A new intercellular adhesion molecule-1 allele identified in West Africans is prevalent in African-Americans in contrast to other North American racial groups.
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Africa, Western↗
Biomedical subjects
B A Boatin
Publications and source records attributed to B A Boatin.
Required duration of combined annual ivermectin treatment and vector control in the Onchocerciasis Control Programme in west Africa.
In the extension areas of the Onchocerciasis Control Programme in West Africa, aerial larviciding is supplemented with annual ivermectin treatment, mainly to achieve better control of morbidity. The purpose of this study is to determine whether and to what extent the addition of annual ivermectin treatment permits earlier cessation of vector control than originally recommended. The effectiveness of combined ivermectin distribution and vector control was assessed using an epidemiological model. Model predictions suggest that, dependent on the pre-control endemicity of the area and the proportion of persons treated during each ivermectin round, large-scale annual treatment permits a considerable reduction in the duration of vector control. Taking into account uncertainty about the efficacy of ivermectin, our results indicate that, provided treatment coverage is at least 65% and there is no importation of infection from elsewhere, 12 years of combined control will be sufficient to reduce the risk of recrudescence to below 1% in even the most afflicted areas.
Adolescent↗
Irreversible effects of ivermectin on adult parasites in onchocerciasis patients in the Onchocerciasis Control Programme in West Africa.
Ivermectin is an effective drug for the treatment of human onchocerciasis, a disease caused by the parasitic filarial nematode Onchocerca volvulus. When humans are treated, the microfilariae normally found in the skin are rapidly and very nearly completely eliminated. Nonetheless, after a delay, microfilariae gradually reappear in the skin. This study is concerned with the causes of this delay. Hypotheses are tested by comparing the results of model calculations with skin microfilaria counts collected from 114 patients during a trial of five annual treatments in the focus area of Asubende, Ghana. The results obtained strongly suggest that annual treatment with ivermectin causes an irreversible decline in microfilariae production of approximately 30%/treatment. This result has important implications for public health strategies designed to eliminate onchocerciasis as a significant health hazard.
Adult↗
Impact of combined large-scale ivermectin distribution and vector control on transmission of Onchocerca volvulus in the Niger basin, Guinea.
As part of the WHO Onchocerciasis Control Programme in West Africa (OCP), the attack phase of operations in the Niger basin in Guinea began in 1989 with the simultaneous use of ivermectin and vector control. Larvicide applications coupled with annual large-scale ivermectin distribution have greatly reduced blackfly infectivity (by 78.8% for the number of infective larvae per 1000 parous flies). The combination of vector control and ivermectin has permitted excellent control of transmission. In the original OCP area, it took 6-8 years of vector control alone to obtain an equivalent decrease in blackfly infectivity. For the same number of flies caught, transmission was much higher in areas where ivermectin had not been distributed. The combined use of ivermectin and vector control has opened up new prospects for carrying out OCP operations with, notably, the possibility of reducing larviciding operations.
Animals↗
A three year follow-up of chemotherapy with praziquantel in a rural Zambian community endemic for schistosomiasis mansoni.
A resurvey for schistosomiasis mansoni was carried out in a community 2 years after chemotherapy with praziquantel was stopped. Data on infection status, morbidity, subjective symptoms, and liver and spleen enlargement were collected from participants. Results show that prevalence of Schistosoma mansoni infection and subjective symptoms of morbidity have returned to pretreatment levels. However, the population mean egg output remained low. Liver and spleen sizes in individuals who received treatment have shown a further decline compared to 2 years before. We conclude that selective mass chemotherapy with praziquantel can give the community as a whole a respite from schistosomiasis morbidity for at least 2 years despite an increase in prevalence.
Adolescent↗
A two year follow-up of persons with a positive fluorescent antibody test for Rhodesian sleeping sickness in the Luangwa Valley, Zambia.
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Adult↗
Use of symptoms and signs for diagnosis of Trypanosoma brucei rhodesiense trypanosomiasis by rural health personnel.
The results are described of a study of 60 patients with sleeping sickness from north-east Zambia together with 60 hospital controls and 27 nearest-neighbour controls. Eight symptoms were significantly commoner among sleeping-sickness patients than among either set of controls, and some of these symptoms were used to devise a scoring system for use by rural medical personnel. Although most patients reported a short history of the illness, almost 90% had abnormal cerebrospinal fluid, and there was a significant tendency for the cerebrospinal fluid of adults with a longer history of sleeping sickness to contain trypanosomes. Enlargement of lymph nodes was significantly more frequent among the patients than among the controls, but often the submandibular, axillary, or inguinal rather than the posterior cervical nodes were enlarged. Signs associated with involvement of the central nervous system were common, but the cheiro-oral reflex was non-specific, also occurring frequently among hospital controls.
Adolescent↗
Evaluation of conjunctival pallor in the diagnosis of anaemia.
The diagnosis of anaemia using conjunctival pallor was evaluated using the concept of predictive values. The presence or absence of pallor in 951 individuals and their haemoglobin levels were matched, defining haemoglobin of 10 g dl-1 or less as representing anaemia. The sensitivity and specificity of the test of pallor were 18.6% and 95.8%, respectively. At 16.3% prevalence of anaemia the positive and negative predictive values were 46.3% and 85.8%, respectively. The findings suggest that conjunctival pallor as a screening test for anaemia may not be very reliable.
Adolescent↗
Risk factors associated with the acquisition of sleeping sickness in north-east Zambia; a case-control study.
A case-control study identified 59 cases of Rhodesian sleeping sickness in the northern Luangwa valley of Zambia together with age- and sex-matched nearest neighbour and hospital controls. Birth outside the trypanosomiasis endemic area was not shown to increase the risk of acquiring sleeping sickness. Significantly more cases under the age of 20 years had lived outside the endemic area compared with neighbour controls, although this was not true for those over 20 years old. Ethnic group and main occupation did not differ between cases and neighbour controls. Fishing as an auxiliary occupation increased the risk infection. Members of the United Church of Zambia had a relative risk of acquiring trypanosomiasis twice as great as other religious groups, perhaps because their scattered churches involve more walking through tsetse-infected bush. Sleeping sickness cases said that there were zebras near their village significantly more often than controls, although zebras are not usually considered a likely source of infection. In a preliminary study there was no difference in blood groups or haemoglobin genotype between cases and controls.
Adolescent↗
The prevalence and distribution of schistosomiasis in Zambia.
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Adolescent↗
Yellow fever in Ghana, 1977-80.
The 3-year yellow fever epidemic in Ghana that started in 1977 and tailed off in 1980 appears to be the heaviest on record. In all, 827 cases and 189 deaths were reported (a fatality rate of 22.8%), the patients coming from many villages scattered over 4 regions in the country. The distribution of cases and other epidemiological characteristics are described in this article.
Animals↗
Parasitic infection in the Kasyasya cluster of villages in north eastern Zambia.
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Adolescent↗
The impact of five years of annual ivermectin treatment on skin microfilarial loads in the onchocerciasis focus of Asubende, Ghana.
Following the registration of ivermectin (Mectizan) for human use in the treatment of onchocerciasis, in 1987 the Onchocerciasis Control Programme in West Africa (OCP) begun a series of trials in order to determine the safety of the drug when used on a large scale and its potential for morbidity control. This paper reports the changes in skin microfilarial loads during the first 5 years of annual treatment in the holoendemic focus of Asubende in Ghana, which was the largest trial area and which also had the longest series of follow-up surveys. The general observed pattern was a marked reduction of microfilarial loads shortly after each treatment followed by a steady repopulation of the skin until a subsequent treatment round. The overall reduction of microfilarial loads observed between the base line survey and one year after the last treatment was 90% for the total population examined and over 93% for a cohort which received the drug at all 5 treatment rounds. In contrast, there was only a very gradual decrease in the prevalence of infection in the population after subsequent treatments. The study further emphasizes that even a single treatment with ivermectin has a significant medium-term impact on microfilarial loads. Microfilarial counts barely increased after 14-16 months of treatment and stabilized around 55% of pre-treatment counts 2-4 years after a single treatment.
Animals↗
Topical application of diethylcarbamazine to detect onchocerciasis recrudescence in west Africa.
The Onchocerciasis Control Programme in West Africa (OCP) has succeeded in eliminating blinding onchocerciasis as a public health problem throughout much of West Africa. The efforts of the OCP are now turning towards surveillance, with the goal of rapidly detecting and controlling outbreaks of infection in the onchocerciasis-free zone. With this goal in mind, cutaneous application of a solution of diethylcarbamazine (the DEC-patch test) was evaluated in 1996-99 as a method to detect patent Onchocerca volvulus infection in children and adolescents, a sentinel population for the detection of recrudescence. In an analysis of 1887 individuals in Côte d'Ivoire and Burkina Faso, the DEC-patch test produced prevalence estimates comparable to those obtained by skin snip. The sensitivity of the DEC-patch assay was marginally greater in children and adolescents than in adults, and was greater in individuals who had received prior Mectizan treatment. These data suggest that the DEC-patch test may be a useful tool for detecting recrudescence of O. volvulus infection in a sentinel population of children and young adults within the onchocerciasis-free zone created by the OCP.
Administration, Cutaneous↗