Bacterial and Viral Coinfections with the Human Respiratory Syncytial Virus.

The human respiratory syncytial virus (hRSV) is one of the leading causes of acute lower respiratory tract infections in children under five years old. Notably, hRSV infections can give way to pneumonia and predispose to other respiratory complications later in life, such as asthma. Even though the social and economic burden associated with hRSV infections is tremendous, there are no approved vaccines to date to prevent the disease caused by this pathogen. Recently, coinfections and superinfections have turned into an active field of study, and interactions between many viral and bacterial pathogens have been studied. hRSV is not an exception since polymicrobial infections involving this virus are common, especially when illness has evolved into pneumonia. Here, we review the epidemiology and recent findings regarding the main polymicrobial infections involving hRSV and several prevalent bacterial and viral respiratory pathogens, such as Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus pneumoniae, Haemophilus influenzae, Moraxella catarrhalis, Klebsiella pneumoniae, human rhinoviruses, influenza A virus, human metapneumovirus, and human parainfluenza viruses. As reports of most polymicrobial infections involving hRSV lack a molecular basis explaining the interaction between hRSV and these pathogens, we believe this review article can serve as a starting point to interesting and very much needed research in this area.

A 28-year study of human parainfluenza in Rio Grande do Sul, Southern Brazil.

PROBLEM: Human parainfluenza virus (hPIV) is an important pathogen in respiratory infections, however the health burden of hPIV is underestimated. This study describes the infections by hPIV1-3 in Rio Grande do Sul, Brazil, from 1990 to 2017, providing data of the frequency and seasonality of cases and associated clinical symptoms. METHOD OF STUDY: Nasopharyngeal samples of patients with respiratory infection were collected, clinical data were analyzed, and immunofluorescence was used to detect hPIV. RESULTS: Respiratory viruses were detected in 33.63% of respiratory infections. In a total of 11 606 cases of viral respiratory infection, 781 were positive for hPIV; hPIV prevalence ranged from 2.14% to 27% of viral respiratory infections. hPIV1 circulates mainly during fall; hPIV3 circulation, in turn, starts in fall and peaks during spring; and cases of hPIV2 are reported along the year, with peaks in fall and early spring. The most affected age group was children, with hPIV prevalence of 74.23% in patients for less than 1 year. A higher proportion of girls were infected than boys, however, no difference by sex was observed considering all age groups. The most frequent type was hPIV3, especially in hospitalized patients. Both hPIV1 and 3 were associated with dyspnea, while hPIV2 caused mild symptoms mainly in nonhospitalized patients. Nineteen fatalities occurred, 89.5% of them associated with risk factors (prematurity; chronic diseases; age, <1 or >60 years). CONCLUSION: hPIV causes a high number of respiratory infections, leading to hospitalization especially in children; epidemiological and surveillance studies are important for the control and management of respiratory infections.