Credit NIAID
# 7083
The audio file, and transcript from today’s CDC teleconference are now online, and the CDC has posted interim guidance documents on this novel virus.
While there remains a great deal about this emerging virus we don’t know, and its future impact remains uncertain, the CDC, ECDC, Hong Kong’s CHP, and the World Health Organization have been publishing information as quickly as they can verify it.
Events and the 24/7 internet news cycle often leap frog ahead of more traditional media channels, which is undoubtedly the reason that today the World Health Organization made the following surprise announcement via @WHO:
In addition, the CDC’s updated H7N9 information now features:
Avian Influenza A (H7N9) Virus
On April 1, 2013, the World Health Organization (WHO) first reported 3 human infections with a new influenza A (H7N9) virus in China. Additional cases have been reported since. At this time, no cases of H7N9 outside of China have been reported. The new H7N9 virus has not been detected in people or birds in the United States.
Most reported cases have severe respiratory illness and, in some cases, have died. According to WHO, no person-to-person spread of the H7N9 virus has been found at this time, and the reported cases are not linked to each other. An investigation by Chinese health authorities is ongoing to find out the source of these infections and detect any more cases.
This new H7N9 virus is an avian (bird) influenza (flu) virus. Human infections with avian influenza (AI, or “bird flu”) are rare but have occurred in the past, most commonly after exposure to infected poultry. However, this is the first time that this bird flu subtype (H7N9) has been found in people. This virus is very different from other H7N9 viruses previously found in birds.
This is a “novel” (non-human) virus and therefore has the potential to cause a pandemic if it were to change to become easily and sustainably spread from person-to-person. So far, this virus has not been determined to have that capability. However, influenza viruses constantly change and it’s possible this virus could gain that ability. CDC takes routine preparedness actions whenever a new virus with pandemic potential is identified, including developing a candidate vaccine virus to make a vaccine if it were to be needed. There is no licensed H7 vaccine available at this time.
CDC is following this situation closely and coordinating with domestic and international partners.
In addition, CDC is:
- Issuing guidance to U.S. clinicians and public health departments on how to test for this virus
- Modifying test kits so that this specific virus can be easily and accurately identified
- Reviewing genetic sequences of the virus to learn more about it
- Gathering more information to make a more extensive assessment of the public health risk posed by this virus
The sequences of the first three viruses were posted to GISAID by China and are publicly available. Some of the genetic changes have been associated with increased transmissibility of other AI viruses to mammals based on animal studies involving ferrets in the past. So far, all three viruses seem to be susceptible to the influenza antiviral drugs oseltamivir and zanamivir, but they are resistant to the adamantanes.
This is an evolving situation and there is still much to learn. CDC will provide updated information as it becomes available.
General information about avian influenza viruses and how they spread is available at Avian Influenza A Virus Infections in Humans.
Additional Information
CDC has issued a Health Alert Network (HAN) to notify clinicians of the current H7N9 situation in China.
WHO has posted Frequently Asked Questions on human infection with A(H7N9) avian influenza virus, China.
The Chinese Center for Disease Control and Prevention has posted a Question & Answer document related to this situation available at "Questions and Answers about human infection withA(H7N9) avian influenza virus."
The European Centre for Disease Prevention and Control has published a rapid assessment on the emergence of the H7N9 virus in China available at "Rapid risk assessment: Severe respiratory disease associated with a novel influenza A virus, A(H7N9) China
."
Interim Guidance on Case Definitions to be Used for Novel Influenza A (H7N9) Case Investigations in the United States
This document provides interim guidance for state and local health departments conducting investigations of infections with novel influenza A (H7N9) viruses. The following definitions are for the purpose of investigations of confirmed and probable cases, and cases of novel influenza A (H7N9) virus infection under investigation. CDC is requesting notification of all confirmed and probable cases of novel influenza A (H7N9) virus infection within 24 hours of identification. When possible, state health departments are encouraged to investigate all potential cases of novel influenza A (H7N9) virus infection further to determine case status.
Case Definitions
Confirmed Case: A patient with novel influenza A (H7N9) virus infection that is confirmed by CDC’s Influenza Laboratory or a CDC certified public health laboratory using methods agreed upon by CDC and CSTE.1
Probable Case: A patient with illness compatible with influenza for whom laboratory diagnostic testing is positive for influenza A, negative for H1, negative for H1pdm09, and negative for H3 by real-time reverse transcriptase polymerase chain reaction (RT-PCR), and therefore unsubtypeable.
Case Under Investigation: A patient with illness compatible with influenza meeting either of the following exposure criteria and for whom laboratory confirmation is not known or pending, or for whom test results do not provide a sufficient level of detail to confirm novel influenza A virus infection.
- A patient who has had recent contact (within ≤ 10 days of illness onset) with a confirmed or probable case of infection with novel influenza A (H7N9) virus.
OR
- A patient who has had recent travel (within ≤ 10 days of illness onset) to a country where human cases of novel influenza A (H7N9) virus have recently been detected2 or where novel influenza A (H7N9) viruses are known to be circulating in animals.
Cases under investigation with severe respiratory illness (including radiographically-confirmed pneumonia, acute respiratory distress syndrome (ARDS), or other severe respiratory illness) of unknown etiology may be prioritized for diagnostic testing.
1 Confirmation of all novel influenza A (H7N9) viruses will initially be performed by CDC’s Influenza Laboratory. Once appropriate diagnostic testing methodology has been identified by CDC, confirmation may be made by public health laboratories following CDC-approved protocols for detection of novel influenza A (H7N9) virus, or by laboratories using an FDA-authorized test specific for detection of novel influenza A (H7N9) virus.
2 Countries that have recently reported novel influenza A (H7N9) human cases include: China.
For more information, please see the CDC Avian Influenza A (H7N9) Virus information page.
