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8. Genetic markers associated with the widespread insecticide resistance in malaria vector Anopheles funestus populations across Tanzania

Author

Odero, Joel O., Nambunga, Ismail H., Masalu, John P., Mkandawile, Gustav, Bwanary, Hamis, Hape, Emmanuel E., Njalambaha, Rukiyah M., Tungu, Patrick, Ngowo, Halfan S., Kaindoa, Emmanuel W., Mapua, Salum A., Kahamba, Najat F., Nelli, Luca, Wondji, Charles, Koekemoer, Lizette L., Weetman, David, Ferguson, Heather M., Baldini, Francesco, and Okumu, Fredros O.

Published
2024
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9. Rapid assessment of the blood-feeding histories of wild-caught malaria mosquitoes using mid-infrared spectroscopy and machine learning

Author

Mwanga, Emmanuel P., Mchola, Idrisa S., Makala, Faraja E., Mshani, Issa H., Siria, Doreen J., Mwinyi, Sophia H., Abbasi, Said, Seleman, Godian, Mgaya, Jacqueline N., Jiménez, Mario González, Wynne, Klaas, Sikulu-Lord, Maggy T., Selvaraj, Prashanth, Okumu, Fredros O., Baldini, Francesco, and Babayan, Simon A.

Published
2024
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22. Toward the Definition of Efficacy and Safety Criteria for Advancing Gene Drive-Modified Mosquitoes to Field Testing

Author

James, Stephanie L, Marshall, John M, Christophides, George K, Okumu, Fredros O, and Nolan, Tony

Subjects
Rare Diseases, Malaria, Vector-Borne Diseases, Infectious Diseases, Infection, Good Health and Well Being, Animals, Animals, Genetically Modified, Culicidae, Gene Drive Technology, Mosquito Control, mosquito, malaria, gene drive, efficacy, biosafety, Public Health and Health Services, Tropical Medicine
Abstract

Mosquitoes containing gene drive systems are being developed as complementary tools to prevent transmission of malaria and other mosquito-borne diseases. As with any new tool, decision makers and other stakeholders will need to balance risks (safety) and benefits (efficacy) when considering the rationale for testing and deploying gene drive-modified mosquito products. Developers will benefit from standards for judging whether an investigational gene drive product meets acceptability criteria for advancing to field trials. Such standards may be formalized as preferred product characteristics and target product profiles, which describe the desired attributes of the product category and of a particular product, respectively. This report summarizes discussions from two scientific workshops aimed at identifying efficacy and safety characteristics that must be minimally met for an investigational gene drive-modified mosquito product to be deemed viable to move from contained testing to field release and the data that will be needed to support an application for first field release.

Published
2020

24. The bionomics of Anopheles arabiensis and Anopheles funestus inside local houses and their implications for vector control strategies in areas with high coverage of insecticide-treated nets in South-eastern Tanzania.

Author

Limwagu, Alex J., Msugupakulya, Betwel J., Ngowo, Halfan S., Mwalugelo, Yohana A., Kilalangongono, Masoud S., Samli, Faraji A., Abbasi, Said K., Okumu, Fredros O., Ngasala, Billy E., and Lyimo, Issa N.

Abstract

Background: Residual malaria transmissions in Africa may be associated with improved coverage of insecticide-treated nets, house features, and livestock husbandry. These human-land use activities may drive the ecology and behaviour of malaria vectors which sustain residual malaria transmission. This study was conducted to assess changes in the ecology and behaviour of Anopheles funestus and Anopheles arabiensis in villages with high coverage of insecticide-treated nets to guide the selection of complementary vector control strategies against residual malaria transmission. Methods: Mosquitoes were collected using a CDC-light trap, miniaturized double net trap, and Prokopack aspirator from 222 households in three villages (Ebuyu, Chirombora, and Mzelezi) within Kilombero Valley. Anopheles mosquitoes were morphologically identified to their physiological status and species-complex levels. A sub-sample of Anopheles mosquitoes was exposed to laboratory analyses of sibling species, host preference, and sporozoite rates. Additionally, the local houses were geo-referenced using Global Positioning Systems (GPS) devise, and house features were recorded and associated with vector abundance. Results: The population of An. funestus s.s was abundant with high Plasmodium sporozoite rates inside houses compared to An. arabiensis. However, these vector species equally blood-fed on humans inside houses, but they also flexibly mixed human and animal blood meal. Fewer An. funestus were caught in houses with metal- than grass roofs and houses with and without animals. Contrastingly, fewer An. arabiensis were caught from houses with screened eaves compared to houses with open eaves. Conclusions: This study confirms that An. funestus dominates residual malaria transmission over An. arabiensis. These vector species exhibit anthropophily and opportunistic blood-feeding behaviour in areas with high coverage of insecticide-treated nets, but they numerically respond differently to local house improvements. These results imply that integrating mosquito-proof houses, improved insecticide-treated nets, and livestock-based interventions could effectively reduce and eventually eliminate residual malaria transmission. [ABSTRACT FROM AUTHOR]

Published
2024
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25. Discovery of Knock‐Down Resistance in the Major African Malaria Vector Anopheles funestus.

Author

Odero, Joel O., Dennis, Tristan P. W., Polo, Brian, Nwezeobi, Joachim, Boddé, Marilou, Nagi, Sanjay C., Hernandez‐Koutoucheva, Anastasia, Nambunga, Ismail H., Bwanary, Hamis, Mkandawile, Gustav, Govella, Nicodem J., Kaindoa, Emmanuel W., Ferguson, Heather M., Ochomo, Eric, Clarkson, Chris S., Miles, Alistair, Lawniczak, Mara K. N., Weetman, David, Baldini, Francesco, and Okumu, Fredros O.

Subjects
DDT (Insecticide), INSECT pests, SODIUM channels, DELTAMETHRIN, LINKAGE disequilibrium
Abstract

A major insecticide resistance mechanism in insect pests is knock‐down resistance (kdr) caused by mutations in the voltage‐gated sodium channel (Vgsc) gene. Despite being common in most malaria Anopheles vector species, kdr mutations have never been observed in Anopheles funestus, the principal malaria vector in Eastern and Southern Africa, with resistance mainly being conferred by detoxification enzymes. In a parallel study, we monitored 10 populations of An. funestus in Tanzania for insecticide resistance unexpectedly identified resistance to a banned insecticide, DDT, in the Morogoro region. Through whole‐genome sequencing of 333 An. funestus samples from these populations, we found eight novel amino acid substitutions in the Vgsc gene, including the kdr variant, L976F (equivalent to L995F in An. gambiae), in tight linkage disequilibrium with another (P1842S). The mutants were found only at high frequency in one region and were accompanied by weak signatures of a selective sweep, with a significant decline between 2017 and 2023. Notably, kdr L976F was strongly associated with survivorship to exposure to DDT insecticide, while no clear association was noted with a pyrethroid insecticide (deltamethrin). The WHO prequalifies no DDT products for vector control, and the chemical is banned in Tanzania. Widespread DDT contamination and a legacy of extensive countrywide stockpiles may have selected for this mutation. Continued monitoring is necessary to understand the origin of kdr in An. funestus, and the threat posed to insecticide‐based vector control in Africa. [ABSTRACT FROM AUTHOR]

Published
2024
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36. Going beyond personal protection against mosquito bites to eliminate malaria transmission: population suppression of malaria vectors that exploit both human and animal blood

Author

Killeen, Gerry F, Kiware, Samson S, Okumu, Fredros O, Sinka, Marianne E, Moyes, Catherine L, Massey, N Claire, Gething, Peter W, Marshall, John M, Chaccour, Carlos J, and Tusting, Lucy S

Subjects
Vector-Borne Diseases, Infectious Diseases, Malaria, Rare Diseases, 2.2 Factors relating to the physical environment, Prevention of disease and conditions, and promotion of well-being, 3.2 Interventions to alter physical and biological environmental risks, Aetiology, Infection, Good Health and Well Being
Abstract

Protecting individuals and households against mosquito bites with long-lasting insecticidal nets (LLINs) or indoor residual spraying (IRS) can suppress entire populations of unusually efficient malaria vector species that predominantly feed indoors on humans. Mosquitoes which usually feed on animals are less reliant on human blood, so they are far less vulnerable to population suppression effects of such human-targeted insecticidal measures. Fortunately, the dozens of mosquito species which primarily feed on animals are also relatively inefficient vectors of malaria, so personal protection against mosquito bites may be sufficient to eliminate transmission. However, a handful of mosquito species are particularly problematic vectors of residual malaria transmission, because they feed readily on both humans and animals. These unusual vectors feed often enough on humans to be potent malaria vectors, but also often enough on animals to evade population control with LLINs, IRS or any other insecticidal personal protection measure targeted only to humans. Anopheles arabiensis and A. coluzzii in Africa, A. darlingi in South America and A. farauti in Oceania, as well as A. culicifacies species E, A. fluviatilis species S, A. lesteri and A. minimus in Asia, all feed readily on either humans or animals and collectively mediate residual malaria transmission across most of the tropics. Eliminating malaria transmission by vectors exhibiting such dual host preferences will require aggressive mosquito population abatement, rather than just personal protection of humans. Population suppression of even these particularly troublesome vectors is achievable with a variety of existing vector control technologies that remain underdeveloped or underexploited.

Published
2017

37. Developing an expanded vector control toolbox for malaria elimination

Author

Killeen, Gerry F, Tatarsky, Allison, Diabate, Abdoulaye, Chaccour, Carlos J, Marshall, John M, Okumu, Fredros O, Brunner, Shannon, Newby, Gretchen, Williams, Yasmin A, Malone, David, Tusting, Lucy S, and Gosling, Roland D

Subjects
Rare Diseases, Malaria, Prevention, Vector-Borne Diseases, Infectious Diseases, 3.2 Interventions to alter physical and biological environmental risks, Prevention of disease and conditions, and promotion of well-being, Infection, Good Health and Well Being
Abstract

Vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) accounts for most of the malaria burden reductions achieved recently in low and middle-income countries (LMICs). LLINs and IRS are highly effective, but are insufficient to eliminate malaria transmission in many settings because of operational constraints, growing resistance to available insecticides and mosquitoes that behaviourally avoid contact with these interventions. However, a number of substantive opportunities now exist for rapidly developing and implementing more diverse, effective and sustainable malaria vector control strategies for LMICs. For example, mosquito control in high-income countries is predominantly achieved with a combination of mosquito-proofed housing and environmental management, supplemented with large-scale insecticide applications to larval habitats and outdoor spaces that kill off vector populations en masse, but all these interventions remain underused in LMICs. Programmatic development and evaluation of decentralised, locally managed systems for delivering these proactive mosquito population abatement practices in LMICs could therefore enable broader scale-up. Furthermore, a diverse range of emerging or repurposed technologies are becoming available for targeting mosquitoes when they enter houses, feed outdoors, attack livestock, feed on sugar or aggregate into mating swarms. Global policy must now be realigned to mobilise the political and financial support necessary to exploit these opportunities over the decade ahead, so that national malaria control and elimination programmes can access a much broader, more effective set of vector control interventions.

Published
2017

38. Discovery of knock-down resistance in the major malaria vectorAnopheles funestusreveals the legacy of persistent DDT pollution

Author

Odero, Joel O., primary, Dennis, Tristan P. W., additional, Polo, Brian, additional, Nwezeobi, Joachim, additional, Boddé, Marilou, additional, Nagi, Sanjay C., additional, Hernandez-Koutoucheva, Anastasia, additional, Nambunga, Ismail H., additional, Bwanary, Hamis, additional, Mkandawile, Gustav, additional, Govella, Nicodem J, additional, Kaindoa, Emmanuel W., additional, Ferguson, Heather M., additional, Ochomo, Eric, additional, Clarkson, Chris S., additional, Miles, Alistair, additional, Lawniczak, Mara K. N., additional, Weetman, David, additional, Baldini, Francesco, additional, and Okumu, Fredros O., additional

Published
2024
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39. Entomological Survey of Sibling Species in the Anopheles funestus Group in Tanzania Confirms the Role of Anopheles parensis as a Secondary Malaria Vector

Author

Mapua, Salum A., primary, Samb, Badara, additional, Nambunga, Ismail H., additional, Mkandawile, Gustav, additional, Bwanaly, Hamis, additional, Kaindoa, Emmanuel W., additional, Odero, Joel, additional, Paliga, John, additional, Kahamba, Najat, additional, Hape, Emmanuel, additional, Govella, Nicodem J., additional, Okumu, Fredros O., additional, and Tripet, Frederic, additional

Published
2024
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