Human Metapneumovirus and Other Respiratory Viral Infections during Pregnancy and Birth, Nepal.

Human metapneumovirus (HMPV) is a respiratory virus that can cause severe lower respiratory tract disease and even death, primarily in young children. The incidence and characteristics of HMPV have not been well described in pregnant women. As part of a trial of maternal influenza immunization in rural southern Nepal, we conducted prospective, longitudinal, home-based active surveillance for febrile respiratory illness during pregnancy through 6 months postpartum. During 2011-2014, HMPV was detected in 55 of 3,693 women (16.4 cases/1,000 person-years). Twenty-five women were infected with HMPV during pregnancy, compared with 98 pregnant women who contracted rhinovirus and 7 who contracted respiratory syncytial virus. Women with HMPV during pregnancy had an increased risk of giving birth to infants who were small for gestational age. An intervention to reduce HMPV febrile respiratory illness in pregnant women may have the potential to decrease risk of adverse birth outcomes in developing countries.

Risk of Respiratory Infection following Diarrhea among Adult Women and Infants in Nepal.

Globally, diarrheal and respiratory infections are responsible for more than 24% of deaths in children aged less than 5 years. Historically, these disease entities have been studied separately; recent evidence suggests that preceding diarrheal disease may be a risk factor for subsequent respiratory illness. We used data from a community-based, prospective randomized trial of maternal influenza immunization of 3,693 pregnant women and their 3,646 infants conducted in rural Nepal from 2011 to 2014. A case-crossover design was used to determine whether the risk of respiratory infection in the 30 days following a diarrheal episode was increased compared with that 30 days prior. Diarrheal illness was a significant risk factor for subsequent respiratory illness in infants but not in women during pregnancy or in women up to six months postpartum. Diarrheal illness and respiratory infections remain important global sources of morbidity and mortality, and our study supports a causal relationship between them in infants.

Transplacental transfer of maternal respiratory syncytial virus (RSV) antibody and protection against RSV disease in infants in rural Nepal.

BACKGROUND: Respiratory syncytial virus (RSV) is the most important viral cause of pneumonia in children. RSV-specific antibody (ab) protects infants from disease, and may be increased by a potential strategy of maternal RSV vaccination. OBJECTIVES: To describe the effect of RSV antibody on RSV infection risk in infants in a resource-limited setting. STUDY DESIGN: In a prospective study in Nepal, women were enrolled during pregnancy and maternal and infant cord blood were collected at birth. Weekly surveillance for respiratory illness was performed from birth to 180days. Nasal swabs were tested for RSV by PCR and serum was tested using an RSV antibody microneutralization assay. Antibody concentrations at time of RSV infection were estimated based on a decay rate of 0.026 log2/day. RESULTS: Cord:maternal RSV antibody transfer ratio was 1.03 (0.88-1.19), with RSV antibody concentration of log2 11.3 and log2 11.7 in 310 paired maternal and infant samples, respectively. Cord blood RSV antibody was log2 12.1 versus 11.6 in those with or without RSV infection (P=0.86). Among infants with RSV infection, estimated RSV antibody concentration at time of infection did not differ in infants with upper (n=8; log2 10.7) versus lower respiratory tract infection (n=21; log2 9.8; P=0.37). Cord blood RSV antibody concentrations did not correlate with age at primary RSV infection (R=0.11; P=0.57). CONCLUSIONS: Transplacental transfer of RSV antibody from mother to the fetus was highly efficient in mother-infant pairs in rural Nepal, though higher antibody concentrations were not protective against earlier or more severe RSV infection in infants.

Febrile Rhinovirus Illness During Pregnancy Is Associated With Low Birth Weight in Nepal.

BACKGROUND: Adverse birth outcomes, including low birth weight (LBW), defined as <2500 grams, small-for-gestational-age (SGA), and prematurity, contribute to 60%-80% of infant mortality worldwide and may be related to infections during pregnancy. The aim of this study was to assess whether febrile human rhinovirus (HRV) illness is associated with adverse birth outcomes. METHODS: Active household-based weekly surveillance was performed for respiratory illness episodes in pregnant women as part of a community-based, prospective, randomized trial of maternal influenza immunization in rural Nepal. Rhinovirus (HRV) febrile illness episodes were defined as fever plus cough, sore throat, runny nose, and/or myalgia with HRV detected on mid-nasal swab. Multivariate regression analysis evaluated the association between febrile HRV respiratory illness and adverse birth outcomes. RESULTS: Overall, 96 (3%) of 3693 pregnant women had HRV-positive febrile respiratory illnesses. Infants born to pregnant women with HRV febrile illness had a 1.6-fold increased risk of being LBW compared with those with non-HRV febrile illness (28 of 96 [38%] vs 109 of 458 [24%]; relative risk [RR], 1.6; 95% confidence interval [CI], 1.1-2.3). No difference in risk of LBW was observed between infants born to mothers with non-HRV febrile respiratory illness and those without respiratory illness during pregnancy (109 of 458 [24%] vs 552 of 2220 [25%], respectively; RR, 1.0; 95% CI, 0.8-1.2). CONCLUSIONS: Febrile illness due to rhinovirus during pregnancy was associated with increased risk of LBW in a rural South Asian population. Interventions to reduce the burden of febrile respiratory illness due to rhinovirus during pregnancy may have a significant impact on LBW and subsequent infant mortality.