Medical expert of the article
New publications
Signs of the flu
Last reviewed: 20.11.2021
All iLive content is medically reviewed or fact checked to ensure as much factual accuracy as possible.
We have strict sourcing guidelines and only link to reputable media sites, academic research institutions and, whenever possible, medically peer reviewed studies. Note that the numbers in parentheses ([1], [2], etc.) are clickable links to these studies.
If you feel that any of our content is inaccurate, out-of-date, or otherwise questionable, please select it and press Ctrl + Enter.
The duration of the incubation period of influenza is from several hours to 2 days with influenza A and up to 3-4 days with influenza B. The disease begins sharply, with the rise in body temperature to high values (39-40 ° C), accompanied by chills, general weakness, , muscular and joint pain. Fever reaches a maximum at the end of the first, less often on the second day of the disease. By this time, all signs of influenza are expressed as much as possible. Children complain of a headache, usually in the temples, forehead, superciliary arches, eyeballs; they lose appetite, worsen sleep, nausea, vomiting, and in severe cases - delirium and hallucinations. Catarrhal phenomena are usually poorly expressed and are represented by coughing, stuffiness and lean mucous discharge from the nose, sore throat, especially when swallowing. In severe cases, possible nasal bleeding, convulsions, short-term loss of consciousness, meningeal symptoms (stiff neck, weakly positive Kernig symptom).
On the 1st day of the disease, blood tests may have neutrophilic leukocytosis with a slight shift to the left, from the 2nd to 3rd day they detect leukopenia, eosinophilia, and lymphocytosis. ESR is normal, the indices of red blood are not changed.
The course of the flu is acute. The duration of the febrile period is usually 3-5 days. After lowering body temperature, the condition of children improves. The recurrence of fever is usually due to the stratification of a bacterial infection or the development of another acute respiratory viral infection. The total duration of the disease (in the absence of complications) is usually 7-10 days. After the influenza carried for 2-3 weeks, the phenomena of postinfection asthenia (increased fatigue, weakness, headache, irritability, insomnia) may persist.
[Influenza in newborns and children of the first year of life
The disease usually begins gradually with a slight rise in body temperature, the symptoms of influenza intoxication are absent or not pronounced. Newborns give up breast, their body weight decreases. There may be mild catarrhal manifestations in the form of coughing, nasal congestion, "sniffing", often there is repeated vomiting. Croup syndrome in children of the first half of life is rare; segmental lesion of the lungs is uncharacteristic. Despite the slightly pronounced initial clinical manifestations, the course of influenza in children of the first year of life is much more severe due to the frequent attachment of bacterial infection and the occurrence of purulent complications (otitis media, pneumonia, etc.). Mortality is 3 times higher than in older children.
Features of "bird flu"
The disease caused by avian influenza viruses (H5N1, H7N7, etc.), is characterized by severe course in both adults and children due to the development in the early stages of primary viral (interstitial) pneumonia complicated by adult respiratory distress syndrome. The expressed intoxication syndrome is associated with liver and kidney damage due to the pantropism of the virus, leukemia and lymphopenia are noted. In countries of South-East Asia, where "avian flu" was first detected, the disease in 70% of cases ended fatal.