Replicated evolution of trophic specializations in an endemic cichlid fish lineage from Lake Tanganyika.
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The current phylogenetic hypothesis for the endemic Lake Tanganyika cichlid fishes of the tribe Eretmodini is based solely on morphology and suggests that more complex trophic morphologies derived only once from a less specialized ancestral condition. A molecular phylogeny of eretmodine cichlids based on partial mitochondrial DNA cytochrome b and control-region sequences was used to reconstruct the evolutionary sequence of trophic adaptations and to test alternative models of morphological divergence. The six mitochondrial lineages found disagree with the current taxonomy and the morphology-based phylogeny. Mitochondrial lineages with similar trophic morphologies are not grouped monophyletically but are typically more closely related to lineages with different trophic phenotypes currently assigned to other genera. Our results indicate multiple independent origins of similar trophic specializations in these cichlids. A pattern of repeated divergent morphological evolution becomes apparent when the phylogeography of the mitochondrial haplotypes is analyzed in the context of the geological and paleoclimatological history of Lake Tanganyika. In more than one instance within Lake Tanganyika, similar morphological divergence of dentitional traits occurred in sympatric species pairs. Possibly, resource-based divergent selective regimes led to resource partitioning and brought about similar trophic morphologies independently and repeatedly. (+info)
Dry supplementary feeding programmes: an effective short-term strategy in food crisis situations.
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Malnutrition is frequently a predominant problem in disasters, and supplementary feeding programmes (SFPs) are often set up in food emergencies. This review analyses the effectiveness of such programmes in crisis situations in Liberia, Burundi and Goma (Congo), concluding that it is feasible to enrol large numbers of children in SFPs and achieve proportions of recovery above 75% if these programmes are implemented as a short-term measure in emergency situations. However, satisfactory SFP results do not necessarily indicate improved nutritional status of the whole population. (+info)
A comparative analysis of the cost-effectiveness of treatment based on parasitological and symptomatic screening for Schistosoma mansoni in Burundi.
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OBJECTIVES: To assess the cost-effectiveness of three alternative screening strategies in delivering treatment to patients presenting with symptoms suggestive of S. mansoni, using data collected from 17 PHCCs in the Rusizi Plain, Burundi. The three strategies were: (1) screening all symptomatic patients using a Kato-Katz smear and treating only the ones found positive; (2) treating all symptomatic patients or (3) treating only those presenting with symptoms of severe diarrhoea (blood in stool). METHODS: The database consisted of 41 051 visits of symptomatic patients to the 17 PHCCs during 1990. Effectiveness was measured as the number of infected patients treated (gold standard: 25-mg Kato-Katz smear). Cost-effectiveness ratios (CERs) (cost in US$ per infected patient treated) were used to compare the control strategies. Sensitivity analysis was performed to assess the effect of drug price and prevalence of infection on the CERs. RESULTS: The overall prevalence of S. mansoni infection was 9.5% (95% CI = 9.1%, 9.9%). Treating only those with severe symptoms of infection would have left 92% of infected patients untreated. Performing a Kato-Katz smear to confirm the diagnosis was more cost-effective than treating all symptomatic patients on a presumptive basis, with CERs of 4.2 US$ and 12.43 US$ per infected person treated, respectively. Sensitivity analysis showed that, for a cost of 0.99 US$ per dose of praziquantel, the Kato-Katz option remained the most cost-effective approach for prevalences under 76%. For a drug price of 0.21 US$ per dose, both strategies would have become equivalent. The latter value varied extensively per PHCC (range 0.17 US$ to 0.51 US$), due to the different prevalences of infection (range 0.5% to 34.3%). CONCLUSION: We found that using severe diarrhoea as an indicator for infection was not appropriate, and that screening symptomatic patients with the Kato-Katz method remained the most cost-effective approach in the given setting. The CER of treating all symptomatic patients on a presumptive basis depended very much on the drug price and the endemic level. (+info)
Specificity of circulating antigen detection for schistosomiasis mansoni in Senegal and Burundi.
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The specificity of schistosome circulating antigen detection was determined in negative individuals from two S. mansoni- endemic countries, Senegal and Burundi, and compared with results from Dutch control individuals. A nearly absolute specificity was achieved for circulating anodic antigen (CAA) detection in serum, irrespective of the target population or sample pretreatment method. Circulating cathodic antigen (CCA) detection in serum and urine resulted in a lower specificity than serum CAA detection. Apparent large differences in specificity of CCA detection between countries were mainly due to pretreatment methods. Apparently, the alkaline/heating pretreatment method is not as effective as trichloroacetic acid (TCA)-pretreatment in removing (certain) interfering components, which may vary between populations. In view of the development of the urine CCA assay into a noninvasive screening test, a slightly lower specificity may still be acceptable. For precise epidemiological analyses the highly specific serum CAA assay remains the method of choice. (+info)
Untruths and consequences: the false hypothesis linking CHAT type 1 polio vaccination to the origin of human immunodeficiency virus.
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A book published in 1999 hypothesized that the scientists who worked with the CHAT type 1 attenuated polio strain tested in the former Belgian Congo in the late 1950s had covertly prepared the vaccine in chimpanzee kidney cells contaminated with a simian immunodeficiency virus, which evolved into HIV-1 group M. This paper summarizes the results of the investigation conducted by the author to determine the legitimacy of the accusation. Testimony by eyewitnesses, documents of the time, epidemiological analysis, and ancillary phylogenetic, virologic and PCR data all concur to reject the hypothesis as false and without factual foundation. (+info)
Postscript relating to new allegations made by Edward Hooper at The Royal Society Discussion Meeting on 11 September 2000.
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At The Royal Society Discussion Meeting, Origins of HIV and the AIDS epidemic, which this issue records, Edward Hooper added two new 'smoking guns' to the accusations published previously in The river. These were proposed as conclusive evidence for the hypothesis that simian immunodeficiency virus-contaminated CHAT polio vaccine caused the HIV-1 group M epidemic. We have investigated the facts in relation to these 'smoking guns'. (+info)
The earliest cases of human immunodeficiency virus type 1 group M in Congo-Kinshasa, Rwanda and Burundi and the origin of acquired immune deficiency syndrome.
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The early cases of acquired immune deficiency syndrome and human immunodeficiency virus type 1 (HIV-1) infection in the 1960s and 1970s in Congo-Kinshasa (Zaire), Rwanda and Burundi are reviewed. These countries appear to be the source of the HIV-1 group M epidemic, which then spread outwards to neighbouring Tanzania and Uganda in the east, and Congo-Brazzaville in the west. Further spread to Haiti and onwards to the USA can be explained by the hundreds of single men from Haiti who participated in the UNESCO educational programme in the Congo between 1960 and 1975. (+info)
An outbreak of measles in Tanzanian refugee camps.
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From March 2000 to May 2001, four camps in Kibondo District, Tanzania, hosting refugees from Burundi reported 1062 cases of measles, a highly infectious and potentially lethal disease. Of 1062 case-patients, 225 (21%) were <9 months old, 286 (27%) were 9 months to 5 years, 324 (31%) were 6-15 years, and 227 (21%) were >/=16 years old. No deaths were reported. Although, in accordance with Sphere Project guidelines for humanitarian emergencies, camp policy was to vaccinate all new arrivals aged 6 months to 15 years against measles, 152 (72%) of 210 newly arrived refugees in this age group were unvaccinated; 143 (94%) of the 152 had lived in the camp >/=1 month before rash onset. This investigation supports Sphere Project recommendations for wide age group vaccination and suggests that in some circumstances vaccination of refugees >15 years old may be beneficial. (+info)