Entomologic Inoculation Rates of Anopheles arabiensis in Southwestern Ethiopia

Massebo, Fekadu; Balkew, Meshesha; Gebre-Michael, Teshome; Lindtjørn, Bernt

doi:10.4269/ajtmh.12-0745

Cited by 56 publications

(85 citation statements)

References 33 publications

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“…The sporozoite rate of An. arabiensis for P. falciparum in Gato was 0.4%, which is similar to 0.32% from Chano-Mille in southern Ethiopia [23] and 0.3% in the south-central Ethiopia [21]. The P. falciparum CSP rate of An.…”

Section: Discussionmentioning

confidence: 61%

“…arabiensis was higher than the annual EIR of 3.66 infective bites per person per year from central highlands of southern Ethiopia [21]. However, it may be difficult to compare with the findings of a study in south-western Ethiopia which was 17.1 infective bites per person per year [23] since the EIR estimations of the current study were for nine months. The EIR of 8.6 in Gato is enough to sustain malaria transmission in the area, and hence the malaria control interventions should be strengthened to reduce the transmission and for future malaria elimination.…”

Section: Discussionmentioning

confidence: 81%

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Variation in species composition and infection rates of Anopheles mosquitoes at different altitudinal transects, and the risk of malaria in the highland of Dirashe Woreda, south Ethiopia

2017

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BackgroundThe transmission of malaria is heterogeneous, and varies due to altitude. The information on whether the transmission of malaria is indigenous or imported to highland areas is scarce. Therefore, this study aimed to assess the species composition and infection rates of Anopheles at different altitudinal transects, and the risk of malaria if any in the highland of Dirashe Woreda, South Ethiopia.MethodsThis study was conducted in Gato (low altitude; average elevation of 1273 m), Onota (mid-altitude; average elevation of 1707 m) and Layignaw-Arguba (high altitude; average elevation of 2337 m) from August 2015 to April 2016. Anopheles mosquitoes were sampled using Centers for Disease Control and Prevention (CDC) light traps from thirty houses (ten houses from each village). The circum-sporozoite proteins (CSPs) rate and entomological inoculation rate (EIR) of Anopheles mosquitoes were estimated. For the epidemiological survey, malaria cases were collected from laboratory registration books of selected health facilities from (August 2015-April 2016). A cross-sectional survey was done to collect data on malaria vector control activities in each village (August-September 2015).ResultsOne thousand two hundred sixty-eight Anopheles mosquitoes comprising Anopheles arabiensis, An. demeilloni, An. cinereus, An. pharoensis, An. funestus-group, An. pretoriensis, An. christyi, An. ardensis and An. tenebrosus were identified in the study area. Anopheles arabiensis was the dominant species in Gato, whereas An. demeilloni was the dominant species in Layignaw-Arguba. Five mosquitoes, three An. arabiensis from Gato and two An. demeilloni from Layignaw-Arguba, were positive for Plasmodium falciparum CSPs. Plasmodium falciparum CSP rate was 0.4% (95% CI: 0.08–1.15) for An. arabiensis in Gato, and it was 0.64% (95% CI: 0.08–2.3) for An. demeilloni from Layignaw-Arguba. The P. falciparum EIR of An. arabiensis was 8.6 (95% CI: 2.4–33.4) infectious bites/person/nine-months in Gato. Plasmodium falciparum parasite was dominant in Gato (88%) and Onota (57.5%), whereas in Layignaw-Arguba P. vivax (59.4%) occurred most frequently. Increased malaria cases were observed in children age 5–14 years in Gato (P < 0.05), whereas in Onota and Layignaw-Arguba there was no statistically significant difference in malaria cases among the age groups. Households owning at least one long lasting insecticidal net were 92.7% in the study area, and 77.6% slept under the net during the preceding night of the survey. About 64.4% of the households in Gato were protected by the indoor residual spray. However, the spraying was done when the density of local malaria vectors was low.ConclusionIncrimination of Plasmodium CSP positive Anopheles species and the presence of malaria in children under five years in high altitude Layignaw-Arguba may justify the existence of indigenous malaria transmission and the need for effective malaria control. Further investigation and confirmation using more sensitive molecular techniques are however needed to consider An. dem...

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Section: Discussionmentioning

confidence: 61%

Section: Discussionmentioning

confidence: 81%

Variation in species composition and infection rates of Anopheles mosquitoes at different altitudinal transects, and the risk of malaria in the highland of Dirashe Woreda, south Ethiopia

2017

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“…The study area has an entomological inoculation rate of 17.1 infectious bites per person per year. 13 Malaria infection is primary due to P. falciparum. Subsistence farming and fishing are the main occupation in the area.…”

Section: Methods and Materials Study Area And Periodmentioning

confidence: 99%

<p>Prevalence of Malaria and Associated Risk Factors Among Febrile Children Under Five Years: A Cross-Sectional Study in Arba Minch Zuria District, South Ethiopia</p>

Abossie¹,

Yohanes²,

Nedu³

et al. 2020

IDR

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Background: Malaria is a major public health problem affecting humans, particularly in the tropics and subtropics. Children under 5 years old are the group most vulnerable to malaria infection because of less developed immune system. Countries have set targets that led to control and eliminate malaria with interventions of the at-risk groups, however malaria infection remained a major public health challenge in endemic areas. Objective: This study aimed at determining the magnitude of malaria and associated factors among febrile children under 5 years old in Arba Minch "Zuria" district. Methods: The study was conducted from April to May 2017. Blood samples were collected from 271 systematically selected febrile children under 5 years old. Thin and thick blood smears were prepared, stained with 10% Giemsa and examined under light microscope. Data of sociodemographic data, determinant factors, and knowledge and prevention practices of malaria were collected using a pretested structured questionnaire. Data were analyzed using binomial and multinomial regression model in SPSS ® Statistics program, version 25. Results: Among those febrile children, 22.1% (60/271) were positive for malaria; 50.0%, 48.33% and 1.66% of them were positive for Plasmodium falciparum, Plasmodium vivax and mixed infections of both parasites, respectively. Malaria infection was associated with nearby presence of stagnant water to resident areas (AOR=8.19; 95%CI: 3.62-18.5, P<0.0001). Children who slept under insecticide-treated mosquito nets (ITNs) were more likely to be protected from malaria infection than those did not sleep under an ITNs (AOR=9.65; 95%CI: 4.623-20.15, P<0.0001). Conclusion: Malaria infection is highly prevalent in children aged between 37 and 59 months old, in Arba Minch "Zuria" district. The proximity of residence to stagnant water and the use of ITNs are the most dominant risk factor for malaria infection. Improved access to all malaria interventions is needed to interrupt the transmission at the community level with a special focus on the risk groups.

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“…arabiensis was confirmed to be the only member of An. gambiae species complex in the study area [25, 31] and also in nearby areas [28, 29]. In order to determine malaria sporozoite infection rate, the head and thorax of each mosquito (n = 6295) were carefully separated from the abdomen and tested for the presence of Plasmodium falciparum and Plasmodium vivax circumsporozoite proteins (CSP) by the direct enzyme-linked immunosorbent assay (ELISA) [33].…”

Section: Methodsmentioning

confidence: 99%

“…arabiensis in highland areas of south-central Ethiopia based on a conversion factor for LTC vs. HLC of 1.91, determined for this species in Zambia [27]. Likewise, Massebo et al [29] estimated annual EIR for the same species in Chano, south-western Ethiopia, using 1.605 a factor determined in Tanzania [2]. The efficiency of a collection method can vary according to the composition of the mosquito species present, mosquito densities, availability of alternative hosts, and city lighting [8], therefore, it is difficult to extrapolate a conversion factor from one local epidemiological situation to another.…”

Section: Introductionmentioning

confidence: 99%

Comparison of two adult mosquito sampling methods with human landing catches in south-central Ethiopia

Kenea

Balkew

Tekie

et al. 2017

Malar J

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BackgroundThe human landing catch (HLC) is the standard reference method for measuring human exposure to mosquito bites. However, HLC is labour-intensive, exposes collectors to infectious mosquito bites and is subjected to collector bias. These necessitate local calibration and application of alternative methods. This study was undertaken to determine the relative sampling efficiency (RSE) of light traps with or without yeast-produced carbon dioxide bait vs. HLC in south-central Ethiopia.MethodsThe experiment was conducted for 39 nights in a 3 × 3 Latin square randomized design with Anopheles arabiensis as the target species in the period between July and November 2014 in Edo Kontola village, south-central Ethiopia. Center for Disease Control and Prevention light trap catches (LTC) and yeast-generated carbon dioxide-baited light trap catches (CB-LTC) were each evaluated against HLC. The total nightly mosquito catches for each Anopheles species in either method was compared with HLC by Pearson correlation and simple linear regression analysis on log-transformed [log10(x + 1)] values. To test if the RSE of each alternative method was affected by mosquito density, the ratio of the number of mosquitoes in each method to the number of mosquitoes in HLC was plotted against the average mosquito abundance.ResultsOverall, 7606 Anopheles females were collected by the three sampling methods. Among these 5228 (68.7%) were Anopheles ziemanni, 1153 (15.2%) An. arabiensis, 883 (11.6%) Anopheles funestus s.l., and 342 (4.5%) Anopheles pharoensis. HLC yielded 3392 (44.6%), CB-LTC 2150 (28.3%), and LTC 2064 (27.1%) Anopheles females. The RSEs of LTC and HLC for An. arabiensis were significantly correlated (p < 0.001) and density independent (p = 0.65). However, for outdoor collection of the same species, RSEs of LTC and CB-LTC were density dependent (p < 0.001). It was estimated that on average, indoor LTC and CB-LTC each caught 0.35 and 0.44 times that of indoor HLC for An. arabiensis respectively.ConclusionsResults showed that HLC was the most efficient method for sampling An. arabiensis. LTC can be used for large-scale indoor An. arabiensis surveillance and monitoring when it is difficult to use HLC. CB-LTC does not substantially improve sampling of this major vector compared to LTC in this setting. Trial registration PACTR201411000882128 (retrospectively registered 8 September, 2014)

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Entomologic Inoculation Rates of Anopheles arabiensis in Southwestern Ethiopia

Cited by 56 publications

References 33 publications

Variation in species composition and infection rates of Anopheles mosquitoes at different altitudinal transects, and the risk of malaria in the highland of Dirashe Woreda, south Ethiopia

Variation in species composition and infection rates of Anopheles mosquitoes at different altitudinal transects, and the risk of malaria in the highland of Dirashe Woreda, south Ethiopia

<p>Prevalence of Malaria and Associated Risk Factors Among Febrile Children Under Five Years: A Cross-Sectional Study in Arba Minch Zuria District, South Ethiopia</p>

Comparison of two adult mosquito sampling methods with human landing catches in south-central Ethiopia

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