Peeping into the Emerging Threat of Novel Influenza D Virus: A Review

In 2011, a new virus was isolated from swine with influenza-like symptoms in Oklahoma, USA. Later in 2013, it was also evidenced in cattle, considered as its natural reservoir, elsewhere in the USA. This new virus has certain resemblance with Influenza C virus (ICV), predominately a human pathogen. Due to its inability to re-assort with ICV, it is now classified as Influenza D virus (IDV) and is a new candidate in the Orthomyxoviridae family. It causes mild respiratory disease in several animal species and replicates in both upper and lower respiratory tract. To date, serological evidence was demonstrated in various animal species and humans in all continents except Australia. It is transmitted through direct contact or through aerosol routes. Not much is known about its potential impact to animal and human health but it poses a potential risk as an emerging threat to cattle-workers. Currently, limited data is available on its global occurrence and distribution. Therefore, in current review, we summarize the global available data regarding epidemiology, pathology, zoonotic potential and future perspectives of this virus. In conclusion, continuous surveillance and risk assessment of this emerging virus is required.