Human immunodeficiency virus type 1 nef quasispecies in pathological tissue.
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The role of the nef gene in human immunodeficiency virus type 1 (HIV-1) infection is poorly understood. To provide a basis for studies on the role of nef in AIDS, we used targeted polymerase chain reaction amplification and DNA sequencing to determine the structure of nef genes in pathologic tissue from HIV-1-infected children and adults. We find that the nef reading frame is open in 92% of clones derived from both brain and lymphocytic tissue of children, suggesting that nef is expressed in these tissues. One HIV-1 clone, BRVA, obtained by coculture from the brain of an adult AIDS patient with progressive dementia, was previously shown to contain a duplicated region in nef. We show here that similar duplications are widespread in both adults and children with AIDS. However, coculture strongly selects against the broad spectrum of nef quasispecies found in tissue. These findings suggest functional selection for nef quasispecies in pathologic tissues during HIV-1 infection of the human host. (+info)
The effectiveness of active population screening and treatment for sleeping sickness control in the Democratic Republic of Congo.
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BACKGROUND: The human African trypanosomiasis (HAT) control programme of the Democratic Republic of Congo (DRC) uses mass screening with the card agglutination test for trypanosomes (CATT). We looked at the contribution of CATT and improved parasitological confirmation to the effectiveness of screening and treatment. METHOD: The effectiveness of the screening and treatment process is measured by the percentage of HAT cases that is effectively cured after a single round of screening. The process is analysed in five steps: (i) the attendance at the screening, (ii) the sensitivity of the screening procedure, (iii) the sensitivity of the parasitological confirmation, (iv) the proportion of the confirmed cases that effectively receive treatment and (v) the cure rate of the treatment. We used a simplified model that multiplies proportions of infected persons that go through each step. We estimated these parameters using a combination of routine data collected by the national control programme over the period January 1997 to December 1998 and published data. For varying attendance rates we compared the effectiveness of screening strategies based on CATT or on CATT combined with improved parasitological confirmation by mini anion exchange column technique (mAECT) with the previously used strategy based on palpation of neck glands and microscopy alone. RESULTS: The model shows that overall effectiveness of the active case detection and treatment strategy is <50% under most scenarios. Attendance rates averaged 74% but showed considerable regional variability and are a major problem in some areas of DRC. The CATT and replacing traditional parasitology by mAECT increases the sensitivity of the screening but a substantial part of the gains are lost at other stages of the screening process. CONCLUSION: Improvements of the HAT screening process such as introduction of CATT or mAECT only make sense if other parameters and attendance rate in particular are optimized at the same time. (+info)
Human African trypanosomiasis amongst urban residents in Kinshasa: a case-control study.
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BACKGROUND: Increasing numbers of human African trypanosomiasis (HAT) cases have been reported in urban residents of Kinshasa, Democratic Republic Congo since 1996. We set up a case-control study to identify risk factors for the disease. METHODS: All residents of the urban part of Kinshasa with parasitologically confirmed HAT and presenting for treatment to the city's specialized HAT clinics between 1 August, 2002 and 28 February, 2003 were included as cases. We defined the urban part as the area with contiguous habitation and a population density >5000 inhabitants per square kilometre. A digital map of the area was drawn based on a satellite image. For each case, two serologically negative controls were selected, matched on age, sex and neighbourhood. Logistic regression models were fitted to control for confounding. RESULTS: The following risk factors were independently associated with HAT: travel, commerce and cultivating fields in Bandundu, and commerce and cultivating fields in the rural part of Kinshasa. No association with activities in the city itself was found. DISCUSSION: In 2002, the emergence of HAT in urban residents of Kinshasa appears mainly linked to disease transmission in Bandundu and rural Kinshasa. We recommend to intensify control of these foci, to target HAT screening in urban residents to people with contact with these foci, to increase awareness of HAT amongst health workers in the urban health structures and to strengthen disease surveillance. (+info)
Recombinant viruses and early global HIV-1 epidemic.
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Central Africa was the epicenter of the HIV type 1 (HIV-1) pandemic. Understanding the early epidemic in the Democratic Republic of the Congo, formerly Zaire, could provide insight into how HIV evolved and assist vaccine design and intervention efforts. Using enzyme immunosorbent assays, we tested 3,988 serum samples collected in Kinshasa in the mid-1980s and confirmed seroreactivity by Western blot. Polymerase chain reaction of gag p17, env C2V3C3, and/or gp41; DNA sequencing; and genetic analyses were performed. Gene regions representing all the HIV-1 group M clades and unclassifiable sequences were found. From two or three short gene regions, 37% of the strains represented recombinant viruses, multiple infections, or both, which suggests that if whole genome sequences were available, most of these strains would have mosaic genomes. We propose that the HIV epidemic was well established in central Africa by the early 1980s and that some recombinant viruses most likely seeded the early global epidemic. (+info)
Malaria in primary school children and infants in kinshasa, democratic republic of the congo: surveys from the 1980s and 2000.
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Kinshasa, the capital of the Democratic Republic of the Congo, has been a perennial malarious area and has grown almost 14 times from 380,000 people in 1960 to 5,293,000 in 2003. The most complete information on malaria prevalence in Kinshasa was first acquired in 1981-1983. Blood smears were obtained from 25,135 children (ages 5-15 years) from 245 schools in 16 of 24 zones. The mean Plasmodium falciparum parasite rate was 17%; the parasite rate was similar for both sexes and was higher (P < 0.001) in older students. The parasite rate varied from 4% (urban zone) to 46% (peri-urban zone). An infant survey confirmed malaria transmission. During the Roll Back Malaria situational analysis in 2000, malaria prevalence was reassessed by the National Malaria Control Program and its partners in schools from selected health zones. A mean parasite rate of 34% was found among school children 5-9 years old. The parasite rate varied from 14% (central urban zone) to 65% (peri urban zone). Plasmodium falciparum was not the only species found, but accounted for more than 97% of the infections. Malaria incidence may have increased in Kinshasa during the last two decades due to difficulties in provision of control and prevention measures. Along with deployment of insecticide-treated bed nets and improved patient management, currently ongoing, other measures that could impact the disease are being considered, including vector control, water management, and proper urban planning. (+info)
Do wildlife laws work? Species protection and the application of a prey choice model to poaching decisions.
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Legislation for the protection of species is a global conservation tool. However, in many developing countries lack of resources means that effectiveness relies on voluntary compliance, leading to contradictory assumptions. On one hand, laws introduced without effective enforcement mechanisms carry an implicit assumption that voluntary compliance will occur. On the other hand, it is often openly assumed that, without enforcement, there will in fact be no compliance. Which assumption holds has rarely been rigorously tested. Here we show that laws for the protection of some species of large mammal have no effect on the prey choice patterns of primarily commercial hunters in the Democratic Republic of Congo, confirming the second assumption. We established this result by using an optimal diet model to predict the pattern of prey choice in the absence of regulation. Prey choice patterns predicted by the model were accurate across a range of conditions defined by time, space and type of hunting weapon. Given that hunters will not comply voluntarily, the protection of vulnerable species can only take place through effective enforcement, for example by wildlife authorities restricting access to protected areas, or by traditional authorities restricting the sale of protected species in local markets. (+info)
Pediatric human immunodeficiency virus screening in an African district hospital.
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In order to evaluate alternative tests and strategies to simplify pediatric human immunodeficiency virus (HIV) screening at the district hospital level, a cross-sectional exploratory study was organized in the Democratic Republic of the Congo. Venous and capillary phlebotomies were performed on 941 Congolese children, aged 1 month to 12 years (153 children under 18 months and 788 children more than 18 months old). The HIV prevalence rate was 4.7%. An algorithm for children more than 18 months old, using serial rapid tests (Determine, InstantScreen, and Uni-Gold) performed on capillary blood stored in EDTA tubes, had a sensitivity of 100.0% (95% confidence interval [CI], 88.9 to 100.0%) and a specificity of 100.0% (95% CI, 99.5 to 100.0%). The results of this study suggest that the ultrasensitive p24 antigen assay may be performed on capillary plasma stored on filter paper (sensitivity and specificity, 100.0%; n=87) instead of venous plasma (sensitivity, 92.3%; specificity, 100.0%; n=150). The use of glucolets (instruments used to perform capillary phlebotomies), instead of syringes and needles, may reduce procedural pain and the risk of needle stick injuries at a comparable cost. Compared to the reference, HIV could have been correctly excluded based on one rapid test for at least 90% of these children. The results of this study point towards underutilized opportunities to simplify phlebotomy and pediatric HIV screening. (+info)
Wild animal mortality monitoring and human Ebola outbreaks, Gabon and Republic of Congo, 2001-2003.
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All human Ebola virus outbreaks during 2001-2003 in the forest zone between Gabon and Republic of Congo resulted from handling infected wild animal carcasses. After the first outbreak, we created an Animal Mortality Monitoring Network in collaboration with the Gabonese and Congolese Ministries of Forestry and Environment and wildlife organizations (Wildlife Conservation Society and Programme de Conservation et Utilisation Rationnelle des Ecosystemes Forestiers en Afrique Centrale) to predict and possibly prevent human Ebola outbreaks. Since August 2001, 98 wild animal carcasses have been recovered by the network, including 65 great apes. Analysis of 21 carcasses found that 10 gorillas, 3 chimpanzees, and 1 duiker tested positive for Ebola virus. Wild animal outbreaks began before each of the 5 human Ebola outbreaks. Twice we alerted the health authorities to an imminent risk for human outbreaks, weeks before they occurred. (+info)