Eliminating onchocerciasis as a public health problem: the beginning of the end.
(65/1101)
Onchocerciasis is one of the diseases targeted by Vision 2020. It is the world's second leading infectious cause of blindness, responsible for at least one million blind or severely visually disabled people. The Onchocerciasis Control Programme (OCP) in sub-Saharan Africa will be closed down in 2002, after 27 years of operation. This is the clearest indication that the prospects of eliminating onchocerciasis as a public health problem may be achieved by the end of this decade. The programme's potential now is to serve as a model of global and multiple partnership, to address other poverty related, serious and intractable problems such as needless blindness in the world. (+info)
HIV testing and high risk sexual behaviour among London's migrant African communities: a participatory research study.
(66/1101)
OBJECTIVES: To describe the demographic and behavioural factors associated with HIV testing among migrant Africans in London. METHODS: A cross sectional survey of migrants from five sub-Saharan African communities (Congo, Kenya, Uganda, Zambia, Zimbabwe) resident in London was carried out. The study formed part of a larger community based participatory research initiative with migrant African communities in London-the MAYISHA project. Trained, ethnically matched interviewers recruited study participants in a variety of community venues. A brief self completion questionnaire collected data on demographic characteristics, utilisation of sexual health services, HIV testing history, sexual behaviour, and attitudes. RESULTS: Valid questionnaires were obtained from 748 participants (396 men and 352 women), median ages 31 and 27 years, respectively. Median length of UK residence was 6 years. 34% of men and 30% of women reported ever having had an HIV test. HIV testing was significantly associated with age and previous STI diagnosis among women; and additionally, nationality, education, employment, and self perceived risk of acquiring HIV among men. After controlling for significant demographic variables, previous diagnosis of an STI (adjusted odds ratio and 95% confidence interval for men: 2.96, 1.63 to 5.38, and women 2.03, 1.06 to 3.88) and perceived risk of acquiring HIV for men (adjusted OR 2.28, 95%CI 1.34 to 3.90) remained independently associated. CONCLUSION: Among these high HIV prevalence migrant communities, these data suggest that HIV testing remains largely associated with an individual's STI history or self perceived risk. This strategy may be inappropriate given the potential for onward and vertical transmission. Antenatal HIV testing combined with proactive targeted HIV testing promotion should be prioritised. (+info)
Geographic range size and determinants of avian species richness.
(67/1101)
Geographic patterns in species richness are mainly based on wide-ranging species because their larger number of distribution records has a disproportionate contribution to the species richness counts. Here we demonstrate how this effect strongly influences our understanding of what determines species richness. Using both conventional and spatial regression models, we show that for sub-Saharan African birds, the apparent role of productivity diminishes with decreasing range size, whereas the significance of topographic heterogeneity increases. The relative importance of geometric constraints from the continental edge is moderate. Our findings highlight the failure of traditional species richness models to account for narrow-ranging species that frequently are also threatened. (+info)
Evidence for balancing selection from nucleotide sequence analyses of human G6PD.
(68/1101)
Glucose-6-phosphate dehydrogenase (G6PD) mutations that result in reduced enzyme activity have been implicated in malarial resistance and constitute one of the best examples of selection in the human genome. In the present study, we characterize the nucleotide diversity across a 5.2-kb region of G6PD in a sample of 160 Africans and 56 non-Africans, to determine how selection has shaped patterns of DNA variation at this gene. Our global sample of enzymatically normal B alleles and A, A-, and Med alleles with reduced enzyme activities reveals many previously uncharacterized silent-site polymorphisms. In comparison with the absence of amino acid divergence between human and chimpanzee G6PD sequences, we find that the number of G6PD amino acid polymorphisms in human populations is significantly high. Unlike many other G6PD-activity alleles with reduced activity, we find that the age of the A variant, which is common in Africa, may not be consistent with the recent emergence of severe malaria and therefore may have originally had a historically different adaptive function. Overall, our observations strongly support previous genotype-phenotype association studies that proposed that balancing selection maintains G6PD deficiencies within human populations. The present study demonstrates that nucleotide sequence analyses can reveal signatures of both historical and recent selection in the genome and may elucidate the impact that infectious disease has had during human evolution. (+info)
East Asian genotypes of Helicobacter pylori strains in Amerindians provide evidence for its ancient human carriage.
(69/1101)
Phylogenies of indigenous microbes have been used as surrogates for the origins of the hosts that carry them. Conversely, polymorphisms may be used to date the spread of a microbial species when information about their host populations is available. Therefore, we examined polymorphisms in Helicobacter pylori, which persistently colonize the human stomach, to test the hypothesis that they have been ancient inhabitants of humans. Three H. pylori loci that previously have been shown to have phylogeographic affinity have been analyzed for two populations with different ethnic origins from Venezuela. In a group of Amerindian subjects from Amazonia, East Asian H. pylori genotypes were present for each of the loci examined but were absent in a mestizo population from Caracas. These findings provide evidence that H. pylori has been present in humans at least since ancestors of Amerindians migrated from Asia more than 11,000 years ago. (+info)
Feeding the world in the coming decades requires improvements in investment, technology and institutions.
(70/1101)
The world is food secure at the global level, yet nearly 800 million are food insecure. "Business as usual" is not going to bring us close to meeting the Millennium Development Goal of halving the proportion of the population consuming less than the minimum energy requirement. So what has to change? The three papers in this session offer clues in three broad areas: (a) increased investment-by developing and developed countries-in public goods such as agricultural research, education, and clean water, (b) technologies to boost agricultural productivity for the poor and institutions that guide the diffusion and application of technology that need to be developed and (c) national-level institutions and governance structures to be strengthened and held accountable for protecting and respecting human rights, for providing the right types of national-level public goods to those that most need them and for preserving peace and stability. (+info)
Self-treatment for malaria: the evidence and methodological issues.
(71/1101)
Malaria remains an important cause of death, especially in sub-Saharan Africa. Self-treatment with antimalarial drugs is a common practice that raises important issues for policy-makers. A number of important questions concerning factors related to self-treatment, adequacy of self-treatment and the role of self-treatment in malaria mortality remain unanswered. Although there are some common patterns, there is considerable diversity in treatment practices, even within a single country. Social science research on malaria treatment needs to move beyond description to evaluation of interventions. This will require a greater degree of methodological rigour and more attention to the generation of data that can be compared across time periods and studies. Definitions of malaria cases and the role of local disease categories in identifying cases need to be made more explicit. Illnesses should be classified by severity, using measures of perceived severity as well as biomedical signs of severity. Each treatment step should be considered in terms of four levels of analysis: who provided the treatment or advice, what the treatment was, where it was obtained and when it was taken in relationship to onset of illness. (+info)
Surgical services for children in developing countries.
(72/1101)
There is growing evidence that childhood surgical conditions, especially injuries, are common in developing countries and that poor care results in significant numbers of deaths and cases of disability. Unfortunately, however, surgical care is not considered an essential component of most child health programmes. Strategies for improving paediatric surgical care should be evidence-based and cost-effective and should aim to benefit the largest possible number of children. The most likely way of achieving policy change is to demonstrate that childhood surgical conditions are a significant public health problem. For paediatric purposes, special attention should also be given to defining a cost-effective package of surgical services, improving surgical care at the community level, and strengthening surgical education. Surgical care should be an essential component of child health programmes in developing countries. (+info)