Biomedical subjects

John M Vulule

Publications and source records attributed to John M Vulule.

46 records · Page 3Linked to original sources

PubMed2003

Community reactions to the introduction of permethrin-treated bed nets for malaria control during a randomized controlled trial in western Kenya.

Prior to implementation of a randomized controlled trial of insecticide (permethrin)-treated bed nets (ITNs) in western Kenya, ethnographic studies were conducted to understand local perceptions of disease, sleeping patterns, and other factors that might affect use of ITNs. Educational activities took place prior to distribution, but immediately after distribution in Asembo only approximately half of the ITNs were in use. A qualitative study was then conducted to identify the community's perceptions about ITNs and the ITN project. While participants ranked malaria as important and recognized that malaria prevention could be beneficial, they believed ITNs would be only partly effective due to the perception that malaria has multiple causes. Concerns expressed included fear of the insecticide, thought by some to be a toxic family planning aid, the taking of blood during clinical studies, and the mixing up of family ITNs during net re-treatment, which would violate cultural taboos. Attempts were made to allay fears by improved communication on these subjects and modification of the study design.

Attitude to Health↗

PubMed2003

Factors affecting use of permethrin-treated bed nets during a randomized controlled trial in western Kenya.

Adherence with permethrin-treated bed net (ITN) use and their proper deployment was directly observed in 2,178 individuals (784 households) participating in a large-scale trial of ITNs on child mortality in western Kenya. The ITNs were distributed free of charge to ensure high coverage, resulting in a ratio of 1.46 persons per ITN. Approximately 30% of ITNs present were unused. The overall percentage adherence was 72.3%. The probability of adherence by individuals depended strongly on age (relative risk [RR] = 0.86, 95% confidence limit [CL] = 0.78-0.94), in which children less than five years of age were less likely to use ITNs than older individuals, and temperature, in which ITNs were more likely to be used in periods of cooler weather. A marginally significant diminution in adherence during the second year of the project was also observed (RR = 0.83, 95% CL = 0.68-1.01). Mosquito numbers, relative wealth, number of house occupants, and the educational level of the head of the household had no effect on adherence. In unstructured questioning of house residents, excessive heat was often cited as a reason for not deploying the child's ITN. The most important reason for non-adherence was disruption of sleeping arrangements, indicating that ITNs were not readily redeployed in the face of shifting sleeping patterns due to visitors, funerals, house construction, and other events. Challenges faced by health education programs to maximize adherence with ITN use are discussed.

Animals↗

PubMed2003

Perceptions of bed nets and malaria prevention before and after a randomized controlled trial of permethrin-treated bed nets in western Kenya.

A study of mothers' perceptions regarding bed nets and malaria was conducted before and after a randomized controlled trial of insecticide (permethrin)-treated bed nets (ITNs) in western Kenya. Awareness about the trial and the rationale for bed net use increased by the end of the trial. Knowledge that mosquitoes caused malaria also increased; however, a higher proportion of mothers from control, rather than intervention villages, cited this (44.4% versus 27.9%; P < 0.001). Mothers from intervention villages were more knowledgeable about the use and maintenance of bed nets and re-treatment with insecticide. Both groups specified advantages of ITNs. Mothers from intervention villages noted practical advantages such as protection against bedbugs and falling roof debris. Few (< 1%) mothers indicated that ITNs protected children against malaria. Intervention homes used significantly fewer mosquito coils, insect spray, medicines, and burned cow dung less often compared with those in control villages. Mothers were willing to pay approximately 4.5 U.S. dollars for a regular bed net, but only 10.5 U.S. cents (intervention) and 0.036 (control) for re-treating a bed net. This study suggests that, despite two years of experience of use, bed nets and insecticides would not be purchased as a household priority in this impoverished rural community.

Adult↗

PubMed2003

The household-level economics of using permethrin-treated bed nets to prevent malaria in children less than five years of age.

We measured the two-week household-level economic impact of insecticide (permethrin)-treated bed nets (ITNs) used to prevent malaria among children less than five years of age in Asembo, Kenya. The ITNs induced a two-week reduction of 15 Kenyan shillings (KSH) (0.25 U.S. dollars; P < 0.0001) in health care expenditures, but a statistically insignificant 0.5 day (P = 0.280) reduction in household time lost due to caring for sick children. The equivalent annual threshold cost was estimated at 6.50 U.S. dollars (95% confidence interval = 3.12-9.86). If the actual purchase price and maintenance costs of ITNs were greater than this threshold, then households would pay more than they would save (and vice-versa). Both seasonal effects and number of children per household had larger impacts than ITNs on health care expenditures and time lost from household activities. Health care expenditures by a household without ITNs and one child were only 32 KSH per two weeks (0.50 U.S. dollars; P = 0.002), leaving little opportunity for household-level, ITN-induced direct savings. The widespread adoption of the ITNs will therefore probably require a subsidy.

Antimalarials↗

PubMed2003

The cost-effectiveness of permethrin-treated bed nets in an area of intense malaria transmission in western Kenya.

This study compared the costs and effects of insecticide (permethrin)-treated bed net (ITN) use in children less than five years of age in an area of intense, perennial malaria transmission in western Kenya. The data were derived from a group-randomized controlled trial of ITNs conducted between 1996 and 1999. The annual net cost per life-year gained was 34 U.S. dollars and the net annual cost per all-cause sick child clinic visit averted was 49 U.S. dollars. After taking into account a community effect (protection from malaria afforded to non-ITN users who lived within 300 meters from users) these estimates decreased to 25 U.S. dollars and 38 U.S. dollars, respectively. This study provides further evidence that ITNs are a highly cost-effective use of scarce health care resources.

Bedding and Linens↗

PubMed2003

Implications of the western Kenya permethrin-treated bed net study for policy, program implementation, and future research.

The fifth, and probably last, large-scale, group-randomized, controlled trial of insecticide (permethrin)-treated bed nets (ITNs) showed that ITNs are efficacious in reducing all-cause post-neonatal mortality in an area of intense, perennial malaria transmission. The trial helped to define pregnant women and infants as target groups for this intervention in high transmission settings. High population coverage with ITNs in both target and non-target groups may be critical to enhance health and survival in pregnant women and infants. The proportion of households with ITNs (coverage), the proportion of individuals properly deploying ITNs each night (adherence), and the proportion of nets properly treated with insecticide (treatment) are the three key determinants of effectiveness of large-scale ITN programs. These three simple outcomes should serve as the basis for program objectives and monitoring and evaluation efforts. Coverage effects and economic analysis support the proposition that ITNs may be viewed as a public good, worthy of public support. Research should continue to improve the intervention tools (the net, the insecticide, and methods for durable treatment and re-treatment) and their deployment.

Animals↗

PubMed2003

Epidemiology of sporadic bloody diarrhea in rural Western Kenya.

We conducted laboratory-based surveillance and a case-control study to characterize the epidemiology of bloody diarrhea in rural Western Kenya. From May 1997 through April 2001, we collected stool from 451 persons with bloody diarrhea presenting to four rural clinics. Cultures of 231 (51%) specimens yielded 247 bacterial pathogens: 198 Shigella (97 S. flexneri, 41 S. dysenteriae type 1, 39 S. dysenteriae type non-1, 13 S. boydii, 8 S. sonnei), 33 Campylobacter, 15 non-typhoidal Salmonella, and 1 Vibrio cholerae O1. More than 90% of the isolates (excluding Campylobacter) were resistant to trimethoprim-sulfamethoxazole and tetracycline, and more than 80% were resistant to ampicillin. Most (74%) ill persons received medication to which their isolate was resistant. Drinking Lake Victoria water and sharing latrines between multiple households increased risk of bloody diarrhea. Washing hands after defecating was protective. Providing safe drinking water and more latrines, and promoting hand washing could reduce the burden of illness from bloody diarrhea while limiting injudicious antimicrobial use.

Adolescent↗

PubMed2003

The use of short-course zidovudine to prevent perinatal transmission of human immunodeficiency virus in rural Kenya.

To determine the feasibility of using short-course zidovudine (ZDV) to prevent mother-to-child transmission of human immunodeficiency virus (HIV) in a breastfeeding population in a rural area in Kenya, pregnant mothers attending clinics in seven health centers in western Kenya between 1996 and 1998 were requested to volunteer for participation in this study. The HIV-infected mothers were given a daily dose of 400 mg of ZDV starting at 36 weeks of gestation and another 300 mg every three hours intrapartum. After delivery, mothers and their children were followed-up and clinically monitored every 3-4 months for two years, and child and mother mortality rates were analyzed. Of the 825 mothers who consented, 216 (26.2%) were infected with HIV. Of those infected, 51 (23.6%) took the full prescribed dose, 69 (31.9%) took only the prenatal dose, and the remaining 96 (44.4%) did not take any dose. Failure to take ZDV was attributed mainly to delivery occurring earlier than expected, while non-compliance to the intrapartum dose was due to mothers giving birth at home and fear of traditional birth attendants. By the end of the second year, 75 HIV-exposed children (34.7%) and 33 HIV-infected mothers (15.3%) had died. The HIV-free survival of children at 24 months was significantly associated with mother survival (P < 0.001) and prenatal ZDV compliance (P < 0.003). Our findings suggest that implementation of programs for prevention of mother-to-child transmission of HIV in rural areas of Africa need to consider the various socioeconomic and cultural barriers that may prevent successful uptake of antiretroviral prophylaxes. Similarly, the rapid disease progression in mothers may eliminate the increase in child survival due to ZDV prophylaxis.

Adult↗

PubMed2003

Evaluating the completeness of demographic surveillance of children less than five years old in western Kenya: a capture-recapture approach.

We evaluated the completeness and differential ascertainment of vital events in children less than five years old registered in two rounds of a demographic surveillance system (DSS) in western Kenya using a two-sample capture-recapture. The primary lists consisted of births and child deaths identified by two rounds of the DSS conducted in October 2000 and August 2001. The secondary lists consisted of births and child deaths identified independently from two surveys of 5,000 randomly selected households conducted immediately after each DSS round, covering the same population over the same time period. Analysis of the overlap between lists yielded the following sensitivities for the two DSS rounds: 62% and 49%, respectively, for identifying neonatal deaths (<1 month); 72% and 78%, respectively, for post-neonatal child deaths (1-59 months); and 88% and 78%, respectively, for identifying newborns. Female deaths were less likely to be reported than male deaths. The primary limitation of using capture-recapture in this setting was difficulty in matching between lists due to inconsistent dates of birth and death and variability in spelling of names. Assuming limitations of current methods are sufficiently addressed, capture-recapture appears to be a useful tool in evaluating DSS completeness and differential ascertainment of vital events.

Birth Rate↗

PubMed2002

Density-dependent development of Anopheles gambiae (Diptera: Culicidae) larvae in artificial habitats.

The growth and development of Anopheles gambiae Giles larvae were studied in artificial habitats in western Kenya. Larvae responded to increasing densities by extending their development time and by emerging as smaller adults, although survival was not significantly affected. Addition of nutrients in the form of cow dung collected near the study site had no impact on larval growth and development. Regression analysis showed that female development time increased by 0.020 d and female dry mass decreased by 0.74 microg with each additional larva. By fitting the data to the pupation window model, the estimated minimum dry mass to achieve pupation was 0.130 mg and the estimated minimum time to pupation was 5 d. The most likely food source for An. gambiae larvae was algal growth, which was significantly reduced by the presence of larvae. Bacterial densities were not significantly affected by the presence of larvae although total bacteria counts were lower at the higher densities indicating they may provide a secondary food source when algal resources are depleted. Similarly, the levels of nitrogen and phosphorus in the habitats were not significantly affected by the presence of larvae although there was evidence of decreasing nitrogen levels occurring with increasing larval densities suggesting that nitrogen may be a limiting resource in the larval environment. The data indicate that competition within the larval environment may indirectly regulate An. gambiae populations by reducing adult body size, which may in turn reduce adult survivorship and fecundity. The potential impact of density-dependent interactions among An. gambiae larvae on the transmission of Plasmodium falciparum is discussed.

Animal Feed↗