FYI: Influenza H7N9 in China
On April 1, 2013, the World Health Organization announced a number of human cases infected with avian influenza A (H7N9) viruses in China. The Maryland Department of Health and Mental Hygiene (DHMH) is working with the U.S. Centers for Disease Control and Prevention (CDC) to better understand the public health risk posed by this virus. Although to date no cases have been reported in the United States, guidance about investigation and reporting of possible cases in Maryland follows. The first cases were laboratory-confirmed on March 29, 2013 by Chinese health authorities. This marks the first time that the H7N9 avian influenza has been detected in humans. As of April 4, 2013, there have been a total of 14 confirmed cases reported to the World Health Organization (WHO), with six deaths. Of these, 13 are adults (ages 27- to 87-years-old) and one is a 4-year-old child. All cases have presented with severe respiratory illness. Onset of illness among confirmed cases dates back as early as February 19, 2013. All cases are residents of provinces in the region of East China, in the areas surrounding the city of Shanghai. Chinese officials have not yet identified any person-to-person transmission and the cases are not known to be epidemiologically linked. Close contacts of confirmed cases are being identified and monitored as the investigation into the source of infection and mode of transmission continues. Preliminary testing suggests that the virus is susceptible to neuraminidase inhibitors (oseltamivir and zanamivir). Persons who meet the criteria below should be reported immediately to DHMH at 410-767-6700 by phone. If after hours, page the on-call epidemiologist at 410-716-8194.
1. Acute respiratory infection, which may include fever (≥ 100°F) with a cough and/or sore throat; 2. AND History of travel from China within 14 days of onset of illness; 3. AND not already explained by any other infection or etiology, including all clinically indicated tests for
Interim Recommendations for Clinicians and Local Health Departments
Case Investigation and Testing
• Patients with illness compatible with influenza who also meet any of the exposure criteria listed below
should be candidates for RT-PCR testing for influenza. Decisions about diagnostic testing for influenza using RT-PCR should be made using available clinical and epidemiologic information, and additional persons in whom clinicians suspect influenza A (H7N9) virus infection may also be tested.
o Patients with recent travel to countries where human cases of novel influenza A (H7N9) virus
infection have recently been detected, especially if there was recent direct or close contact with animals (such as wild birds, poultry, or pigs) or where influenza A (H7N9) viruses are known to be circulating in animals. Currently, China is the only country that has recently reported novel influenza A (H7N9) human cases.
o Patients who have had recent contact with confirmed human cases of infection with novel
• Clinicians should obtain a nasopharyngeal swab or aspirate from these patients, place the swab or
aspirate in viral transport medium, and contact their local health department to arrange transport and request testing at DHMH. We will arrange for testing at CDC if indicated. For patients with pneumonia or other lower respiratory tract disease, a lower respiratory tract specimen (like sputum or a BAL sample) would also be helpful. For additional guidance on diagnostic testing of patients under investigation for novel influenza A (H7N9) virus infection, please see Interim Guidance for Laboratory Testing of Persons with Suspected Infection with Highly Pathogenic Avian Influenza A (H5N1) Virus in the United States at
• If infection with influenza A (H7N9) virus is suspected based on current clinical and epidemiological
screening criteria, specimens should be collected with appropriate infection control precautions for novel virulent influenza viruses and sent to the state or local health department for testing. Viral culture should not be attempted in these cases.
• Commercially available rapid influenza diagnostic tests (RIDTs) may not detect avian or variant
influenza A viruses in respiratory specimens. Therefore, a negative rapid influenza diagnostic test result does not exclude infection with influenza viruses. In addition, a positive test result for influenza A cannot confirm variant or avian influenza virus infection because these tests cannot distinguish between influenza A virus subtypes (they do not differentiate between human influenza A viruses and avian or variant viruses). Therefore, when RIDTs are positive for influenza A and there is concern for novel influenza A virus infection, respiratory specimens should be collected and sent for RT-PCR testing at a state public health laboratory. Clinical treatment decisions should not be made on the basis of a negative rapid influenza diagnostic test result since the test has only moderate sensitivity.
• CDC states that clinicians should be aware of appropriate infection control guidelines for patients under
investigation for infection with novel influenza A viruses. Because it has been shown to cause severe respiratory illness in cases identified so far, healthcare personnel (HCP) caring for patients under investigation for novel influenza A (H7N9) virus infection should adhere to Standard Precautions and Airborne Precautions, including eye protection, an Airborne Infection Isolation Room, and N95 respirators until more is known about the transmission characteristics of the A (H7N9) virus.
• All clusters of respiratory illness in HCP caring for patients with severe acute respiratory illness should
• CDC also recommends that for persons hospitalized with suspected influenza, including suspected novel
H7N9 virus infection, clinicians should start empiric treatment with influenza antiviral medications (oral oseltamivir, inhaled zanamivir) as soon as possible, without waiting for laboratory confirmation.
• For high-risk persons (persons <5 years of age, ≥65 years of age, and those with certain underlying
medical conditions) with suspected influenza of any severity , including suspected novel H7N9 virus infection, clinicians should start empiric treatment with influenza antiviral medications (oral oseltamivir, inhaled zanamivir) as soon as possible, without waiting for laboratory confirmation.
• Antiviral treatment is most effective when started as soon as possible after influenza illness onset. Early
initiation of treatment provides a more optimal clinical response, although treatment of moderate, severe, or progressive disease begun after 48 hours of symptoms may still provide benefit.
For More Information
• World Health Organization (WHO) “H7N9 avian influenza human infections in China” is available
• CDC avian influenza A (H7N9) information page is available at
• WHO “Frequently Asked Questions on human infection with A (H7N9) virus, China” is available
• The Chinese Center for Disease Control and Prevention “Questions and Answers about human infection
with A(H7N9) avian influenza virus" is available at
• CDC general information about avian influenza viruses and how they spread is available
• CDC “Interim Guidance on Case Definitions to be Used for Investigations of Influenza A (H3N2)
Variant Virus Cases” for state and local health departments is available at
• CDC “Prevention Strategies for Seasonal and Influenza A (H3N2)v in Health Care Settings” is available
• CDC “Interim Guidance on Specimen Collection, Processing, and Testing for Patients with Suspected
Influenza A (H3N2)v Virus Infection” for public health professionals is available at
• CDC “Interim Guidance for Enhanced Influenza Surveillance: Additional Specimen Collection for
Detection of Influenza A (H3N2) Variant Virus Infections” for state and local health departments is available at
• National Association of State Public Health Veterans “Compendium of Measures to Prevent Disease
Associated with Animals in Public Settings, 2011” is available as the first bulleted item at.