SOME FURTHER OBSERVATIONS ON SCHISTOSOME TRANSMISSION IN THE EASTERN TRANSVAAL.
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By immersing groups of rodents into several types of natural waters at Malelane, Eastern Transvaal, and subsequently recovering schistosomes from them, the authors have shown that there is seasonal transmission, which is more marked with Schistosoma mansoni than with S. mattheei. Laboratory confirmation of this periodicity was obtained by infecting groups of snails with the appropriate parasite and studying the pattern of sporocyst development and cercarial shedding under outdoor conditions. It was also found that, apart from seasonal periodicity, the amount of transmission is dependent on the density of human population, the proximity of the definitive host to the immersion site, the degree to which the water is protected from pollution and the distance downstream from the polluting source.Negligible numbers of S. haematobium adults were recovered; possible reasons for this are discussed.The authors consider that an annual transmission cycle may be more common in bilharziasis than is generally supposed-although not exclusively or necessarily for the reasons given in this paper-and suggest that such a cycle be taken into consideration in the planning of control schemes. (+info)
Prevalence of HIV in workforces in southern Africa, 2000-2001.
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OBJECTIVES: Most data on HIV prevalence in low-risk populations in sub-Saharan Africa are drawn from sentinel surveys of pregnant women attending antenatal clinics and are not representative of formal sector workforces. We surveyed workforces in southern Africa to determine HIV prevalence among formally employed, largely male populations. METHODS: Voluntary, anonymous, unlinked seroprevalence surveys of 34 workforces with 44,000 employees were carried out in South Africa, Botswana, and Zambia in 2000-2001. Results were stratified to obtain estimates of prevalence by industrial sector, location, age, sex, and job level. RESULTS: Average HIV prevalence for the entire sample was 16.6% (95% CI: 16.3-17.0%). Country-wide prevalence was 14.5% (14.1-14.9%) in South Africa, 17.9% (17.1-18.7%) in Zambia, and 24.6% (23.6-25.7%) in Botswana. Among industrial sectors, mining (18.0%, 17.6-18.5%) and metal processing (17.3%, 15.9-18.7%) had the highest infection rates. Males, who comprised 85% of participants of known sex, were more likely (16.3%, 15.3-17.4%) to be infected than were females (10.7%, 8.7-12.7%). Contract (23%, 21.9-24.1%), unskilled (18.3%, 17.5-19.1%), and semi-skilled workers (18.7%, 18.1-19.4%) were much more likely to be infected than were skilled workers (10.5%, 9.5-11.4%) and managers (4.5%, 3.4-5.6%). Participation in the surveys averaged 63% of eligible employees. CONCLUSIONS: HIV prevalence among formally employed workers in southern Africa shows different patterns than among antenatal clinic attendees. Anonymous workplace surveys generate prevalence estimates for demographic groups that are not represented in antenatal surveys and can strengthen support for prevention and treatment interventions. (+info)
Hypertension guideline 2003 update.
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OUTCOMES: Extensive data from many randomised controlled trials have shown the benefit of treating hypertension. The target blood pressure (BP) for antihypertensive management should be systolic BP < 140 mmHg, diastolic < 90 mmHg, with minimal or no drug side-effects. However, a lesser reduction will elicit benefit although this is not optimal. The reduction of BP in the elderly and in those with severe hypertension should be achieved gradually over 6 months. Stricter BP control is required for patients with end organ damage, co-existing risk factors and co-morbidity, e.g. diabetes mellitus. Co-existent risk factors should also be controlled. BENEFITS: Reduction in risk of stroke, cardiac failure, renal insufficiency and probably coronary artery disease. The major precautions and contraindications to each antihypertensive drug recommended are listed. RECOMMENDATIONS: Correct BP measurement procedure is described. Evaluation of cardiovascular risk factors and recommendations for antihypertensive therapy are stipulated. The total cardiovascular disease risk profile should be determined for all patients and this should inform management strategies. Lifestyle modification and patient education plays an essential role in the management strategy. Drug therapy: First line--low dose thiazide-like diuretics; second line--add one of the following: reserpine, or beta-blockers or ACE inhibitors or calcium channel blockers; third line--add another second line drug or hydralazine or alpha-blocker. The guideline includes management of specific situations, i.e. hypertensive emergency and urgency, severe hypertension with target organ damage and refractory hypertension (BP > 160/95 mmHg on triple therapy), hypertension in diabetes mellitus, etc. VALIDITY: Developed by the Working Groups established by the Executive Committee of the Southern African Hypertension Society with broader consensus meeting endorsement. The 2001 version was endorsed by the South African Medical Association Guideline Committee. The 2003 revisions were endorsed by the Executive Committee and a wider Working Group. (+info)
Epidemiology in the era of globalization: skills transfer or new skills?
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BACKGROUND: Globalization carries information and technology opportunities and risks in widened inequalities, a resurgence of old health risks and reversal of health gains. METHODS: The paper explores the implications for epidemiological work in southern Africa and through two case studies-occupational health and equity in health-profiles challenges faced in that region. RESULTS: Occupational epidemiology is confronted by weak monitoring and regulatory systems, healthy worker effects, surveillance filters, and migration. Occupational disease determinants are masked by the combined effects of work, wider environmental risks, and high poverty-related disease. Health burdens associated with new production and trade patterns are thus largely unrecognized. Even when made visible, they may be ignored by economically vulnerable states and workers. Work on equity in health indicates the relevance of social and political determinants in the distribution of health resources. The shift of the cost burden of human immunodeficiency virus (HIV)/AIDS to poor communities and the weak public health response to HIV/AIDS suggest that economic and health reforms associated with globalization have both increased health inequalities and weakened social and political forces promoting equity and solidarity values in public health. CONCLUSIONS: Epidemiology can demystify disease sources and explain determinants in a manner that impacts on public policy and action. Under current conditions of globalization this implies addressing methodological challenges and enhancing uptake of evidence in policy processes. Given the intensifying political struggle around health resources, increased attention needs to be given to participatory forms of inquiry that strengthen the influence of poor communities and public interest values in health policy. (+info)
Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying.
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Indoor residual house-spraying (IRS) mainly with dichlorodiphenyltrichloroethane (DDT) was the principal method by which malaria was eradicated or greatly reduced in many countries in the world between the 1940s and 1960s. In sub-Saharan Africa early malarial eradication pilot projects also showed that malaria is highly responsive to vector control by IRS but transmission could not be interrupted in the endemic tropical and lowland areas. As a result IRS was not taken to scale in most endemic areas of the continent with the exception of southern Africa and some island countries such as Reunion, Mayotte, Zanzibar, Cape Verde and Sao Tome. In southern Africa large-scale malarial control operations based on IRS with DDT and benzene hexachloride (BHC) were initiated in a number of countries to varying degrees. The objective of this review was to investigate the malarial situation before and after the introduction of indoor residual insecticide spraying in South Africa, Swaziland, Botswana, Namibia, Zimbabwe and Mozambique using historical malarial data and related information collected from National Malaria Control Programmes, national archives and libraries, as well as academic institutions in the respective countries. Immediately after the inception of IRS with insecticides, dramatic reductions in malaria and its vectors were recorded. Countries that developed National Malaria Control Programmes during this phase and had built up human and organizational resources made significant advances towards malarial control. Malaria was reduced from hyper- to meso-endemicity and from meso- to hypo-endemicity and in certain instances to complete eradication. Data are presented on the effectiveness of IRS as a malarial control tool in six southern African countries. Recent trends in and challenges to malarial control in the region are also discussed. (+info)
Evidence of unique genotypes of beak and feather disease virus in southern Africa.
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Psittacine beak and feather disease (PBFD), caused by Beak and feather disease virus (BFDV), is the most significant infectious disease in psittacines. PBFD is thought to have originated in Australia but is now found worldwide; in Africa, it threatens the survival of the indigenous endangered Cape parrot and the vulnerable black-cheeked lovebird. We investigated the genetic diversity of putative BFDVs from southern Africa. Feathers and heparinized blood samples were collected from 27 birds representing 9 psittacine species, all showing clinical signs of PBFD. DNA extracted from these samples was used for PCR amplification of the putative BFDV coat protein (CP) gene. The nucleotide sequences of the CP genes of 19 unique BFDV isolates were determined and compared with the 24 previously described sequences of BFDV isolates from Australasia and America. Phylogenetic analysis revealed eight BFDV lineages, with the southern African isolates representing at least three distinctly unique genotypes; 10 complete genome sequences were determined, representing at least one of every distinct lineage. The nucleotide diversity of the southern African isolates was calculated to be 6.4% and is comparable to that found in Australia and New Zealand. BFDVs in southern Africa have, however, diverged substantially from viruses found in other parts of the world, as the average distance between the southern African isolates and BFDV isolates from Australia ranged from 8.3 to 10.8%. In addition to point mutations, recombination was found to contribute substantially to the level of genetic variation among BFDVs, with evidence of recombination in all but one of the genomes analyzed. (+info)
Novel and promiscuous CTL epitopes in conserved regions of Gag targeted by individuals with early subtype C HIV type 1 infection from southern Africa.
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Characterization of optimal CTL epitopes in Gag can provide crucial information for evaluation of candidate vaccines in populations at the epicenter of the HIV-1 epidemic. We screened 38 individuals with recent subtype C HIV-1 infection using overlapping consensus C Gag peptides and hypothesized that unique HLA-restricting alleles in the southern African population would determine novel epitope identity. Seventy-four percent of individuals recognized at least one Gag peptide pool. Ten epitopic regions were identified across p17, p24, and p2p7p1p6, and greater than two-thirds of targeted regions were directed at: TGTEELRSLYNTVATLY (p17, 35%); GPKEPFRDYVDRFFKTLRAEQATQDV (p24, 19%); and RGGKLDKWEKIRLRPGGKKHYMLKHL (p17, 15%). After alignment of these epitopic regions with consensus M and a consensus subtype C sequence from the cohort, it was evident that the regions targeted were highly conserved. Fine epitope mapping revealed that five of nine identified optimal Gag epitopes were novel: HLVWASREL, LVWASRELERF, LYNTVATLY, PFRDYVDRFF, and TLRAEQATQD, and were restricted by unique HLA-Cw*08, HLA-A*30/B*57, HLA-A*29/B*44, and HLA-Cw*03 alleles, respectively. Notably, three of the mapped epitopes were restricted by more than one HLA allele. Although these epitopes were novel and restricted by unique HLA, they overlapped or were embedded within previously described CTL epitopes from subtype B HIV-1 infection. These data emphasize the promiscuous nature of epitope binding and support our hypothesis that HLA diversity between populations can shape fine epitope identity, but may not represent a constraint for universal recognition of Gag in highly conserved domains. (+info)
Improving epidemic malaria planning, preparedness and response in Southern Africa. Report on the 1st Southern African Regional Epidemic Outlook Forum, Harare, Zimbabwe, 26-29 September, 2004.
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Malaria is a major public health problem for countries in the Southern Africa Development Community (SADC). While the endemicity of malaria varies enormously across this region, many of the countries have districts that are prone to periodic epidemics, which can be regional in their extent, and to resurgent outbreaks that are much more localized. These epidemics are frequently triggered by climate anomalies and often follow periods of drought. Many parts of Southern Africa have suffered rainfall deficit over the past three years and countries expect to see increased levels of malaria when the rains return to more 'normal' levels. Problems with drug and insecticide resistance are documented widely and the region contains countries with the highest rates of HIV prevalence to be found anywhere in the world. Consequently, many communities are vulnerable to severe disease outcomes should epidemics occur. The SADC countries have adopted the Abuja targets for Roll Back Malaria in Africa, which include improved epidemic detection and response, i.e., that 60% of epidemics will be detected within two weeks of onset, and 60% of epidemics will be responded to within two weeks of detection. The SADC countries recognize that to achieve these targets they need improved information on where and when to look for epidemics. The WHO integrated framework for improved early warning and early detection of malaria epidemics has been recognized as a potentially useful tool for epidemic preparedness and response planning. Following evidence of successful adoption and implementation of this approach in Botswana, the SADC countries, the WHO Southern Africa Inter-Country Programme on Malaria Control, and the SADC Drought Monitoring Centre decided to organize a regional meeting where countries could gather to assess their current control status and community vulnerability, consider changes in epidemic risk, and develop a detailed plan of action for the forthcoming 2004-2005 season. The following is a report on the 1st Southern African Regional Epidemic Outlook Forum, which was held in Harare, Zimbabwe, 26th-29th September, 2004. (+info)