Bernard Abong'o1,2, John E Gimnig3, Bradley Longman4, Tobias Odongo4, Celestine Wekesa4, Amos Webwile4, Benjamin Oloo4, Mercy Nduta4, Margaret Muchoki4, Diana Omoke5, Daniel Wacira6, Kevin Opondo4, Eric Ochomo5, Stephen Munga5, Martin J Donnelly7, Richard M Oxborough8. 1. Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya. abongoben@gmail.com. 2. PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya. abongoben@gmail.com. 3. Division of Parasitic Diseases and Malaria, Center for Global Health, Centers for Disease Control and Prevention, Atlanta, GA, 30333, USA. 4. PMI VectorLink Project, Abt Associates Inc., Whitehouse, Milimani, Kisumu, Ojijo Oteko Road, P.O. Box 895-40123, Kisumu, Kenya. 5. Centre for Global Health Research, Kenya Medical Research Institute, P.O. Box 1578, Kisumu, Kenya. 6. The United States President's Malaria Initiative (PMI), US Embassy Nairobi, United Nations Avenue, Nairobi, Kenya. 7. Liverpool School of Tropical Medicine, Pembroke Place, Liverpool, L3 5QA, UK. 8. PMI VectorLink Project, Abt Associates Inc., 6130 Executive Blvd, Rockville, MD, 20852, USA.
Abstract
INTRODUCTION: Longitudinal monitoring of outdoor-biting malaria vector populations is becoming increasingly important in understanding the dynamics of residual malaria transmission. However, the human landing catch (HLC), the gold standard for measuring human biting rates indoors and outdoors, is costly and raises ethical concerns related to increased risk of infectious bites among collectors. Consequently, routine data on outdoor-feeding mosquito populations are usually limited because of the lack of a scalable tool with similar sensitivity to outdoor HLC. METHODOLOGY: The Anopheles trapping sensitivity of four baited proxy outdoor trapping methods-Furvela tent trap (FTT), host decoy trap (HDT), mosquito electrocuting traps (MET) and outdoor CDC light traps (OLT)-was assessed relative to HLC in a 5 × 5 replicated Latin square conducted over 25 nights in two villages of western Kenya. Indoor CDC light trap (ILT) was run in one house in each of the compounds with outdoor traps, while additional non-Latin square indoor and outdoor HLC collections were performed in one of the study villages. RESULTS: The MET, FTT, HDT and OLT sampled approximately 4.67, 7.58, 5.69 and 1.98 times more An. arabiensis compared to HLC, respectively, in Kakola Ombaka. Only FTT was more sensitive relative to HLC in sampling An. funestus in Kakola Ombaka (RR = 5.59, 95% CI 2.49-12.55, P < 0.001) and Masogo (RR = 4.38, 95% CI 1.62-11.80, P = 0.004) and in sampling An. arabiensis in Masogo (RR = 5.37, 95% CI 2.17-13.24, P < 0.001). OLT sampled significantly higher numbers of An. coustani in Kakola Ombaka (RR = 3.03, 95% CI 1.65-5.56, P < 0.001) and Masogo (RR = 2.88, 95% CI 1.15-7.22, P = 0.02) compared to HLC. OLT, HLC and MET sampled mostly An. coustani, FTT had similar proportions of An. funestus and An. arabiensis, while HDT sampled predominantly An. arabiensis in both villages. FTT showed close correlation with ILT in vector abundance for all three species at both collection sites. CONCLUSION: FTT and OLT are simple, easily scalable traps and are potential replacements for HLC in outdoor sampling of Anopheles mosquitoes. However, the FTT closely mirrored indoor CDC light trap in mosquito indices and therefore may be more of an indoor mimic than a true outdoor collection tool. HDT and MET show potential for sampling outdoor host-seeking mosquitoes. However, the traps as currently designed may not be feasible for large-scale, longitudinal entomological monitoring. Therefore, the baited outdoor CDC light trap may be the most appropriate tool currently available for assessment of outdoor-biting and malaria transmission risk.
INTRODUCTION: Longitudinal monitoring of outdoor-biting malaria vector populations is becoming increasingly important in understanding the dynamics of residual malaria transmission. However, the human landing catch (HLC), the gold standard for measuring human biting rates indoors and outdoors, is costly and raises ethical concerns related to increased risk of infectious bites among collectors. Consequently, routine data on outdoor-feeding mosquito populations are usually limited because of the lack of a scalable tool with similar sensitivity to outdoor HLC. METHODOLOGY: The Anopheles trapping sensitivity of four baited proxy outdoor trapping methods-Furvela tent trap (FTT), host decoy trap (HDT), mosquito electrocuting traps (MET) and outdoor CDC light traps (OLT)-was assessed relative to HLC in a 5 × 5 replicated Latin square conducted over 25 nights in two villages of western Kenya. Indoor CDC light trap (ILT) was run in one house in each of the compounds with outdoor traps, while additional non-Latin square indoor and outdoor HLC collections were performed in one of the study villages. RESULTS: The MET, FTT, HDT and OLT sampled approximately 4.67, 7.58, 5.69 and 1.98 times more An. arabiensis compared to HLC, respectively, in Kakola Ombaka. Only FTT was more sensitive relative to HLC in sampling An. funestus in Kakola Ombaka (RR = 5.59, 95% CI 2.49-12.55, P < 0.001) and Masogo (RR = 4.38, 95% CI 1.62-11.80, P = 0.004) and in sampling An. arabiensis in Masogo (RR = 5.37, 95% CI 2.17-13.24, P < 0.001). OLT sampled significantly higher numbers of An. coustani in Kakola Ombaka (RR = 3.03, 95% CI 1.65-5.56, P < 0.001) and Masogo (RR = 2.88, 95% CI 1.15-7.22, P = 0.02) compared to HLC. OLT, HLC and MET sampled mostly An. coustani, FTT had similar proportions of An. funestus and An. arabiensis, while HDT sampled predominantly An. arabiensis in both villages. FTT showed close correlation with ILT in vector abundance for all three species at both collection sites. CONCLUSION: FTT and OLT are simple, easily scalable traps and are potential replacements for HLC in outdoor sampling of Anopheles mosquitoes. However, the FTT closely mirrored indoor CDC light trap in mosquito indices and therefore may be more of an indoor mimic than a true outdoor collection tool. HDT and MET show potential for sampling outdoor host-seeking mosquitoes. However, the traps as currently designed may not be feasible for large-scale, longitudinal entomological monitoring. Therefore, the baited outdoor CDC light trap may be the most appropriate tool currently available for assessment of outdoor-biting and malaria transmission risk.
Authors: R A Wirtz; F Zavala; Y Charoenvit; G H Campbell; T R Burkot; I Schneider; K M Esser; R L Beaudoin; R G Andre Journal: Bull World Health Organ Date: 1987 Impact factor: 9.408
Authors: Isaac Haggai Namango; Carly Marshall; Adam Saddler; Amanda Ross; David Kaftan; Frank Tenywa; Noely Makungwa; Olukayode G Odufuwa; Godfrey Ligema; Hassan Ngonyani; Isaya Matanila; Jameel Bharmal; Jason Moore; Sarah J Moore; Manuel W Hetzel Journal: Malar J Date: 2022-06-11 Impact factor: 3.469