Geographic and seasonal variation in malaria prevalence on islands in Lake Victoria (western Kenya): results from three cross sectional studies

Abstract Background Mosquito-proofing of houses using wire mesh screens is gaining greater recognition as a practical intervention for reducing exposure to malaria transmitting mosquitoes. Screening potentially protects all persons sleeping inside the house against transmission of mosquito-borne diseases indoors. The study assessed the effectiveness of house eaves screening in reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya. Methods 160 houses were selected for the study, with half of them randomly chosen for eaves screening with fibre-glass coated wire mesh (experimental group) and the other half left without screening (control group). Randomization was carried out by use of computer-generated list in permuted blocks of ten houses and 16 village blocks, with half of them allocated treatment in a ratio of 1:1. Cross-sectional baseline entomological and parasitological data were collected before eave screening. After baseline data collection, series of sampling of indoor adult mosquitoes were conducted once a month in each village using CDC light traps. Three cross-sectional malaria parasitological surveys were conducted at three month intervals after installation of the screens. The primary outcome measures were indoor Anopheles mosquito density and malaria parasite prevalence. Results A total of 15,286 mosquitoes were collected over the two year period using CDC light traps in 160 houses distributed over 16 study villages (mean mosquitoes = 4.35, SD = 11.48). Of all mosquitoes collected, 2,872 (18.8%) were anophelines (2,869 Anopheles gambiae sensu lato, 1 Anopheles funestus and 2 other Anopheles spp). Overall, among An. gambiae collected, 92.6% were non-blood fed, 3.57% were blood fed and the remaining 0.47% were composed of gravid and half gravid females. More indoor adult mosquitoes were collected in the control than experimental arms of the study. Results from cross-sectional parasitological surveys showed that screened houses recorded relatively low malaria parasite prevalence rates compared to the control houses. Overall, malaria prevalence was 5.6% (95% CI: 4.2–7.5) n = 1,918, with baseline prevalence rate of 6.1% (95% CI: 3.9–9.4), n = 481 and 3rd follow-up survey prevalence of 3.6% (95% CI: 2.0–6.8) n = 494. At all the three parasitological follow-up survey points, house screening significantly reduced the malaria prevalence by 100% (p < 0.001), 63.6% (p = 0.026), and 100% (p < 0.001) in the 1st, 2nd and 3rd follow-up surveys respectively. Conclusions The study demonstrated that house eave screening has potential to reduce indoor vector densities and malaria prevalence in high transmission areas.

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Evaluating effectiveness of screening house eaves as an intervention for integrated vector management for malaria control in Nyabondo, Western Kenya.

10.21203/rs.2.18504/v1 ◽

2019 ◽

Author(s):

Peter Njoroge Ng'ang'a ◽

Collins Okoyo ◽

Charles Mbogo ◽

Clifford Maina Mutero

Keyword(s):

Malaria Transmission ◽

Malaria Prevalence ◽

Wire Mesh ◽

Control Group ◽

Cross Sectional ◽

Western Kenya ◽

Study Results ◽

Entry Points ◽

Mosquito Entry

Abstract BackgroundMosquito-proofing of houses with appropriate screens fixed at potential mosquito entry points is gaining greater recognition as a practical intervention for reducing malaria transmission indoors. The study aimed at evaluating the effectiveness of house eaves screening in preventing mosquito entry and malaria prevalence in Nyabondo, western Kenya. Methods160 houses were selected for the study, with half of them randomly chosen for screening at the eaves with fibre-glass coated wire mesh (experimental group) and the other half left without screening (control group). Randomization was carried out by use of computer-generated list, in permuted blocks of ten houses and 16 village blocks in the study site, with treatments in the ratio of 1:1. Cross-sectional baseline entomological and malaria parasitological data were collected before house eave screening. After the baseline period, series of sampling of indoor adult mosquitoes were conducted once a month in each village using CDC light traps. Three cross-sectional malaria parasitological surveys were also conducted at three month intervals after installation of the screens. The primary outcome measures were indoor Anopheles mosquito density and malaria parasite prevalence. ResultsA total of 15,286 mosquitoes were collected over the two years period using CDC light trap in 160 houses distributed over 16 study villages (mean = 4.35, SD = 11.48). Of all mosquitoes collected, 2,872 were anophelines (2,869 An. gambiae s.l., 1 An. funestus and 2 other anopheles). Overall, among An. gambiae collected, 92.6% were non-blood fed, 3.57% were blood fed and the remaining 0.47% were composed of gravid and half gravid females. Overall more mosquitoes were collected in the control than experimental arms of the study. Results from four cross-sectional prevalence surveys showed that screened houses recorded relatively low malaria prevalence rates compared to the control houses. Overall, malaria prevalence was 5.6% (95%CI: 4.2-7.5) N=1,918, with baseline survey recording 6.1% prevalence (95%CI: 3.9-9.4), n=481 and third follow-up survey recording 3.6% prevalence (95%CI: 2.0-6.8) n=494. At all the three follow-up survey points, house screening significantly reduced the malaria prevalence by 100% (p<0.001), 63.6% (p=0.026), and 100% (p<0.001) for first, second and third follow-ups surveys respectively. The house screening significantly reduced malaria prevalence by 54% (OR = 0.46, 95%CI: 0.24-0.87, p = 0.017). ConclusionsThe study demonstrated that house eave screening has potential to reduce indoor vector densities and malaria transmission in high transmission areas in Kenya.

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Evaluating effectiveness of screening house eaves as a potential intervention for reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya .

10.21203/rs.2.18504/v2 ◽

2020 ◽

Author(s):

PETER N. NG'ANG'A ◽

Collins Okoyo ◽

Charles Mbogo ◽

Clifford Maina Mutero

Keyword(s):

Malaria Parasite ◽

Light Trap ◽

Parasite Prevalence ◽

Malaria Prevalence ◽

Wire Mesh ◽

Control Group ◽

Cross Sectional ◽

Western Kenya ◽

Study Results

Abstract Background: Mosquito-proofing of houses using wire mesh screens is gaining greater recognition as a practical intervention for reducing exposure to malaria transmitting mosquitoes. Screening potentially protects all persons sleeping inside the house against transmission of mosquito-borne diseases indoors. The study assessed the effectiveness of house eaves screening in reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya. Methods: 160 houses were selected for the study, with half of them randomly chosen for eaves screening with fibre-glass coated wire mesh (experimental group) and the other half left without screening (control group). Randomization was carried out by use of computer-generated list in permuted blocks of ten houses and 16 village blocks, with half of them allocated treatment in a ratio of 1:1. Cross-sectional baseline entomological and parasitological data were collected before eave screening. After baseline data collection, series of sampling of indoor adult mosquitoes were conducted once a month in each village using CDC light traps. Three cross-sectional malaria parasitological surveys were conducted at three month intervals after installation of the screens. The primary outcome measures were indoor Anopheles mosquito density and malaria parasite prevalence. Results: A total of 15,286 mosquitoes were collected over the two years period using CDC light trap in 160 houses distributed over 16 study villages (mean = 4.35, SD = 11.48). Of all mosquitoes collected, 2,872 were anophelines (2,869 An. gambiae s.l., 1 An. funestus and 2 other Anopheles spp ). Overall, among An. gambiae collected, 92.6% were non-blood fed, 3.57% were blood fed and the remaining 0.47% were composed of gravid and half gravid females. More indoor adult mosquitoes were collected in the control than experimental arms of the study. Results from cross-sectional parasitological surveys showed that screened houses recorded relatively low malaria parasite prevalence rates compared to the control houses. Overall, malaria prevalence was 5.6% (95%CI: 4.2-7.5) n=1,918, with baseline prevalence rate of 6.1% (95%CI: 3.9-9.4), n=481 and 3 rd follow-up survey prevalence of 3.6% (95%CI: 2.0-6.8) n=494. At all the three parasitological follow-up survey points, house screening significantly reduced the malaria prevalence by 100% (p<0.001), 63.6% (p=0.026), and 100% (p<0.001) in the 1 st , 2 nd and 3 rd follow-up surveys respectively. Conclusions: The study demonstrated that house eave screening has potential to reduce indoor vector densities and malaria prevalence in high transmission areas.

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FACTORS ASSOCIATED WITH HEMOGLOBIN CONCENTRATIONS IN PRE-SCHOOL CHILDREN IN WESTERN KENYA: CROSS-SECTIONAL STUDIES

American Journal of Tropical Medicine and Hygiene ◽

10.4269/ajtmh.2005.72.47 ◽

2005 ◽

Vol 72 (1) ◽

pp. 47-59 ◽

Cited By ~ 37

Author(s):

MEGHNA R. DESAI ◽

PENELOPE A. PHILLIPS-HOWARD ◽

DIANNE J. TERLOUW ◽

ARTHUR M. KWENA ◽

YA PING SHI ◽

...

Keyword(s):

School Children ◽

Cross Sectional ◽

Western Kenya ◽

Factors Associated ◽

Cross Sectional Studies

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Evaluating effectiveness of screening house eaves as a potential intervention for reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya

10.21203/rs.2.18504/v4 ◽

2020 ◽

Author(s):

PETER N. NG'ANG'A ◽

Collins Okoyo ◽

Charles Mbogo ◽

Clifford Maina Mutero

Keyword(s):

Malaria Parasite ◽

Parasite Prevalence ◽

Malaria Prevalence ◽

Wire Mesh ◽

Control Group ◽

Light Traps ◽

Cross Sectional ◽

Western Kenya ◽

Study Results

Abstract Background Mosquito-proofing of houses using wire mesh screens is gaining greater recognition as a practical intervention for reducing exposure to malaria transmitting mosquitoes. Screening potentially protects all persons sleeping inside the house against transmission of mosquito-borne diseases indoors. The study assessed the effectiveness of house eaves screening in reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya. Methods 160 houses were selected for the study, with half of them randomly chosen for eaves screening with fibre-glass coated wire mesh (experimental group) and the other half left without screening (control group). Randomization was carried out by use of computer-generated list in permuted blocks of ten houses and 16 village blocks, with half of them allocated treatment in a ratio of 1:1. Cross-sectional baseline entomological and parasitological data were collected before eave screening. After baseline data collection, series of sampling of indoor adult mosquitoes were conducted once a month in each village using CDC light traps. Three cross-sectional malaria parasitological surveys were conducted at three month intervals after installation of the screens. The primary outcome measures were indoor Anopheles mosquito density and malaria parasite prevalence. Results A total of 15,286 mosquitoes were collected over the two year period using CDC light traps in 160 houses distributed over 16 study villages (mean mosquitoes = 4.35, SD = 11.48). Of all mosquitoes collected, 2,872 (18.8%) were anophelines (2,869 Anopheles gambiae sensu lato, 1 Anopheles funestus and 2 other Anopheles spp). Overall, among An. gambiae collected, 92.6% were non-blood fed, 3.57% were blood fed and the remaining 0.47% were composed of gravid and half gravid females. More indoor adult mosquitoes were collected in the control than experimental arms of the study. Results from cross-sectional parasitological surveys showed that screened houses recorded relatively low malaria parasite prevalence rates compared to the control houses. Overall, malaria prevalence was 5.6% (95%CI: 4.2-7.5) n=1,918, with baseline prevalence rate of 6.1% (95%CI: 3.9-9.4), n=481 and 3rd follow-up survey prevalence of 3.6% (95%CI: 2.0-6.8) n=494. At all the three parasitological follow-up survey points, house screening significantly reduced the malaria prevalence by 100% (p<0.001), 63.6% (p=0.026), and 100% (p<0.001) in the 1st, 2nd and 3rd follow-up surveys respectively.Conclusions The study demonstrated that house eave screening has potential to reduce indoor vector densities and malaria prevalence in high transmission areas.

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Prevalence and severity of malnutrition and age at menarche; cross-sectional studies in adolescent schoolgirls in western Kenya

European Journal of Clinical Nutrition ◽

10.1038/sj.ejcn.1602031 ◽

2004 ◽

Vol 59 (1) ◽

pp. 41-48 ◽

Cited By ~ 48

Author(s):

T Leenstra ◽

L T Petersen ◽

S K Kariuki ◽

A J Oloo ◽

P A Kager ◽

...

Keyword(s):

Age At Menarche ◽

Cross Sectional ◽

Western Kenya ◽

Cross Sectional Studies

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Prevalence and severity of anemia and iron deficiency: cross-sectional studies in adolescent schoolgirls in western Kenya

European Journal of Clinical Nutrition ◽

10.1038/sj.ejcn.1601865 ◽

2004 ◽

Vol 58 (4) ◽

pp. 681-691 ◽

Cited By ~ 32

Author(s):

T Leenstra ◽

S K Kariuki ◽

J D Kurtis ◽

A J Oloo ◽

P A Kager ◽

...

Keyword(s):

Iron Deficiency ◽

Cross Sectional ◽

Western Kenya ◽

Cross Sectional Studies

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Evaluating effectiveness of screening house eaves as a potential intervention for reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya .

10.21203/rs.2.18504/v3 ◽

2020 ◽

Author(s):

PETER N. NG'ANG'A ◽

Collins Okoyo ◽

Charles Mbogo ◽

Clifford Maina Mutero

Keyword(s):

Malaria Parasite ◽

Parasite Prevalence ◽

Malaria Prevalence ◽

Wire Mesh ◽

Control Group ◽

Light Traps ◽

Cross Sectional ◽

Western Kenya ◽

Study Results

Abstract Background: Mosquito-proofing of houses using wire mesh screens is gaining greater recognition as a practical intervention for reducing exposure to malaria transmitting mosquitoes. Screening potentially protects all persons sleeping inside the house against transmission of mosquito-borne diseases indoors. The study assessed the effectiveness of house eaves screening in reducing indoor vector densities and malaria prevalence in Nyabondo, western Kenya. Methods: 160 houses were selected for the study, with half of them randomly chosen for eaves screening with fibre-glass coated wire mesh (experimental group) and the other half left without screening (control group). Randomization was carried out by use of computer-generated list in permuted blocks of ten houses and 16 village blocks, with half of them allocated treatment in a ratio of 1:1. Cross-sectional baseline entomological and parasitological data were collected before eave screening. After baseline data collection, series of sampling of indoor adult mosquitoes were conducted once a month in each village using CDC light traps. Three cross-sectional malaria parasitological surveys were conducted at three month intervals after installation of the screens. The primary outcome measures were indoor Anopheles mosquito density and malaria parasite prevalence. Results: A total of 15,286 mosquitoes were collected over the two year period using CDC light traps in 160 houses distributed over 16 study villages (mean mosquitoes = 4.35, SD = 11.48). Of all mosquitoes collected, 2,872 (18.8%) were anophelines (2,869 An. gambiae s.l., 1 An. funestus and 2 other Anopheles spp). Overall, among An. gambiae collected, 92.6% were non-blood fed, 3.57% were blood fed and the remaining 0.47% were composed of gravid and half gravid females. More indoor adult mosquitoes were collected in the control than experimental arms of the study. Results from cross-sectional parasitological surveys showed that screened houses recorded relatively low malaria parasite prevalence rates compared to the control houses. Overall, malaria prevalence was 5.6% (95%CI: 4.2-7.5) n=1,918, with baseline prevalence rate of 6.1% (95%CI: 3.9-9.4), n=481 and 3rd follow-up survey prevalence of 3.6% (95%CI: 2.0-6.8) n=494. At all the three parasitological follow-up survey points, house screening significantly reduced the malaria prevalence by 100% (p<0.001), 63.6% (p=0.026), and 100% (p<0.001) in the 1st, 2nd and 3rd follow-up surveys respectively.Conclusions: The study demonstrated that house eave screening has potential to reduce indoor vector densities and malaria prevalence in high transmission areas.

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Long lasting insecticidal mosquito nets (LLINs) ownership, use and coverage following mass distribution campaign in Lake Victoria basin, Western Kenya

BMC Public Health ◽

10.1186/s12889-021-11062-7 ◽

2021 ◽

Vol 21 (1) ◽

Author(s):

Peter N. Ng’ang’a ◽

Polycarp Aduogo ◽

Clifford M. Mutero

Keyword(s):

Mass Distribution ◽

Lake Victoria ◽

Signs And Symptoms ◽

Malaria Prevention ◽

Lake Victoria Basin ◽

Previous Night ◽

Cross Sectional ◽

Western Kenya ◽

Mass Distribution Campaign ◽

Distribution Campaign

Abstract Background Long-lasting insecticidal nets (LLINs) are the most widely used malaria prevention and control intervention in Africa. However, their effectiveness may vary depending on their local geographic coverage, ownership and use at household level. This study aimed at assessing LLINs ownership and use following mass distribution campaign in western Kenya. Methods A cross-sectional study was conducted in November 2017. A total of 160 households were randomly selected from 16 villages. Structured questionnaires were used to collect data on households’ knowledge on malaria, LLINs ownership, utilization and their perceived benefits. Data was analyzed using IBM Statistical Package for Social Sciences (SPSS) version 21 for windows. Variables were presented as proportions and associations between variables tested using Pearson’s chi-square test. Results Malaria was reported to be the most frequently occurring disease (87.5%) in the area. Children under 5 years of age were reported to be at higher risks of malaria infection (28.6%). Around 31% of the respondents reported to have at least one member of the household sick with malaria a week before the interview. Commonly cited signs and symptoms of malaria were; fever (24.1%), headache (17.7%), vomiting (14.5%) feeling cold (12.6%) and loss of appetite (10%). There were 382 reported LLINs among 753 occupants in the 160 households surveyed. The average LLIN ownership was 2.4 nets per household and 1.97 persons per LLIN. Among the surveyed households, 96.9% owned at least one LLIN and 64.1% owned at least one LLIN for every two people. Among those who owned LLINs, 98.1% reported using them the previous night. Ownership per household ranged from 0 to 6 with a mean of 2.39. More than three quarter of the nets were acquired through free mass distribution campaigns and 80% were acquired less than 6 months prior to the survey. Conclusion Despite high net coverage and use, a number of households experienced malaria episodes in the study area. There is need to investigate the likelihood of outdoor malaria transmission and assess the physical integrity of the existing LLINs and their insecticidal effectiveness in protecting household members against malaria.

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Geographical distribution of schistosomiasis and soil-transmitted helminths among school children in informal settlements in Kisumu City, Western Kenya

Parasitology ◽

10.1017/s003118201100059x ◽

2011 ◽

Vol 138 (12) ◽

pp. 1569-1577 ◽

Cited By ~ 30

Author(s):

MAURICE R. ODIERE ◽

SELPHA OPISA ◽

GLADYS ODHIAMBO ◽

WALTER G. Z. O. JURA ◽

JOHN M. AYISI ◽

...

Keyword(s):

Primary Schools ◽

Lake Victoria ◽

Informal Settlements ◽

Cross Sectional Study ◽

Geographical Information ◽

Health Priorities ◽

Cross Sectional ◽

Western Kenya ◽

Kisumu City ◽

Urban Settlements

SUMMARYThis cross-sectional study determined the prevalence and distribution of schistosome and soil-transmitted helminth (STH) infections among 1,308 children aged 10–18 years in 34 primary schools in 8 informal urban settlements in Kisumu City, western Kenya. Stool samples were collected and examined for eggs of Schistosoma mansoni and STH (Hookworms, Ascaris lumbricoides and Trichuris trichiura) using the Kato-Katz technique. Haematuria was used as a proxy indicator of urinary schistosomiasis. Schools and water bodies were mapped using a geographical information system. Overall, 34% of children were infected with one or more helminth species whereas 16·2% of children were infected with one or more STH species. Schools in closest proximity to Lake Victoria and River Nyamasaria had the highest S. mansoni prevalence while schools with STH were more homogenously distributed. Mean school prevalence of S. mansoni infection was 21% (range=0–69·7%), S. haematobium 3·6% (range=0–12%), hookworms 6·1% (range=0–20%), A. lumbricoides 4·9% (range=0–18·4%), and T. trichiura 7·7% (range=0–18·6%). Helminth-related morbidities were not associated with infection. Our study demonstrates that schistosomiasis and STH are important health priorities among schools in informal settlements of Kisumu City, and highlights the need for routine deworming in similar settings.

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