Comparison of in vivo and in vitro tests of resistance in patients treated with chloroquine in Yaounde, Cameroon.
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The usefulness of an isotopic in vitro assay in the field was evaluated by comparing its results with the therapeutic response determined by the simplified WHO in vivo test in symptomatic Cameroonian patients treated with chloroquine. Of the 117 enrolled patients, 102 (87%) completed the 14-day follow-up, and 95 isolates obtained from these patients (46 children, 49 adults) yielded an interpretable in vitro test. A total of 57 of 95 patients (60%; 28 children and 29 adults) had an adequate clinical response with negative smears (n = 46) or with an asymptomatic parasitaemia (n = 11) on day 7 and/or day 14. The geometric mean 50% inhibitory concentration of the isolates obtained from these patients was 63.3 nmol/l. Late and early treatment failure was observed in 29 (30.5%) and 9 (9.5%) patients, respectively. The geometric mean 50% inhibitory concentrations of the corresponding isolates were 173 nmol/l and 302 nmol/l. Among the patients responding with late and early treatment failure, five isolates and one isolate, respectively, yielded a discordant result (in vivo resistance and in vitro sensitivity). The sensitivity, specificity, and predictive value of the in vitro test to detect chloroquine-sensitive cases was 67%, 84% and 86%, respectively. There was moderate concordance between the in vitro and in vivo tests (kappa value = 0.48). The in vitro assay agrees relatively well with the therapeutic response and excludes several host factors that influence the results of the in vivo test. However, in view of some discordant results, the in vitro test cannot substitute for in vivo data on therapeutic efficacy. The only reliable definition of "resistance" in malaria parasites is based on clinical and parasitological response in symptomatic patients, and the in vivo test provides the standard method to determine drug sensitivity or resistance as well as to guide national drug policies. (+info)
Standardized comparison of glucose intolerance in west African-origin populations of rural and urban Cameroon, Jamaica, and Caribbean migrants to Britain.
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OBJECTIVE: To compare the prevalence of glucose intolerance in genetically similar African-origin populations within Cameroon and from Jamaica and Britain. RESEARCH DESIGN AND METHODS: Subjects studied were from rural and urban Cameroon or from Jamaica, or were Caribbean migrants, mainly Jamaican, living in Manchester, England. Sampling bases included a local census of adults aged 25-74 years in Cameroon, districts statistically representative in Jamaica, and population registers in Manchester. African-Caribbean ethnicity required three grandparents of this ethnicity. Diabetes was defined by the World Health Organization (WHO) 1985 criteria using a 75-g oral glucose tolerance test (2-h > or = 11.1 mmol/l or hypoglycemic treatment) and by the new American Diabetes Association criteria (fasting glucose > or = 7.0 mmol/l or hypoglycemic treatment). RESULTS: For men, mean BMIs were greatest in urban Cameroon and Manchester (25-27 kg/m2); in women, these were similarly high in urban Cameroon and Jamaica and highest in Manchester (27-28 kg/m2). The age-standardized diabetes prevalence using WHO criteria was 0.8% in rural Cameroon, 2.0% in urban Cameroon, 8.5% in Jamaica, and 14.6% in Manchester, with no difference between sexes (men: 1.1%, 1.0%, 6.5%, 15.3%, women: 0.5%, 2.8%, 10.6%, 14.0%), all tests for trend P < 0.001. Impaired glucose tolerance was more frequent in Jamaica. CONCLUSIONS: The transition in glucose intolerance from Cameroon to Jamaica and Britain suggests that environment determines diabetes prevalence in these populations of similar genetic origin. (+info)
Measuring time utilization in rural health centres.
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OBJECTIVES: During the recent re-design of the primary health care system in Cameroon a time-motion study was undertaken to determine how health workers at rural health centres use their time before redefining their roles. METHODS: The study developed a simple, effective and inexpensive tool which uses the activity sampling technique, and was applied to 20 health centres with a total of 19,080 observations being made of 64 health workers who represented all grades of worker in the government health services. RESULTS: The study developed a clear picture of how health centre staff apportion their time, and how the division of labour and tasks is carried out in a rural health centre. It found that only 27% of health workers' time is currently being spent on productive, health-related activities, and of this time, the largest proportion is spent on curative, clinical work. Less than 1% of health workers' time is spent on preventive and outreach activities. DISCUSSION: This study has developed a simple and inexpensive tool which can be used in any health facility to determine how health-related activities are carried out. This is an important step if changes in the delivery structure are to be made, because it establishes the discrepancy between expected and actual behaviour, and provides an important baseline for the evaluation of the effectiveness of any changes that are introduced within the system. (+info)
Dracunculiasis in Cameroon at the threshold of elimination.
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BACKGROUND: Dracunculiasis is endemic in Mayo Sava Division in the Far North Province of Cameroon. Transmission occurs during the rainy season with a peak in the months of July and August. METHODS: A combination of interventions consisting of active surveillance, social mobilization, health education, distribution of filters, construction of new water sources, chemical treatment of unsafe water sources with temephos, and case containment were applied in Mayo Sava in 1990-1995 by the national Guinea Worm Elimination Programme (GWEP). Dracunculiasis cases were detected by village health workers, confirmed by health outreach teams and reported weekly to the GWEP. RESULTS: A decline in the incidence of dracunculiasis by 98.1% from 778 cases in 1990 to 15 in 1995, and in the number of endemic villages by 92.7% from 82 in 1990 to 6 in 1995 was achieved. The proportion of cases identified < or =24 hours of worm emergence increased from 19% in 1991 to 73.6% in 1993. Over 1500 nylon monofilament filters were distributed yearly to endemic villages lacking safe drinking water sources, while 81 new water sources were constructed (boreholes, wells and dikes), 55% in 1992-1993. The success of GWEP is attributed mainly to: intensive and simultaneous implementation of interventions in highly endemic villages in the first 3 years of the programme, case containment, and cash reward. CONCLUSIONS: Cameroon is on the threshold of eliminating dracunculiasis from Mayo Sava but the major remaining obstacle is the ever increasing threat of re-infestation from neighbouring countries. (+info)
An epidemic of bloody diarrhea: Escherichia coli O157 emerging in Cameroon?
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Between November 1997 and April 20, 1998, bloody diarrhea sickened 298 persons in Cameroon. Laboratory investigation of the epidemic (case-fatality rate, 16.4%) documented amoebiasis in one of three patients and three types of pathogens: multidrug-resistant Shigella dysenteriae type 1, S. boydii, and enterohemorrhagic Escherichia coli. We report the first isolation of E. coli O157:H7 in Cameroon and the second series of cases in the Central African region. (+info)
Population biology of human onchocerciasis.
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Human onchocerciasis (river blindness) is the filarial infection caused by Onchocerca volvulus and transmitted among people through the bites of the Simulium vector. Some 86 million people around the world are at risk of acquiring the nematode, with 18 million people infected and 600,000 visually impaired, half of them partially or totally blind. 99% of cases occur in tropical Africa; scattered foci exist in Latin America. Until recently control programmes, in operation since 1975, have consisted of antivectorial measures. With the introduction of ivermectin in 1988, safe and effective chemotherapy is now available. With the original Onchocerciasis Control Programme of West Africa coming to an end, both the new African Programme for Onchocerciasis Control and the Onchocerciasis Elimination Programme for the Americas, rely heavily on ivermectin self-sustained mass delivery. In consequence, the need for understanding the processes regulating parasite abundance in human and simuliid populations is of utmost importance. We present a simple mathematical framework built around recent analyses of exposure- and density-dependent processes operating, respectively, within the human and vector hosts. An expression for the basic reproductive ratio, R0, is derived and related to the minimum vector density required for parasite persistence in localities of West Africa in general and northern Cameroon in particular. Model outputs suggest that constraints acting against parasite establishment in both humans and vectors are necessary to reproduce field observations, but those in humans may not fully protect against reinfection. Analyses of host age-profiles of infection prevalence, intensity, and aggregation for increasing levels of endemicity and intensity of transmission in the Vina valley of northern Cameroon are in agreement with these results and discussed in light of novel work on onchocerciasis immunology. (+info)
Human immunodeficiency virus type 1 intergroup (M/O) recombination in cameroon.
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Here we describe, for the first time, recombinants between two highly divergent major groups of human immunodeficiency virus type 1 (HIV-1), M and O, within a Cameroonian woman infected with three different HIV-1 strains, a group O virus, a subtype D virus, and a recently reported IBNG (A/G)-like recombinant virus. Using nested extra-long PCR amplification, we sequenced from the pol region to the env region including accessory genes of the viral genome obtained from the patient's uncultured peripheral blood mononuclear cells and examined the phylogenetic position of each gene. Compared with sequential blood samples obtained in 1995 and 1996, there were multiple segmental exchanges between three HIV-1 strains (O, D, and IBNG) and all the recombinants appeared to be derived from a common M/O ancestor. Importantly, recombination between groups M and O occurred, even though the homology between these two groups is 69, 76, 68, and 55% in the gag, pol, vif-vpr, and env regions, respectively. Recombination between strains with such distant lineages may contribute substantially to generating new HIV-1 variants. (+info)
Relationships between malaria prevalence and malaria-related morbidity in school children from two villages in central Africa.
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To investigate the relationship between parasite prevalence and malaria-related morbidity, we carried out a comparative study among cohorts of school children from two villages, Dienga, Gabon, and Pouma, Cameroon, both located in malaria-endemic areas. Seven to 17 year-old children attending primary schools were similarly followed-up at each site to evaluate the frequency of malaria attacks. Follow-up involved daily temperature recording (and blood smears in the case of fever) and preparation of blood smears every two weeks. In Pouma, 186 children were followed-up for six months. In Dienga, 228 children were followed-up for nine months. The mean prevalence rate of Plasmodium falciparum infections (as assessed by the blood smears) was twice as high in Pouma compared with Dienga (45.2% versus 26.8%; P < 0.0001), whereas the monthly malaria attack rate (as assessed by the daily surveillance) was twice as high in Dienga compared with Pouma (21.5% versus 41.4%; P = 0.003). The possible implication of several parameters that may differ between the two areas, such as the malaria transmission level, the economical and social status of the inhabitants, the characteristics of infecting parasite strains, and the genetic background of the population, is discussed. (+info)