Both lineages are in circulation in humans, disproportionately affecting children. IBVs contribute to seasonal epidemics alongside IAVs but have never been associated with a pandemic.ICV, like IBV, is primarily found in humans, though it also has been detected in pigs, feral dogs, dromedary camels, cattle, and dogs. ICV infection primarily affects children and is usually asymptomatic or has mild cold-like symptoms, though more severe symptoms such as gastroenteritis and pneumonia can occur. Unlike IAV and IBV, ICV has not been a major focus of research pertaining to antiviral drugs, vaccines, and other measures against influenza. ICV is subclassified into six genetic/antigenic lineages.IDV has been isolated from pigs and cattle, the latter being the natural reservoir. Infection has also been observed in humans, horses, dromedary camels, and small ruminants such as goats and sheep. IDV is distantly related to ICV. While cattle workers have occasionally tested positive to prior IDV infection, it is not known to cause disease in humans. ICV and IDV experience a slower rate of antigenic evolution than IAV and IBV. Because of this antigenic stability, relatively few novel lineages emerge. Genome and structure
Influenza viruses have a negative-sense, single-stranded RNA genome that is segmented. The negative sense of the genome means it can be used as a template to synthesize messenger RNA (mRNA). IAV and IBV have eight genome segments that encode 10 major proteins. ICV and IDV have seven genome segments that encode nine major proteins.
Rapid influenza diagnostic tests (RIDTs) are a simple way of obtaining assay results, are low cost, and produce results quickly, at less than 30 minutes, so they are commonly used, but they cant distinguish between IAV and IBV or between IAV subtypes and are not as sensitive as nucleic-acid based tests.Nucleic acid-based tests (NATs) amplify and detect viral nucleic acid. Most of these tests take a few hours, but rapid molecular assays are as fast as RIDTs. Among NATs, reverse transcription polymerase chain reaction (RT-PCR) is the most traditional and considered the gold standard for diagnosing influenza because it is fast and can subtype IAV, but it is relatively expensive and more prone to false-positives than cultures. Other NATs that have been used include loop-mediated isothermal amplification-based assays, simple amplification-based assays, and nucleic acid sequence-based amplification. Nucleic acid sequencing methods can identify infection by obtaining the nucleic acid sequence of viral samples to identify the virus and antiviral drug resistance. The traditional method is Sanger sequencing, but it has been largely replaced by next-generation methods that have greater sequencing speed and throughput. Treatment
Treatment of influenza in cases of mild or moderate illness is supportive and includes anti-fever medications such as acetaminophen and ibuprofen, adequate fluid intake to avoid dehydration, and resting at home. Cough drops and throat sprays may be beneficial for sore throat. It is recommended to avoid alcohol and tobacco use while sick with the flu. Aspirin is not recommended to treat influenza in children due to an elevated risk of developing Reye syndrome.