Eric Ochomo

Verified

Eric verified their affiliation via an institutional email.

Learn more

Verified

Eric verified their affiliation via an institutional email.

Learn more

• PhD Entomology and Vector Science
• Entomology Chief at Kenya Medical Research Institute

Background: The discovery of Microsporidia MB , a malaria-impairing symbiont in Anopheles arabiensis , suggests its potential for malaria control. This study investigated its prevalence and diversity in An. gambiae s.l. and An. funestus in Busia, Kenya. The study also explored its association with insecticide resistance and environmental factors. M...

Background Increasing unplanned urbanization in tropical Africa may create new niches for malaria vectors, raising transmission risk, yet control efforts focus on rural ecosystems. Understanding mosquito diversity, ecology and biting behaviour in urban areas is crucial for effective control. This study assessed Anopheles diversity, abundance, behav...

Identification of blood sources for maximum production of Anopheles mosquitoes is an important consideration for colony maintenance which involves mass rearing. High feeding rates, eggs production, hatching rates, larval, pupal, and adult survivorship are essential parameters to consider when selecting a blood host for mass production of An. gambia...

Larval source management (LSM) has a long history of advocacy and successes but is rarely adopted where funds are limited. The World Health Organization (WHO) guidelines on malaria prevention recommend the use of LSM as a supplementary intervention to the core vector control methods (insecticide-treated nets and indoor residual spraying), arguing t...

Background Global progress toward malaria elimination and eradication goals has stagnated in recent years, with many African countries reporting increases in malaria morbidity and mortality. Insecticide-treated nets and indoor residual spraying are effective, but the emergence and increased intensity of insecticide resistance and the challenge of o...

Attractive targeted sugar baits (ATSBs) are a novel malaria control tool designed to target mosquitoes outdoors. We conducted a cluster-randomised trial to evaluate the impact of ATSBs on malaria indicators in Kenya. Seventy clusters ( > 100 households/cluster) in Siaya county were randomly assigned (1:1) to intervention or control. Pyrethroid-only...

Background In western Kenya, a cluster-randomized trial is assessing the impact of attractive targeted sugar baits (ATSBs) on malaria in children enrolled in three consecutive cohorts. Here, characteristics of children and households at enrolment, and factors associated with baseline malaria prevalence are described. Methods Children aged 1 to < 1...

Anopheles funestus s.s. is a formidable human malaria vector across sub-Saharan Africa. To understand how the species is evolving, especially in response to malaria vector control, we sequenced 656 modern specimens (collected 2014-2018) and 45 historic specimens (collected 1927-1967) from 16 African countries. We find high levels of genetic variati...

Introduction Attractive targeted sugar baits (ATSBs) are effective against Anopheles mosquitoes in semiarid climates with low humidity. High humidity, however, promotes growth of moulds on the surface of ATSBs. The impact of mould on ATSB efficacy against malaria vectors remains unknown. This study explored how mould growth affects the performance...

This study analyzes the distribution, genetic diversity, and spread of An. stephensi in Kenya following initial detection in December 2022. A total of 114 larval and 33 adult An. stephensi samples were confirmed in 7 of 18 surveyed counties majorly along transportation routes. Genetic analyses revealed three distinct genetic compositions with diffe...

Background The rise of insecticide resistance poses a growing challenge to the effectiveness of vector control tools, particularly in rural areas. However, the urban setting has received comparatively less focus despite its significance in attracting rural to urban migration. Unplanned urbanization, often overlooked, exacerbates insecticide resista...

Background Pyrethroid-chlorfenapyr nets have shown significant epidemiological impact over pyrethroid-only and pyrethroid plus piperonyl-butoxide (PBO) in Africa. A non-inferiority evaluation of PermaNet® Dual, a new chlorfenapyr plus deltamethrin net, compared to Interceptor® G2, was conducted in experimental huts in Siaya, Kenya against free-flyi...

Background The burden of malaria in Kenya was showing a declining trend, but appears to have reached a plateau in recent years. This study estimated changes in the geographical distribution of malaria parasite risk in the country between the years 2015 and 2020, and quantified the contribution of malaria control interventions and climatic/ environm...

Background Insecticide resistance in disease vectors poses a significant threat to the control of transmission globally. In Anopheles mosquitoes, resistance has jeopardized gains made in malaria control and led to the resurgence of cases. Although Anopheles arabiensis is a major malaria vector, little is known about its genetic diversity and insect...

Background Despite the application of various tools for the control of vectors of Plasmodium falciparum, malaria remains the major killer disease in sub-Saharan Africa accounting for up to 90% of deaths due to the disease. Due to limitations of the useage of chemical insecticides such as resistance, negative impact on the environment and to nontarg...

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, wi...

Background Increasing urbanization in tropical Africa may create new niches for malaria vectors, potentially leading to higher disease transmission rates. Vector control efforts remain largely targeted at ecologically rural bio-complexities with multiple hosts. Understanding mosquito species composition, ecology, host diversity and biting behavior...

Background The rapid increase in global temperatures coupled with persistent malaria transmission has significant public health ramifications, especially in Sub-Saharan Africa. Indoor thermal comfort and malaria transmission depend on building designs and structural properties of houses. This study assessed the impact of housing modification, combi...

Spread of the Anopheles stephensi mosquito, an invasive malaria vector, threatens to put an additional 126 million persons per year in Africa at risk for malaria. To accelerate the early detection and rapid response to this mosquito species, confirming its presence and geographic extent is critical. However, existing molecular species assays requir...

Indoor residual spraying (IRS) and insecticide-treated nets (ITNs) are the main methods used to control mosquito populations for malaria prevention. The efficacy of these strategies is threatened by the spread of insecticide resistance (IR), limiting the success of malaria control. Studies of the genetic evolution leading to insecticide resistance...

Background The rise of insecticide resistance poses a growing challenge to the effectiveness of vector control tools, particularly in rural areas. However, the urban setting has received comparatively less focus despite its significance in attracting rural to urban migration. Unplanned urbanization, often overlooked, exacerbates insecticide resista...

Background Anopheles coluzzii is a primary vector of malaria found in West and Central Africa, but its presence has hitherto never been documented in Kenya. A thorough understanding of vector bionomics is important as it enables the implementation of targeted and effective vector control interventions. Malaria vector surveillance efforts in the cou...

Background Insecticide resistance (IR) is one of the major threats to malaria vector control programs in endemic countries. However, the mechanisms underlying IR are poorly understood. Thus, investigating gene expression patterns related to IR can offer important insights into the molecular basis of IR in mosquitoes. In this study, RNA-Seq was used...

Background Effective vector control is key to malaria prevention. However, this is now compromised by increased insecticide resistance due to continued reliance on insecticide-based control interventions. In Kenya, we have observed heterogenous resistance to pyrethroids and organophosphates in Anopheles arabiensis which is one of the most widesprea...

Background Vector surveillance is among the World Health Organization global vector control response (2017–2030) pillars. Human landing catches are a gold standard but difficult to implement and potentially expose collectors to malaria infection. Other methods like light traps, pyrethrum spray catches and aspiration are less expensive and less risk...

A major mechanism of insecticide resistance 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....

Background Insecticide-treated nets (ITNs) contributed significantly to the decline in malaria since 2000. Their protective efficacy depends not only on access, use, and net integrity, but also location of people within the home environment and mosquito biting profiles. Anopheline mosquito biting and human location data were integrated to identify...

Background Anopheles coluzzii is a primary vector of malaria found in West and Central Africa, but its presence has hitherto never been documented in Kenya. A thorough understanding of vector bionomics is important as it enables the implementation of targeted and effective vector control interventions. Malaria vector surveillance efforts in the cou...

Anopheles stephensi , an invasive malaria vector in Africa, has the potential to impact the landscape of malaria on the continent, threatening to put an additional 126 million people per year at risk of malaria, largely in peri-urban/urban areas. To accelerate the early detection and rapid response to An. stephensi and ensure no gains made in malar...

Long-lasting insecticidal nets are an effective tool in reducing malaria transmission. However, with increasing insecticide resistance little is known about how physiologically resistant malaria vectors behave around a human-occupied bed net, despite their importance in malaria transmission. This study assessed the host-seeking behavior of the majo...

Introduction Human habitats remain the main point of human-vector interaction leading to malaria transmission despite the sustained use of insecticide-treated nets and indoor residual spraying. Simple structural modifications involving screening of doors, windows and eaves have great potential for reducing indoor entry of mosquitoes. Moreover, inse...

Indoor residual spraying (IRS) and insecticide-treated nets (ITNs) are the main methods used to control mosquito populations for malaria prevention. The efficacy of these strategies is threatened by the spread of insecticide resistance (IR), limiting the success of malaria control. Studies of the genetic evolution leading to insecticide resistance...

Pyrethroid-chlorfenapyr nets have shown significant epidemiological impact over pyrethroid-only and pyrethroid plus piperonal-butoxide (PBO) in Africa. Here we describe a non-inferiority evaluation of PermaNet Dual, a new chlorfenapyr plus deltamethrin net, compared to Interceptor G2, in experimental huts in Siaya, Kenya against free-flying pyrethr...

Africa and the United States are both large, heterogeneous geographies with a diverse range of ecologies, climates and mosquito species diversity which contribute to disease transmission and nuisance biting. In the United States, mosquito control is nationally, and regionally coordinated and in so much as the Centers for Disease Control (CDC) provi...

Background Spatial repellents (SR) may complement current vector control tools and provide additional coverage when people are not under their bednets or are outdoors. Here we assessed the efficacy of a metofluthrin-based SR in reducing exposure to pyrethroid-resistant Anopheles funestus in Siaya County, western Kenya. Methods Metofluthrin was vap...

Background Children in Kenya spend a substantial amount of time at school, including at dawn and dusk when mosquitoes are active. With changing vector behaviour towards early morning biting, it is important to determine whether there is an additional risk of transmission in schools. This study sought to understand whether late morning biting by Ano...

Vector control interventions often lack comprehensive information on vector population distribution and dynamics. This knowledge gap poses challenges in targeting interventions effectively, especially in areas with heterogeneous transmission and where complementary vector control tools may be required to achieve sustained impact on disease transmis...

The Anopheles stephensi mosquito is an invasive malaria vector recently reported in Djibouti, Ethiopia, Sudan, Somalia, Nigeria, and Ghana. The World Health Organization has called on countries in Africa to increase surveillance efforts to detect and report this vector and institute appropriate and effective control mechanisms. In Kenya, the Divisi...

Background Designing, implementing, and upscaling of effective malaria vector control strategies necessitates an understanding of when and where transmission occurs. This study assessed the biting patterns of potentially infectious malaria vectors at various hours, locations, and associated human behaviors in different ecological settings in wester...

Introduction. Insecticide treated nets (ITNs) contributed significantly to the decline in malaria since 2000. Their protective efficacy depends not only on access, use, and net integrity, but also location of people within the home environment and mosquito biting profiles. Anopheline mosquito biting and human location data were integrated to identi...

Background: Children in Kenya spend a substantial amount of time at school, including at dawn and dusk when mosquitoes are active. If schools do not have adequate malaria transmission prevention, they can become hotspots for infection. With changing vector behaviour towards early morning biting, it is important to determine whether there is an addi...

Background Insecticide resistance (IR) is one of the major threats to malaria vector control programs in endemic countries. However, the mechanisms underlying insecticide resistance are poorly understood. Thus, investigating gene expression patterns related to IR can offer important insights into the molecular basis of IR in mosquitoes. In this stu...

Background The demonstration that the recently discovered Anopheles symbiont Microsporidia MB blocks malaria transmission in Anophelesarabiensis and undergoes vertical and horizontal transmission suggests that it is a promising candidate for the development of a symbiont-based malaria transmission-blocking strategy. The infection prevalence and cha...

Background Effective vector control is key to malaria prevention. However, this is now compromised by increased insecticide resistance due to continued reliance on insecticide-based control interventions. In Kenya, we have observed heterogenous resistance to pyrethroids and organophosphates in Anopheles arabiensis which is one of the most widesprea...

Background Sustained transmission of malaria, despite high coverage of indoor-based interventions (including long-lasting insecticidal nets and indoor residual spraying of insecticides), may be attributable to exposure of people to infectious bites outdoors or at times other than when people are sleeping under bed nets, or to insecticide resistance...

Background Enhanced vector surveillance, is one of the 4 pillars of the WHO’s global vector control response (2017–2030). Human landing catches are the gold standard for entomological surveys but are difficult to implement and expose collectors to mosquito bites and potentially to malaria infection. Other surveillance tools such as light traps, pyr...

The massive and inappropriate use of synthetic insecticides is causing significant and increasing environmental disruption. Therefore, developing effective natural mosquitocidal compounds could be an alternative tool for malarial vector control. The present study investigates the larvicidal and adulticidal effect of methanol and acetone extracts of...

Introduction Human habitats remain the main point of human-vector interaction leading to malaria transmission despite sustained use of insecticide treated nets (ITNs) and indoor residual spraying (IRS). Simple structural modifications involving screening of doors, windows and eaves have great potential for reducing indoor entry of mosquitoes and he...

Background Entomological surveillance is traditionally conducted by supervised teams of trained technicians. However, it is expensive and limiting in the number of sites visited. Surveillance through community-based collectors (CBC) may be more cost-effective and sustainable for longitudinal entomological monitoring. This study evaluated the effici...

Attractive Targeted Sugar Baits (ATSB) have been demonstrated to result in significant reductions in malaria vector numbers in areas of scarce vegetation cover such as in Mali and Israel, but it is not clear whether such an effect can be replicated in environments where mosquitoes have a wide range of options for sugar resources. The current study...

Progress in malaria control has stalled over the recent years. Knowledge on main drivers of transmission explaining small-scale variation in prevalence can inform targeted control measures. We collected finger-prick blood samples from 3061 individuals irrespective of clinical symptoms in 20 clusters in Busia in western Kenya and screened for Plasmo...

Background: Designing, implementing, and upscaling effective malaria vector control strategies necessitates understanding of when and where transmission occurs. This study assessed the biting patterns of potentially infectious malaria vectors at various hours, locations, and human behavior in different ecological settings in western Kenya. Methods:...

Background: The discovery of the Anopheles symbiont, Microsporidia MB in An. arabiensis and the subsequent demonstration that it blocks malaria transmission, undergoes vertical and horizontal transmission suggests that it is a promising candidate for developing a symbiont-based malaria transmission-blocking strategy. We investigated the prevalence...

Introduction. Entomological surveillance is traditionally conducted by supervised teams of trained technicians. However, it is expensive and limiting in the number of sites visited. Surveillance through community-based collectors (CBC) may be more cost-effective and sustainable for longitudinal entomological monitoring. This study evaluated the eff...

Anopheles stephensi is an invasive malaria vector that is endemic to south Asia and the Arabian Peninsula. It was recently reported in the Horn of Africa countries including Djibouti (2012), Ethiopia, Sudan (2019), Somalia (2019) and most recently Nigeria (2020). This mosquito is a competent vector for both Plasmodium falciparum and P. vivax. It is...

Anopheles stephensi is an invasive malaria vector recently reported in Djibouti (2012), Ethiopia, Sudan (2019), Somalia (2019) and most recently Nigeria (2020). The World Health Organization (WHO) has called on all countries to scale up surveillance efforts to detect and report invasion by this vector and institute appropriate and effective control...

Background. Progress in malaria control has stalled over the recent years. Knowledge on main drivers of transmission explaining small-scale variation in prevalence can inform targeted control measures. Methods. We collected finger-prick blood samples from 3061 individuals irrespective of clinical symptoms in 20 clusters in Busia in western Kenya an...

Background Despite the scale-up of insecticide-treated nets and indoor residual spraying, the bulk of malaria transmission in western Kenya still occurs indoors, late at night. House improvement is a potential long-term solution to further reduce malaria transmission in the region. Methods The impact of eave screening on mosquito densities was eva...

Background Spatial repellents are widely used for prevention of mosquito bites and evidence is building on their public health value, but their efficacy against malaria incidence has never been evaluated in Africa. To address this knowledge gap, a trial to evaluate the efficacy of Mosquito Shield™, a spatial repellent incorporating transfluthrin, w...

Spatial repellent (SR) products are envisioned to complement existing vector control methods through the continual release of volatile active ingredients (AI) providing: (i) protection against day-time and early-evening biting; (ii) protection in enclosed/semi-enclosed and peri-domestic spaces; (iii) various formulations to fit context-specific app...

Attractive targeted sugar baits (ATSBs) are a potential vector control tool that exploits the sugar-feeding behaviour of mosquitoes. We evaluated the sugar-feeding behaviour of Anopheles mosquitoes as part of baseline studies for cluster randomised controlled trials of ATSBs. Mosquitoes were collected indoors and outdoors from two villages in weste...

Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) target night-time indoor biting mosquitoes and effectively reduce malaria transmission in rural settings across Africa, but additional vector control tools are needed to interrupt transmission. Attractive targeted sugar baits (ATSBs) attract and kill mosquitoes, in...

Background: Despite the scale-up of insecticide treated nets and indoor residual spraying, the bulk of malaria transmission in western Kenya still occurs indoors, late at night. House improvement is a potential long-term solution to further reduce malaria transmission in the region. Methods: We evaluated the impact of eave screening on mosquito den...

Abstract Widespread insecticide resistance in African malaria vectors raises concerns over the potential to compromise malaria vector control interventions. Understanding the evolution of resistance mechanisms, and whether the selective disadvantages are large enough to be useful in resistance management or designing suitable control strategies is...

Background Long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) target night-time indoor biting mosquitoes and effectively reduce malaria transmission in rural settings across Africa, but additional vector control tools are needed to interrupt transmission. Attractive targeted sugar baits (ATSBs) attract and kill mosquitoes, in...

Background Long-lasting insecticidal nets are an effective tool in reducing malaria transmission. However, with increasing insecticide resistance little is known about how physiologically resistant malaria vectors behave around a human-occupied bed net, despite their importance in malaria transmission. We used the Mbita bednet trap to assess the ho...

Botanical biopesticides have potential for use in mosquito control because they exhibit low mammalian toxicity, are readily biodegraded, show target specificity and insecticidal activity. As populations of mosquito species grow more resistant to currently used organic insecticides, a need for new and effective insecticides for vector control becomes...

Rapid development of resistance in vector mosquitoes to synthetic insecticides is a major challenge for malaria control. The use of plant-derived essential oils (EOs) is an attractive strategy in controlling mosquito populations because they are environmentally safe and may have a lower chance of developing resistance. This study assessed the larvi...

Background Molecular diagnostic tools have been incorporated in insecticide resistance monitoring programmes to identify underlying genetic basis of resistance and develop early warning systems of vector control failure. Identifying genetic markers of insecticide resistance is crucial in enhancing the ability to mitigate potential effects of resist...

Background: Widespread insecticide resistance in African malaria vectors raises concerns over the potential to compromise malaria vector control interventions. Understanding the evolution of resistance mechanisms, and whether the selective disadvantages are large enough to be useful in resistance management or designing suitable control strategies...

Background: Spatial repellents are widely used for prevention of mosquito bites and evidence is building on their public health value, but their efficacy against malaria incidence has never been evaluated in Africa. To address this knowledge gap, a trial to evaluate the efficacy of Mosquito Shield™, a spatial repellent incorporating transfluthrin,...

BACKGROUND Natural disasters, such as earthquakes, hurricanes, and floods create ideal mosquito breeding conditions while simultaneously disrupting government services that prevent outbreaks where Aedes-transmitted diseases, and possibly other vector-borne diseases (VBD), are circulating. UNICEF, the MENTOR Initiative, and Kenya Medical Research In...

Introduction: Longitudinal monitoring of outdoor-biting malaria vector populations is becoming increasingly important in understanding the dynamics of residual malaria transmission. However, the human landing catch (HLC), the gold standard for measuring human biting rates indoors and outdoors, is costly and raises ethical concerns related to incre...