Influenza (Flu): Complications

The following are the most important diseases or complications that may be contributed to by influenza (flu):

Respiratory system (J00-J99)

Cardiovascular system (I00-I99)

  • Cardiomyopathy (heart muscle disease) → severe left heart failure (left heart failure).
  • Myocardial infarction (heart attack) – in the first seven days of influenza infection, the risk of myocardial infarction increases 6-fold compared to non-infected individuals.
  • Myocarditis (inflammation of the heart muscle).
  • Pericarditis (inflammation of the pericardium)

Infectious and parasitic diseases (A00-B99).

  • Bacterial superinfection – this refers to the grafting of a bacterial infection (e.g., pneumococcal pneumonia/pneumonia) onto a viral infection
  • Invasive pulmonary aspergillosis (IPA) – influenza patients treated in an intensive care unit for a severe course; 90-day mortality (death rate) was 51% vs. 28% in influenza patients without IPA, according to the report

Musculoskeletal system and connective tissue (M00-M99).

  • Myositis (muscle inflammation)
  • Rhabdomyolysis – dissolution of skeletal muscle.

Liver, gallbladder, and bile ducts – Pancreas (pancreas) (K70-K77; K80-K87).

  • Sclerosing cholangitis – inflammation of the extrahepatic and intrahepatic (located outside and inside the liver) bile ducts (1 case report)

Ears – mastoid process (H60-H95).

  • Otitis media (inflammation of the middle ear)

Psyche – nervous system (F00-F99; G00-G99)

Pregnancy, childbirth, and puerperium (O00-O99).

  • Preterm birth (< 37 weeks’ gestation) 3.9-fold risk compared with pregnant women without influenza
  • Low birth weight (< 2,500 g) 4.6-fold risk compared with pregnant women without influenza
  • Low Apgar score (≤ 6, collected five minutes after birth) 8.7-fold risk compared with pregnant women without influenza

Symptoms and abnormal clinical and laboratory findings not elsewhere classified (R00-R99)

  • Multi-organ failure (MODS, multi-organ dysfunction syndrome; MOF: multiple organ failure) – simultaneous or sequential failure or severe functional impairment of multiple vital organ systems of the body.
  • Febrile convulsions

Further

  • Increase in heart attack deaths one to three weeks after infection

Prognostic factors

  • Mutations in IFITM3 (for “interferon-induced transmembrane protein 3″), present in about 20% of Chinese and 4% of people of European ancestry, result in increased replication of the virus. This is known to lead to severe courses of influenza pneumonia (swine flu H1N1 2009/10) and, according to a recent study, also to increased cardiac complications.For carriers of the IFITM3 mutations, this means they are likely to be at increased risk for sudden cardiac death (PHT).