Cargando…

Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda

BACKGROUND: The Plasmodium falciparum entomological inoculation rate (PfEIR) is a measure of exposure to infectious mosquitoes. It is usually interpreted as the number of P. falciparum infective bites received by an individual during a season or annually (aPfEIR). In an area of perennial transmissio...

Descripción completa

Detalles Bibliográficos
Autores principales: Kilama, Maxwell, Smith, David L, Hutchinson, Robert, Kigozi, Ruth, Yeka, Adoke, Lavoy, Geoff, Kamya, Moses R, Staedke, Sarah G, Donnelly, Martin J, Drakeley, Chris, Greenhouse, Bryan, Dorsey, Grant, Lindsay, Steve W
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2014
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4001112/
https://www.ncbi.nlm.nih.gov/pubmed/24656206
http://dx.doi.org/10.1186/1475-2875-13-111
_version_ 1782313706465525760
author Kilama, Maxwell
Smith, David L
Hutchinson, Robert
Kigozi, Ruth
Yeka, Adoke
Lavoy, Geoff
Kamya, Moses R
Staedke, Sarah G
Donnelly, Martin J
Drakeley, Chris
Greenhouse, Bryan
Dorsey, Grant
Lindsay, Steve W
author_facet Kilama, Maxwell
Smith, David L
Hutchinson, Robert
Kigozi, Ruth
Yeka, Adoke
Lavoy, Geoff
Kamya, Moses R
Staedke, Sarah G
Donnelly, Martin J
Drakeley, Chris
Greenhouse, Bryan
Dorsey, Grant
Lindsay, Steve W
author_sort Kilama, Maxwell
collection PubMed
description BACKGROUND: The Plasmodium falciparum entomological inoculation rate (PfEIR) is a measure of exposure to infectious mosquitoes. It is usually interpreted as the number of P. falciparum infective bites received by an individual during a season or annually (aPfEIR). In an area of perennial transmission, the accuracy, precision and seasonal distribution (i.e., month by month) of aPfEIR were investigated. Data were drawn from three sites in Uganda with differing levels of transmission where falciparum malaria is transmitted mainly by Anopheles gambiae s.l. Estimates of aPfEIR derived from human-landing catches – the classic method for estimating biting rates – were compared with data from CDC light traps, and with catches of knock down and exit traps separately and combined. METHODS: Entomological surveillance was carried out over one year in 2011/12 in three settings: Jinja, a peri-urban area with low transmission; Kanungu, a rural area with moderate transmission; and Nagongera, Tororo District, a rural area with exceptionally high malaria transmission. Three sampling approaches were used from randomly selected houses with collections occurring once a month: human-landing collections (eight houses), CDC light traps (100 houses) and paired knock-down and exit traps each month (ten houses) for each setting. Up to 50 mosquitoes per month from each household were tested for sporozoites with P. falciparum by ELISA. Human biting rate (HBR) data were estimated month by month. P. falciparum Sporozoite rate (PfSR) for yearly and monthly data and confidence intervals were estimated using the binomial exact test. Monthly and yearly estimates of the HBR, the PfSR, and the PfEIR were estimated and compared. RESULTS: The estimated aPfEIR values using human-landing catch data were 3.8 (95% Confidence Intervals, CI 0-11.4) for Jinja, 26.6 (95% CI 7.6-49.4) for Kanungu, and 125 (95% CI 72.2-183.0) for Tororo. In general, the monthly PfEIR values showed strong seasonal signals with two peaks from May-June and October-December, although the precise timing of the peaks differed between sites. Estimated HBRs using human-landing catches were strongly correlated with those made using CDC light traps (r(2) = 0.67, p < 0.001), and with either knock-down catches (r(2) = 0.56, p < 0.001) and exit traps (r(2) = 0.82, p < 0.001) or the combined catches (r(2) = 0.73, p < 0.001). Using CDC light trap catch data, the PfSR in Tororo was strongly negatively correlated with monthly HBR (r(2) = 0.44, p = 0.01). In other sites, no patterns in the PfSR were discernible because either the number P. falciparum of sporozoite positive mosquitoes or the total number of mosquitoes caught was too low. CONCLUSIONS: In these settings, light traps provide an alternative method for sampling indoor-resting mosquitoes to human-landing catches and have the advantage that they protect individuals from being bitten during collection, are easy to use and are not subject to collector bias. Knock-down catches and exit traps could also be used to replace human-landing catches. Although these are cheaper, they are subject to collector bias.
format Online
Article
Text
id pubmed-4001112
institution National Center for Biotechnology Information
language English
publishDate 2014
publisher BioMed Central
record_format MEDLINE/PubMed
spelling pubmed-40011122014-05-09 Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda Kilama, Maxwell Smith, David L Hutchinson, Robert Kigozi, Ruth Yeka, Adoke Lavoy, Geoff Kamya, Moses R Staedke, Sarah G Donnelly, Martin J Drakeley, Chris Greenhouse, Bryan Dorsey, Grant Lindsay, Steve W Malar J Methodology BACKGROUND: The Plasmodium falciparum entomological inoculation rate (PfEIR) is a measure of exposure to infectious mosquitoes. It is usually interpreted as the number of P. falciparum infective bites received by an individual during a season or annually (aPfEIR). In an area of perennial transmission, the accuracy, precision and seasonal distribution (i.e., month by month) of aPfEIR were investigated. Data were drawn from three sites in Uganda with differing levels of transmission where falciparum malaria is transmitted mainly by Anopheles gambiae s.l. Estimates of aPfEIR derived from human-landing catches – the classic method for estimating biting rates – were compared with data from CDC light traps, and with catches of knock down and exit traps separately and combined. METHODS: Entomological surveillance was carried out over one year in 2011/12 in three settings: Jinja, a peri-urban area with low transmission; Kanungu, a rural area with moderate transmission; and Nagongera, Tororo District, a rural area with exceptionally high malaria transmission. Three sampling approaches were used from randomly selected houses with collections occurring once a month: human-landing collections (eight houses), CDC light traps (100 houses) and paired knock-down and exit traps each month (ten houses) for each setting. Up to 50 mosquitoes per month from each household were tested for sporozoites with P. falciparum by ELISA. Human biting rate (HBR) data were estimated month by month. P. falciparum Sporozoite rate (PfSR) for yearly and monthly data and confidence intervals were estimated using the binomial exact test. Monthly and yearly estimates of the HBR, the PfSR, and the PfEIR were estimated and compared. RESULTS: The estimated aPfEIR values using human-landing catch data were 3.8 (95% Confidence Intervals, CI 0-11.4) for Jinja, 26.6 (95% CI 7.6-49.4) for Kanungu, and 125 (95% CI 72.2-183.0) for Tororo. In general, the monthly PfEIR values showed strong seasonal signals with two peaks from May-June and October-December, although the precise timing of the peaks differed between sites. Estimated HBRs using human-landing catches were strongly correlated with those made using CDC light traps (r(2) = 0.67, p < 0.001), and with either knock-down catches (r(2) = 0.56, p < 0.001) and exit traps (r(2) = 0.82, p < 0.001) or the combined catches (r(2) = 0.73, p < 0.001). Using CDC light trap catch data, the PfSR in Tororo was strongly negatively correlated with monthly HBR (r(2) = 0.44, p = 0.01). In other sites, no patterns in the PfSR were discernible because either the number P. falciparum of sporozoite positive mosquitoes or the total number of mosquitoes caught was too low. CONCLUSIONS: In these settings, light traps provide an alternative method for sampling indoor-resting mosquitoes to human-landing catches and have the advantage that they protect individuals from being bitten during collection, are easy to use and are not subject to collector bias. Knock-down catches and exit traps could also be used to replace human-landing catches. Although these are cheaper, they are subject to collector bias. BioMed Central 2014-03-21 /pmc/articles/PMC4001112/ /pubmed/24656206 http://dx.doi.org/10.1186/1475-2875-13-111 Text en Copyright © 2014 Kilama et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Methodology
Kilama, Maxwell
Smith, David L
Hutchinson, Robert
Kigozi, Ruth
Yeka, Adoke
Lavoy, Geoff
Kamya, Moses R
Staedke, Sarah G
Donnelly, Martin J
Drakeley, Chris
Greenhouse, Bryan
Dorsey, Grant
Lindsay, Steve W
Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda
title Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda
title_full Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda
title_fullStr Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda
title_full_unstemmed Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda
title_short Estimating the annual entomological inoculation rate for Plasmodium falciparum transmitted by Anopheles gambiae s.l. using three sampling methods in three sites in Uganda
title_sort estimating the annual entomological inoculation rate for plasmodium falciparum transmitted by anopheles gambiae s.l. using three sampling methods in three sites in uganda
topic Methodology
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4001112/
https://www.ncbi.nlm.nih.gov/pubmed/24656206
http://dx.doi.org/10.1186/1475-2875-13-111
work_keys_str_mv AT kilamamaxwell estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT smithdavidl estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT hutchinsonrobert estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT kigoziruth estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT yekaadoke estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT lavoygeoff estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT kamyamosesr estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT staedkesarahg estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT donnellymartinj estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT drakeleychris estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT greenhousebryan estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT dorseygrant estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda
AT lindsaystevew estimatingtheannualentomologicalinoculationrateforplasmodiumfalciparumtransmittedbyanophelesgambiaeslusingthreesamplingmethodsinthreesitesinuganda