The Centers for Disease Control and Prevention (CDC) has issued a health advisory regarding the possibility of highly-pathogenic avian influenza (HPAI) H5 virus infection in humans after more than 200 infections in birds have been reported since December 2014.
The U.S. Department of Agriculture (USDA) has confirmed more than 200 findings of birds infected with HPA1 A (H5N2), (H5N8), and (H5N1) viruses between December 15, 2014 and May 29, 2015.
These are the first reported infections with these viruses in U.S. wild or domestic birds and the majority of the infections have occurred in poultry. The appearance of these recently-identified HPAI H5 viruses may increase the risk of human infection in the United States, although the viruses are not known to have caused disease in humans.
The CDC considers the risk to be low, but those with close or prolonged unprotected contact with infected birds or contaminated environments may be at an increased risk of infection.
It is recommended that clinicians consider HPAI H5 virus infection in persons showing signs or symptoms of respiratory illness who have relevant exposure history, including those who have had contact with potentially-infected birds (eg, handling, slaughtering, defeathering, butchering, culling, preparation for consumption); direct contact with surfaces contaminated with feces or parts (carcasses, internal organs, etc.) of potentially infected birds; and prolonged exposure to potentially infected birds in a confined space.
Those who meet clinical and exposure criteria should be tested for HPAI H5 virus infection by reverse-transcription polymerase chain reaction (RT-PCR) assay with H5-specific primers and probes.
The CDC recommends the following for HPAI treatment and chemoprophylaxis:
- Chemoprophylaxis with influenza antiviral medications can be considered for all persons meeting bird exposure criteria. Decisions to initiate antiviral chemoprophylaxis should be based on clinical judgment, with consideration given to the type of exposure and to whether the exposed person is at high risk for complications from influenza.
- Chemoprophylaxis is not routinely recommended for personnel who used proper PPE while handling sick or potentially-infected birds or decontaminating infected environments (including animal disposal).
- If antiviral chemoprophylaxis is initiated, treatment dosing for the neuraminidase inhibitors oseltamivir or zanamivir (one dose twice daily) is recommended instead of the typical antiviral chemoprophylaxis regimen (once daily). Physicians should consult the manufacturer’s package insert for dosing, limitations of populations studied, contraindications, and adverse effects. If exposure was time-limited and not ongoing, five days of medication (one dose twice daily) from the last known exposure is recommended.
- Patients meeting bird exposure criteria who develop symptoms compatible with influenza should be referred for prompt medical evaluation and empiric initiation of influenza antiviral treatment with a neuraminidase inhibitor as soon as possible. Clinical benefit is greatest when antiviral treatment is administered early, especially within 48 hours of illness onset. Antiviral treatment should not be delayed while waiting for laboratory testing results.
- If a case of human infection with HPAI H5 virus is identified in the US, recommendations for monitoring and chemoprophylaxis of close contacts of the infected person are different than those that apply to persons who meet bird exposure criteria.
Currently there are no human vaccines available in the United States for HPAI (H5N1), (H5N2), or (H5N8); seasonal influenza vaccines provide no protection against human infection with HPAI H5 viruses. There are efforts underway to develop vaccines against these HPAI H5 viruses.
For more information call (800) 232-4636 or visit CDC.gov.
This article originally appeared on MPR