Treatment of pigs with endectocides as a complementary tool for combating malaria transmission by Anopheles farauti (s.s.) in Papua New Guinea

Pasay, Cielo; Yakob, Laith; Meredith, Hannah R.; Stewart, Romal; Mills, Paul C.; Dekkers, Milou H.; Ong, Oselyne; Llewellyn, Stacey; Hugo, Leon E.; McCarthy, James S.; Devine, Gregor J.

doi:10.1186/s13071-019-3392-0

Cited by 22 publications

(19 citation statements)

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“…These drugs are not restricted to www.nature.com/scientificreports www.nature.com/scientificreports/ human use and several studies have documented their efficacy in controlling mosquito vectors when applied to local livestock 40,41 . Models have demonstrated when and where this technology could be most successful either as a standalone tool 42,43 or as part of an integrated vector management programme 44,45 . For these projection efforts to be built upon to inform operational control, reliable data are required for describing: how bites are distributed among different host species; how host choice is impacted by local host availability; and, how this behaviour is impacted in the presence of different control measures (e.g.…”

Section: Discussionmentioning

confidence: 99%

Evidence of extrinsic factors dominating intrinsic blood host preferences of major African malaria vectors

Orsborne

Mohammed

Jeffries

et al. 2020

Sci Rep

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one of the key determinants of a haematophagous vector's capacity to transmit pathogens is its selection of which host to secure a blood meal from. This choice is influenced by both intrinsic (genetic) and extrinsic (environmental) factors, but little is known of their relative contributions. Blood fed Anopheles mosquitoes were collected from a malaria endemic village in Ghana. collections were conducted across a range of different host availabilities and from both indoor and outdoor locations. these environmental factors were shown to impact dramatically the host choice of caught malaria vectors: mosquitoes caught indoors were ten-fold more likely to have sourced their blood meal from humans; and a halving in odds of being human-fed was found for mosquitoes caught only 25 m from the centre of the village. For the first time, we demonstrate that anthropophagy was better explained by extrinsic factors (namely, local host availability and indoor/outdoor trapping location) than intrinsic factors (namely, the (sibling) species of the mosquito caught) (respective Akaike information criterion estimates: 243.0 versus 359.8). Instead of characterizing biting behaviour on a taxonomic level, we illustrate the importance of assessing local entomology. Accounting for this behavioural plasticity is important, both in terms of measuring effectiveness of control programmes and in informing optimal disease control strategies.Mosquitoes are responsible for the transmission of multiple human pathogens with malaria the most prominent of the resulting diseases. Malaria is transmitted by the bite of several Anopheles mosquito species when infected with Plasmodium parasites. As the successful transmission of the parasite requires two successful bites (one for the mosquito to become infected and one for the parasite to be transmitted to the human host), the mosquito's choice of which host species to bite has an exaggerated, non-linear impact on malaria transmission intensity 1 . The way in which host availability impacts the choice of host is largely unknown despite the dramatic impact it has on transmission and control of vector-borne diseases of diverse aetiology 2 . Similarly little is known of the short-and long-term impacts of different control methods on host choice.The introduction of indoor residual spraying and insecticidal nets has resulted in a change in the biting behaviour of major malaria vectors with many mosquito species seeking a higher proportion of blood meals outdoors 3-6 and/or from non-human hosts 7-10 . Coupled with increasing rates of insecticide resistance 11 , these behavioural changes indicate potential inadequacies of current leading vector-control tools to target outdoor biting and, correspondingly, sustained residual malaria transmission [12][13][14][15][16][17][18][19] . Therefore, understanding this behaviour is becoming increasingly important when implementing vector control strategies.In the field, which host is ultimately bitten is a complex balance between intrinsic (genetic) and extrinsic (environme...

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Section: Discussionmentioning

confidence: 99%

Evidence of extrinsic factors dominating intrinsic blood host preferences of major African malaria vectors

Orsborne

Mohammed

Jeffries

et al. 2020

Sci Rep

Self Cite

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“…This has mainly been studied in areas where An. arabiensis is the dominant vector species [56,60,[66][67][68], but has the potential to be applied to any system with highly zoophagic, exophagic vectors [51,54,69,70], providing a One Health solution to residual malaria transmission.…”

Section: Zooprophylaxis and Cattle In Madagascarmentioning

confidence: 99%

Widespread zoophagy and detection of Plasmodium spp. in Anopheles mosquitoes in southeastern Madagascar

Finney

McKenzie

Rabaovola

et al. 2021

Malar J

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Background Malaria is a top cause of mortality on the island nation of Madagascar, where many rural communities rely on subsistence agriculture and livestock production. Understanding feeding behaviours of Anopheles in this landscape is crucial for optimizing malaria control and prevention strategies. Previous studies in southeastern Madagascar have shown that Anopheles mosquitoes are more frequently captured within 50 m of livestock. However, it remains unknown whether these mosquitoes preferentially feed on livestock. Here, mosquito blood meal sources and Plasmodium sporozoite rates were determined to evaluate patterns of feeding behaviour in Anopheles spp. and malaria transmission in southeastern Madagascar. Methods Across a habitat gradient in southeastern Madagascar 7762 female Anopheles spp. mosquitoes were collected. Of the captured mosquitoes, 492 were visibly blood fed and morphologically identifiable, and a direct enzyme-linked immunosorbent assay (ELISA) was used to test for swine, cattle, chicken, human, and dog blood among these specimens. Host species identification was confirmed for multiple blood meals using PCR along with Sanger sequencing. Additionally, 1,607 Anopheles spp. were screened for the presence of Plasmodium falciparum, P. vivax-210, and P. vivax 247 circumsporozoites (cs) by ELISA. Results Cattle and swine accounted, respectively, for 51% and 41% of all blood meals, with the remaining 8% split between domesticated animals and humans. Of the 1,607 Anopheles spp. screened for Plasmodium falciparum, Plasmodium vivax 210, and Plasmodium vivax 247 cs-protein, 45 tested positive, the most prevalent being P. vivax 247, followed by P. vivax 210 and P. falciparum. Both variants of P. vivax were observed in secondary vectors, including Anopheles squamosus/cydippis, Anopheles coustani, and unknown Anopheles spp. Furthermore, evidence of coinfection of P. falciparum and P. vivax 210 in Anopheles gambiae sensu lato (s.l.) was found. Conclusions Here, feeding behaviour of Anopheles spp. mosquitoes in southeastern Madagascar was evaluated, in a livestock rich landscape. These findings suggest largely zoophagic feeding behaviors of Anopheles spp., including An. gambiae s.l. and presence of both P. vivax and P. falciparum sporozoites in Anopheles spp. A discordance between P. vivax reports in mosquitoes and humans exists, suggesting high prevalence of P. vivax circulating in vectors in the ecosystem despite low reports of clinical vivax malaria in humans in Madagascar. Vector surveillance of P. vivax may be relevant to malaria control and elimination efforts in Madagascar. At present, the high proportion of livestock blood meals in Madagascar may play a role in buffering (zooprophylaxis) or amplifying (zoopotentiation) the impacts of malaria. With malaria vector control efforts focused on indoor feeding behaviours, complementary approaches, such as endectocide-aided vector control in livestock may be an effective strategy for malaria reduction in Madagascar.

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“…In pigs, a single dose of 200 μg/kg with a 1% formulation of ivermectin can result in 1.5 weeks of mosquito-killing effect. 40,60 Some of the factors determining the efficacy of livestockdelivered ivermectin will be the livestock species and presence (e.g., surface area of the animal, variation in ivermectin metabolism by species, proximity of the animals to humans, and the livestock/ human ratio), the local mosquito species composition, and the local mosquito feeding preference (e.g., the degree of zoophagy versus anthropophagy) as determined by blood meal analyses. FIGURE 4.…”

Section: Studies Of Drug-drug Interactions Between Ivermectin Andmentioning

confidence: 99%

A Roadmap for the Development of Ivermectin as a Complementary Malaria Vector Control Tool

Billingsley

Binka

Chaccour

et al. 2020

The American Journal of Tropical Medicine and Hygiene

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In the context of stalling progress against malaria, resistance of mosquitoes to insecticides, and residual transmission, mass drug administration (MDA) of ivermectin, an endectocide used for neglected tropical diseases (NTDs), has emerged as a promising complementary vector control method. Ivermectin reduces the life span of Anopheles mosquitoes that feed on treated humans and/or livestock, potentially decreasing malaria parasite transmission when administered at the community level. Following the publication by WHO of the preferred product characteristics for endectocides as vector control tools, this roadmap provides a comprehensive view of processes needed to make ivermectin available as a vector control tool by 2024 with a completely novel mechanism of action. The roadmap covers various aspects, which include 1) the definition of optimal dosage/regimens for ivermectin MDA in both humans and livestock, 2) the risk of resistance to the drug and environmental impact, 3) ethical issues, 4) political and community engagement, 5) translation of evidence into policy, and 6) operational aspects of large-scale deployment of the drug, all in the context of a drug given as a prevention tool acting at the community level. The roadmap reflects the insights of a multidisciplinary group of global health experts who worked together to elucidate the path to inclusion of ivermectin in the toolbox against malaria, to address residual transmission, counteract insecticide resistance, and contribute to the end of this deadly disease.

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Treatment of pigs with endectocides as a complementary tool for combating malaria transmission by Anopheles farauti (s.s.) in Papua New Guinea

Cited by 22 publications

References 50 publications

Evidence of extrinsic factors dominating intrinsic blood host preferences of major African malaria vectors

Evidence of extrinsic factors dominating intrinsic blood host preferences of major African malaria vectors

Widespread zoophagy and detection of Plasmodium spp. in Anopheles mosquitoes in southeastern Madagascar

A Roadmap for the Development of Ivermectin as a Complementary Malaria Vector Control Tool

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