Human Parainfluenza Virus (HPIV) Detection in Hospitalized Children with Acute Respiratory Tract Infection in the Western Cape, South Africa during 2014–2022 Reveals a Shift in Dominance of HPIV 3 and 4 Infections

Abstract

The epidemiology of human parainfluenza viruses (HPIV), particularly its role as a cause of acute respiratory infection (ARI) in infants, has not been formally studied in South Africa. We evaluated HPIV prevalence in diagnostic samples from hospitalized children from public sector hospitals in the Western Cape between 2014 and 2022. HPIV infection was detected in 2–10% of patients, with the majority of infections detected in children less than 1 year of age. Prior to 2020, HPIV 4 (40%) and HPIV 3 (34%) were the most prevalent types, with seasonal peaks in late winter/spring for HPIV 3 and autumn/winter for HPIV 4. HPIV 4A and 4B co-circulated during the seasonal activity between 2014 and 2017. Pandemic restrictions in 2020 had a profound effect on HPIV circulation and the rebound was dominated by waves of HPIV 3, accounting for 66% of detections and a sustained decline in the circulation of HPIV 1, 2 and 4. An immunity gap could account for the surge in HPIV 3 infections, but the decline in prior HPIV 4 dominance is unexplained and requires further study.

Epidemiological Characteristics of Human Parainfluenza Viruses Infections — China, 2019–2023

“…The recent surge of ARIs in children within China has garnered international concern (9), epidemic trends of HPIVs were examined in this study. The current analysis found an overall HPIVs detection rate of 6.15% in ARIs and 5.40% in SARIs, aligning with the results of earlier research (10)(11). HPIVs ranked third among the most commonly identified respiratory pathogens, following HRSV and HRV.…”

“…This study found that HPIVs predominantly infected children under five years old. However, HPIV2 was more frequently diagnosed in both children and adolescents, whereas HPIV4 was often detected in the elderly, confirming earlier reports ( 12 ). Furthermore, although HPIVs infections are known to cause a broad spectrum of clinical symptoms, certain serotype-specific manifestations such as fever, phlegm, and headache have been particularly associated with HPIV2 infections.…”

“…In 2021, two successive epidemic peaks of HPIV1 were recorded in July and October, which directly succeeded the peak of HPIV3. A comparable delay in HPIVs seasonal peaks has been documented in South Africa post-pandemic ( 12 ). These timing shifts may be attributed to the enactment of NPIs, changes in societal behaviors, and the presence of immunity gaps among the population.…”