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PubMed2004

Palaeobotanical studies from tropical Africa: relevance to the evolution of forest, woodland and savannah biomes.

Fossil plants provide data on climate, community composition and structure, all of which are relevant to the definition and recognition of biomes. Macrofossils reflect local vegetation, whereas pollen assemblages sample a larger area. The earliest solid evidence for angiosperm tropical rainforest in Africa is based primarily on Late Eocene to Late Oligocene (ca. 39-26 Myr ago) pollen assemblages from Cameroon, which are rich in forest families. Plant macrofossil assemblages from elsewhere in interior Africa for this time interval are rare, but new work at Chilga in the northwestern Ethiopian Highlands documents forest communities at 28 Myr ago. Initial results indicate botanical affinities with lowland West African forest. The earliest known woodland community in tropical Africa is dated at 46 Myr ago in northern Tanzania, as documented by leaves and fruits from lake deposits. The community around the lake was dominated by caesalpinioid legumes, but included Acacia, for which this, to my knowledge, is the earliest record. This community is structurally similar to modern miombo, although it is different at the generic level. The grass-dominated savannah biome began to expand in the Middle Miocene (16 Myr ago), and became widespread in the Late Miocene (ca. 8 Myr ago), as documented by pollen and carbon isotopes from both West and East Africa.

Africa↗
PubMed2002

Time to the most recent common ancestor and divergence times of populations of common chaffinches (Fringilla coelebs) in Europe and North Africa: insights into Pleistocene refugia and current levels of migration.

We analyzed sequences from a 275-bp hypervariable region in the 5' end of the mitochondrial DNA control region in 190 common chaffinches (Fringilla coelebs) from 19 populations in Europe and North Africa, including new samples from Greece and Morocco. Coalescent techniques were applied to estimate the time to the most recent common ancestor (TMRCA) and divergence times of these populations. The first objective of this study was to infer the locations of refugia where chaffinches survived the last glacial episode, and this was achieved by estimating the TMRCA of populations in regions surrounding the Mediterranean that were unglaciated in the late Pleistocene. Although extant populations in Iberia, Corsica, Greece, and North Africa harbor haplotypes that are basal in a phylogenetic tree, this information alone cannot be used to infer that these localities served as refugia, because it is impossible to infer the ages of populations and their divergence times without also considering the population genetic processes of mutation, migration, and drift. Provided we assume the TMRCAs of populations are a reasonable estimate of a population's age, coalescent-based methods place resident populations in Iberia, Corsica, Greece, and North Africa during the time of the last glacial maximum, suggesting these regions served as refugia for the common chaffinch. The second objective was to determine when populations began diverging from each other and to use this as a baseline to estimate current levels of gene flow. Divergence time estimates suggest that European populations began diverging about 60,000 years before present. The relatively recent divergence of populations in North Africa, Italy, and Iberia may explain why classic migration estimates based on equilibrium assumptions are high for these populations. We compare these estimates with nonequilibrium-based estimates and show that the nonequilibrium estimates are consistently lower than the equilibrium estimates.

Africa, Northern↗
PubMed2006

Mapping the environmental coverage of the INDEPTH demographic surveillance system network in rural Africa.

OBJECTIVES: The INDEPTH DSS network was founded in 1998 to provide an international network of field sites for continuous demographic evaluation of populations and their health. Results from the network have been used to derive estimates of mortality, morbidity and health equity. Spatial extrapolation and logical summaries of these findings are dependent on the network covering a representative sample of the environments in a region and their interrelationships being known. Here, we investigate how comprehensive is the coverage of the network of rural DSS sites in Africa in terms of the range of ecological zones found across the continent. METHODS: We used satellite imagery to define an environmental signature for each INDEPTH DSS site, and then calculate Euclidean distances from these signatures to the environmental signatures of every image pixel across Africa. These distances were then mapped and a gridded population surface used to mask uninhabited areas to illustrate the extent of the environmental coverage of the INDEPTH network. Environmental similarities between DSS sites were also calculated, hierarchically clustered and visualized as a dendrogram to examine between site relationships. Finally, an ecozonation of Africa was used to analyse the per-ecozone environmental similarity of the INDEPTH DSS network. RESULTS AND CONCLUSIONS: The current INDEPTH DSS network in Africa spans all the major environmental zones, but within these zones the environmental coverage of the network varies. These variations were mapped by ecozone. These maps provide valuable information in determining the confidence with which relationships derived from rural INDEPTH DSS sites can be extended to other areas. The results also indicate suites of sites that form environmentally cohesive groups and from which data can be logically summarized. Finally, the results highlight areas where the location of new INDEPTH DSS sites would increase significantly the environmental coverage of the network.

Africa↗
PubMed2005

Chronic hepatitis B virus infection in the Asia-Pacific region and Africa: review of disease progression.

Countries in the the Asia-Pacific region and Africa tend to have the highest prevalence of hepatitis B infection worldwide. Hepatitis B infection progresses from an asymptomatic persistently infected status to chronic hepatitis B, cirrhosis, decompensated liver disease and/or hepatocellular carcinoma. The aim of this review was to summarize rates and risk factors for progression between disease states in the Asia-Pacific region and Africa. A literature search was conducted employing MEDLINE and EMBASE (1975-2003) using the following key words: hepatitis B, natural history, disease progression, cirrhosis, hepatocellular carcinoma, mortality, Africa and the Asia-Pacific region. Bibliographies of articles reviewed were also searched. Ranges for annual progression rates were: (i) asymptomatic persistent infection to chronic hepatitis B, 0.84-2.7%; (ii) chronic hepatitis B to cirrhosis, 1.0-2.4%; and (iii) cirrhosis to hepatocellular carcinoma, 3.0-6.6%. Patients with asymptomatic persistent infection and chronic hepatitis B had relatively low 5-year mortality rates (<4%); rates (>50%) were much higher in patients with decompensated liver disease and hepatocellular carcinoma. No data were found for progression rates in African populations. Hepatitis B e antigen was a risk factor for chronic hepatitis B, and bridging hepatic necrosis in chronic hepatitis B increased the risk of cirrhosis. Risk factors for hepatocellular carcinoma included cirrhosis, co-infection with hepatitis C virus, and genetic and environmental factors. In this review, wide ranges of disease progression estimates are documented, emphasizing the need for further studies, particularly in Africa, where progression rates are largely not available. Summarizing information on factors associated with disease progression should assist in focusing efforts to arrest the disease process in those at most risk.

Africa↗
PubMed2000

An unbridgeable gap? Comparing the HIV/AIDS epidemics in Australia and sub-Saharan Africa.

OBJECTIVE: To compare the HIV/AIDS epidemics in Australia and sub-Saharan Africa, to outline reasons for differences, and to consider implications for the Asia and Pacific region. METHODS: Comparison of key indicators of the epidemic in Australia, and Africa viewed largely through the experience of the Hlabisa health district, South Africa. RESULTS: To the end of 1997, for all Australia, the estimated cumulative number of HIV infections was approximately 19,000, whereas in Hlabisa 31,000 infections are estimated to have occurred. Compared with the low and declining incidence of HIV in Australia (< 1%), estimated incidence in Hlabisa rose to 10% in 1997. In all, 94% of Australian infections have been amongst men; in Hlabisa equal numbers of males and females are infected. Consequently, whereas 3000 children were perinatally exposed to HIV in Hlabisa in 1998 alone, 160 Australian children have been exposed this way. In Australia, HIV-related disease is characterised by opportunistic infection whereas in Hlabisa tuberculosis and wasting dominate. Surveys among gay men in Sydney and Melbourne indicate > 80% of HIV infected people receive antiretroviral therapy whereas in Hlabisa these drugs are not available. IMPLICATIONS: It seems possible that Asia and the Pacific will experience a similar HIV/AIDS epidemic to that in Africa. Levels of HIV are already high in parts of Asia, and social conditions in parts of the region might be considered ripe for the spread of HIV. As Australia strengthens economic and political ties within the region, so should more be done to help Pacific and Asian neighbours to prevent and respond to the HIV epidemic.

Adolescent↗
PubMed2004

Australian public health: some history lessons from South Africa.

OBJECTIVE: To draw historical parallels between inequalities in South Africa and Australia and their implications for public health, and especially Aboriginal health, in the latter. METHODS: To use the work of Terreblanche in South Africa and Houston in Australia to demonstrate the relevance of past inequalities to some of today's health problems. RESULTS: Economic structural issues remain crucial to the development of and the future health of these two countries. There are more grounds for hope for a more equal society in South Africa than there are in Australia. CONCLUSIONS: South Africa has made some attempt to face its past while Australia has not. Attempts to kill off Aboriginal culture continue. Aboriginal health will only improve when white Australia is prepared to face its 'black' past and move beyond the racism and indifference that surround Aboriginal affairs. The neo liberalism of both countries serves their disadvantaged populations ill.

Australia↗
PubMed2006

Caesarean section and subsequent fertility in sub-Saharan Africa.

OBJECTIVE: To determine the impact of caesarean section on fertility among women in sub-Saharan Africa. DESIGN: Analysis of standardised cross-sectional surveys (Demographic and Health Surveys). SETTING: Twenty-two countries in sub-Saharan Africa, 1993-2003. SAMPLE: A total of 35 398 women of childbearing age (15-49 years). METHODS: Time to subsequent pregnancy was compared by mode of delivery using Cox proportional hazards regression models. MAIN OUTCOME MEASURES: Natural fertility rates subsequent to delivery by caesarean section compared with natural fertility rates subsequent to vaginal delivery. RESULTS: The natural fertility rate subsequent to delivery by caesarean section was 17% lower than the natural fertility rate subsequent to vaginal delivery (hazard ratio = 0.83, 95% CI 0.73-0.96, P < 0.01; controlling for age, parity, level of education, urban/rural residence and young age at first intercourse). Caesarean section was also associated with prior fertility and desire for further children: among multiparous women, an interval > or =3 versus <3 years between the index birth and the previous birth was associated with higher odds of caesarean section at the index birth (OR = 1.4, 95% CI 1.1-1.7, P= 0.005); among all women, the odds of desiring further children were lower among women who had previously delivered by caesarean section (OR = 0.67, 95% CI 0.54-0.84, P < 0.001). Caesarean section did not appear to increase the risk of a subsequent pregnancy ending in miscarriage, abortion or stillbirth. CONCLUSIONS: Among women in sub-Saharan Africa, caesarean section is associated with lower subsequent natural fertility. Although this reflects findings from developed countries, the roles of pathological and psychological factors may be quite different because a much higher proportion of caesarean sections in sub-Saharan Africa are emergency procedures for maternal indication.

Adolescent↗
PubMed1999

Health risks of travelers in South Africa.

Large numbers of tourists visit South Africa every year. Travelers to urban areas are at little risk of contracting an infectious disease, however the adventure traveler is at increased risk. Yellow fever is not known to occur in South Africa. Malaria is endemic in Mpumalanga and KwaZula-Natal. Schistosomiasis is endemic in large parts of the country. Although rabies is found throughout the country, only a small number of human cases is reported. High risk areas are KwaZulu-Natal, the eastern Cape and Mpumalanga provinces. The incidence of human immunodeficiency virus (HIV) infection is high and counseling regarding sexually transmitted diseases is important. Sanitation of water is excellent in most large cities and towns; however travelers to rural areas should exercise caution. Arbovirus infections do occur but relatively few cases are reported. The hiker is at risk for tick bite fever and should be counseled. Since the abolition of apartheid, South Africa has been seen as an inexpensive, high quality destination by many tourists. In 1997, a total of 5,436,848 travelers from many different countries visited the country. Areas most frequently visited include Johannesburg, Cape Town, Durban, the Garden Route, Kruger National Park, KwaZulu-Natal and Pretoria. The most common reason for visiting the country was holiday (44%), followed by visiting friends and relatives (23%), business travel (27%) other (6%).1 Travelers, to the larger cities such as Johannesburg, Cape Town and Durban are at little risk of acquiring an infectious disease. The adventure traveler however is at greater risk as parts of the country are endemic for malaria, schistosomiasis, rabies, food and waterborne diseases, sexually transmitted diseases and arbovirus infections. Accidental deaths due to motor vehicle accidents and interpersonal violence are important health risks in South Africa. Travelers visiting popular attractions are at significantly lower risk. However this has never been quantified. This review aims to address the occurrence of infectious diseases and attempts to give guidelines to practitioners caring for travelers.

Communicable Disease Control↗
PubMedDate not supplied

Diarrhea and respiratory symptoms among travelers to Asia, Africa, and South and Central America from Scotland.

Surveillance using admissions to hospital, while being useful, is a poor indicator of the real incidence of disease encountered by travelers. An alternative is self-reported illness among those who attended at a pretravel clinic prior to their travels. Estimates of incidence and risk factors were determined for attendees at a travel clinic in Scotland using a questionnaire. Analysis for risk factors was carried out for those travelers visiting countries in Africa, Asia, or South and Central America, who had traveled for 1 week or more and had returned between 1997 and 2001 (N= 4,856). Multivariate logistic regression was used to test the hypotheses that time abroad and age-group would be significant for both respiratory and diarrheal symptoms regardless of which of the three geographical areas are visited. From 2006 returned questionnaires (response rate = 41.3%), diarrhea and respiratory symptoms were reported by 44.2 and 16.8% of respondents, respectively; the incidence was significantly greater among travelers to Asia for both diarrheal (55.5%) and respiratory (23.7%) symptoms than among travelers to Africa (36.6 and 12.2%, respectively) or South and Central America (39.5 and 16.2%, respectively). For diarrhea, age was a highly significant risk factor for travelers to Asia, South and Central America, and Africa. Being a self-organized tourist/backpacker, traveling to Asia was associated with increased risk, while for Africa and South and Central America visiting family or friends was associated with a lower risk. For travelers to Asia, traveling to the Indian subcontinent was significantly associated with increased risk. The majority of travelers had an adverse event while traveling abroad, with diarrhea and respiratory conditions being especially common despite attending a travel clinic for advice prior to departure. However, the limitations of this surveillance-based strategy have highlighted the requirement for more research to understand more fully the issues of risk and incidence among travelers to high-risk destinations from Scotland.

Adolescent↗
PubMed2001

Adolescent pregnancy and parenthood in South Africa.

South Africa's total fertility rate is estimated to be one of the lowest in sub-Saharan Africa, fewer than three births per woman nationally and declining. At the same time, adolescent childbearing levels remain high: More than 30 percent of 19-year-old girls are reported to have given birth at least once. Evidence from focus-group discussions conducted in urban and rural areas in South Africa with young black women and men, and with the parents of teenage mothers, is used to consider the experience of early parenthood, including the role of paternity, education, work opportunities, and subsequent fertility. In South Africa, in contrast to many other settings, teenage mothers may return to school once they have given birth, and this opportunity is strongly related to a long delay before the birth of a second child. Educated girls also tend to bring more bridewealth, which may encourage parents to support their daughters' schooling, and perhaps their return to school following childbirth. The support of the child, however, is often subject to paternal recognition and commitment, even though boys are unwilling to admit paternity because it jeopardizes their educational and employment opportunities.

Adaptation, Psychological↗
PubMed1999

Establishing networks for health promoting schools in South Africa.

South African schools were segregated by years of discriminatory practice. Apartheid policies adversely affected the health and social status of children in South Africa. The conceptual framework suggested by the health promoting schools movement was adopted in South Africa to address school health comprehensively. This approach provides a useful framework because it focuses not on the curriculum but on the school environment, community involvement, policy development, and appropriate health and social services. Currently, several initiatives in South Africa focus on developing networks of health promoting schools. Initiatives seen as a mechanism to address the historical inequities among children in South Africa are described.

Child↗
PubMed2006

The mtDNA legacy of the Levantine early Upper Palaeolithic in Africa.

Sequencing of 81 entire human mitochondrial DNAs (mtDNAs) belonging to haplogroups M1 and U6 reveals that these predominantly North African clades arose in southwestern Asia and moved together to Africa about 40,000 to 45,000 years ago. Their arrival temporally overlaps with the event(s) that led to the peopling of Europe by modern humans and was most likely the result of the same change in climate conditions that allowed humans to enter the Levant, opening the way to the colonization of both Europe and North Africa. Thus, the early Upper Palaeolithic population(s) carrying M1 and U6 did not return to Africa along the southern coastal route of the "out of Africa" exit, but from the Mediterranean area; and the North African Dabban and European Aurignacian industries derived from a common Levantine source.

Africa↗
PubMed1998

beta-Lactamases responsible for resistance to expanded-spectrum cephalosporins in Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis isolates recovered in South Africa.

Although resistance to the expanded-spectrum cephalosporins among members of the family Enterobacteriaceae lacking inducible beta-lactamases occurs virtually worldwide, little is known about this problem among isolates recovered in South Africa. Isolates of Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis resistant to expanded-spectrum cephalosporins recovered from patients in various parts of South Africa over a 3-month period were investigated for extended-spectrum beta-lactamase production. Antibiotic susceptibility was determined by standard disk diffusion and agar dilution procedures. Production of extended-spectrum beta-lactamases was evaluated by using the double-disk test, and the beta-lactamases were characterized by spectrophotometric hydrolysis assays and an isoelectric focusing overlay technique which simultaneously determined isoelectric points and general substrate or inhibitor characteristics. DNA amplification and sequencing were performed to confirm the identities of these enzymes. The P. mirabilis and E. coli isolates were found to produce TEM-26-type, SHV-2, and SHV-5 extended-spectrum beta-lactamases. An AmpC-related enzyme which had a pI of 8.0 and which conferred resistance to cefoxitin as well as the expanded-spectrum cephalosporins was found in a strain of K. pneumoniae. This is the first study which has identified organisms producing different extended-spectrum beta-lactamases from South Africa and the first report describing strains of P. mirabilis producing a TEM-26-type enzyme. The variety of extended-spectrum beta-lactamases found among members of the family Enterobacteriaceae isolated from major medical centers in South Africa is troubling and adds to the growing list of countries where these enzymes pose a serious problem for antimicrobial therapy.

Cephalosporin Resistance↗
PubMed2004

Infections with nontyphoidal Salmonella species producing TEM-63 or a novel TEM enzyme, TEM-131, in South Africa.

Salmonella spp. producing extended-spectrum beta-lactamases (ESBLs) have been reported in many countries, but there is no information on their prevalence in Africa. ESBL-producing Salmonella enterica serotype Isangi and S. enterica serotype Typhimurium strains have been noted in South Africa since 2001. A total of 160 consecutive isolates of Salmonella spp. were collected from 13 hospitals located in different cities in South Africa over a 5-month period from December 2002 to April 2003. All strains were screened for production of ESBLs by the double disk diffusion test and for AmpC production by assessing resistance to cefoxitin. bla(SHV), bla(TEM), bla(CTX-M), and bla(CMY-2) were sought from all ESBL-positive and cefoxitin-resistant isolates. A total of 15.6% (25 of 160) isolates produced SHV or TEM ESBLs, and 1.9% (3 of 160) produced CMY-2. Nine S. enterica serotype Typhimurium, eight S. enterica serotype Isangi, and three S. enterica serotype Muenchen strains produced either TEM-63 or a derivative of TEM-63 designated TEM-131. Both TEM-63 and TEM-131 have an isoelectric point of 5.6, and their sequences have the following amino acid substitutions compared to the TEM-1 sequence: Leu21Phe, Glu104Lys, Arg164Ser, and Met182Thr. Additionally, TEM-131 has an Ala237Thr substitution. ESBL-producing Salmonella spp. have become a significant public health problem in South Africa with particular implications for the treatment of serious nontyphoidal Salmonella infections in children, for whom extended-spectrum cephalosporins were the preferred treatment.

Anti-Bacterial Agents↗
PubMed1969

Oesophageal cancer and alcoholic spirits in central Africa.

A geographical pathology survey of a large area in central Africa is described and a contrast is recognized between neighbouring areas with apparently many and apparently few cases of oesophageal cancer. This distribution is compared first with other known areas of high and low incidence in sub-Saharan Africa and then with the drinking of indigenous types of distilled spirits. A significant order of spatial correlation is shown between the geographical pattern of the disease and the drinking of sugar-based alcoholic spirit in central Africa. Samples of spirits from eastern Zambia, central Kenya, and the Transkei, although prepared in apparently dissimilar utensils, were all shown to be contaminated in varying degree with zinc. Nitrosamine-like compounds in native spirits were also reported in all these areas. The need for a geographical survey of indigenous drinking habits in Africa is illustrated. Since legislation against distilling is ineffective, a simple means of excluding carcinogenic compounds from illicit spirits should be ascertained and widely promulgated at village level.

Africa, Central↗
PubMed1987

Pregnancy loss, infant death, and suffering: legacy of syphilis and gonorrhoea in Africa.

Africa in the 1980s appears to be facing problems associated with syphilis and gonorrhoea during pregnancy similar in severity and magnitude to those faced by the western world in the early 1900s. From a review of published reports, the prevalence of syphilis seroreactivity in pregnant women in many parts of Africa is at least 10%. Assuming this level of seroreactivity, we estimate that 5% to 8% of all pregnancies surviving past 12 weeks will have an adverse outcome caused by syphilis, such as spontaneous abortion, perinatal or infant death, or a living infant with syphilis. Our findings on gonorrhoea during pregnancy are almost as startling. The prevalence of gonorrhoea in pregnant women in many parts of Africa is at least 10% and it approaches 20% in some areas. The incidence of gonococcal ophthalmia neonatorum in neonates appears to be between 2% and 4%. We recommend commitment of health resources to initiatives to prevent and control sexually transmitted disease in Africa and additional research into the cost effectiveness of different prevention and control approaches.

Abortion, Spontaneous↗
PubMed2003

Development of oral health in Africa.

Around 80% of African communities can be considered to be materially deprived. The presence of widespread poverty and underdevelopment in Africa means that communities are increasingly exposed to all of the major environmental determinants of oral disease. Previous approaches to oral health in Africa have failed to recognize the epidemiological priorities of the region or identify reliable and appropriate strategies to address them. Efforts have consisted of providing unplanned, ad hoc and spasmodic curative oral health services, which in most cases are poorly distributed and only reach affluent or urban communities. Realizing the limited impact of existing strategies, the World Health Organization Regional Office for Africa (WHO/AFRO) developed a regional oral health strategy to assist African countries and their partners in identifying priorities and planning preventive-oriented programmes, particularly at the district level. The long-term objective is to provide equitable and universal access to cost-effective quality oral healthcare and thereby significantly reduce the incidence of oral diseases in Africa.

Africa↗
PubMed2005

Rheumatic and nonrheumatic valvular heart disease: epidemiology, management, and prevention in Africa.

BACKGROUND: Unlike the Western world, valvular disease ranks among the major cardiovascular afflictions in Africa. Acute rheumatic fever and chronic rheumatic valvular disease in their most virulent form are still commonly encountered and impose a huge burden on limited healthcare resources. METHODS AND RESULTS: We performed a systematic review of the literature with PubMed using rheumatic fever, rheumatic heart disease, valvular disease, warfarin anticoagulation, and pregnancy as search items. Literature emanating from Africa was emphasized. Epidemiology, current concepts on pathogenesis, and aspects of the medical and surgical management of this disease as seen from an African perspective are presented. The association of pregnancy with mitral stenosis is common and may be fatal if not managed appropriately. A practical approach to these patients is presented to optimize maternal and fetal outcome. Pregnant patients with mechanical valves require careful attention to ensure maternal survival and prevent fetal warfarin embryopathy. Prolonged subcutaneous heparin and frequent monitoring of the partial thromboplastin time are impractical in this setting, and the merits of different anticoagulation regimens are discussed. Congenital submitral aneurysms are a unique cause of mitral regurgitation, with the vast majority of cases originating from sub-Saharan Africa. Although the precise etiology is as yet unclear, the clinical and echocardiographic features are sufficiently characteristic to allow a preoperative diagnosis to be made. Transesophageal echocardiography allows much better definition of the size and anatomic relationships of the aneurysm. Surgical resection can be difficult but is usually curative. Mitral valve prolapse and endocarditis constitute the remaining frequent causes of valvular disease and are discussed briefly. CONCLUSIONS: The spectrum and presentation of valvular disease in Africa are uniquely different from elsewhere. Together with socioeconomic issues and the HIV pandemic, this fact makes it imperative that further epidemiological and clinical studies be undertaken and guidelines developed that are appropriate to the practice of medicine on the African continent.

Africa↗