Biomedical subjects

Joseph Keating

Publications and source records attributed to Joseph Keating.

12 recordsLinked to original sources

PubMed2006

Assessing effects of a media campaign on HIV/AIDS awareness and prevention in Nigeria: results from the VISION Project.

BACKGROUND: In response to the growing HIV epidemic in Nigeria, the U.S. Agency for International Development (USAID) initiated the VISION Project, which aimed to increase use of family planning, child survival, and HIV/AIDS services. The VISION Project used a mass-media campaign that focused on reproductive health and HIV/AIDS prevention. This paper assesses to what extent program exposure translates into increased awareness and prevention of HIV/AIDS. METHODS: This analysis is based on data from the 2002 and 2004 Nigeria (Bauchi, Enugu, and Oyo) Family Planning and Reproductive Health Surveys, which were conducted among adults living in the VISION Project areas. To correct for endogeneity, two-stage logistic regression is used to investigate the effect of program exposure on 1) discussion of HIV/AIDS with a partner, 2) awareness that consistent condom use reduces HIV risk, and 3) condom use at last intercourse. RESULTS: Exposure to the VISION mass media campaign was high: 59%, 47%, and 24% were exposed to at least 1 VISION radio, printed advertisement, or TV program about reproductive health, respectively. The differences in outcome variables between 2002 baseline data and the 2004 follow-up data were small. However, those with high program exposure were almost one and a half (Odds Ratio [O.R.] = 1.47, 95% Confidence Interval [C.I.] 1.01-2.16) times more likely than those with no exposure to have discussed HIV/AIDS with a partner. Those with high program exposure were over twice (O.R. = 2.20, C.I. 1.49-3.25) as likely as those with low exposure to know that condom use can reduce risk of HIV infection. Program exposure had no effect on condom use at last sex. CONCLUSION: The VISION Project reached a large portion of the population and exposure to mass media programs about reproductive health and HIV prevention topics can help increase HIV/AIDS awareness. Programs that target rural populations, females, and unmarried individuals, and disseminate information on where to obtain condoms, are needed to reduce barriers to condom use. Improvements in HIV/AIDS prevention behaviour are likely to require that these programmatic efforts be continued, scaled up, done in conjunction with other interventions, and targeted towards individuals with specific socio-demographic characteristics.

Acquired Immunodeficiency Syndrome↗

PubMed2006

Rolling out insecticide treated nets in Eritrea: examining the determinants of possession and use in malarious zones during the rainy season.

OBJECTIVE: This paper describes determinants of insecticide treated net (ITN) ownership and use in malarious areas of Eritrea. With ITN distribution and re-treatment now free for all living in these areas, we examine barriers (other than cost) to access and use of ITNs. We explore the differences between use of an ITN as a proportion of all households in the survey (the roll back malaria indicator), and use of an ITN as a proportion of those households who already own an ITN. METHODS: A modified two-stage cluster design was used to collect data from a sample of households (n = 2341) in the three most malarious administrative zobas (zones or provinces). Logistic regression was used to analyse the data. RESULTS: Our findings suggest environmental heterogeneity among zobas (including program effects specific to each zoba), perception of risk, and proximity to a clinic are important predictors of ITN possession and use. Among households with at least one ITN, 17.0% reported that children under five were not under an ITN the night before the survey, while half of all such households did not have all occupants using them the night before the survey. The number of ITNs, as well as zoba, was also significant determinants of use in these households with at least one ITN. CONCLUSION: Current efforts to disseminate ITNs to vulnerable populations in Eritrea are working, as suggested by high ITN ownership and net-to-person ratios inside households. However, the gap between ITN ownership and use, given ownership, is large, and may represent lost opportunities to prevent infection. Closing this gap requires concerted efforts to change behaviour to ensure that all household members use ITNs as consistently and correctly as possible during and following the rains.

Attitude to Health↗

PubMed2005

Self-reported malaria and mosquito avoidance in relation to household risk factors in a Kenyan coastal city.

A geographically stratified cross-sectional survey was conducted in 2002 to investigate household-level factors associated with use of mosquito control measures and self-reported malaria in Malindi, Kenya. A total of 629 households were surveyed. Logistic regressions were used to analyse the data. Half of all households (51%) reported all occupants using an insecticide-treated bed net and at least one additional mosquito control measure such as insecticides or removal of standing water. Forty-nine per cent reported a history of malaria in the household. Of the thirteen household factors analysed, low (OR=0.23, CI 0.11, 0.48) and medium (OR=0.50, CI 0.29, 0.86) education, mud--wood--coral (OR=0.0.39, CI 0.24, 0.66) and mud block--plaster (OR=0.47, CI 0.25, 0.87) wall types, farming (OR=1.38, CI 1.01, 1.90) and travel to rural areas (OR=0.48, CI 0.26, 0.91) were significantly associated with the use of mosquito control, while controlling for other covariates in the model. History of reported malaria was not associated with the use of mosquito control (OR=1.22, CI 0.79, 1.88). Of the thirteen covariates analysed in the second model, only two household factors were associated with history of malaria: being located in the well-drained stratum (OR=0.49, CI 0.26, 0.96) and being bitten while in the house (OR=1.22, CI 0.19, 0.49). These results suggest that high socioeconomic status is associated with increased household-level mosquito control use, although household-level control may not be enough, as many people are exposed to biting mosquitoes while away from the house and in areas that are more likely to harbour mosquitoes.

Animals↗

PubMed2005

Anopheles gambiae s.l. and Anopheles funestus mosquito distributions at 30 villages along the Kenyan coast.

This study investigated whether Anopheles gambiae s.l. and Anopheles funestus Giles mosquito populations were distributed randomly among houses on the coast of Kenya. Sample means and variances of mosquitoes were estimated from bimonthly pyrethrum spray collections at 30 villages from July 1997 through May 1998. In total, 5,476 An. gambiae s.l. and 3,461 An. funestus were collected. The number of An. gambiae s.l. collected was highest in November/December and lowest in May. The number of An. funestus collected was highest during September/October and lowest during May. As the density of mosquitoes decreased, there was a tendency toward randomness in the distribution. The proportion of An. gambiae s.l. and An. funestus mosquitoes collected per house for each sampling period also showed patterns of clustering, with 80% of An. gambiae s.l. collected from <30% of the houses and 80% of An. funestus collected from <20% of the total houses. The total number of mosquitoes collected from any one house ranged from 0 to 121 for An. gambiae s.l. and from 0 to 152 for An. funestus. This coupled with the results of the variance to mean ratio plots suggests extensive clustering in the distribution of An. gambiae s.l. and An. funestus mosquito populations throughout the year along the coast of Kenya.

Animals↗

PubMed2004

Characterization of potential larval habitats for Anopheles mosquitoes in relation to urban land-use in Malindi, Kenya.

BACKGROUND: This study characterized Anopheles mosquito larval habitats in relation to ecological attributes about the habitat and community-level drainage potential, and investigated whether agricultural activities within or around urban households increased the probability of water body occurrence. Malindi, a city on the coast of Kenya, was mapped using global positioning system (GPS) technology, and a geographic information system (GIS) was used to overlay a measured grid, which served as a sampling frame. Grid cells were stratified according to the level of drainage in the area, and 50 cells were randomly selected for the study. Cross-sectional household and entomological surveys were conducted during November and December 2002 within the 50 grid cells. Chi-square analysis was used to test whether water bodies differed fundamentally between well and poorly drained areas, and multi-level logistic regression was used to test whether household-level agricultural activity increased the probability of water body occurrence in the grid cell. RESULTS: Interviews were conducted with one adult in 629 households. A total of 29 water bodies were identified within the sampled areas. This study found that characteristics of water bodies were fundamentally the same in well and poorly drained areas. This study also demonstrated that household-level urban agriculture was not associated with the occurrence of water bodies in the grid cell, after controlling for potential confounders associated with distance to the city center, drainage, access to resources, and population density. CONCLUSIONS: Household-level urban agricultural activity may be less important than the other types of human perturbation in terms of mosquito larval habitat creation. The fact that many larvae were coming from few sites, and few sites in general were found under relatively dry conditions suggests that mosquito habitat reduction is a reasonable and attainable goal in Malindi.

Journal Article↗

PubMed2004

Ecological limitations on aquatic mosquito predator colonization in the urban environment.

Urban malaria cases are becoming common in Africa as more people move into cities and industrialization proceeds. While many species of Anopheles mosquitoes vector malaria in rural areas, only a few are found within cities. The success of anthropophilic species in cities, such as members of the An. gambiae complex, may be explained by limitations on colonization by predator species in urban environments. Habitats that are temporal or structurally simple have lower predator survivorship in a variety of ecosystems, but these have not been investigated previously in an urban area. Areas within and around the Kenyan coastal town of Malindi were previously sampled for the presence of standing water using a geographic sampling strategy with probability proportional to size sampling of planned well-drained, unplanned poorly-drained, planned poorly-drained, unplanned well-drained, and peri-urban locations. Standing aquatic habitats in these areas were reassessed. During monthly sampling, presence/absence of mosquitoes and predator taxa were noted, as were ecological habitat variables: structural complexity and presence of water. Lambda statistics were calculated to associate predator guilds, habitat types, location variables, and ecological variables. All predator guilds found in habitats were strongly associated with habitat type, as were the structural complexity and temporal nature of the habitats. Types of habitat were heterogeneously distributed throughout Malindi, with swimming pools as a common habitat type in planned urban areas and tire track pools a common habitat type in peri-urban areas of Malindi. Predator colonization of aquatic habitats in Malindi was strongly influenced by habitat type, and not associated with location characteristics. Ecological variables were affected by the type of habitats, which are co-associated with planning and drainage in Malindi. While habitat types are distributed heterogeneously within Malindi, habitats with low predation pressure are available for mosquito colonization in both urban and peri-urban areas. The temporal, peri-urban tire track pools and the structural simplicity of urban swimming pools may discourage predator colonization, thereby increasing the probability of malaria vectors in these areas of Malindi. Future studies should evaluate habitats for use in malaria surveillance and experimentally test the effects of structural complexity and temporal nature of urban habitats on the densities of mosquito larvae and their aquatic predators.

Animals↗

PubMed2003

Linking field-based ecological data with remotely sensed data using a geographic information system in two malaria endemic urban areas of Kenya.

BACKGROUND: Remote sensing technology provides detailed spectral and thermal images of the earth's surface from which surrogate ecological indicators of complex processes can be measured. METHODS: Remote sensing data were overlaid onto georeferenced entomological and human ecological data randomly sampled during April and May 2001 in the cities of Kisumu (population asymptotically equal to 320,000) and Malindi (population asymptotically equal to 81,000), Kenya. Grid cells of 270 meters x 270 meters were used to generate spatial sampling units for each city for the collection of entomological and human ecological field-based data. Multispectral Thermal Imager (MTI) satellite data in the visible spectrum at five meter resolution were acquired for Kisumu and Malindi during February and March 2001, respectively. The MTI data were fit and aggregated to the 270 meter x 270 meter grid cells used in field-based sampling using a geographic information system. The normalized difference vegetation index (NDVI) was calculated and scaled from MTI data for selected grid cells. Regression analysis was used to assess associations between NDVI values and entomological and human ecological variables at the grid cell level. RESULTS: Multivariate linear regression showed that as household density increased, mean grid cell NDVI decreased (global F-test = 9.81, df 3,72, P-value = <0.01; adjusted R2 = 0.26). Given household density, the number of potential anopheline larval habitats per grid cell also increased with increasing values of mean grid cell NDVI (global F-test = 14.29, df 3,36, P-value = <0.01; adjusted R2 = 0.51). CONCLUSIONS: NDVI values obtained from MTI data were successfully overlaid onto georeferenced entomological and human ecological data spatially sampled at a scale of 270 meters x 270 meters. Results demonstrate that NDVI at such a scale was sufficient to describe variations in entomological and human ecological parameters across both cities.

Journal Article↗

PubMed2003

Occurrence and distribution of Anopheles (Diptera: Culicidae) larval habitats on land cover change sites in urban Kisumu and urban Malindi, Kenya.

A multitemporal, land use land cover (LULC) classification dataset incorporating distributions of mosquito larval habitats was produced in ERDAS Imagine using the combined images from the Multispectral Thermal Imager (MTI) at 5 m spatial resolution from 2001 with Thematic Mapper-classification data at 28.5 m spatial resolution from 1987 and 1989 for Kisumu and Malindi, Kenya. Total LULC change for Kisumu over 14 yr was 30.2%. Total LULC change for Malindi over 12 yr was 30.6%. Of those areas in which change was detected, the LULC change for Kisumu was 72.5% for nonurban to urban, 21.7% urban to nonurban, 0.4% urban to water, 4.5% water to urban, and 0.9% water to nonurban. The proportion of LULC change for Malindi was 93.5% for nonurban to urban, 5.9% urban to nonurban, 0.2% urban to water, 0.3% nonurban to water, and 0.1% water to urban. A grid (270 m x 270 m cells) was overlaid over the maps stratifying grid cells based on drainage and planning. Of 84 aquatic habitats in Kisumu, 32.1% were located in LULC change sites and 67.9% were located in LULC nonchange sites. Of 170 aquatic habitats in Malindi, 26.5% were located in LULC change sites and 73.5% were located in LULC nonchange sites. The most abundant LULC change per strata with anopheline habitats was unplanned and poorly drained. Ditches and puddles in Kisumu and car tracks in Malindi displayed the highest number of anopheline larval habitats for all LULC change sites. The proportion of site positive aquatic habitats for anopheline larvae was higher in LULC change sites than for LULC nonchange sites for Kisumu. This evidence suggests LULC change can influence anopheline larval habitat distribution.

Animals↗

PubMed2003

Malaria transmission in urban sub-Saharan Africa.

The rapid increase in the world's urban population has major implications for the epidemiology of malaria. A review of malaria transmission in sub-Saharan African cities shows the strong likelihood of transmission occurring within these sprawling cities, whatever the size or characteristics of their bioecologic environment. A meta-analysis of results from studies of malaria transmission in sub-Saharan Africa shows a loose linear negative relationship between mean annual entomologic inoculation rates (EIR) and the level of urbanicity. Few studies have failed to find entomologic evidence of some transmission. Our results show mean annual EIRs of 7.1 in the city centers, 45.8 in periurban areas, and 167.7 in rural areas. The impact of urbanization in reducing transmission is more marked in areas where the mean rainfall is low and seasonal. Considerable variation in the level of transmission exists among cities and within different districts in the same city. This article presents evidence from past literature to build a conceptual framework to begin to explain this heterogeneity. The potential for malaria epidemics owing to decreasing levels of natural immunity may be offset by negative impacts of urbanization on the larval ecology of anopheline mosquitoes. Malaria control in urban environments may be simpler as a result of urbanization; however, much of what we know about malaria transmission in rural environments might not hold in the urban context.

Africa South of the Sahara↗

PubMed2003

A geographic sampling strategy for studying relationships between human activity and malaria vectors in urban Africa.

This paper describes a geographic sampling strategy for ecologic studies and describes the relationship between human activities and anopheline larval ecology in urban areas. Kisumu and Malindi, Kenya were mapped using global positioning systems, and a geographic information system was used to overlay a measured grid, which served as a sampling frame. Grid cells were stratified and randomly selected according to levels of planning and drainage. A cross-sectional survey was conducted in April and May 2001 to collect entomologic and human ecologic data. Multivariate regression analysis was used to test the relationship between the abundance of potential larval habitats, and house density, socioeconomic status, and planning and drainage. In Kisumu, 98 aquatic habitats were identified, 65% of which were human made and 39% were positive for anopheline larvae. In Malindi, 91 aquatic habitats were identified, of which, 93% were human made and 65% were harboring anopheline larvae. The regression model explains 82% of the variance associated with the abundance of potential larval habitats in Kisumu. In Malindi, 59% of the variance was explained. As the number of households increased, the number of larval habitats increased correspondingly to a point. Beyond a critical threshold, the density of households appeared to suppress the development of aquatic habitats. The proportion of high-income households and the planning and drainage variables tested insignificant in both locations. The integration of social and biologic sciences will allow local mosquito and malaria control groups an opportunity to assess the risk of encountering potentially infectious mosquitoes in a given area, and concentrate resources accordingly.

Africa↗

PubMed2003

Spatial and temporal heterogeneity of Anopheles mosquitoes and Plasmodium falciparum transmission along the Kenyan coast.

The seasonal dynamics and spatial distributions of Anopheles mosquitoes and Plasmodium falciparum parasites were studied for one year at 30 villages in Malindi, Kilifi, and Kwale Districts along the coast of Kenya. Anopheline mosquitoes were sampled inside houses at each site once every two months and malaria parasite prevalence in local school children was determined at the end of the entomologic survey. A total of 5,476 Anopheles gambiae s.l. and 3,461 An. funestus were collected. Species in the An. gambiae complex, identified by a polymerase chain reaction, included 81.9% An. gambiae s.s., 12.8% An. arabiensis, and 5.3% An. merus. Anopheles gambiae s.s. contributed most to the transmission of P. falciparum along the coast as a whole, while An. funestus accounted for more than 50% of all transmission in Kwale District. Large spatial heterogeneity of transmission intensity (< 1 up to 120 infective bites per person per year) resulted in correspondingly large and significantly related variations in parasite prevalence (range = 38-83%). Thirty-two percent of the sites (7 of 22 sites) with malaria prevalences ranging from 38% to 70% had annual entomologic inoculation rates (EIR) less than five infective bites per person per year. Anopheles gambiae s.l. and An. funestus densities in Kwale were not significantly influenced by rainfall. However, both were positively correlated with rainfall one and three months previously in Malindi and Kilifi Districts, respectively. These unexpected variations in the relationship between mosquito populations and rainfall suggest environmental heterogeneity in the predominant aquatic habitats in each district. One important conclusion is that the highly non-linear relationship between EIRs and prevalence indicates that the consistent pattern of high prevalence might be governed by substantial variation in transmission intensity measured by entomologic surveys. The field-based estimate of entomologic parameters on a district level does not provide a sensitive indicator of transmission intensity in this study.

Animals↗

PubMed2002

Examining the determinants of mosquito-avoidance practices in two Kenyan cities.

BACKGROUND: This study assesses the behavioural and socio-economic factors associated with avoiding mosquitoes and preventing malaria in urban environments in Kenya. METHODS: Data from two cities in Kenya were gathered using a household survey and a two-stage cluster sample design. The cities were stratified based on planning and drainage observed across the urban areas. This helped control for the strong environmental and topographical variation that we assumed influences mosquito ecology. Individual interviews given to each household included questions on socio-economic status, education, housing type, water source, rubbish disposal, mosquito-prevention practices and knowledge of mosquitoes. In multivariate regression, factors measuring wealth, education level, and the communities' level of planning and drainage were used to estimate the probability that a household engages in multiple mosquito-avoidance activities, or has all members sleeping under a bed net. RESULTS: Our analysis shows that people from wealthier, more educated households were more likely to sleep under a net, in Kisumu (OR = 6.88; 95% CI = 2.56,18.49) and Malindi (OR = 3.80; 95% CI = 1.91,7.55). Similarly, the probability that households use several mosquito-prevention activities was highest among the wealthiest, best-educated households in Kisumu (OR = 5.15; 95% CI = 2.04,12.98), while in Malindi household wealth alone is the major determinant. CONCLUSION: We demonstrate the importance of examining human-mosquito interaction in terms of how access to resources may enhance human activities. The findings illustrate that the poorest segments of society are already doing many things to protect themselves from being bitten, but they are doing less than their richer neighbours.

Animals↗