Browsing by Author "Coleman, Sylvester"

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    Estimating malaria transmission risk through surveillance of human–vector interactions in northern Ghana
    (Parasites & Vectors, 2023) Yihdego, Yemane; Coleman, Sylvester; Gyamfi, Frank; Kolyada, Lena; Tongren, Jon Eric; Zigrumgabe, Sixte; Dery, Dominc B.; Badu, Kingsley; Obiri-Danso, Kwasi; Boakye, Daniel; , Szumlas, Daniel; Armstead, Jennifer S.; Dadzie, Daniel K.; 0000-0002-0964-0894; 0000-0002-7886-5528
    Background Vector bionomics are important aspects of vector-borne disease control programs. Mosquito-biting risks are afected by environmental, mosquito behavior and human factors, which are important for assessing exposure risk and intervention impacts. This study estimated malaria transmission risk based on vector–human interactions in north‑ ern Ghana, where indoor residual spraying (IRS) and insecticide-treated nets (ITNs) have been deployed. Methods Indoor and outdoor human biting rates (HBRs) were measured using monthly human landing catches (HLCs) from June 2017 to April 2019. Mosquitoes collected were identifed to species level, and Anopheles gambiae sensu lato (An. gambiae s.l.) samples were examined for parity and infectivity. The HBRs were adjusted using mosquito parity and human behavioral observations. Results Anopheles gambiae was the main vector species in the IRS (81%) and control (83%) communities. Indoor and outdoor HBRs were similar in both the IRS intervention (10.6 vs. 11.3 bites per person per night [b/p/n]; z = −0.33, P=0.745) and control communities (18.8 vs. 16.4 b/p/n; z = 1.57, P=0.115). The mean proportion of parous An. gambiae s.l. was lower in IRS communities (44.6%) than in control communities (71.7%). After adjusting for human behavior observations and parity, the combined efect of IRS and ITN utilization (IRS: 37.8%; control: 57.3%) on reducing malaria transmission risk was 58% in IRS + ITN communities and 27% in control communities with ITNs alone (z = −4.07, P<0.001). However, this also revealed that about 41% and 31% of outdoor adjusted bites in IRS and control communities respectively, occurred before bed time (10:00 pm). The mean directly measured annual entomologic inoculation rates (EIRs) during the study were 6.1 infective bites per person per year (ib/p/yr) for IRS communities and 16.3 ib/p/yr for control communities. After considering vector survival and observed human behavior, the estimated EIR for IRS communities was 1.8 ib/p/yr, which represents about a 70% overestimation of risk compared to the directly measured EIR; for control communities, it was 13.6 ib/p/yr (16% overestimation). Conclusion Indoor residual spraying signifcantly impacted entomological indicators of malaria transmission. The results of this study indicate that vector bionomics alone do not provide an accurate assessment of malaria transmission exposure risk. By accounting for human behavior parameters, we found that high coverage of ITNs alone had less impact on malaria transmission indices than combining ITNs with IRS, likely due to observed low net use. Reinforcing effective communication for behavioral change in net use and IRS could further reduce malaria transmission.
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    Studies of Entomological Parameters and Perception of Malaria Transmission on the Kwame Nkrumah University of Science and Technology campus, in the Ashanti Region of Ghana
    (2009) Coleman, Sylvester
    Malaria is a major public health problem in Ghana. Estimations are that 3.5 million people contract malaria every year. In order to develop effective control interventions targeted at reducing the malaria burden in any setting, it is important to understand the major factors that affect transmission and sustenance of the disease. The study was conducted on the Kwame Nkrumah University of Science and Technology (KNUST) campus to determine the vector species present and their roles in malaria transmission, map out areas of high malaria risk using GIS, and seek the perception of inhabitants of the KNUST campus on malaria. Monthly mosquito sampling surveys revealed the existence of varied larval habitat types within the area, mostly characterised by clear or turbid shallow and sunlit conditions, with the greatest larval density contributed, mainly by vegetable gardens and irrigated farmlands. A. gambiae Giles complex, A. funestus Giles complex and A. zieamanni Grunberg were the three Anopheles species that were identified from 843 Anopheles spp that were caught from all night human landing collection during the survey. Of the 3 species A. gambiae proved to be the main species, with a sporozoite index of 1.01% and 0.57% for the dry and rainy seasons respectively. An average entomological inoculation rate (EIR) of 0.059 infective b/m/n and an annual EIR of 22 ib/m/yr were estimated. The faculty area was identified as area with the highest malaria risk, with respect to entomological parameters that were measured during the period. A KAP survey revealed that respondents had high malaria knowledge with 97.4% of respondents relating malaria to mosquito bites. Some respondents on the other hand also thought that eating too much oil and long exposure to sunshine caused malaria. However, high knowledge of malaria did not necessarily result in correct attitudes and practices. This study reveals that though malaria transmission appeared low on the KNUST campus, misconceptions of some inhabitants on malaria transmission coupled with the high abundance of Anopheles gambiae Giles complex, on the KNUST campus could result in high levels of transmission if an infectious gametocyte pool comes into play. The study also provides a GIS based malaria information, which needs to be considered and integrated into the design and implementation of future malaria control interventions on the KNUST campus and its immediate surroundings. Educational programs aimed at increasing awareness on the correct attitudes and practices towards malaria transmission could promote community participation for effective malaria control in the study area.