were also observed at the Francistown referral hospital and at prenatal clinics nationwide. These findings highlight the potential public health impact of routine HIV testing with rapid, same-day results for programs seeking to increase the number of persons with access to HIV-prevention and treatment services.  (+info)

Spatially explicit analyses unveil density dependence. (32/208)

Density-dependent processes are fundamental in the understanding of species population dynamics. Whereas the benefits of considering the spatial dimension in population biology are widely acknowledged, the implications of doing so for the statistical detection of spatial density dependence have not been examined. The outcome of traditional tests may therefore differ from those that include ecologically relevant locational information on both the prey species and natural enemy. Here, we explicitly incorporate spatial information on individual counts when testing for density dependence between an insect herbivore and its parasitoids. The spatially explicit approach used identified significant density dependence more frequently and in different instances than traditional methods. The form of density dependence detected also differed between methods. These results demonstrate that the explicit consideration of patch location in density-dependence analyses is likely to significantly alter current understanding of the prevalence and form of spatial density dependence in natural populations.  (+info)