The Impact of Maternal Human Immunodeficiency Virus Infection on the Burden of Respiratory Syncytial Virus Among Pregnant Women and Their Infants, Western Kenya.

BACKGROUND: Respiratory syncytial virus (RSV) is an important cause of respiratory illness worldwide; however, burden data on mother-infant pairs remain sparse in sub-Saharan Africa, where human immunodeficiency virus (HIV) is prevalent. We evaluated the impact of maternal HIV infection on the burden of RSV among mothers and their infants in western Kenya. METHODS: We enrolled pregnant women (≤20 weeks' gestation) and followed them and their newborns weekly for up to 3-6 months postpartum, to document cases of acute respiratory illness (ARI). Nasal/oropharyngeal swabs were collected and tested for RSV using polymerase chain reaction. Analyses were stratified by maternal HIV status and incidence was computed per 1000 person-months. RESULTS: Compared to RSV-negative ARI cases, RSV-positive cases were associated with cough, apnea, and hospitalization among infants. RSV incidence per 1000 person-months among mothers was 4.0 (95% confidence interval [CI], 3.2-4.4), and was twice that among the HIV-infected mothers (8.4 [95% CI, 5.7-12.0]) compared to the HIV-uninfected mothers (3.1 [95% CI, 2.3-4.0]). Among infants, incidence per 1000 person-months was 15.4 (95% CI, 12.5-18.8); incidence did not differ by HIV exposure or prematurity. CONCLUSIONS: HIV infection may increase the risk of RSV illness among pregnant women. Future maternal RSV vaccines may have added benefit in areas with high HIV prevalence.

Seroprevalence of influenza A virus in pigs and low risk of acute respiratory illness among pig workers in Kenya.

BACKGROUND: Influenza A viruses pose a significant risk to human health because of their wide host range and ability to reassort into novel viruses that can cause serious disease and pandemics. Since transmission of these viruses between humans and pigs can be associated with occupational and environmental exposures, we investigated the association between occupational exposure to pigs, occurrence of acute respiratory illness (ARI), and influenza A virus infection. METHODS: The study was conducted in Kiambu County, the county with the highest level of intensive small-scale pig farming in Kenya. Up to 3 participants (> 2 years old) per household from pig-keeping and non-pig-keeping households were randomly recruited and followed up in 2013 (Sept-Dec) and 2014 (Apr-Aug). Oropharyngeal (OP) and nasopharyngeal (NP) swabs were collected from participants with ARI at the time of study visit. For the animal study, nasal and oropharyngeal swabs, and serum samples were collected from pigs and poultry present in enrolled households. The human and animal swab samples were tested for viral nucleic acid by RT-PCR and sera by ELISA for antibodies. A Poisson generalized linear mixed-effects model was developed to assess the association between pig exposure and occurrence of ARI. RESULTS: Of 1137 human participants enrolled, 625 (55%) completed follow-up visits including 172 (27.5%) pig workers and 453 (72.5%) non-pig workers. Of 130 human NP/OP swabs tested, four (3.1%) were positive for influenza A virus, one pig worker, and three among non-pig workers. Whereas none of the 4462 swabs collected from pig and poultry tested positive for influenza A virus by RT-PCR, 265 of 4273 (6.2%) of the sera tested positive for virus antibodies by ELISA, including 11.6% (230/1990) of the pigs and 1.5% (35/2,283) of poultry. The cumulative incidence of ARI was 16.9% among pig workers and 26.9% among the non-pig workers. The adjusted risk ratio for the association between being a pig worker and experiencing an episode of ARI was 0.56 (95% CI [0.33, 0.93]), after adjusting for potential confounders. CONCLUSIONS: Our findings demonstrate moderate seropositivity for influenza A virus among pigs, suggesting the circulation of swine influenza virus and a potential for interspecies transmission.

Detection of pandemic influenza A/H1N1/pdm09 virus among pigs but not in humans in slaughterhouses in Kenya, 2013-2014.

OBJECTIVE: We conducted four cross-sectional studies over 1 year among humans and pigs in three slaughterhouses in Central and Western Kenya (> 350 km apart) to determine infection and exposure to influenza A viruses. Nasopharyngeal (NP) and oropharyngeal (OP) swabs were collected from participants who reported acute respiratory illness (ARI) defined as fever, cough or running nose. Nasal swabs and blood samples were collected from pigs. Human NP/OP and pig nasal swabs were tested for influenza A virus by real-time reverse transcriptase polymerase chain reaction (PCR) and pig serum was tested for anti-influenza A antibodies by ELISA. RESULTS: A total of 288 participants were sampled, 91.3% of them being male. Fifteen (5.2%) participants had ARI but the nine swabs collected from them were negative for influenza A virus by PCR. Of the 1128 pigs sampled, five (0.4%) nasal swabs tested positive for influenza A/H1N1/pdm09 by PCR whereas 214 of 1082 (19.8%) serum samples tested for Influenza A virus antibodies. There was higher seroprevalence in colder months and among pigs reared as free-range. These findings indicate circulation of influenza A/H1N1/pdm09 among pigs perhaps associated with good adaptation of the virus to the pig population after initial transmission from humans to pigs.

Comparison of respiratory pathogen yields from Nasopharyngeal/Oropharyngeal swabs and sputum specimens collected from hospitalized adults in rural Western Kenya.

Molecular diagnostic methods are becoming increasingly available for assessment of acute lower respiratory illnesses (ALRI). However, nasopharyngeal/oropharyngeal (NP/OP) swabs may not accurately reflect etiologic agents from the lower respiratory tract where sputum specimens are considered as a more representative sample. The pathogen yields from NP/OP against sputum specimens have not been extensively explored, especially in tropical countries. We compared pathogen yields from NP/OP swabs and sputum specimens from patients ≥18 years hospitalized with ALRI in rural Western Kenya. Specimens were tested for 30 pathogens using TaqMan Array Cards (TAC) and results compared using McNemar's test. The agreement for pathogen detection between NP/OP and sputum specimens ranged between 85-100%. More viruses were detected from NP/OP specimens whereas Klebsiella pneumoniae and Mycobacterium tuberculosis were more common in sputum specimens. There was no clear advantage in using sputum over NP/OP specimens to detect pathogens of ALRI in adults using TAC in the context of this tropical setting.