High entomological inoculation rate of malaria vectors in area of high coverage of interventions in southwest Ethiopia: Implication for residual malaria transmission

Abraham, Misrak; Massebo, Fekadu; Lindtjørn, Bernt

doi:10.1016/j.parepi.2017.04.003

Cited by 46 publications

(49 citation statements)

References 35 publications

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“…The expansion of maize farming (maize pollen) in the district is enhanced mosquito populations that can participate directly in cycles of human biting and malaria transmission [90]. On the contrary, the overall sporozoite rate of all Anopheles species in this study is very lower as compared to other reports from different parts of Ethiopia [57,73,91,92,93] and in Africa [82,94,95]. This very low all over sporozoite rate may be due to the cumulative effects of intensive usage of LLINs and application of IRS, resulted in a decline in human-vector contact, a decrease in the number of mosquitoes and a reduction entomological inoculation rate into people [96][97][98][99].…”

Section: Discussioncontrasting

confidence: 62%

Species Diversity and Entomological Inoculation Rate of Anophelines Mosquitoes in an Epidemic Prone Areas of Bure District, Northwestern Ethiopia

Wassie¹,

Gebru²,

Degaga³

2020

Preprint

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Background: Malaria is the leading health problem in Ethiopia. The country has been prevented malaria vectors mostly using long-lasting insecticide-treated nets, the application of indoor residual spraying chemicals, and source reductions. Before interventions, identifying the responsible malaria vector in disease transmission (sporozoite rate) is very vital; hence, the present study was designed to assess species diversity and entomological inoculation rate of Anopheles mosquito in Bure district, Northwest Ethiopia. Methods: Adult mosquitoes were collected from July 2015 to June 2016 using the center for disease control and prevention light traps, pyrethrum spray catches, and artificial pit shelters. Mosquitoes were morphologically identified. Following this, An. gambiae s.l was identified molecularly. Head-thorax sporozoite infectivity of the adult female Anopheles mosquitoes was assessed using enzyme-linked immunosorbent assays. Results: Morphologically, nine species of the genus Anopheles were identified in the three villages, composed of Anopheles demeilloni, An. arabiensis, An. funestus, An. coustani, An. squamosus, An. cinereus, An. pharoensis, An. rupicolus, and An. natalensis. Of these species, An. demeilloni was the most predominant, whereas An. cinereus, An. rupicolus and An. natalensis were the least representative species (p < 0.0001). Greater number of adult Anopheles mosquitoes were collected in Shnebekuma, non-irrigated villages than non- irrigated village (Workmidr) and irrigated village (Bukta) (p < 0.0001). The overall Plasmodium infective rate (P. falciparum and P. vivax) in the district was 0.31%. The overall annual sporozoite rate in non-irrigated villages (Shnebekuma and Workmidr) was 0.35%, whereas zero in irrigated village (Bukta). The overall estimated EIR of Anopheles mosquitoes was 5.7 infectious bites /person /year for both P. falciparum and P. vivax in the district. The annual EIR Anopheles species in non-irrigated villages was 5.65 ib/p/y, which was higher than irrigated village (0 ib/p/y). Conclusions: Both the primary (An. arabiensis) and secondary (An. funestus and An. pharoensis) malaria vectors of Ethiopia were identified in the three villages. Three of Anopheles species, An. arabiensis, An. funestus, and An. coustani were found to be infected only in irrigated villages. Source reduction and proper usage of long-lasting insecticide nets and indoor residual spraying could be implemented in the non- irrigated villages to cut the vector abundance and EIR.

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Section: Discussioncontrasting

confidence: 62%

Species Diversity and Entomological Inoculation Rate of Anophelines Mosquitoes in an Epidemic Prone Areas of Bure District, Northwestern Ethiopia

Wassie¹,

Gebru²,

Degaga³

2020

Preprint

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“…This is particularly the case here because, although the zoophilic mosquitoes were not found to have sporozoites, published evidence shows that An. pharoensis can be sporozoite-positive [13,14]. Similarly, the presence of animals and humans in the same house increased biting from malaria vectors (pulling potential of animals) whereas those people living in separate sheds experienced reduced the human biting rates of malaria mosquitoes [15].…”

Section: Discussionmentioning

confidence: 99%

“…pharoensis breeding, and small water bodies created by hoof prints of cattle and hippopotami make the lakeshore a potential mosquito breeding site. This species prefers breeding habitats with permanent water bodies and vegetation and is widely distributed in Ethiopia [6,14,20]. No sporozoite-infected An.…”

Section: Discussionmentioning

confidence: 99%

Exploring the impact of cattle on human exposure to malaria mosquitoes in the Arba Minch area district of southwest Ethiopia

2020

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Background: The success of indoor interventions that target mosquitoes for malaria control is partially dependent on early evening and outdoor biting behaviours of mosquito vectors. In southwest Ethiopia, people and cattle live in proximity, which calls to investigate whether the presence of cattle increase or decrease bites from malaria mosquito vectors. This study assessed both host-seeking and overnight activity of malaria mosquito vectors given the presence or absence of cattle in Chano Mille village, Arba Minch district, Ethiopia. Methods: Anopheles species density and activity time was compared when a calf was: (i) placed inside; (ii) 1 m away from; or (iii) absent from a tent with a human volunteer resting insides using hourly human landing catches (HLC) conducted from 18:00-0:00 h for 3 months. This trial was performed close to the shore of the Lake Abaya to minimize the interference of other animals on mosquito movement. The overnight activity of malaria vectors was assessed within a Chano village from 18:00-6:00 h with collections carried out both indoors and outdoors by HLC. Generalized estimating equations were used to statistically assess differences. Results: Anopheles pharoensis was significantly more prevalent when a calf was present either inside (42%, P < 0.001), or adjacent to (46%, P = 0.002) a tent relative to a tent without a calf present. The presence of a calf did not affect densities of the primarily anthropophilic species A. gambiae (s.l.), or An. tenebrosus. Anopheles gambiae (s.l.) (P < 0.001) and An. pharoensis (P = 0.015) both had a tendency for early evening biting between 19:00 h and 20:00 h. Anopheles gambiae (s.l.) was mainly biting humans outdoors in the village. Conclusions: The presence of calves within and close to human dwellings acts to draw malaria mosquitoes toward the human occupant with the potential to increase their risk of malaria. Hence, deployment of cattle far from human residence could be recommended to reduce human exposure. Outdoor and early evening biting could threaten the success of current indoor-based interventions. Hence, tools could be designed to reduce this threat.

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“…In 2011, pyrethroid-based IRS was replaced by carbamate, due to the high level of resistance in malaria vector populations. Currently, carbamate insecticides are in use for IRS and the principal malaria vector, Anopheles arabiensis is susceptible to these insecticides in most parts of the country [ 5 , 6 ].…”

Section: Introductionmentioning

confidence: 99%

Wall-type and indoor residual spraying application quality affect the residual efficacy of indoor residual spray against wild malaria vector in southwest Ethiopia

Desalegn

Wegayehu

Massebo

2018

Malar J

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BackgroundResidual efficacy of indoor residual spray may vary with different spray quality and wall surfaces types. This study evaluated the impact of spray quality and wall surface types on residual efficacy of propoxur against wild Anopheles gambiae sensu lato (s.l.) in southwest Ethiopia.MethodsThirty houses of different mud wall surfaces (10 smooth, 10 rough, 10 painted) were selected and randomly allocated into routine and standard spray. The routine spray was conducted by district health office as usual, while the standard spray was done by strictly following guidelines. Three control houses were selected from unsprayed nearby semi-urban. Wild An. gambiae s.l. were used for wall bioassay tests. Two-way mixed model analysis of variance was used to analyse the data. The mean variation between wall and spray types was compared by post hoc analysis of IBM SPSS version 20.ResultsOn standard spray, knockdown rate was 95.3% on painted, 82% on smooth and 72.5% on rough surface at week 17 of post-spray, whereas on routine spray it was 82.7% on painted, 48.7% on smooth and 60% on rough surface. On standard spray, mortality rate of An. gambiae s.l. was 99.3% on painted surface, 90% on smooth and 80% on rough surface. On routine spray, it was 89.3% on painted, 61.3% on smooth and 65% on rough surface at week 17 of post-spray. The painted wall surface showed the highest knockdown rate (86.4–100%) on standard and (73.8–91.5%) routine spray; mortality rate was more than 80% on both spray types during the 17 weeks of follow-up regardless of spray types. The lower mortality rate and residual effect was observed on routine smooth and rough wall surfaces. The residual efficacy of propoxur was > 80% at week 17 on standard spray regardless of the wall types and it was < 80% on routine spray except painted wall surface.ConclusionThe painted wall surface and standard spray showed better residual efficacy. Therefore, it is recommended to consider the wall surface available in the community to estimate the residual lifespan of the insecticide, and strictly to follow the spray guideline to improve the effectiveness of indoor residual spray.

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High entomological inoculation rate of malaria vectors in area of high coverage of interventions in southwest Ethiopia: Implication for residual malaria transmission

Cited by 46 publications

References 35 publications

Species Diversity and Entomological Inoculation Rate of Anophelines Mosquitoes in an Epidemic Prone Areas of Bure District, Northwestern Ethiopia

Species Diversity and Entomological Inoculation Rate of Anophelines Mosquitoes in an Epidemic Prone Areas of Bure District, Northwestern Ethiopia

Exploring the impact of cattle on human exposure to malaria mosquitoes in the Arba Minch area district of southwest Ethiopia

Wall-type and indoor residual spraying application quality affect the residual efficacy of indoor residual spray against wild malaria vector in southwest Ethiopia

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