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PubMed2004

Transmission of HIV-1 infection in sub-Saharan Africa and effect of elimination of unsafe injections.

During the past year, a group has argued that unsafe injections are a major if not the main mode of HIV-1 transmission in sub-Saharan Africa. We review the main arguments used to question the epidemiological interpretations on the lead role of unsafe sex in HIV-1 transmission, and conclude there is no compelling evidence that unsafe injections are a predominant mode of HIV-1 transmission in sub-Saharan Africa. Conversely, though there is a clear need to eliminate all unsafe injections, epidemiological evidence indicates that sexual transmission continues to be by far the major mode of spread of HIV-1 in the region. Increased efforts are needed to reduce sexual transmission of HIV-1.

Adolescent↗
PubMed1984

Meningococcal disease and season in sub-Saharan Africa.

The incidence of meningococcal disease varies seasonally in both tropical and temperate countries. This association is most apparent in sub- Saharan Africa, where almost all epidemics start in the dry season and abate during the rains . Meningococcal carriage rates do not vary with season either in Africa or in temperate countries, suggesting that seasonal factors have little influence on the frequency of meningococcal transmission. It is suggested that changes in the ratio of clinical to subclinical cases of infection are more important than changes in the frequency of transmission in producing seasonal variations in the incidence of meningococcal disease. Some evidence to support this hypothesis was obtained during an epidemic of group A meningococcal disease in northern Nigeria in 1977-79.

Carrier State↗
PubMed1999

Cost-effectiveness of malaria control in sub-Saharan Africa.

BACKGROUND: Information on the cost-effectiveness of malaria control is needed for the WHO Roll Back Malaria campaign, but is sparse. We used mathematical models to calculate cost-effectiveness ratios for the main prevention and treatment interventions in sub-Saharan Africa. METHODS: We analysed interventions to prevent malaria in childhood (insecticide-treated nets, residual spraying of houses, and chemoprophylaxis) and pregnancy (chloroquine chemoprophylaxis and sulfadoxine-pyrimethamine intermittent treatment), and to improve malaria treatment (improved compliance, improved availability of second-line and third-line drugs, and changes in first-line drug). We developed models that included probabilistic sensitivity analysis to calculate ranges for the cost per disability-adjusted life year (DALY) averted for each intervention in three economic strata. Data were obtained from published and unpublished sources, and consultations with researchers and programme managers. FINDINGS: In a very-low-income country, for insecticide treatment of existing nets, the cost-effectiveness range was US$4-10 per DALY averted; for provision of nets and insecticide treatment $19-85; for residual spraying (two rounds per year) $32-58; for chemoprophylaxis for children $3-12 (assuming an existing delivery system); for intermittent treatment of pregnant women $4-29; and for improvement in case management $1-8. Although some interventions are inexpensive, achieving high coverage with an intervention to prevent childhood malaria would use a high proportion of current health-care expenditure. INTERPRETATION: Cost-effective interventions are available. A package of interventions to decrease the bulk of the malaria burden is not, however, affordable in very-low-income countries. Coverage of the most vulnerable groups in Africa will require substantial assistance from external donors.

Adolescent↗
PubMed1999

Cost effectiveness of single-dose nevirapine regimen for mothers and babies to decrease vertical HIV-1 transmission in sub-Saharan Africa.

BACKGROUND: Identification of economical interventions to decrease HIV-1 transmission to children is an urgent public-health priority in sub-Saharan Africa. We assessed the cost effectiveness of the HIVNET 012 nevirapine regimen. METHODS: We assessed cost effectiveness in a hypothetical cohort of 20,000 pregnant women in sub-Saharan Africa. Our main outcome measures were programme cost, paediatric HIV-1 cases averted, cost per case averted, and cost per disability-adjusted life-year (DALY). We compared HIVNET 012 with other short-course antiretroviral regimens. We also compared two implementation strategies: counselling and HIV-1 testing before treatment (targeted treatment), or nevirapine for all pregnant women (universal treatment, no counselling and testing). We did univariate and multivariate sensitivity analyses. FINDINGS: For universal treatment with 30% HIV-1 seroprevalence, the HIVNET 012 regimen would avert 603 cases of HIV-1 in babies, cost US$83,333, and generate 15,862 DALYs. The associated cost-effectiveness ratios were $138 per case averted or $5.25 per DALY. At 15% seroprevalence, the universal treatment option would cost $83,333 and avert 302 cases at $276 per case averted or $10.51 per DALY. For targeted treatment at 30% seroprevalence, HIVNET 012 would cost $141,922 and avert 476 cases at $298 per case averted or $11.29 per DALY. With seroprevalence higher than 3.0% for universal and 4.5% for targeted treatment, the HIVNET 012 regimen was likely to be as cost effective as other public-health interventions. The cost effectiveness of HIVNET 012 was robust under a wide range of parameters in the sensitivity analysis. INTERPRETATION: The HIVNET 012 regimen can be highly cost-effective in high seroprevalence settings. In lower seroprevalence areas, when multidose regimens are not cost effective, nevirapine therapy could have a major public-health impact at a reasonable cost.

Africa South of the Sahara↗
PubMed1988

Trypanosoma congolense: the distribution of enzymic variants in east and west Africa.

A total of 114 stocks of Trypanosoma congolense originating from Kenya, Uganda, Tanzania, Zambia and Sudan, but including, for comparison, stocks from The Gambia, Liberia, Ivory Coast, Nigeria and Cameroun, were compared by isoenzyme electrophoresis for 6 enzymes. The zymodemes were grouped, both from a dendrogram and using a cladistic method, after calculating the dissimilarity, or distance, between profiles. Previous observations are broadly confirmed, the zymodemes clustering separately according to geographical origin and ecological zone. Thus, one group was composed almost entirely of East African stocks, and another of stocks from both East and West Africa, although each group was of savanna origin. A third group was composed of stocks from the humid, rain-forest zones of West Africa, and was particularly characterized by isoenzyme variants of superoxide dismutase and glucose-phosphate isomerase. Two stocks from the Kenyan coast formed a markedly separate group, which may be taxonomically distinct.

Africa, Eastern↗
PubMed1998

Prevalence of minor psychiatric disorders in an adult African rural community in South Africa.

BACKGROUND: This paper reports on a two-stage community-based epidemiological study of selected minor psychiatric disorders conducted on an adult African population in South Africa. METHODS: Using a modified random cluster sampling method, 354 adults were identified as the first-stage sample, with the SRQ-20 being used as a first-stage screen. Clinical interviews based on DSM-IV checklists for generalized anxiety disorder, major depression and dysthymia were administered as the second-stage criterion to 81 subjects from the sample. RESULTS: The weighted prevalence for generalised anxiety and depressive disorders was 23.9% (95% CI 15.1%-32.7%), comprising: generalized anxiety 3.7%, major depression 4.8%, dysthymia 7.3%, and major depression and dysthymia 8.2%. Statistically significant associations were found between caseness and age, marital status, employment, income and educational level. CONCLUSIONS: The results are discussed in relation to comparative local and international data as well as in the context of the current restructuring of the mental-health care system in South Africa from tertiary curative care to integrated primary mental-health care.

Adolescent↗
PubMed1992

Iron overload in Africa. Interaction between a gene and dietary iron content.

BACKGROUND AND METHODS: In contrast to hemochromatosis, which in white populations is inherited through a gene linked to the HLA locus, iron overload in sub-Saharan Africa is believed to result solely from increased dietary iron derived from traditional home-brewed beer. To examine the hypothesis that African iron overload also involves a genetic factor, we used likelihood analysis to test for an interaction between a gene (the hypothesized iron-loading locus) and an environmental factor (increased dietary iron) that determines transferrin saturation and unsaturated iron-binding capacity. We studied 236 members of 36 African families chosen because they contained index subjects with iron overload. Linkage to the HLA region was tested with use of lod scores. RESULTS: In the index subjects, increased iron was present in both hepatocytes and cells of the mononuclear-phagocyte system. Among family members with increased dietary iron due to the consumption of traditional beer, transferrin saturation in serum was distributed bimodally, with 56 normal values (less than 60 percent saturation) and 44 elevated values; the mean serum ferritin concentration was five times higher in the subjects with elevated transferrin saturation (P less than 0.005). The pedigree analysis provided evidence of both a genetic effect (P less than 0.005) and an effect of increased dietary iron (P less than 0.005) on transferrin saturation and unsaturated iron-binding capacity. In the most likely model, increased dietary iron raised the mean transferrin saturation from 30 to 81 percent and lowered the mean unsaturated iron-binding capacity from 38 to 13 mumol per liter in subjects heterozygous for the iron-loading locus. The hypothesis of tight linkage to HLA was rejected. CONCLUSIONS: Iron overload in Africa may be caused by an interaction between the amount of dietary iron and a gene distinct from any HLA-linked gene.

Adult↗
PubMed2004

Defining minimum standards of practice for incorporating African traditional medicine into HIV/AIDS prevention, care, and support: a regional initiative in eastern and southern Africa.

In many resource-poor settings of Africa, a majority of people living with HIV/AIDS depend on and choose traditional healers for psychosocial counseling and health care. If the current pan-African prevention and care efforts spurred by the HIV pandemic do not actively engage African Traditional Medicine, they will effectively miss 80%, the vast majority of the African people who, according to the World Health Organization, rely on traditional medicine for their primary health care needs. In 2001, the Ugandan nongovernmental organization, Traditional and Modern Health Practitioners Together Against AIDS and Other Diseases, in Kampala, identified the need for a concerted, systematic, and sustained effort at both local and regional levels to support and validate African Traditional Medicine on several fronts. The Eastern & Southern Africa Regional Initiative on Traditional Medicine and AIDS was borne out of this assessment. It convened a regional consultation in May 2003, which produced a series of proposed standards around six main themes related to traditional medicine and HIV/AIDS: the systematic evaluation of traditional remedies; spiritual aspects of healing; HIV prevention and care; processing and packaging of traditional remedies; protection of indigenous knowledge; and intellectual property rights related to traditional health systems. These standards, summarized in this paper, will be incorporated into programs on traditional medicine and HIV/AIDS by various implementers in the region. A number of strategies to test and implement these recommendations are also defined.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Infection with hepatitis A and B viruses in French volunteers working in tropical Africa.

The risks of developing hepatitis A and B virus infections were studied in 233 French volunteers working for 18 to 35 months in the field in West and Central Africa. During their stay in Africa, the seroconversion rates to antibody to hepatitis A virus of the immunoglobulin G (IgG) class and hepatitis B marker(s) were 48.1% and 10.5%, respectively; 21.5% of the volunteers developed jaundice, and 78.0% of the jaundice cases were associated with hepatitis A seroconversion, 14.0% with hepatitis B seroconversion, 4.0% with seroconversion to both, and 4.0% without seroconversion. Male health workers were at lower risk than other male occupations for hepatitis A infection. Female health workers were at higher risk than other female occupations for hepatitis A infection. Health workers were at a lower risk of hepatitis B infection, but the significance was borderline. Populations such as these volunteers should receive immunoprophylaxis against hepatitis A and B infections.

Adult↗
PubMed2000

Causes of death in a rural area of South Africa: an international perspective.

The study compares the cause of death profile in a rural area of South Africa (Agincourt), with that in a rural area of West Africa (Niakhar), and in a developed country with the same life expectancy (France, 1951) in order to determine causes with high and low mortality and priorities for future health interventions. In the two African sites, causes of death were assessed by verbal autopsies, whereas they were derived from regular cause of death registration in France. Age-standardized death rates were used to compare cause-specific mortality in the three studies. Life expectancy in Agincourt was estimated at 66 years, similar to that of France in 1951, and much higher than that of Niakhar. Causes of death with outstandingly high mortality in Agincourt were violent deaths (homicide and suicide), accidents (road traffic accidents and household accidents), certain infectious diseases (HIV/AIDS, tuberculosis, diarrhea and dysentery), certain chronic diseases (cancer of genital organs, liver cirrhosis, gastrointestinal hemorrhage, maternal mortality, epilepsy, acute rheumatic fever, and pneumoconiosis) and malnutrition of young children (kwashiorkor). Causes of death with lower mortality than expected were primarily respiratory diseases (pneumonia, bronchitis, influenza, lung cancer), other cancers, vaccine preventable diseases (measles, whooping cough, tetanus), and marasmus. Verbal autopsies could be used in a rural area of a developing country without formal cause of death registration to identify the most salient health problems of the population, and could be compared with a formal cause of death registration system of a developed country.

Acquired Immunodeficiency Syndrome↗
PubMed1997

Geographical distribution of HIV-1 group O viruses in Africa.

OBJECTIVE: To determine to what extent HIV-1 group O strains are present in different African countries. MATERIALS AND METHODS: A total of 14,682 samples of sera from a range of patients from 12 different African countries were tested. All the sera were tested with an enzyme-linked immunosorbent assay (ELISA) using a combination of V3 peptides from ANT-70 and MVP-5180. Samples reactive in ELISA were retested in a line immunoassay (LIA-O). Samples reactive in ELISA were also retested with an in-house Western blot to determine the presence of antibodies to gp120 of HIV-1 ANT-70. Polymerase chain reaction was performed on HIV-1 group O and group O indeterminate sera. RESULTS: Of all the sera samples tested, only 19 sera had antibodies to group O V3 peptides exclusively and 46 were indeterminate for group O infection in LIA-O. The highest prevalence of HIV-1 group O infection among HIV-positive sera was observed in Cameroon (2.1%) and neighbouring countries, 1.1% in Nigeria and 0.9% in Gabon. The lowest rates were seen in west Africa: 0.07% in Senegal, 0.14% in Togo, 0.16% in Chad and 0.3% in Niger. Group O sera were observed in almost all the population categories tested. The ANT-70 V3 peptide in LIA-O was reactive with all of the sera considered to be HIV-1 group O antibody positive by LIA, versus 78.9% for the MVP-5180 peptide. Thirteen out of 19 group O samples of sera were tested in PCR. Eight samples were identified as group O by specific group O pol and/or V3 primers; in the remaining five samples no HIV RNA could be detected. Of the indeterminate sera samples, two were identified as group O. CONCLUSION: In eight of the 12 countries tested, antibodies to group O viruses were identified. Numbers of HIV-1 group O viruses are low. Their presence is not restricted to Cameroon and neighbouring countries but can also be found in west and south-east Africa.

Africa↗
PubMedDate not supplied

Chlamydia trachomatis, infertility, and population growth in sub-Saharan Africa.

In sub-Saharan Africa, Neisseria gonorrhoeae and Chlamydia trachomatis are common infections. These pathogens are also the major causes of post-salpingitis tubal infertility, and infertility is a frequent problem in this region. A mathematical model, recently devised to estimate the effect of gonococcal infection on population growth, was used to estimate the potential effect of chlamydial infection on population growth. The model predictions for chlamydial infection were compared with those previously reported for gonococcal infection. The model predicts that both infections may be exerting severe effects on population growth at realistic prevalence rates of infection. The model also predicts that N. gonorrhoeae produces a steeper reduction in population growth than does C. trachomatis because its transmission dynamics result in a higher force of infection (incidence rate) at any given prevalence of infection. Large scale changes in the epidemiology of these infections can be expected to occur in sub-Saharan Africa because of improved sexually transmitted disease (STD) diagnosis and treatment services as a component of AIDS prevention. Changes in the epidemiology of gonococcal and chlamydial infection are predicted to result in accelerated population growth unless STD control programs are linked to effective contraception programs.

Africa↗
PubMed1992

Age-dependent choice of sexual partners and the transmission dynamics of HIV in Sub-Saharan Africa.

A mathematical model of the transmission of HIV-1 within heterosexual populations in Sub-Saharan Africa is described and its properties analysed. The model incorporates epidemiological and demographic processes and extends previous work in this area via the inclusion of age and sex dependency in rates of sexual partner change, and sexual partner choice dependent on age. Parameter assignments are made on the basis of current data on the transmission dynamics of HIV-1 and the demography of human populations in Africa. Both age-dependent rates of sexual activity and the sexual contact of males with females younger than themselves act to enhance the predicted demographic impact. With realistic parameter values, the model suggests AIDS is able to reverse the sign of population growth rates from positive to negative values over a timescale of a few decades. The sensitivity of this prediction is examined in relation to changes in the pattern of sexual contact between different age classes of females and males, different patterns of change in the age-dependent rate of sexual partner change, different assumptions concerning the doubling time of the epidemic in its early stages, and the relative efficiencies of viral transmission between men and women, and vice versa. The impact AIDS is predicted to have on the number of young and elderly persons as a fraction of the number of productive adults (the dependancy ratio) is examined under various assumptions concerning the weighting to be applied to mirror the burden imposed by the care of those with AIDS. The paper includes an assessment of the influence of the timing of changes in sexual behaviour, or the promotion of the use of condoms, on the predicted course of the epidemic. The paper concludes with a discussion of data needs and the model refinements required to more accurately mirror current understanding of the epidemiology of HIV-1.

Acquired Immunodeficiency Syndrome↗
PubMed2003

Anopheles arabiensis and An. quadriannulatus resistance to DDT in South Africa.

The malaria control programme of KwaZulu-Natal Province, South Africa, includes Mamfene and Mlambo communities. Western-type houses there are currently sprayed with deltamethrin, whereas traditional houses are sprayed with DDT for malaria control. In 2002, mosquitoes of the Anopheles gambiae complex (Diptera: Culicidae) were collected from DDT-sprayed houses, by window exit traps, and from man-baited nets outdoors. Larval collections were also carried out at Mzinweni Pan near Mlambo. Species of the An. gambiae complex were identified by rDNA polymerase chain reaction assay. The majority of samples collected by window trap and baited nets were identified as the malaria vector An. arabiensis Patton, with a few An. merus Dönitz and An. quadriannulatus (Theobald). The larval collections were predominantly An. quadriannulatus with a small number of An. arabiensis. Standard WHO insecticide susceptibility tests using 4% DDT and 0.05% deltamethrin were performed on both wild-caught females and laboratory-reared progeny from wild-caught females. Wild-caught An. arabiensis samples from window traps gave 63% and 100% mortality 24-h post-exposure to DDT or deltamethrin, respectively. Wild-caught An. arabiensis samples from man-baited net traps gave 81% mortality 24-h post-exposure to DDT. The F1 progeny from 22 An. arabiensis females showed average mortality of 86.5% 24-h post-exposure to DDT. Less than 80% mortality was recorded from five of these families. Biochemical analyses of samples from each of the families revealed comparatively high levels of glutathione-S-transferases and non-specific esterases in some families, but without significant correlation to bioassay results. Wild-caught An. quadriannulatus larvae were reared through to adults and assayed on 4% DDT, giving 47% (n = 36) mortality 24-h post-exposure. Finding DDT resistance in the vector An. arabiensis, close to the area where we previously reported pyrethroid-resistance in the vector An. funestus Giles, indicates an urgent need to develop a strategy of insecticide resistance management for the malaria control programmes of southern Africa.

Africa, Southern↗
PubMed2006

Guide to blackflies of the Simulium damnosum complex in eastern and southern Africa.

At least 26 members of the Simulium damnosum Theobald complex (Diptera: Simuliidae) are known from eastern Africa, most of which are assumed to be non-anthropophilic and some are restricted to small areas of endemicity. Their discovery was based on polytene chromosome inversion polymorphisms and since then they have been cited as cytological entities, but, in many cases, with inadequate descriptions (e.g. without illustrations of the chromosomes). The present distribution, taxonomy and vector identity have been re-evaluated during the last decade in conjunction with ongoing onchocerciasis control programmes. Here, a summary of the relevant data is presented, integrating results of cytotaxonomic, morphotaxonomic and molecular investigations into a guide that provides a comprehensive system of identification for the cytoforms 'Kagera', 'Kasyabone', 'Kibwezi', 'Kisiwani', 'Kisiwani E', 'Kulfo', 'Linthipe', 'Mombo', 'Mutonga', 'Njombe', 'Nkusi', 'Nkusi SA', 'Nkusi SW', 'Nyika', 'Pienaars', 'Sanje', 'Sebwe', 'Turiani', Simulium damnosum sensu stricto, Simulium kaffaense Hadis et al., Simulium kilibanum Gouteux, Simulium kipengere Krueger, Simulium latipollex (Enderlein), Simulium pandanophilum Krüger, Nurmi & Garms, Simulium plumbeum Krueger, Simulium thyolense Vajime et al. and for five newly recognized molecular forms of 'Nkusi' and S. kilibanum. All taxa except S. pandanophilum are assigned to one of five subcomplexes (damnosum, Ketaketa, Kibwezi, Sanje, squamosum) within the S. damnosum complex. The guide encompasses anthropophilic and non-anthropophilic segregates for the whole of eastern and southern Africa, and is not restricted to larval chromosome criteria; in many cases it also allows the typing of adult flies.

Africa, Eastern↗
PubMedDate not supplied

Risk of HIV infection among Dutch expatriates in sub-Saharan Africa.

In order to study the prevalence of human immunodeficiency virus (HIV) infections and related risk factors, Dutch expatriates returning from sub-Saharan Africa were asked to complete a questionnaire on sexual, occupational and other risk factors, and to donate a sample of blood to test for antibodies against HIV. The 1968 participants were workers of various professions and their family members over 16 years of age posted in sub-Saharan African countries by Dutch governmental, non-governmental and commercial organizations for at least 6 months cumulative time between 1 January 1979 and 1 January 1990. Antibodies against HIV-1 were found among 4 of 1122 men (0.4%) and 1 of 846 women (0.1%). The woman and 3 of the men had had sexual contact with African partners and had been treated for sexually transmitted diseases, 2 of these 3 men also had an African life partner. One man reported occupational exposure only. Of the 1968 participants 89 men (7.9%) and 18 women (2.1%) lived with an African partner; 344 men (30.7%) and 111 women (13.1%) had heterosexual contact with other African partners. Only 22.3% (men) and 18.6% (women) of casual sexual contacts with African partners were always protected by a condom. Two hundred and thirty-two of 408 (56.9%) (para)medics reported needlesticks. Groups at risk of HIV infection through sexual exposure were identified using logistic regression models. In conclusion, the observed prevalence of HIV-1 is low. However, unprotected sexual contact with African partners and needlestick accidents were common. This study underscores the continuous need for health education of expatriates on the risks of transmission of HIV in Africa.

Adolescent↗
PubMed1986

The impact of smoking in developing countries with special reference to Africa.

The health effects of smoking have been well documented in developed countries. This article highlights the impact of smoking and tobacco production on health and agricultural production in Africa. It shows that smoking represents an important current and future health risk to people in Africa, which will place stresses on the development of their health services. Tobacco production is shown to be associated with food imports, deforestation, and an economic dependence on transnational corporations. Possible solutions are proposed.

Adolescent↗
PubMed2004

A genome-wide search for type 2 diabetes susceptibility genes in West Africans: the Africa America Diabetes Mellitus (AADM) Study.

The incidence of type 2 diabetes is growing rapidly, not only in developed countries but also worldwide. We chose to study type 2 diabetes in West Africa, where diabetes is less common than in the U.S., reasoning that in an environment where calories are less abundant, incident cases of type 2 diabetes might carry a proportionately greater genetic component. Through the Africa America Diabetes Mellitus (AADM) study, we carried out a genome-wide linkage analysis of type 2 diabetes in a cohort of 343 affected sibling pairs (691 individuals) enrolled from five West African centers in two countries (Ghana: Accra and Kumasi; Nigeria: Enugu, Ibadan, and Lagos). A total of 390 polymorphic markers were genotyped, and multipoint linkage analysis was conducted using the GENEHUNTER-PLUS and ASM programs. Suggestive evidence of linkage was observed in four regions on three chromosomes (12, 19, and 20). The two largest logarithm of odds scores of 2.63 and 1.92 for chromosomes 20q13.3 and 12q24, respectively, are particularly interesting because these regions have been reported to harbor diabetes susceptibility genes in several other populations and ethnic groups. Given the history of forced migration of West African populations during the slave trade, these results should have considerable relevance to the study of type 2 diabetes in African Americans.

Africa, Western↗