Prevalence of pfdhfr and pfdhps mutations in Plasmodium falciparum associated with drug resistance among pregnant women receiving IPTp-SP at Msambweni County Referral Hospital, Kwale County, Kenya.

BACKGROUND: Prevention and treatment of malaria during pregnancy is crucial in dealing with maternal mortality and adverse fetal outcomes. The World Health Organization recommendation to treat all pregnant women with sulfadoxine-pyrimethamine (SP) through antenatal care structures was implemented in Kenya in the year 1998, but concerns about its effectiveness in preventing malaria in pregnancy has arisen due to the spread of SP resistant parasites. This study aimed to determine the prevalence of SP resistance markers in Plasmodium falciparum parasites isolated from pregnant women seeking antenatal care at Msambweni County Referral Hospital, located in coastal Kenya, between the year 2013 and 2015. METHODS: This hospital-based study included 106 malaria positive whole blood samples for analysis of SP resistance markers within the Pfdhfr gene (codons 51, 59 and 108) and Pfdhps gene (codons 437 and 540). The venous blood collected from all pregnant women was tested for malaria via light microscopy, then the malaria positive samples were separated into plasma and red cells and stored in a - 86° freezer for further studies. Archived red blood cells were processed for molecular characterization of SP resistance markers within the Pfdhfr and Pfdhps genes using real time PCR platform and Sanger sequencing. RESULTS: All samples had at least one mutation in the genes associated with drug resistance; polymorphism prevalence of Pfdhfr51I, 59R and 108N was at 88.7%, 78.3% and 93.4%, respectively, while Pfdhps polymorphism accounted for 94.3% and 91.5% at 437G and 540E, respectively. Quintuple mutations (at all the five codons) conferring total SP resistance had the highest prevalence of 85.8%. Quadruple mutations were observed at a frequency of 10.4%, and 24.5% had a mixed outcome of both wildtype and mutant genotypes in the genes of interest. CONCLUSION: The data suggest a high prevalence of P. falciparum genetic variations conferring resistance to SP among pregnant women, which may explain reduced efficacy of IPTp treatment in Kenya. There is need for extensive SP resistance profiling in Kenya to inform IPTp drug choices for successful malaria prevention during pregnancy.

The population-based burden of influenza-associated hospitalization in rural western Kenya, 2007-2009.

OBJECTIVE: To estimate the burden and age-specific rates of influenza-associated hospitalization in rural western Kenya. METHODS: All 3924 patients with respiratory illness (defined as acute cough, difficulty in breathing or pleuritic chest pain) who were hospitalized between June 2007 and May 2009 in any inpatient health facility in the Kenyan district of Bondo were enrolled. Nasopharyngeal and oropharyngeal swabs were collected and tested for influenza viruses using real-time reverse transcriptase polymerase chain reaction (RT-PCR). In the calculation of annual rates, adjustments were made for enrolled patients who did not have swabs tested for influenza virus. FINDINGS: Of the 2079 patients with tested swabs, infection with influenza virus was confirmed in 204 (10%); 176, 27 and 1 were found to be RT-PCR-positive for influenza A virus only, influenza B virus only, and both influenza A and B viruses, respectively. Among those tested for influenza virus, 6.8% of the children aged < 5 years and 14.0% of the patients aged ≥ 5 years were found positive. The case-fatality rate among admitted patients with PCR-confirmed infection with influenza virus was 2.0%. The annual rate of hospitalization (per 100,000 population) was 699.8 among patients with respiratory illness and 56.2 among patients with influenza (with 143.7, 18.8, 55.2, 65.1 and 57.3 hospitalized patients with influenza virus per 100,000 people aged < 5, 5-19, 20-34, 35-49 and ≥ 50 years, respectively). CONCLUSION: In a rural district of western Kenya, the rate of influenza-associated hospitalization was highest among children aged less than 5 years.

Postmortem Study of Cause of Death Among Children Hospitalized With Respiratory Illness in Kenya.

BACKGROUND: In resource-limited settings, acute respiratory infections continue to be the leading cause of death in young children. We conducted postmortem investigations in children <5 years hospitalized with a clinical diagnosis of respiratory disease at Kenya's largest referral hospital. METHODS: We collected respiratory and other tissues postmortem to examine pathologic processes using histology, molecular and immunohistochemistry assays. Nasopharyngeal, trachea, bronchi and lung specimens were tested using 21-target respiratory pathogen real-time reverse transcription polymerase chain reaction assays deployed on Taqman Array Cards. Expert panels reviewed all findings to determine causes of death and associated pathogens. RESULTS: From 2014 to 2015, we investigated 64 pediatric deaths (median age 7 months). Pneumonia was determined as cause of death in 70% (42/52) of cases where death was associated with an infectious disease process. The main etiologies of pneumonia deaths were respiratory syncytial virus (RSV) (n = 7, 19%), Pneumocystis jirovecii (n = 7, 19%), influenza A (n = 5, 14%) and Streptococcus pneumoniae (n = 5, 14%)-10% of cases had multi-pathogen involvement. Among the other 10 deaths associated with a nonpneumonia infectious process, 4 did not have an etiology assigned, the others were associated with miliary tuberculosis (2), cerebral thrombosis due to HIV (1), Enterobacteriaceae (1), rotavirus (1), and 1 case of respiratory infection with severe hypokalemia associated with RSV. CONCLUSIONS: In spite of well-established vaccination programs in Kenya, some deaths were still vaccine preventable. Accelerated development of RSV monoclonal antibodies and vaccines, introduction of seasonal influenza vaccination, and maintenance or improved uptake of existing vaccines can contribute to further reductions in childhood mortality.

Comparison of Minimally Invasive Tissue Sampling With Conventional Autopsy to Detect Pulmonary Pathology Among Respiratory Deaths in a Resource-Limited Setting.

OBJECTIVES: We compared minimally invasive tissue sampling (MITS) with conventional autopsy (CA) in detection of respiratory pathology/pathogens among Kenyan children younger than 5 years who were hospitalized with respiratory disease and died during hospitalization. METHODS: Pulmonary MITS guided by anatomic landmarks was followed by CA. Lung tissues were triaged for histology and molecular testing using TaqMan Array Cards (TACs). MITS and CA results were compared for adequacy and concordance. RESULTS: Adequate pulmonary tissue was obtained by MITS from 54 (84%) of 64 respiratory deaths. Comparing MITS to CA, full histologic diagnostic concordance was present in 23 (36%) cases and partial concordance in 19 (30%), an overall 66% concordance rate. Pathogen detection using TACs had full concordance in 27 (42%) and partial concordance in 24 (38%) cases investigated, an overall 80% concordance rate. CONCLUSIONS: MITS is a viable alternative to CA in respiratory deaths in resource-limited settings, especially if combined with ancillary tests to optimize diagnostic accuracy.

Determining the Cause of Death Among Children Hospitalized With Respiratory Illness in Kenya: Protocol for Pediatric Respiratory Etiology Surveillance Study (PRESS).

BACKGROUND: In sub-Saharan Africa, where the burden of respiratory disease-related deaths is the highest, information on the cause of death remains inadequate because of poor access to health care and limited availability of diagnostic tools. Postmortem examination can aid in the ascertainment of causes of death. This manuscript describes the study protocol for the Pediatric Respiratory Etiology Surveillance Study (PRESS). OBJECTIVE: This study protocol aims to identify causes and etiologies associated with respiratory disease-related deaths among children (age 1-59 months) with respiratory illness admitted to the Kenyatta National Hospital (KNH), the largest public hospital in Kenya, through postmortem examination coupled with innovative approaches to laboratory investigation. METHODS: We prospectively followed children hospitalized with respiratory illness until the end of clinical care or death. In case of death, parents or guardians were offered grief counseling, and postmortem examination was offered. Lung tissue specimens were collected using minimally invasive tissue sampling and conventional autopsy where other tissues were collected. Tissues were tested using histopathology, immunohistochemistry, and multipathogen molecular-based assays to identify pathogens. For each case, clinical and laboratory data were reviewed by a team of pathologists, clinicians, laboratorians, and epidemiologists to assign a cause of and etiology associated with death. RESULTS: We have enrolled pediatric cases of respiratory illness hospitalized at the KNH at the time of this submission; of those, 14.8% (140/945) died while in the hospital. Both analysis and interpretation of laboratory results and writing up of findings are expected in 2019-2020. CONCLUSIONS: Postmortem studies can help identify major pathogens contributing to respiratory-associated deaths in children. This information is needed to develop evidence-based prevention and treatment policies that target important causes of pediatric respiratory mortality and assist with the prioritization of local resources. Furthermore, PRESS can provide insights into the interpretation of results using multipathogen testing platforms in resource-limited settings. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/10854.

Seroprevalence of Infections with Dengue, Rift Valley Fever and Chikungunya Viruses in Kenya, 2007.

Arthropod-borne viruses are a major constituent of emerging infectious diseases worldwide, but limited data are available on the prevalence, distribution, and risk factors for transmission in Kenya and East Africa. In this study, we used 1,091 HIV-negative blood specimens from the 2007 Kenya AIDS Indicator Survey (KAIS 2007) to test for the presence of IgG antibodies to dengue virus (DENV), chikungunya virus (CHIKV) and Rift Valley fever virus (RVFV).The KAIS 2007 was a national population-based survey conducted by the Government of Kenya to provide comprehensive information needed to address the HIV/AIDS epidemic. Antibody testing for arboviruses was performed on stored blood specimens from KAIS 2007 through a two-step sandwich IgG ELISA using either commercially available kits or CDC-developed assays. Out of the 1,091 samples tested, 210 (19.2%) were positive for IgG antibodies against at least one of the three arboviruses. DENV was the most common of the three viruses tested (12.5% positive), followed by RVFV and CHIKV (4.5% and 0.97%, respectively). For DENV and RVFV, the participant's province of residence was significantly associated (P≤.01) with seropositivity. Seroprevalence of DENV and RVFV increased with age, while there was no correlation between province of residence/age and seropositivity for CHIKV. Females had twelve times higher odds of exposure to CHIK as opposed to DENV and RVFV where both males and females had the same odds of exposure. Lack of education was significantly associated with a higher odds of previous infection with either DENV or RVFV (p <0.01). These data show that a number of people are at risk of arbovirus infections depending on their geographic location in Kenya and transmission of these pathogens is greater than previously appreciated. This poses a public health risk, especially for DENV.

A household serosurvey to estimate the magnitude of a dengue outbreak in Mombasa, Kenya, 2013.

Dengue appears to be endemic in Africa with a number of reported outbreaks. In February 2013, several individuals with dengue-like illnesses and negative malaria blood smears were identified in Mombasa, Kenya. Dengue was laboratory confirmed and an investigation was conducted to estimate the magnitude of local transmission including a serologic survey to determine incident dengue virus (DENV) infections. Consenting household members provided serum and were questioned regarding exposures and medical history. RT-PCR was used to identify current DENV infections and IgM anti-DENV ELISA to identify recent infections. Of 1,500 participants from 701 households, 210 (13%) had evidence of current or recent DENV infection. Among those infected, 93 (44%) reported fever in the past month. Most (68, 73%) febrile infected participants were seen by a clinician and all but one of 32 participants who reportedly received a diagnosis were clinically diagnosed as having malaria. Having open windows at night (OR = 2.3; CI: 1.1-4.8), not using daily mosquito repellent (OR = 1.6; CI: 1.0-2.8), and recent travel outside of Kenya (OR = 2.5; CI: 1.1-5.4) were associated with increased risk of DENV infection. This survey provided a robust measure of incident DENV infections in a setting where cases were often unrecognized and misdiagnosed.

Additional diagnostic yield of adding serology to PCR in diagnosing viral acute respiratory infections in Kenyan patients 5 years of age and older.

The role of serology in the setting of PCR-based diagnosis of acute respiratory infections (ARIs) is unclear. We found that acute- and convalescent-phase paired-sample serologic testing increased the diagnostic yield of naso/oropharyngeal swabs for influenza virus, respiratory syncytial virus (RSV), human metapneumovirus, adenovirus, and parainfluenza viruses beyond PCR by 0.4% to 10.7%. Although still limited for clinical use, serology, along with PCR, can maximize etiologic diagnosis in epidemiologic studies.

Viral and bacterial causes of severe acute respiratory illness among children aged less than 5 years in a high malaria prevalence area of western Kenya, 2007-2010.

BACKGROUND: Few comprehensive data exist on the etiology of severe acute respiratory illness (SARI) among African children. METHODS: From March 1, 2007 to February 28, 2010, we collected blood for culture and nasopharyngeal and oropharyngeal swabs for real-time quantitative polymerase chain reaction for 10 viruses and 3 atypical bacteria among children aged <5 years with SARI, defined as World Health Organization-classified severe or very severe pneumonia or oxygen saturation <90%, who visited a clinic in rural western Kenya. We collected swabs from controls without febrile or respiratory symptoms. We calculated odds ratios for infection among cases, adjusting for age and season in logistic regression. We calculated SARI incidence, adjusting for healthcare seeking for SARI in the community. RESULTS: Two thousand nine hundred seventy-three SARI cases were identified (54% inpatient, 46% outpatient), yielding an adjusted incidence of 56 cases per 100 person-years. A pathogen was detected in 3.3% of noncontaminated blood cultures; non-typhi Salmonella (1.9%) and Streptococcus pneumoniae (0.7%) predominated. A pathogen was detected in 84% of nasopharyngeal/oropharyngeal specimens, the most common being rhino/enterovirus (50%), respiratory syncytial virus (RSV, 22%), adenovirus (16%) and influenza viruses (8%). Only RSV and influenza viruses were found more commonly among cases than controls (odds ratio 2.9, 95% confidence interval: 1.3-6.7 and odds ratio 4.8, 95% confidence interval: 1.1-21, respectively). Incidence of RSV, influenza viruses and S. pneumoniae were 7.1, 5.8 and 0.04 cases per 100 person-years, respectively. CONCLUSIONS: Among Kenyan children with SARI, RSV and influenza virus are the most likely viral causes and pneumococcus the most likely bacterial cause. Contemporaneous controls are important for interpreting upper respiratory tract specimens.

Etiology and Incidence of viral and bacterial acute respiratory illness among older children and adults in rural western Kenya, 2007-2010.

BACKGROUND: Few comprehensive data exist on disease incidence for specific etiologies of acute respiratory illness (ARI) in older children and adults in Africa. METHODOLOGY/PRINCIPAL FINDINGS: From March 1, 2007, to February 28, 2010, among a surveillance population of 21,420 persons >5 years old in rural western Kenya, we collected blood for culture and malaria smears, nasopharyngeal and oropharyngeal swabs for quantitative real-time PCR for ten viruses and three atypical bacteria, and urine for pneumococcal antigen testing on outpatients and inpatients meeting a ARI case definition (cough or difficulty breathing or chest pain and temperature >38.0 °C or oxygen saturation <90% or hospitalization). We also collected swabs from asymptomatic controls, from which we calculated pathogen-attributable fractions, adjusting for age, season, and HIV-status, in logistic regression. We calculated incidence by pathogen, adjusting for health-seeking for ARI and pathogen-attributable fractions. Among 3,406 ARI patients >5 years old (adjusted annual incidence 12.0 per 100 person-years), influenza A virus was the most common virus (22% overall; 11% inpatients, 27% outpatients) and Streptococcus pneumoniae was the most common bacteria (16% overall; 23% inpatients, 14% outpatients), yielding annual incidences of 2.6 and 1.7 episodes per 100 person-years, respectively. Influenza A virus, influenza B virus, respiratory syncytial virus (RSV) and human metapneumovirus were more prevalent in swabs among cases (22%, 6%, 8% and 5%, respectively) than controls. Adenovirus, parainfluenza viruses, rhinovirus/enterovirus, parechovirus, and Mycoplasma pneumoniae were not more prevalent among cases than controls. Pneumococcus and non-typhi Salmonella were more prevalent among HIV-infected adults, but prevalence of viruses was similar among HIV-infected and HIV-negative individuals. ARI incidence was highest during peak malaria season. CONCLUSIONS/SIGNIFICANCE: Vaccination against influenza and pneumococcus (by potential herd immunity from childhood vaccination or of HIV-infected adults) might prevent much of the substantial ARI incidence among persons >5 years old in similar rural African settings.

Risk factors for hospitalized seasonal influenza in rural western Kenya.

BACKGROUND: Risk factors for influenza hospitalization in Africa are unknown, including the role of HIV. METHODS: We conducted a case-control study of risk factors for hospitalized seasonal influenza among persons in rural western Kenya, a high HIV prevalence area, from March 2006-August 2008. Eligible cases were ≥five years old, admitted to health facilities with respiratory symptoms, and had nasopharyngeal/oropharyngeal swab specimens that tested positive for influenza A or B by real-time reverse transcription-PCR. Three randomly selected age-, sex- and neighborhood-matched controls were enrolled per case. A structured questionnaire was administered and home-based HIV testing was performed. Risk factors were evaluated using conditional logistic regression. RESULTS: A total of 64 cases (38 with influenza A and 26 with influenza B) and 190 controls were enrolled. The median age was 16 years (range 5-69 years). Among cases, 24.5% were HIV-infected versus 12.5% of controls (p = 0.004). Among persons ≥18 years old, 13 (59%) of 22 tested cases were HIV-positive compared with 15 (24%) of 62 tested controls (p = 0.005). In multivariable analysis, HIV-infection was associated with hospitalization due to influenza [adjusted Odds Ratio (aOR) 3.56, 95% CI 1.25-10.1]. The mean CD4 count among HIV-infected cases and controls was similar (399 vs. 387, respectively, p = 0.89). Chronic lung disease (aOR 6.83, 95% CI 1.37-34.0) was also associated with influenza hospitalization in multivariable analysis. Active pulmonary tuberculosis was associated with influenza hospitalization in bivariate, but not multivariable, analysis. CONCLUSIONS: People with HIV infection and chronic lung disease were at increased risk of hospitalized influenza in rural Kenya. HIV infection is common in many parts of sub-Saharan Africa. Influenza vaccine might prevent severe influenza in these risk groups.