1. Seasonal influenza is an acute febrile illness caused by either influenza A or B viruses that occur in outbreaks of varying severity every winter season.

2. Highly pathogenic avian influenza virus A (H5N1) is a new influenza strain now endemic among bird and poultry population in Eurasia that rarely causes human disease. A second avian influenza A (H7N9) causing human disease has now been identified in China, and future avian influenza A strains are likely to emerge.

3. Suspect avian influenza (H5N1 or H7N9) infection in a patient who has traveled in an H5N1- or H7N9-affected country within 10 days of symptom onset and develops an acute respiratory distress syndrome (ARDS) or other severe respiratory illness for which an alternate etiology cannot be established.

4. Secondary bacterial pneumonia (often due to Staphylococcus aureus, Streptococcus pneumoniae, or Haemophilus influenzae) is an important complication of influenza infection and needs to be considered when exacerbation of fever and respiratory symptoms occurs after initial improvement.

1. Human cases of H5N1 and H7N9 influenza have almost exclusively occurred after direct exposure to infected birds, with viral replication occurring in the retropharyngeal area and lower respiratory tract.

2. Uncomplicated illness usually resolves in 2 to 5 days. The predominant complication is superimposed bacterial pneumonia. Rare complications include myositis, myocarditis, encephalitis, and Guillain-Barré syndrome.

1. Acute febrile illness with malaise, myalgias, headache, and upper and lower respiratory tract symptoms in appropriate epidemiologic setting.

2. Routine laboratory studies are nonspecific.

3. Molecular techniques (e.g., polymerase chain reaction [PCR] assay).

4. Diagnosis can be confirmed by detection of virus or viral antigen or fourfold or greater rise in specific antibody titers.

5. Growth of the H5N1 or H7N9 viruses should only be attempted in a biosafety level 3 plus laboratory. This must be coordinated in conjunction with state and local health departments and, when highly suspected, the Centers for Disease Control and Prevention (CDC).

1. Institute droplet precautions: In suspected avian influenza (H5N1 or H7N9) infection, place the patients in airborne precautions in a negative-pressure room.

2. Oseltamivir 75 mg orally twice daily or zanamivir 10 mg (two inhalations) twice daily for at least 5 days of therapy. Both agents can reduce duration of symptoms, although oseltamivir resistance has been reported in H5N1 strains.

3. Start empiric antibiotic therapy if secondary bacterial pneumonia is suspected.

1. Hantavirus cardiopulmonary syndrome (HCPS) is an acute febrile illness, characterized by bilateral diffuse interstitial edema that may radiographically resemble the ARDS, with respiratory compromise requiring supplemental oxygen, often developing within 72 hours of hospitalization.

1. The illness is caused by rodent-borne viruses within the genus Hantaviridae.

2.

Stay updated, free articles. Join our Telegram channel

Join