Respiratory Virus Surveillance In Hospitalized Pneumonia Patients On The Thailand-Myanmar Border

Background: Pneumonia is a significant cause of morbidity and mortality in the developing world, especially in children. Viruses, in particular influenza and respiratory syncitial viruses (RSV), contribute significantly to the burden of pneumonia, although data for low-income and tropical countries are scarce. We characterized the epidemiology of respiratory virus infections among Karen refugees living on the Thailand-Myanmar border through laboratory-enhanced, hospital-based surveillance. Methods: Maela camp provides shelter for >40,000 refugees. Inside the camp, a humanitarian organization provides free inpatient care in a 158-bed inpatient department (IPD). Between 1st April 2009 and 30th September 2011, all patients admitted to the IPD with a clinical diagnosis of pneumonia were invited to participate in surveillance. Clinical symptoms and signs were recorded and a nasopharyngeal aspirate (NPA) collected. NPAs were tested for adenoviruses, human metapneumovirus (hMPV), influenza A & B, and RSV by real-time RT-PCR. Results: Among 2,231 admitted with a clinical diagnosis of lower respiratory tract infection,708 (31.7%) patients participated in surveillance. The median age was 1 year (range: 0-70), and 90.4% were aged <5 years. 57.3% were male and 42.7% female. Patients presented at a median of 4 days of illness (IQR: 2-6). 284/701 (40.5%) patients reported taking an antibiotic in the two weeks prior to admission, most commonly amoxicillin (270/283, 95.4%). At least one virus was detected in 53.7% (380/708) of patients. RSV was detected in 176/708 (24.9%); an adenovirus in 133/708 (18.8%); an influenza virus in 68/708 (9.6%); and hMPV in 33/708 (4.7%). Twenty eight multiple viral infections were identified, most commonly adenovirus plus another virus. RSV was more likely to be detected in children <5 years (p<0.0001) and influenza viruses in patients ≥5 years (p=0.001). IPD treatment was documented in 702/708 cases; all but one patient received antimicrobials, most commonly a beta-lactam (amoxicillin/ampicillin +/- gentamicin in 664/701, 94.7%). Conclusion: Viral nucleic acid was identified in the nasopharynx of over half of patients admitted with clinically diagnosed pneumonia. Immunisations targeting common respiratory viruses are likely to significantly reduce the incidence of pneumonia in children living refugee camps and similar settings. Immunisation may also result in reduced antimicrobial consumption.