Previous Malaria Exposures and Immune Dysregulation: Developing Strategies To Improve Malaria Vaccine Efficacy in Young Children.

After several decades in development, two malaria vaccines based on the same antigen and with very similar constructs and adjuvants, RTS,S/AS01 (RTS,S) and R21/Matrix-M (R21), were recommended by the WHO for widespread vaccination of children. These vaccines are much-needed additions to malaria control programs that, when used in conjunction with other control measures, will help to accelerate reductions in malaria morbidity and mortality. Although R21 is not yet available, RTS,S is currently being integrated into routine vaccine schedules in some areas.

Wind-assisted high-altitude dispersal of mosquitoes and other insects in East Africa.

Knowledge of insect dispersal is relevant to the control of agricultural pests, vector-borne transmission of human and veterinary pathogens, and insect biodiversity. Previous studies in a malaria endemic area of the Sahel region in West Africa revealed high-altitude, long-distance migration of insects and various mosquito species. The objective of the current study was to assess whether similar behavior is exhibited by mosquitoes and other insects around the Lake Victoria basin region of Kenya in East Africa.

Rare Alleles and Signatures of Selection on the Immunodominant Domains of Pfs230 and Pfs48/45 in Malaria Parasites From Western Kenya.

Malaria elimination and eradication efforts can be advanced by including transmission-blocking or reducing vaccines (TBVs) alongside existing interventions. Key transmission-blocking vaccine candidates, such as domain one and domain 3, should be genetically stable to avoid developing ineffective vaccines due to antigenic polymorphisms. We evaluated genetic polymorphism and temporal stability of domain one and domain three in parasites from western Kenya.

Signatures of selection and drivers for novel mutation on transmission-blocking vaccine candidate Pfs25 gene in western Kenya.

Background: Leading transmission-blocking vaccine candidates such as Plasmodium falciparum surface protein 25 (Pfs25 gene) may undergo antigenic alterations which may render them ineffective or allele-specific. This study examines the level of genetic diversity, signature of selection and drivers of Pfs25 polymorphisms of parasites population in regions of western Kenya with varying malaria transmission intensities.

Methods: Dry blood spots (DBS) were collected in 2018 and 2019 from febrile outpatients with malaria at health facilities in malaria-endemic areas of Homa Bay, Kisumu (Chulaimbo) and the epidemic-prone highland area of Kisii.

Hyper-prevalence of submicroscopic Plasmodium falciparum infections in a rural area of western Kenya with declining malaria cases.

Background: The gold standard for diagnosing Plasmodium falciparum infection is microscopic examination of Giemsa-stained peripheral blood smears. The effectiveness of this procedure for infection surveillance and malaria control may be limited by a relatively high parasitaemia detection threshold. Persons with microscopically undetectable infections may go untreated, contributing to ongoing transmission to mosquito vectors.

Factors influencing mothers' decisions regarding obstetrical care in Western Kenya: a mixed-methods study.

Background: Siaya County in Western Kenya has one of the highest maternal mortality rates in Kenya. We sought to elucidate factors that influence mothers' decisions regarding where to seek obstetrical care, to inform interventions that seek to promote effective use of obstetric services and reduce maternal mortalities. To guide our research, we used the "Three Delays Model", focusing on the first delay-seeking care.

Multi-Indicator and Multistep Assessment of Malaria Transmission Risks in Western Kenya.

Malaria risk factor assessment is a critical step in determining cost-effective intervention strategies and operational plans in a regional setting. We develop a multi-indicator multistep approach to model the malaria risks at the population level in western Kenya. We used a combination of cross-sectional seasonal malaria infection prevalence, vector density, and cohort surveillance of malaria incidence at the village level to classify villages into malaria risk groups through unsupervised classification.

Adaptive interventions for optimizing malaria control: an implementation study protocol for a block-cluster randomized, sequential multiple assignment trial.

Background: In the past two decades, the massive scale-up of long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS) has led to significant reductions in malaria mortality and morbidity. Nonetheless, the malaria burden remains high, and a dozen countries in Africa show a trend of increasing malaria incidence over the past several years. This underscores the need to improve the effectiveness of interventions by optimizing first-line intervention tools and integrating newly approved products into control programs.

Gaps between Knowledge and Malaria Treatment Practices after Intensive Anti-Malaria Campaigns in Western Kenya: 2004-2016.

Effective case management is central for malaria control, but not all of those affected by malaria have access to prompt, effective treatment. In Kenya, free malaria treatment has been implemented since 2006. However, questions remain regarding effective treatment.

Microbial larvicides for mosquito control: Impact of long lasting formulations of var. and on non-target organisms in western Kenya highlands.

The microbial larvicides var. and have been used extensively for mosquito control and have been found to be effective and safe to non-target organisms cohabiting with mosquito larvae. Recently developed long lasting microbial larvicides (LLML), although evading the previous challenge of short duration of activity, increase the risk of persistence of toxins in the treated larval habitats.

Utility of passive malaria surveillance in hospitals as a surrogate to community infection transmission dynamics in western Kenya.

Background: Malaria continued to be the major public health concern in sub-Sahara Africa, thus for better planning of control activities, periodic surveillance of both clinical and asymptomatic cases remains important. However, the usability of routinely collected malaria data in Kenyan hospitals as a predictor of the asymptomatic malaria infection in the community amidst rapid infection resurgence or reduction in different areas of disease endemicities remains widely unstudied. This study was therefore aimed to evaluate the utility of passive surveillance of malaria in health facilities as a proxy of infection transmission of the surrounding community in different transmission intensities.

Multiplicity and molecular epidemiology of Plasmodium vivax and Plasmodium falciparum infections in East Africa.

Background: Parasite genetic diversity and multiplicity of infection (MOI) affect clinical outcomes, response to drug treatment and naturally-acquired or vaccine-induced immunity. Traditional methods often underestimate the frequency and diversity of multiclonal infections due to technical sensitivity and specificity. Next-generation sequencing techniques provide a novel opportunity to study complexity of parasite populations and molecular epidemiology.

Insecticide-Treated Net Campaign and Malaria Transmission in Western Kenya: 2003-2015.

Insecticide-treated nets (ITNs) are among the three major intervention measures that have reduced malaria transmission in the past decade. However, increased insecticide resistance in vectors, together with outdoor transmission, has limited the efficacy of the ITN scaling-up efforts. Observations on longitudinal changes in ITN coverage and its impact on malaria transmission allow policy makers to make informed adjustments to control strategies.

The impact of long-lasting microbial larvicides in reducing malaria transmission and clinical malaria incidence: study protocol for a cluster randomized controlled trial.

Background: The massive scale-up of insecticide-treated nets (ITNs) and indoor residual spraying (IRS) has led to a substantial increase in malaria vector insecticide resistance as well as in increased outdoor transmission, both of which hamper the effectiveness and efficiency of ITN and IRS. Long-lasting microbial larvicide can be a cost-effective new supplemental intervention tool for malaria control.

Methods/design: We will implement the long-lasting microbial larvicide intervention in 28 clusters in two counties in western Kenya.

Pyrethroid and DDT Resistance and Organophosphate Susceptibility among Anopheles spp. Mosquitoes, Western Kenya.

We conducted standard insecticide susceptibility testing across western Kenya and found that the Anopheles gambiae mosquito has acquired high resistance to pyrethroids and DDT, patchy resistance to carbamates, but no resistance to organophosphates. Use of non-pyrethroid-based vector control tools may be preferable for malaria prevention in this region.

Evaluation of universal coverage of insecticide-treated nets in western Kenya: field surveys.

Background: Mass distribution of insecticide-treated nets (ITNs) is a cost-effective way to achieve universal coverage, but maintaining this coverage is more difficult. In addition to commonly used indicators, evaluation of universal coverage should include coverage of effective nets and changes in coverage over time.

Methods: Longitudinal and cross-sectional household ITN surveys were carried out from 2010 to 2013 in six locations representing a variety of settings across western Kenya.

Determinants of cervical screening services uptake among 18-49 year old women seeking services at the Jaramogi Oginga Odinga Teaching and Referral Hospital, Kisumu, Kenya.

Background: Kenyan women aged ≥ 15 years are at risk of developing cervical cancer. Currently, cervical cytology reduces cervical cancer incidence, since it allows for early diagnosis and treatment. Uptake of cervical screening services is a priority research area in Kenya.

Modest additive effects of integrated vector control measures on malaria prevalence and transmission in western Kenya.

Background: The effect of integrating vector larval intervention on malaria transmission is unknown when insecticide-treated bed-net (ITN) coverage is very high, and the optimal indicator for intervention evaluation needs to be determined when transmission is low.

Methods: A post hoc assignment of intervention-control cluster design was used to assess the added effect of both indoor residual spraying (IRS) and Bacillus-based larvicides (Bti) in addition to ITN in the western Kenyan highlands in 2010 and 2011. Cross-sectional, mass parasite screenings, adult vector populations, and cohort of active case surveillance (ACS) were conducted before and after the intervention in three study sites with two- to three-paired intervention-control clusters at each site each year.

Anopheline larval habitats seasonality and species distribution: a prerequisite for effective targeted larval habitats control programmes.

Background: Larval control is of paramount importance in the reduction of malaria vector abundance and subsequent disease transmission reduction. Understanding larval habitat succession and its ecology in different land use managements and cropping systems can give an insight for effective larval source management practices. This study investigated larval habitat succession and ecological parameters which influence larval abundance in malaria epidemic prone areas of western Kenya.

Topography as a modifier of breeding habitats and concurrent vulnerability to malaria risk in the western Kenya highlands.

Background: Topographic parameters such as elevation, slope, aspect, and ruggedness play an important role in malaria transmission in the highland areas. They affect biological systems, such as larval habitats presence and productivity for malaria mosquitoes. This study investigated whether the distribution of local spatial malaria vectors and risk of infection with malaria parasites in the highlands is related to topography.

Insecticide-treated net (ITN) ownership, usage, and malaria transmission in the highlands of western Kenya.

Background: Insecticide-treated bed nets (ITNs) are known to be highly effective in reducing malaria morbidity and mortality. However, usage varies among households, and such variations in actual usage may seriously limit the potential impact of nets and cause spatial heterogeneity on malaria transmission. This study examined ITN ownership and underlying factors for among-household variation in use, and malaria transmission in two highland regions of western Kenya.