Shifts in malaria vector species composition and transmission dynamics along the Kenyan coast over the past 20 years

Abstract Background Vector control through long-lasting insecticidal nets (LLINs) and focal indoor residual spraying (IRS) is a major component of the Tanzania national malaria control strategy. In mainland Tanzania, IRS has been conducted annually around Lake Victoria basin since 2007. Due to pyrethroid resistance in malaria vectors, use of pyrethroids for IRS was phased out and from 2014 to 2017 pirimiphos-methyl (Actellic® 300CS) was sprayed in regions of Kagera, Geita, Mwanza, and Mara. Entomological surveillance was conducted in 10 sprayed and 4 unsprayed sites to determine the impact of IRS on entomological indices related to malaria transmission risk. Methods WHO cone bioassays were conducted monthly on interior house walls to determine residual efficacy of pirimiphos-methyl CS. Indoor CDC light traps with or without bottle rotator were hung next to protected sleepers indoors and also set outdoors (unbaited) as a proxy measure for indoor and outdoor biting rate and time of biting. Prokopack aspirators were used indoors to capture resting malaria vectors. A sub-sample of Anopheles was tested by PCR to determine species identity and ELISA for sporozoite rate. Results Annual IRS with Actellic® 300CS from 2015 to 2017 was effective on sprayed walls for a mean of 7 months in cone bioassay. PCR of 2016 and 2017 samples showed vector populations were predominantly Anopheles arabiensis (58.1%, n = 4,403 IRS sites, 58%, n = 2,441 unsprayed sites). There was a greater proportion of Anopheles funestus sensu stricto in unsprayed sites (20.4%, n = 858) than in sprayed sites (7.9%, n = 595) and fewer Anopheles parensis (2%, n = 85 unsprayed, 7.8%, n = 591 sprayed). Biting peaks of Anopheles gambiae sensu lato (s.l.) followed periods of rainfall occurring between October and April, but were generally lower in sprayed sites than unsprayed. In most sprayed sites, An. gambiae s.l. indoor densities increased between January and February, i.e., 10–12 months after IRS. The predominant species An. arabiensis had a sporozoite rate in 2017 of 2.0% (95% CI 1.4–2.9) in unsprayed sites compared to 0.8% (95% CI 0.5–1.3) in sprayed sites (p = 0.003). Sporozoite rates were also lower for An. funestus collected in sprayed sites. Conclusion This study contributes to the understanding of malaria vector species composition, behaviour and transmission risk following IRS around Lake Victoria and can be used to guide malaria vector control strategies in Tanzania.

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Molecular Identification, Species Composition and Distribution Maps of Malaria Vector Species in SelectedCommunities in Benue State, North Central Nigeria.

IOSR Journal of Biotechnology and Biochemistry ◽

10.9790/264x-03020109 ◽

2017 ◽

Vol 03 (02) ◽

pp. 01-09 ◽

Cited By ~ 1

Author(s):

Aju- Ameh

Keyword(s):

Species Composition ◽

Molecular Identification ◽

Malaria Vector ◽

Vector Species ◽

North Central ◽

Distribution Maps ◽

Species Composition And Distribution

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Malaria vector species composition and entomological indices following indoor residual spraying in regions bordering Lake Victoria, Tanzania

10.21203/rs.3.rs-27952/v3 ◽

2020 ◽

Author(s):

Charles Elias Kakilla ◽

Alphaxard Manjurano ◽

Karen Nelwin ◽

Jackline Martin ◽

Fabian Mashauri ◽

...

Keyword(s):

Species Composition ◽

Vector Control ◽

Malaria Vector ◽

Lake Victoria ◽

Indoor Residual Spraying ◽

Transmission Risk ◽

Malaria Vectors ◽

Vector Species ◽

Sporozoite Rate ◽

Pirimiphos Methyl

Abstract BackgroundVector control through long-lasting insecticidal nets (LLINs) and focal indoor residual spraying (IRS) is a major component of the Tanzania national malaria control strategy. In mainland Tanzania, IRS has been conducted annually around Lake Victoria basin since 2007. Due to pyrethroid resistance in malaria vectors, use of pyrethroids for IRS was phased out and from 2014 to 2017 pirimiphos-methyl (Actellic® 300CS) was sprayed in regions of Kagera, Geita, Mwanza, and Mara. Entomological surveillance was conducted in 10 sprayed and 4 unsprayed sites to determine the impact of IRS on entomological indices related to malaria transmission risk.MethodsWHO cone bioassays were conducted monthly on interior house walls to determine residual efficacy of pirimiphos-methyl CS. Indoor CDC light traps with or without bottle rotator were hung next to protected sleepers indoors and also set outdoors (unbaited) as a proxy measure for indoor and outdoor biting rate and time of biting. Prokopack aspirators were used indoors to capture potentially resting malaria vectors. A sub-sample of Anopheles was tested by PCR to determine species identity and ELISA for sporozoite rate. ResultsAnnual IRS with Actellic® 300CS from 2015 to 2017 was effective on sprayed walls for a mean of 7 months in cone bioassay. PCR of 2016 and 2017 samples showed vector populations were predominantly Anopheles arabiensis (58.1%, n=4,403 IRS sites, 58%, n=2,441 unsprayed sites). There was a greater proportion of Anopheles funestus sensu stricto (s.l) in unsprayed sites (20.4%, n=858) than in sprayed sites (7.9%, n=595) and fewer Anopheles parensis (2%, n=85 unsprayed, 7.8%, n=591 sprayed). Biting peaks of Anopheles gambiae sensu lato (s.l.) followed periods of rainfall occurring between October and April, but were generally lower in sprayed sites than unsprayed. In most sprayed sites, An. gambiae s.l. indoor densities increased between January and February, i.e., 10-12 months after IRS. The predominant species An. arabiensis had a sporozoite rate in 2017 of 2.0% (95% CI: 1.4-2.9) in unsprayed sites compared to 0.8% (95% CI: 0.5-1.3) in sprayed sites (p=0.003). Sporozoite rates were also lower for An. funestus collected in sprayed sites. ConclusionThis study contributes to the understanding of malaria vector species composition, behaviour and transmission risk following IRS around Lake Victoria and can be used to guide malaria vector control strategies in Tanzania.

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Malaria vector species composition and relative abundance in Mutare and Mutasa districts, Zimbabwe

Journal of Entomological and Acarological Research ◽

10.4081/jear.2015.4955 ◽

2015 ◽

Vol 47 (3) ◽

pp. 79 ◽

Cited By ~ 7

Author(s):

S. Sande ◽

M. Zimba ◽

P. Chinwada ◽

H.T. Masendu ◽

A. Makuwaza

Keyword(s):

Species Composition ◽

Relative Abundance ◽

Malaria Vector ◽

Sibling Species ◽

Mosquito Species ◽

Sensu Stricto ◽

Malaria Vectors ◽

Morphological Identification ◽

Vector Species ◽

Vector Behaviour

Regular entomological monitoring is important to determine changes in mosquito species composition and relative densities of malaria vectors in relation to vector control interventions. A study to gain insights into malaria vector species composition and relative abundance was undertaken in Mutare and Mutasa districts, Zimbabwe. Two methods; indoor resting catches and larval sampling were used to collect indoor resting adults and larvae from May 2013 to April 2014. Mosquitoes collected as adults and reared from larvae that were identified morphologically as potential malaria vectors were further processed to sibling species by polymerase chain reaction (PCR). Morphological identification of anopheline mosquitoes showed presence of two complexes: An. funestus and An. gambiae. The total number of female members of the An. funestus group and An. gambiae complex collected by both methods from the two sites was 840 and 31 respectively. Malaria vector species of both complexes were more abundant in Mutare than in Mutasa. The PCR-based assays showed the presence of four sibling species: An. funestus sensu stricto (90.8%, 267/294) and An. leesoni (5.1%, 15/294), of An. funestus group; An. arabiensis (41.9%, 13/31) and An. quadriannulatus (48.4%, 15/31) of the An. gambiae complex. About 4% and 5% of specimens of An. gambiae complex and An. funestus group respectively did not amplify. Of the two identified malaria vector sibling species, An. funestus sensu stricto was more abundant (95.4%, 267/280) than An. arabiensis (4.6%, 13/280), suggesting the replacement to secondary vector of An. arabiensis, which was previously the predominant vector species. An. funestus sensu stricto and An. arabiensis, the most important vectors of human malaria were identified in this study, but their resting and biting habits as well as insecticide susceptibility are unclear. Further studies on vector behaviour are therefore recommended.

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Anopheline Mosquito Species Composition, Kdr Mutation Frequency, and Parasite Infectivity Status in Northern Tanzania

Journal of Medical Entomology ◽

10.1093/jme/tjz245 ◽

2020 ◽

Vol 57 (3) ◽

pp. 933-938 ◽

Cited By ~ 1

Author(s):

Eliningaya J Kweka ◽

Humphrey D Mazigo ◽

Lucile J Lyaruu ◽

Emmanuel A Mausa ◽

Nelius Venter ◽

...

Keyword(s):

Species Composition ◽

Malaria Transmission ◽

Malaria Vector ◽

Mosquito Species ◽

Malaria Prevalence ◽

Vector Species ◽

Anopheline Mosquito ◽

Larval Stages ◽

Northern Tanzania ◽

Homozygous Resistant

Abstract The scaling-up of malaria control interventions in northern Tanzania has resulted in a decline in malaria prevalence and vector species composition. Despite this achievement, residual malaria transmission remains a concern in the area. The main aim of this study was to investigate malaria vector species composition, parasite infectivity rates, and the presence of insecticide knockdown resistance (kdr) mutations in three sites that have experienced a significant decline in malaria in northern Tanzania. Adult mosquitoes were sampled using light traps in houses and hand-aspirators in cowsheds, whereas the standard dipping method was used for sampling mosquito larvae. Adult mosquitoes identified as Anopheles gambiae s.l. and An. funestus s.l. and larval stages III and IV of An. gambiae s.l. were stored in absolute ethanol for further laboratory molecular identification. The identified species in the An. gambiae complex were An. gambiae s.s., An. merus, An. quadriannulatus, and An. arabiensis, whereas the An. funestus group comprised An. funestus s.s., An. rivulorum, and An. leesoni. For An. gambiae s.s. analyzed from Zeneth, 47.6% were kdr-East homozygous susceptible, 35.7% kdr-East heterozygous resistant, 9.6% kdr-East homozygous resistant, and 7.1% undefined, whereas specimens from Kwakibuyu were 45.5% kdr-East homozygous susceptible, 32.7% kdr-East heterozygous resistant, 16.3% kdr-East homozygous resistant, and 5.5% undefined. There were no kdr-West alleles identified from any specimen. The overall malaria parasite infectivity rate was 0.75%. No infections were found in Moshi. The findings indicate that populations of the major malaria vector mosquitoes are still present in the study area, with An. funestus taking a lead in malaria transmission.

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Malaria vector species composition and entomological indices following indoor residual spraying in regions bordering Lake Victoria, Tanzania

10.21203/rs.3.rs-27952/v2 ◽

2020 ◽

Author(s):

Charles Elias Kakilla ◽

Alphaxard Manjurano ◽

Karen Nelwin ◽

Jackline Martin ◽

Fabian Mashauri ◽

...

Keyword(s):

Species Composition ◽

Vector Control ◽

Malaria Vector ◽

Lake Victoria ◽

Indoor Residual Spraying ◽

Transmission Risk ◽

Vector Species ◽

Sporozoite Rate ◽

Pirimiphos Methyl ◽

The Impact

Abstract Background: Vector control through long lasting insecticidal nets and focal indoor residual spraying (IRS) is a major component of the Tanzania national malaria control strategy. In mainland Tanzania, IRS has been conducted annually around Lake Victoria basin since 2007. Due to pyrethroid resistance in malaria vectors, use of pyrethroids for IRS was phased out and from 2014 to 2017 pirimiphos-methyl (Actellic® 300CS) was sprayed in regions of Kagera, Geita, Mwanza and Mara. Entomological surveillance was conducted in ten sprayed and four unsprayed sites to determine the impact of IRS on entomological indices related to malaria transmission risk. Methods: WHO Cone bioassays were conducted monthly on interior house walls to determine residual efficacy of pirimiphos-methyl CS. Indoor CDC light traps with or without bottle rotator were hung next to protected sleepers indoors and also set outdoors (un-baited) as a proxy measure for indoor and outdoor biting rate and time of biting. Prokopack aspirators were used indoors to capture potentially resting malaria vector. A sub-sample of Anopheles were tested by PCR to determine species identity and ELISA for sporozoite rate. Results: Annual IRS with Actellic® 300CS from 2015 to 2017 was effective on sprayed walls for a mean of 7 months in cone bioassay. PCR of 2016 and 2017 samples showed vector populations were predominantly An. arabiensis (58.1%, n=4,403 IRS sites, 58%, n=2,441 unsprayed sites). There was a greater proportion of An. funestus s.s. in unsprayed sites (20.4%, n=858) than sprayed sites (7.9%, n=595) and fewer An. parensis (2%, n=85 unsprayed, 7.8%, n=591 sprayed). Biting peaks of An. gambiae s.l. followed periods of rainfall occurring between October and April, but were generally lower in sprayed sites than unsprayed. In most sprayed sites, An. gambiae s.l. indoor densities increased between January and February, i.e. 10-12 months after IRS. The predominant species An. arabiensis had a sporozoite rate in 2017 of 2.0% (95% CI: 1.4-2.9) in unsprayed sites compared to 0.8% (95% CI: 0.5-1.3) in sprayed sites (p=0.003). Sporozoite rates were also lower for An. funestus collected in sprayed sites. Conclusion: This study contributes to the understanding of malaria vector species composition, behavior and transmission risk following IRS around Lake Victoria and can be used to guide malaria vector control strategies in Tanzania.

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Historical discarding in Mediterranean fisheries: a fishers' perception

ICES Journal of Marine Science ◽

10.1093/icesjms/fsv141 ◽

2015 ◽

Vol 72 (9) ◽

pp. 2600-2608 ◽

Cited By ~ 21

Author(s):

Dimitrios Damalas ◽

Christos D. Maravelias ◽

Giacomo C. Osio ◽

Francesc Maynou ◽

Mario Sbrana ◽

...

Keyword(s):

Species Composition ◽

Market Demand ◽

Sampling Protocol ◽

The Past ◽

Regulatory Constraints ◽

Fishing Strategies ◽

Commercially Important ◽

Trawl Fisheries ◽

Important Fish

Abstract Discarding of commercially important fish species in the bottom trawl fisheries in the northern Mediterranean Sea was investigated by soliciting the long-term recollections of fishers engaged or formerly engaged in such fisheries. The main aim of our investigation was to describe the prevalence of discarding and its evolution over the past 70 years using information gathered through individual questionnaire-based interviews with fishers from ports in Spain, Italy, and Greece, following a standardized sampling protocol. Although it proved impossible to derive absolute estimates of the volume of discarded catches over the period investigated, we conclude that over the past 70 years, discarding as a practice has gradually increased in the northern Mediterranean trawl fisheries and has been accompanied by a shift in the species composition of the discarded catch. While discarding can occur for a number of reasons, our investigations indicate that discarding in the past was mostly driven by market demand, but recent legal and regulatory constraints have led to changes in fishing strategies and became a significant reason for discards.

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Thermal limits of wild and laboratory strains of two African malaria vector species, Anopheles arabiensis and Anopheles funestus

Malaria Journal ◽

10.1186/1475-2875-11-226 ◽

2012 ◽

Vol 11 (1) ◽

Cited By ~ 34

Author(s):

Candice L Lyons ◽

Maureen Coetzee ◽

John S Terblanche ◽

Steven L Chown

Keyword(s):

Malaria Vector ◽

Anopheles Arabiensis ◽

Anopheles Funestus ◽

Vector Species ◽

Thermal Limits

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Effect of the Gabčíkovo Waterworks (Slovakia) on riparian floodplain forest ecosystems in the Danube inland delta: vegetation dynamics and trends

Biologia ◽

10.1515/biolog-2017-0082 ◽

2017 ◽

Vol 72 (7) ◽

Cited By ~ 2

Author(s):

Mária Petrášová-Šibíková ◽

Igor Matečný ◽

Eva Uherčíková ◽

Peter Pišút ◽

Silvia Kubalová ◽

...

Keyword(s):

Species Composition ◽

Forest Ecosystems ◽

Supply System ◽

Floodplain Forest ◽

Soil Conditions ◽

Plant Species Composition ◽

Forest Species ◽

The Past ◽

The Impact ◽

Rare Opportunity

AbstractHuman alteration of watercourses is global phenomenon that has had significant impacts on local ecosystems and the services they provide. Monitoring of abiotic and biotic changes is essential to mitigating long-lasting effects, and the 23-year dataset from the Gabčíkovo Waterworks provided a rare opportunity to assess the impact of groundwater regimes on vegetation. The main aim of this study was to describe the effect of the Gabčíkovo Waterworks on vegetation structure and species composition of the adjacent riparian floodplain forests over the past 23 years. The results are based on studies of three permanent monitoring plots (PMPs) located in the Danube inland delta – two outside (PMP 1 and 3) and one (PMP 2) fully under the influence of the artificial supply system. Our results demonstrate that the Danube inland delta was negatively affected by the Gabčíkovo construction, particularly for sites outside of the artificial supply system. There was a significant decrease in soil moisture and increase in nitrogen at both external PMPs (1 and 3). Alter soil conditions were accompanied by negative changes in plant species composition demonstrated by decreases in the number of typical floodplain forest species that are characteristic for the alliance

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