Last data update: Jan 27, 2025. (Total: 48650 publications since 2009)
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Query Trace: Macharia D[original query] |
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Healthcare-seeking behavior for respiratory illnesses in Kenya: implications for burden of disease estimation
Emukule GO , Osoro E , Nyawanda BO , Ngere I , Macharia D , Bigogo G , Otieno NA , Chaves SS , Njenga MK , Widdowson MA . BMC Public Health 2023 23 (1) 353 BACKGROUND: Understanding healthcare-seeking patterns for respiratory illness can help improve estimation of disease burden and target public health interventions to control acute respiratory disease in Kenya. METHODS: We conducted a cross-sectional survey to determine healthcare utilization patterns for acute respiratory illness (ARI) and severe pneumonia in four diverse counties representing urban, peri-urban, rural mixed farmers, and rural pastoralist communities in Kenya using a two-stage (sub-locations then households) cluster sampling procedure. Healthcare seeking behavior for ARI episodes in the last 14 days, and severe pneumonia in the last 12 months was evaluated. Severe pneumonia was defined as reported cough and difficulty breathing for > 2 days and report of hospitalization or recommendation for hospitalization, or a danger sign (unable to breastfeed/drink, vomiting everything, convulsions, unconscious) for children < 5 years, or report of inability to perform routine chores. RESULTS: From August through September 2018, we interviewed 28,072 individuals from 5,407 households. Of those surveyed, 9.2% (95% Confidence Interval [CI] 7.9-10.7) reported an episode of ARI, and 4.2% (95% CI 3.8-4.6) reported an episode of severe pneumonia. Of the reported ARI cases, 40.0% (95% CI 36.8-43.3) sought care at a health facility. Of the74.2% (95% CI 70.2-77.9) who reported severe pneumonia and visited a medical health facility, 28.9% (95% CI 25.6-32.6) were hospitalized and 7.0% (95% CI 5.4-9.1) were referred by a clinician to the hospital but not hospitalized. 21% (95% CI 18.2-23.6) of self-reported severe pneumonias were hospitalized. Children aged < 5 years and persons in households with a higher socio-economic status were more likely to seek care for respiratory illness at a health facility. CONCLUSION: Our findings suggest that hospital-based surveillance captures less than one quarter of severe pneumonia in the community. Multipliers from community household surveys can account for underutilization of healthcare resources and under-ascertainment of severe pneumonia at hospitals. |
Adopting World Health Organization Multimodal Infection Prevention and Control Strategies to Respond to COVID-19, Kenya
Kimani D , Ndegwa L , Njeru M , Wesangula E , Mboya F , Macharia C , Oliech J , Weyenga H , Owiso G , Irungu K , Luvsansharav UO , Herman-Roloff A . Emerg Infect Dis 2022 28 (13) S247-s254 The World Health Organization advocates a multimodal approach to improving infection prevention and control (IPC) measures, which Kenya adopted in response to the COVID-19 pandemic. The Kenya Ministry of Health formed a national IPC committee for policy and technical leadership, coordination, communication, and training. During March-November 2020, a total of 69,892 of 121,500 (57.5%) healthcare workers were trained on IPC. Facility readiness assessments were conducted in 777 health facilities using a standard tool assessing 16 domains. A mean score was calculated for each domain across all facilities. Only 3 domains met the minimum threshold of 80%. The Ministry of Health maintained a national list of all laboratory-confirmed SARS-CoV-2 infections. By December 2020, a total of 3,039 healthcare workers were confirmed to be SARS-CoV-2-positive, an infection rate (56/100,000 workers) 12 times higher than in the general population. Facility assessments and healthcare workers' infection data provided information to guide IPC improvements. |
Mortuary and hospital-based HIV mortality surveillance among decedents in a low-resource setting: lessons from Western Kenya
Nyakeriga E , Waruiru W , Opollo V , Waruru A , Kingwara L , Onyango D , Junghae M , Muuo S , Macharia T , Ngugi C , Mwangome M , Ali H . BMC Public Health 2022 22 (1) 609 BACKGROUND: Lack of dependable morbidity and mortality data complicates efforts to measure the demographic or population-level impact of the global HIV/AIDS epidemic. Mortuary-based mortality surveillance can address gaps in vital statistics in low-resource settings by improving accuracy of measuring HIV-associated mortality and indicators of access to treatment services among decedents. This paper describes the process and considerations taken in conducting mortuary and hospital-based HIV mortality surveillance among decedents in Kenya. MAIN TEXT: We conducted HIV mortuary and hospital-based mortality surveillance at two of the largest mortuaries in Kisumu County, Kenya (April 16-July 12, 2019). Medical charts were reviewed for documentation of HIV status among eligible decedents. HIV testing was done on blood and oral fluid samples from decedents with undocumented HIV status and those whose medical records indicated HIV-negative test results > 3 months before death. A panel of experts established the cause of death according to the International Classification of Diseases, 10th Revision rules. Civil registry data for the year 2017 were abstracted and coded to corresponding ICD-10 codes. Of the 1004 decedents admitted to the two mortuaries during the study period, 49 (4.9%) were unavailable because they had been transferred to other facilities or dispatched for burial before enrolment. Of the 955 available decedents, 104 (10.9%) were ineligible for the study. Blood samples were collected from 659 (77.4%) decedents, and 654 (99.2%) were tested for HIV. Of the 564 decedents eligible for the OraQuick® validation sub-study, 154 were eligible for oral sample collection, and 132 (85.7%) matched pre- and post-embalming oral samples were collected and tested. Of the 851 eligible decedents, 241 (28.3%) had evidence of HIV infection: 119 had a diagnosis of HIV infection recorded in their patient files, and 122 had serological evidence of HIV infection. CONCLUSION: This study shows that in low-resource settings, conducting hospital and mortuary-based surveillance is feasible and can be an alternative source of mortality data when civil registry data are inadequate. |
High HIV prevalence among decedents received by two high-volume mortuaries in Kisumu, western Kenya, 2019
Onyango DO , van der Sande MAB , Musingila P , Kinywa E , Opollo V , Oyaro B , Nyakeriga E , Waruru A , Waruiru W , Mwangome M , Macharia T , Young PW , Junghae M , Ngugi C , De Cock KM , Rutherford GW . PLoS One 2021 16 (7) e0253516 BACKGROUND: Accurate data on HIV-related mortality are necessary to evaluate the impact of HIV interventions. In low- and middle-income countries (LMIC), mortality data obtained through civil registration are often of poor quality. Though not commonly conducted, mortuary surveillance is a potential complementary source of data on HIV-associated mortality. METHODS: During April-July 2019, we assessed HIV prevalence, the attributable fraction among the exposed, and the population attributable fraction among decedents received by two high-volume mortuaries in Kisumu County, Kenya, where HIV prevalence in the adult population was estimated at 18% in 2019 with high ART coverage (76%). Stillbirths were excluded. The two mortuaries receive 70% of deaths notified to the Kisumu East civil death registry; this registry captures 45% of deaths notified in Kisumu County. We conducted hospital chart reviews to determine the HIV status of decedents. Decedents without documented HIV status, including those dead on arrival, were tested using HIV antibody tests or polymerase chain reaction (PCR) consistent with national HIV testing guidelines. Decedents aged less than 15 years were defined as children. We estimated annual county deaths by applying weights that incorporated the study period, coverage of deaths, and mortality rates observed in the study. RESULTS: The two mortuaries received a total of 1,004 decedents during the study period, of which 95.1% (955/1004) were available for study; 89.1% (851/955) of available decedents were enrolled of whom 99.4% (846/851) had their HIV status available from medical records and post-mortem testing. The overall population-based, age- and sex-adjusted mortality rate was 12.4 per 1,000 population. The unadjusted HIV prevalence among decedents was 28.5% (95% confidence interval (CI): 25.5-31.6). The age- and sex-adjusted mortality rate in the HIV-infected population (40.7/1000 population) was four times higher than in the HIV-uninfected population (10.2/1000 population). Overall, the attributable fraction among the HIV-exposed was 0.71 (95% CI: 0.66-0.76) while the HIV population attributable fraction was 0.17 (95% CI: 0.14-0.20). In children the attributable fraction among the exposed and population attributable fraction were 0.92 (95% CI: 0.89-0.94) and 0.11 (95% CI: 0.08-0.15), respectively. CONCLUSIONS: Over one quarter (28.5%) of decedents received by high-volume mortuaries in western Kenya were HIV-positive; overall, HIV was considered the cause of death in 17% of the population (19% of adults and 11% of children). Despite substantial scale-up of HIV services, HIV disease remains a leading cause of death in western Kenya. Despite progress, increased efforts remain necessary to prevent and treat HIV infection and disease. |
Impact of Kenya's Frontline Epidemiology Training Program on Outbreak Detection and Surveillance Reporting: A Geographical Assessment, 2014-2017
Macharia D , Jinnai Y , Hirai M , Galgalo T , Lowther SA , Ekechi CO , Widdowson MA , Turcios-Ruiz R , Williams SG , Baggett HKC , Bunnell RE , Oyugi E , Langat D , Makayotto L , Gura Z , Cassell CH . Health Secur 2021 19 (3) 243-253 Rapid detection and response to infectious disease outbreaks requires a robust surveillance system with a sufficient number of trained public health workforce personnel. The Frontline Field Epidemiology Training Program (Frontline) is a focused 3-month program targeting local ministries of health to strengthen local disease surveillance and reporting capacities. Limited literature exists on the impact of Frontline graduates on disease surveillance completeness and timeliness reporting. Using routinely collected Ministry of Health data, we mapped the distribution of graduates between 2014 and 2017 across 47 Kenyan counties. Completeness was defined as the proportion of complete reports received from health facilities in a county compared with the total number of health facilities in that county. Timeliness was defined as the proportion of health facilities submitting surveillance reports on time to the county. Using a panel analysis and controlling for county-fixed effects, we evaluated the relationship between the number of Frontline graduates and priority disease reporting of measles. We found that Frontline training was correlated with improved completeness and timeliness of weekly reporting for priority diseases. The number of Frontline graduates increased by 700%, from 57 graduates in 2014 to 456 graduates in 2017. The annual average rates of reporting completeness increased from 0.8% in 2014 to 55.1% in 2017. The annual average timeliness reporting rates increased from 0.1% in 2014 to 40.5% in 2017. These findings demonstrate how global health security implementation progress in workforce development may influence surveillance and disease reporting. |
Use of technology for public health surveillance reporting: opportunities, challenges and lessons learnt from Kenya
Njeru I , Kareko D , Kisangau N , Langat D , Liku N , Owiso G , Dolan S , Rabinowitz P , Macharia D , Ekechi C , Widdowson MA . BMC Public Health 2020 20 (1) 1101 BACKGROUND: Effective public health surveillance systems are crucial for early detection and response to outbreaks. In 2016, Kenya transitioned its surveillance system from a standalone web-based surveillance system to the more sustainable and integrated District Health Information System 2 (DHIS2). As part of Global Health Security Agenda (GHSA) initiatives in Kenya, training on use of the new system was conducted among surveillance officers. We evaluated the surveillance indicators during the transition period in order to assess the impact of this training on surveillance metrics and identify challenges affecting reporting rates. METHODS: From February to May 2017, we analysed surveillance data for 13 intervention and 13 comparison counties. An intervention county was defined as one that had received refresher training on DHIS2 while a comparison county was one that had not received training. We evaluated the impact of the training by analysing completeness and timeliness of reporting 15 weeks before and 12 weeks after the training. A chi-square test of independence was used to compare the reporting rates between the two groups. A structured questionnaire was administered to the training participants to assess the challenges affecting surveillance reporting. RESULTS: The average completeness of reporting for the intervention counties increased from 45 to 62%, i.e. by 17 percentage points (95% CI 16.14-17.86) compared to an increase from 49 to 52% for the comparison group, i.e. by 3 percentage points (95% CI 2.23-3.77). The timeliness of reporting increased from 30 to 51%, i.e. by 21 percentage points (95% CI 20.16-21.84) for the intervention group, compared to an increase from 31 to 38% for the comparison group, i.e.by 7 percentage points (95% CI 6.27-7.73). Major challenges for the low reporting rates included lack of budget support from government, lack of airtime for reporting, health workers strike, health facilities not sending surveillance data, use of wrong denominator to calculate reporting rates and surveillance officers having other competing tasks. CONCLUSIONS: Training plays an important role in improving public health surveillance reporting. However, to improve surveillance reporting rates to the desired national targets, other challenges affecting reporting must be identified and addressed accordingly. |
Epidemiological profile of individuals diagnosed with HIV: results from the preliminary phase of case-based surveillance in Kenya
Harklerode R , Waruiru W , Humwa F , Waruru A , Kellogg T , Muthoni L , Macharia J , Zielinski-Gutierrez E . AIDS Care 2019 32 (1) 1-7 Understanding the characteristics of individuals who are newly diagnosed with HIV is critical to controlling the HIV epidemic. Characterizing this population can improve strategies to identify undiagnosed positives and assist in targeting the provision of HIV services to improve health outcomes. We describe the characteristics of newly diagnosed HIV cases in western Kenya from 124 health facilities. The study cohort cases were matched to prevent duplication and patients newly diagnosed between January and June 2015 were identified and descriptive analysis performed. Among 8664 newly identified HIV cases, during the pilot timeframe, 3.1% (n=265) had retested for HIV after initial diagnosis. Linkage to care was recorded for approximately half (45.3%, n = 3930) and 28.0% (n = 2425) had a CD4 count available during the pilot timeframe. The median baseline CD4 count was 332 cells/mL (IQR: 156-544). Among the newly diagnosed age 15 years or older with a CD4 test, 53.0% (n = 1216) were diagnosed late, including 32.9% (n = 755) who had advanced HIV at diagnosis. Factors associated with late diagnosis included being male and in an age group older than 34 years. In western Kenya, continued efforts are needed in the area of testing to enhance early HIV diagnosis and epidemic control. |
Cholera outbreak in Dadaab refugee camp, Kenya - November 2015-June 2016
Golicha Q , Shetty S , Nasiblov O , Hussein A , Wainaina E , Obonyo M , Macharia D , Musyoka RN , Abdille H , Ope M , Joseph R , Kabugi W , Kiogora J , Said M , Boru W , Galgalo T , Lowther SA , Juma B , Mugoh R , Wamola N , Onyango C , Gura Z , Widdowson MA , DeCock KM , Burton JW . MMWR Morb Mortal Wkly Rep 2018 67 (34) 958-961 Dadaab Refugee camp in Garissa County, Kenya, hosts nearly 340,000 refugees in five subcamps (Dagahaley, Hagadera, Ifo, Ifo2, and Kambioos) (1). On November 18 and 19, 2015, during an ongoing national cholera outbreak (2), two camp residents were evaluated for acute watery diarrhea (three or more stools in </=24 hours); Vibrio cholerae serogroup O1 serotype Ogawa was isolated from stool specimens collected from both patients. Within 1 week of the report of index cases, an additional 45 cases of acute watery diarrhea were reported. The United Nations High Commissioner for Refugees and their health-sector partners coordinated the cholera response, community outreach and water, sanitation, and hygiene (WASH) activities; Medecins Sans Frontieres and the International Rescue Committee were involved in management of cholera treatment centers; CDC performed laboratory confirmation of cases and undertook GIS mapping and postoutbreak response assessment; and the Garissa County Government and the Kenya Ministry of Health conducted a case-control study. To prevent future cholera outbreaks, improvements to WASH and enhanced disease surveillance systems in Dadaab camp and the surrounding area are needed. |
Notes from the field: Ongoing cholera outbreak - Kenya, 2014-2016
George G , Rotich J , Kigen H , Catherine K , Waweru B , Boru W , Galgalo T , Githuku J , Obonyo M , Curran K , Narra R , Crowe SJ , O'Reilly CE , Macharia D , Montgomery J , Neatherlin J , De Cock KM , Lowther S , Gura Z , Langat D , Njeru I , Kioko J , Muraguri N . MMWR Morb Mortal Wkly Rep 2016 65 (3) 68-69 On January 6, 2015, a man aged 40 years was admitted to Kenyatta National Hospital in Nairobi, Kenya, with acute watery diarrhea. The patient was found to be infected with toxigenic Vibrio cholerae serogroup O1, serotype Inaba. A subsequent review of surveillance reports identified four patients in Nairobi County during the preceding month who met either of the Kenya Ministry of Health suspected cholera case definitions: 1) severe dehydration or death from acute watery diarrhea (more than four episodes in 12 hours) in a patient aged ≥5 years, or 2) acute watery diarrhea in a patient aged ≥2 years in an area where there was an outbreak of cholera. An outbreak investigation was immediately initiated. A confirmed cholera case was defined as isolation of V. cholerae O1 or O139 from the stool of a patient with suspected cholera or a suspected cholera case that was epidemiologically linked to a confirmed case. By January 15, 2016, a total of 11,033 suspected or confirmed cases had been reported from 22 of Kenya's 47 counties. The outbreak is ongoing. |
Environmental transmission of typhoid fever in an urban slum
Akullian A , Ng'eno E , Matheson AI , Cosmas L , Macharia D , Fields B , Bigogo G , Mugoh M , John-Stewart G , Walson JL , Wakefield J , Montgomery JM . PLoS Negl Trop Dis 2015 9 (12) e0004212 BACKGROUND: Enteric fever due to Salmonella Typhi (typhoid fever) occurs in urban areas with poor sanitation. While direct fecal-oral transmission is thought to be the predominant mode of transmission, recent evidence suggests that indirect environmental transmission may also contribute to disease spread. METHODS: Data from a population-based infectious disease surveillance system (28,000 individuals followed biweekly) were used to map the spatial pattern of typhoid fever in Kibera, an urban informal settlement in Nairobi Kenya, between 2010-2011. Spatial modeling was used to test whether variations in topography and accumulation of surface water explain the geographic patterns of risk. RESULTS: Among children less than ten years of age, risk of typhoid fever was geographically heterogeneous across the study area (p = 0.016) and was positively associated with lower elevation, OR = 1.87, 95% CI (1.36-2.57), p <0.001. In contrast, the risk of typhoid fever did not vary geographically or with elevation among individuals less than 6b ten years of age. CONCLUSIONS: Our results provide evidence of indirect, environmental transmission of typhoid fever among children, a group with high exposure to fecal pathogens in the environment. Spatially targeting sanitation interventions may decrease enteric fever transmission. |
An analysis of pregnancy-related mortality in the KEMRI/CDC Health and Demographic Surveillance System in western Kenya
Desai M , Phillips-Howard PA , Odhiambo FO , Katana A , Ouma P , Hamel MJ , Omoto J , Macharia S , van Eijk A , Ogwang S , Slutsker L , Laserson KF . PLoS One 2013 8 (7) e68733 BACKGROUND: Pregnancy-related (PR) deaths are often a result of direct obstetric complications occurring at childbirth. METHODS AND FINDINGS: To estimate the burden of and characterize risk factors for PR mortality, we evaluated deaths that occurred between 2003 and 2008 among women of childbearing age (15 to 49 years) using Health and Demographic Surveillance System data in rural western Kenya. WHO ICD definition of PR mortality was used: "the death of a woman while pregnant or within 42 days of termination of pregnancy, irrespective of the cause of death". In addition, symptoms and events at the time of death were examined using the WHO verbal autopsy methodology. Deaths were categorized as either (i) directly PR: main cause of death was ascribed as obstetric, or (ii) indirectly PR: main cause of death was non-obstetric. Of 3,223 deaths in women 15 to 49 years, 249 (7.7%) were PR. One-third (34%) of these were due to direct obstetric causes, predominantly postpartum hemorrhage, abortion complications and puerperal sepsis. Two-thirds were indirect; three-quarters were attributable to human immunodeficiency virus (HIV/AIDS), malaria and tuberculosis. Significantly more women who died in lower socio-economic groups sought care from traditional birth attendants (p = 0.034), while less impoverished women were more likely to seek hospital care (p = 0.001). The PR mortality ratio over the six years was 740 (95% CI 651-838) per 100,000 live births, with no evidence of reduction over time (chi(2) linear trend = 1.07; p = 0.3). CONCLUSIONS: These data supplement current scanty information on the relationship between infectious diseases and poor maternal outcomes in Africa. They indicate low uptake of maternal health interventions in women dying during pregnancy and postpartum, suggesting improved access to and increased uptake of skilled obstetric care, as well as preventive measures against HIV/AIDS, malaria and tuberculosis among all women of childbearing age may help to reduce pregnancy-related mortality. |
The burden and consequences of inherited blood disorders among young children in western Kenya.
Suchdev PS , Ruth LJ , Earley M , Macharia A , Williams TN . Matern Child Nutr 2012 10 (1) 135-44 ![]() Although inherited blood disorders are common among children in many parts of Africa, limited data are available about their prevalence or contribution to childhood anaemia. We conducted a cross-sectional survey of 858 children aged 6-35 months who were randomly selected from 60 villages in western Kenya. Haemoglobin (Hb), ferritin, malaria, C-reactive protein (CRP) and retinol binding protein (RBP) were measured from capillary blood. Using polymerase chain reaction (PCR), Hb type, -3.7 kb alpha-globin chain deletion, glucose-6-phosphate dehydrogenase (G6PD) genotype and haptoglobin (Hp) genotype were determined. More than 2 out of 3 children had at least one measured blood disorder. Sickle cell trait (HbAS) and disease (HbSS) were found in 17.1% and 1.6% of children, respectively; 38.5% were heterozygotes and 9.6% were homozygotes for alpha(+) -thalassaemia. The Hp 2-2 genotype was found in 20.4% of children, whereas 8.2% of males and 6.8% of children overall had G6PD deficiency. There were no significant differences in the distribution of malaria by the measured blood disorders, except among males with G6PD deficiency who had a lower prevalence of clinical malaria than males of normal G6PD genotype (P = 0.005). After excluding children with malaria parasitaemia, inflammation (CRP > 5 mg L(-1) ), iron deficiency (ferritin < 12 mcg L(-1) ) or vitamin A deficiency (RBP < 0.7 mcg L(-1) ), the prevalence of anaemia among those without alpha(+) -thalassaemia (43.0%) remained significantly lower than that among children who were either heterozygotes (53.5%) or homozygotes (67.7%, P = 0.03). Inherited blood disorders are common among pre-school children in western Kenya and are important contributors to anaemia. |
Detection of influenza A virus in live bird markets in Kenya, 2009-2011
Munyua PM , Githinji JW , Waiboci LW , Njagi LM , Arunga G , Mwasi L , Murithi Mbabu R , Macharia JM , Breiman RF , Njenga MK , Katz MA . Influenza Other Respir Viruses 2012 7 (2) 113-9 BACKGROUND: Surveillance for influenza viruses within live bird markets (LBMs) has been recognized as an effective tool for detecting circulating avian influenza viruses (AIVs). In Sub-Saharan Africa, limited data exist on AIVs in animal hosts, and in Kenya the presence of influenza virus in animal hosts has not been described. OBJECTIVES: This surveillance project aimed to detect influenza A virus in poultry traded in five LBMs in Kenya. METHODS: We visited each market monthly and collected oropharyngeal and cloacal specimens from poultry and environmental specimens for virological testing for influenza A by real time RT-PCR. On each visit, we collected information on the number and types of birds in each market, health status of the birds, and market practices. RESULTS: During March 24, 2009-February 28, 2011, we collected 5221 cloacal and oropharyngeal swabs. Of the 5199 (99.6%) specimens tested, influenza A virus was detected in 42 (0.8%), including 35/4166 (0.8%) specimens from chickens, 3/381 (0.8%) from turkeys, and 4/335 (1.2%) from geese. None of the 317 duck specimens were positive. Influenza was more commonly detected in oropharyngeal [33 (1.3%)] than in cloacal [9 (0.4%)] specimens. None of the 485 environmental specimens were positive. Virus was detected in all five markets during most (14/22) of the months. Ducks and geese were kept longer at the market (median 30 days) than chickens (median 2 days). CONCLUSIONS: Influenza A was detected in a small percentage of poultry traded in LBMs in Kenya. Efforts should be made to promote practices that could limit the maintenance and transmission of AIVs in LBMs. |
Rift Valley fever in Kenya: history of epizootics and identification of vulnerable districts
Murithi RM , Munyua P , Ithondeka PM , Macharia JM , Hightower A , Luman ET , Breiman RF , Njenga MK . Epidemiol Infect 2011 139 (3) 372-80 Since Kenya first reported Rift Valley fever (RVF)-like disease in livestock in 1912, the country has reported the most frequent epizootics of RVF disease. To determine the pattern of disease spread across the country after its introduction in 1912, and to identify regions vulnerable to the periodic epizootics, annual livestock disease records at the Department of Veterinary Services from 1910 to 2007 were analysed in order to document the number and location of RVF-infected livestock herds. A total of 38/69 (55%) administrative districts in the country had reported RVF epizootics by the end of 2007. During the 1912-1950 period, the disease was confined to a district in Rift Valley province that is prone to flooding and where livestock were raised in proximity with wildlife. Between 1951 and 2007, 11 national RVF epizootics were recorded with an average inter-epizootic period of 3.6 years (range 1-7 years); in addition, all epizootics occurred in years when the average annual rainfall increased by more than 50% in the affected districts. Whereas the first two national epizootics in 1951 and 1955 were confined to eight districts in the Rift Valley province, there was a sustained epizootic between 1961 and 1964 that spread the virus to over 30% of the districts across six out of eight provinces. The Western and Nyanza provinces, located on the southwestern region of the country, had never reported RVF infections by 2007. The probability of a district being involved in a national epizootic was fivefold higher (62%) in districts that had previously reported disease compared to districts that had no prior disease activity (11%). These findings suggests that once introduced into certain permissive ecologies, the RVF virus becomes enzootic, making the region vulnerable to periodic epizootics that were probably precipitated by amplification of resident virus associated with heavy rainfall and flooding. |
Rift Valley fever outbreak in livestock in Kenya, 2006-2007
Munyua P , Murithi RM , Wainwright S , Githinji J , Hightower A , Mutonga D , Macharia J , Ithondeka PM , Musaa J , Breiman RF , Bloland P , Njenga MK . Am J Trop Med Hyg 2010 83 58-64 We analyzed the extent of livestock involvement in the latest Rift Valley fever (RVF) outbreak in Kenya that started in December 2006 and continued until June 2007. When compared with previous RVF outbreaks in the country, the 2006-07 outbreak was the most extensive in cattle, sheep, goats, and camels affecting thousands of animals in 29 of 69 administrative districts across six of the eight provinces. This contrasted with the distribution of approximately 700 human RVF cases in the country, where over 85% of these cases were located in four districts; Garissa and Ijara districts in Northeastern Province, Baringo district in Rift Valley Province, and Kilifi district in Coast Province. Analysis of livestock and human data suggests that livestock infections occur before virus detection in humans, as supported by clustering of human RVF cases around livestock cases in Baringo district. The highest livestock morbidity and mortality rates were recorded in Garissa and Baringo districts, the same districts that recorded a high number of human cases. The districts that reported RVF in livestock for the first time in 2006/07 included Kitui, Tharaka, Meru South, Meru central, Mwingi, Embu, and Mbeere in Eastern Province, Malindi and Taita taveta in Coast Province, Kirinyaga and Murang'a in Central Province, and Baringo and Samburu in Rift Valley Province, indicating that the disease was occurring in new regions in the country. |
Identification of potential vectors of and detection of antibodies against Rift Valley fever virus in livestock during interepizootic periods
Rostal MK , Evans AL , Sang R , Gikundi S , Wakhule L , Munyua P , Macharia J , Feikin DR , Breiman RF , Njenga MK . Am J Vet Res 2010 71 (5) 522-6 OBJECTIVE: To evaluate the prevalence of Rift Valley fever virus (RVFV) antibodies in livestock and presence of competent mosquito vectors of RVFV during an interepizootic period (IEP) in Kenya. ANIMALS: 208 sheep and 84 goats ranging in age from 4 months to 15 years, from 2 breeding herds. PROCEDURES: Blood specimens were collected from the sheep and goats during the 1999-2006 IEP in Rift Valley Province, and serum was harvested. Serum specimens were tested for IgG and IgM antibodies against RVFV by use of an ELISA. In addition, 7,134 mosquitoes were trapped in Naivasha, Nairobi, and Northeastern Province, and speciation was performed. RESULTS: No animals were seropositive for IgM against RVFV. Of the animals born after the 1997-1998 epizootic, 18% (34/188) of sheep were seropositive for IgG against RVFV, compared with 3% (2/75) of goats. Seventy percent (8,144/11,678) of the mosquitoes collected were of the Culex subgenera; 18% (2,102/11,678) were Aedes spp. CONCLUSIONS AND CLINICAL RELEVANCE: Detection of IgG in the sera of sheep and goats born after the 1997-1998 epizootic and before the 2006 epizootic indicated that virus activity existed during the IEP. Detection of Aedes mosquitoes, which are competent vectors of RVFV, suggested that a cryptic vector-to-vertebrate cycle may exist during IEPs. |
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