Indirect Effects of 10-Valent Pneumococcal Conjugate Vaccine Against Adult Pneumococcal Pneumonia in Rural Western Kenya.

BACKGROUND: Data on pneumococcal conjugate vaccine (PCV) indirect effects in low-income countries with high human immunodeficiency virus (HIV) burden are limited. We examined adult pneumococcal pneumonia incidence before and after PCV introduction in Kenya in 2011. METHODS: From 1 January 2008 to 31 December 2016, we conducted surveillance for acute respiratory infection (ARI) among ~12 000 adults (≥18 years) in western Kenya, where HIV prevalence is ~17%. ARI cases (cough or difficulty breathing or chest pain, plus temperature ≥38.0°C or oxygen saturation <90%) presenting to a clinic underwent blood culture and pneumococcal urine antigen testing (UAT). We calculated ARI incidence and adjusted for healthcare seeking. The proportion of ARI cases with pneumococcus detected among those with complete testing (blood culture and UAT) was multiplied by adjusted ARI incidence to estimate pneumococcal pneumonia incidence. RESULTS: Pre-PCV (2008-2010) crude and adjusted ARI incidences were 3.14 and 5.30/100 person-years-observation (pyo), respectively. Among ARI cases, 39.0% (340/872) had both blood culture and UAT; 21.2% (72/340) had pneumococcus detected, yielding a baseline pneumococcal pneumonia incidence of 1.12/100 pyo (95% confidence interval [CI]: 1.0-1.3). In each post-PCV year (2012-2016), the incidence was significantly lower than baseline; with incidence rate ratios (IRRs) of 0.53 (95% CI: 0.31-0.61) in 2012 and 0.13 (95% CI: 0.09-0.17) in 2016. Similar declines were observed in HIV-infected (IRR: 0.13; 95% CI: 0.08-0.22) and HIV-uninfected (IRR: 0.10; 95% CI: 0.05-0.20) adults. CONCLUSIONS: Adult pneumococcal pneumonia declined in western Kenya following PCV introduction, likely reflecting vaccine indirect effects. Evidence of herd protection is critical for guiding PCV policy decisions in resource-constrained areas.

Risk factors for death among children less than 5 years old hospitalized with diarrhea in rural western Kenya, 2005-2007: a cohort study.

BACKGROUND: Diarrhea is a leading cause of childhood morbidity and mortality in sub-Saharan Africa. Data on risk factors for mortality are limited. We conducted hospital-based surveillance to characterize the etiology of diarrhea and identify risk factors for death among children hospitalized with diarrhea in rural western Kenya. METHODS AND FINDINGS: We enrolled all children <5 years old, hospitalized with diarrhea (≥3 loose stools in 24 hours) at two district hospitals in Nyanza Province, western Kenya. Clinical and demographic information was collected. Stool specimens were tested for bacterial and viral pathogens. Bivariate and multivariable logistic regression analyses were carried out to identify risk factors for death. From May 23, 2005 to May 22, 2007, 1,146 children <5 years old were enrolled; 107 (9%) children died during hospitalization. Nontyphoidal Salmonella were identified in 10% (118), Campylobacter in 5% (57), and Shigella in 4% (42) of 1,137 stool samples; rotavirus was detected in 19% (196) of 1,021 stool samples. Among stools from children who died, nontyphoidal Salmonella were detected in 22%, Shigella in 11%, rotavirus in 9%, Campylobacter in 5%, and S. Typhi in <1%. In multivariable analysis, infants who died were more likely to have nontyphoidal Salmonella (adjusted odds ratio [aOR] = 6·8; 95% CI 3·1-14·9), and children <5 years to have Shigella (aOR = 5·5; 95% CI 2·2-14·0) identified than children who survived. Children who died were less likely to be infected with rotavirus (OR = 0·4; 95% CI 0·2-0·8). Further risk factors for death included being malnourished (aOR = 4·2; 95% CI 2·1-8·7); having oral thrush on physical exam (aOR = 2·3; 95% CI 1·4-3·8); having previously sought care at a hospital for the illness (aOR = 2·2; 95% CI 1·2-3·8); and being dehydrated as diagnosed at discharge/death (aOR = 2·5; 95% CI 1·5-4·1). A clinical diagnosis of malaria, and malaria parasites seen on blood smear, were not associated with increased risk of death. This study only captured in-hospital childhood deaths, and likely missed a substantial number of additional deaths that occurred at home. CONCLUSION: Nontyphoidal Salmonella and Shigella are associated with mortality among rural Kenyan children with diarrhea who access a hospital. Improved prevention and treatment of diarrheal disease is necessary. Enhanced surveillance and simplified laboratory diagnostics in Africa may assist clinicians in appropriately treating potentially fatal diarrheal illness.

Characterization of toxigenic Vibrio cholerae from Haiti, 2010-2011.

In October 2010, the US Centers for Disease Control and Prevention received reports of cases of severe watery diarrhea in Haiti. The cause was confirmed to be toxigenic Vibrio cholerae, serogroup O1, serotype Ogawa, biotype El Tor. We characterized 122 isolates from Haiti and compared them with isolates from other countries. Antimicrobial drug susceptibility was tested by disk diffusion and broth microdilution. Analyses included identification of rstR and VC2346 genes, sequencing of ctxAB and tcpA genes, and pulsed-field gel electrophoresis with SfiI and NotI enzymes. All isolates were susceptible to doxycycline and azithromycin. One pulsed-field gel electrophoresis pattern predominated, and ctxB sequence of all isolates matched the B-7 allele. We identified the tcpETCIRS allele, which is also present in Bangladesh strain CIRS 101. These data show that the isolates from Haiti are clonally and genetically similar to isolates originating in Africa and southern Asia and that ctxB-7 and tcpET(CIRS) alleles are undergoing global dissemination.

Rotavirus disease burden and impact and cost-effectiveness of a rotavirus vaccination program in kenya.

BACKGROUND: The projected impact and cost-effectiveness of rotavirus vaccination are important for supporting rotavirus vaccine introduction in Africa, where limited health intervention funds are available. METHODS: Hospital records, health utilization surveys, verbal autopsy data, and surveillance data on diarrheal disease were used to determine rotavirus-specific rates of hospitalization, clinic visits, and deaths due to diarrhea among children <5 years of age in Nyanza Province, Kenya. Rates were extrapolated nationally with use of province-specific data on diarrheal illness. Direct medical costs were estimated using record review and World Health Organization estimates. Household costs were collected through parental interviews. The impact of vaccination on health burden and on the cost-effectiveness per disability-adjusted life-year and lives saved were calculated. RESULTS: Annually in Kenya, rotavirus infection causes 19% of hospitalizations and 16% of clinic visits for diarrhea among children <5 years of age and causes 4471 deaths, 8781 hospitalizations, and 1,443,883 clinic visits. Nationally, rotavirus disease costs the health care system $10.8 million annually. Routine vaccination with a 2-dose rotavirus vaccination series would avert 2467 deaths (55%), 5724 hospitalizations (65%), and 852,589 clinic visits (59%) and would save 58 disability-adjusted life-years per 1000 children annually. At $3 per series, a program would cost $2.1 million in medical costs annually; the break-even price is $2.07 per series. CONCLUSIONS: A rotavirus vaccination program would reduce the substantial burden of rotavirus disease and the economic burden in Kenya.

High burden of rotavirus gastroenteritis in young children in rural western Kenya, 2010-2011.

BACKGROUND: Diarrhea is a leading cause of hospitalization and death in children <5 years of age. OBJECTIVES: To facilitate evaluation of the impact of rotavirus vaccine introduction in western Kenya, we estimated baseline rates of rotavirus-associated hospitalization and mortality among children <5 years of age. METHODS: From January 2010 to December 2011, we collected demographic, clinical and laboratory data for children <5 years of age seeking care at the district hospital and 2 outpatient facilities within a Health and Demographic Surveillance System (HDSS). Children with acute gastroenteritis (AGE), defined as ≥3 loose stools and/or ≥1 episode of unexplained vomiting followed by loose stool within a 24-hour period, were asked to provide a stool sample for rotavirus ELISA testing. Rates of rotavirus-associated hospitalization and mortality were estimated using time of residence in the HDSS to calculate person-years of observation. To estimate the rotavirus-associated mortality rate, we applied the percentage positive for rotavirus among AGE hospitalizations to verbal autopsy estimates of diarrhea deaths in the HDSS. RESULTS: There were 4991 hospitalizations of children <5 years of age; 1134 (23%) were for AGE and stool specimens were obtained from 790 (70%). Rotavirus was detected in 211 (27%) specimens. Among 4951 <5 outpatient sick visits, 608 (12%) were for AGE; 320 (51%) provided specimens and 62 (20%) were positive for rotavirus. Rotavirus AGE accounted for 501 <5 hospitalizations per 100,000 person-years of observation. Rotavirus-associated <5 mortality was 136 deaths per 100,000 person-years of observation. CONCLUSIONS: Continued surveillance of rotavirus AGE will provide timely data on the population-level impact of rotavirus vaccine following its likely introduction in 2014.

Differing burden and epidemiology of non-Typhi Salmonella bacteremia in rural and urban Kenya, 2006-2009.

BACKGROUND: The epidemiology of non-Typhi Salmonella (NTS) bacteremia in Africa will likely evolve as potential co-factors, such as HIV, malaria, and urbanization, also change. METHODS: As part of population-based surveillance among 55,000 persons in malaria-endemic, rural and malaria-nonendemic, urban Kenya from 2006-2009, blood cultures were obtained from patients presenting to referral clinics with fever ≥38.0°C or severe acute respiratory infection. Incidence rates were adjusted based on persons with compatible illnesses, but whose blood was not cultured. RESULTS: NTS accounted for 60/155 (39%) of blood culture isolates in the rural and 7/230 (3%) in the urban sites. The adjusted incidence in the rural site was 568/100,000 person-years, and the urban site was 51/100,000 person-years. In both sites, the incidence was highest in children <5 years old. The NTS-to-typhoid bacteremia ratio in the rural site was 4.6 and in the urban site was 0.05. S. Typhimurium represented >85% of blood NTS isolates in both sites, but only 21% (urban) and 64% (rural) of stool NTS isolates. Overall, 76% of S. Typhimurium blood isolates were multi-drug resistant, most of which had an identical profile in Pulse Field Gel Electrophoresis. In the rural site, the incidence of NTS bacteremia increased during the study period, concomitant with rising malaria prevalence (monthly correlation of malaria positive blood smears and NTS bacteremia cases, Spearman's correlation, p = 0.018 for children, p = 0.16 adults). In the rural site, 80% of adults with NTS bacteremia were HIV-infected. Six of 7 deaths within 90 days of NTS bacteremia had HIV/AIDS as the primary cause of death assigned on verbal autopsy. CONCLUSIONS: NTS caused the majority of bacteremias in rural Kenya, but typhoid predominated in urban Kenya, which most likely reflects differences in malaria endemicity. Control measures for malaria, as well as HIV, will likely decrease the burden of NTS bacteremia in Africa.

Does cotrimoxazole prophylaxis for the prevention of HIV-associated opportunistic infections select for resistant pathogens in Kenyan adults?

We assessed the effect of daily cotrimoxazole, essential for HIV care, on development of antifolate-resistant Plasmodium falciparum, naso-pharyngeal Streptococcus pneumoniae (pneumococcus), and commensal Escherichia coli. HIV-positive subjects with CD4 cell count < 350 cells/muL (lower-CD4; N = 692) received cotrimoxazole; HIV-positive with CD4 cell count > or = 350 cells/muL (higher-CD4; N = 336) and HIV-negative subjects (N = 132) received multivitamins. Specimens were collected at baseline, 2 weeks, monthly, and at sick visits during 6 months of follow-up to compare changes in resistance, with higher-CD4 as referent. P. falciparum parasitemia incidence density was 16 and 156/100 person-years in lower-CD4 and higher-CD4, respectively (adjusted rate ratio [ARR] = 0.11; 95% confidence interval [CI] = 0.06-0.15; P < 0.001) and 97/100 person-years in HIV-negative subjects (ARR = 0.62; 95% CI = 0.44-0.86; P = 005). Incidence density of triple and quintuple dihydrofolate-reductase/dihydropteroate-synthetase mutations was 90% reduced in lower-CD4 compared with referent. Overall, cotrimoxazole non-susceptibility was high among isolated pneumococcus (92%) and E. coli (76%) and increased significantly in lower-CD4 subjects by Week 2 (P < 0.005). Daily cotrimoxazole prevented malaria and reduced incidence of antifolate-resistant P. falciparum but contributed to increased pneumococcus and commensal Escherichia coli resistance.