New strain of bird flu jumps to humans
H7N9, one serotype of the influenza A H7 virus, has jumped from animals to humans in China.We have posted on avian influenza in the past, but with
recent activity in China, thought it was important to relay this health
warning.
The following Q&A section is taken directly from the World Health Organization
website.
Frequently Asked
Questions on human infection with influenza A(H7N9) virus, China
Update as of 5 April 2013
Note that this
document supersedes the previous version. Updates will be posted as new
information becomes available.
1. What is the
influenza A(H7N9) virus?
Influenza A H7 viruses are a group of influenza viruses that
normally circulate among birds. The influenza A(H7N9) virus is one subgroup
among the larger group of H7 viruses. Although some H7 viruses (H7N2, H7N3 and
H7N7) have occasionally been found to infect humans, no human infections with
H7N9 viruses have been reported until recent reports from China.
2. What are the main
symptoms of human infection with influenza A(H7N9) virus?
Thus far, most patients with this infection have had severe
pneumonia. Symptoms include fever, cough and shortness of breath. However,
information is still limited about the full spectrum of disease that infection
with influenza A(H7N9) virus might cause.
3. How many human
cases of influenza A(H7N9) virus have been reported in China to date?
New cases that are reported are now being compiled and
posted daily. The most current information on cases can be found in Disease
Outbreak News.
4. Why is this virus
infecting humans now?
We do not know the answer to this question yet, because we
do not know the source of exposure for these human infections. However,
analysis of the genes of these viruses suggests that although they have evolved
from avian (bird) viruses, they show signs of adaption to growth in mammalian
species. These adaptations include an ability to bind to mammalian cells, and
to grow at temperatures close to the normal body temperature of mammals (which
is lower than that of birds).
5. What is known
about previous human infections with H7 influenza viruses globally?
From 1996 to 2012, human infections with H7 influenza
viruses (H7N2, H7N3, and H7N7) were reported in the Netherlands, Italy, Canada,
United States of America, Mexico and the United Kingdom. Most of these
infections occurred in association with poultry outbreaks. The infections
mainly resulted in conjunctivitis and mild upper respiratory symptoms, with the
exception of one death, which occurred in the Netherlands. Until now, no human
infections with H7 influenza viruses have been reported in China.
6. Is the influenza
A(H7N9) virus different from influenza A(H1N1) and A(H5N1) viruses?
Yes. All three viruses are influenza A viruses but they are
distinct from each other. H7N9 and H5N1 are considered animal influenza viruses
that sometimes infect people. H1N1 viruses can be divided into those that
normally infect people and those that normally infect animals.
7. How did people
become infected with the influenza A(H7N9) virus?
Some of the confirmed cases had contact with animals or with
an animal environment. The virus has been found in a pigeon in a market in
Shanghai. It is not yet known how persons became infected. The possibility of
animal-to-human transmission is being investigated, as is the possibility of
person-to-person transmission.
8. How can infection
with influenza A(H7N9) virus be prevented?
Although both the source of infection and the mode of
transmission are uncertain, it is prudent to follow basic hygienic practices to
prevent infection. They include hand and respiratory hygiene and food safety
measures.
Hand hygiene:
• Wash your hands before, during, and after you prepare
food; before you eat; after you use the toilet; after handling animals or
animal waste; when your hands are dirty; and when providing care when someone
in your home is sick. Hand hygiene will also prevent the transmission of
infections to yourself (from touching contaminated surfaces) and in hospitals
to patients, health care workers and others.
• Wash your hands with soap and running water when visibly
dirty; if not visibly dirty, wash your hands with soap and water or use an
alcohol-based hand cleanser.
Respiratory hygiene:
• Cover your mouth and nose with a medical mask, tissue, or
a sleeve or flexed elbow when coughing or sneezing; throw the used tissue into
a closed bin immediately after use; perform hand hygiene after contact with
respiratory secretions.
9. Is it safe to eat
meat, i.e. poultry and pork products?
Influenza viruses are not transmitted through consuming
well-cooked food. Because influenza viruses are inactivated by normal
temperatures used for cooking (so that food reaches 70°C in all parts—
"piping" hot — no "pink" parts), it is safe to eat properly
prepared and cooked meat, including from poultry and game birds.
Diseased animals and animals that have died of diseases
should not be eaten.
In areas experiencing outbreaks, meat products can be safely
consumed provided that these items are properly cooked and properly handled
during food preparation. The consumption of raw meat and uncooked blood-based
dishes is a high-risk practice and should be discouraged.
10. Is it safe to
visit live markets and farms in areas where human cases have been recorded?
When visiting live markets, avoid direct contact with live
animals and surfaces in contact with animals. If you live on a farm and raise
animals for food, such as pigs and poultry, be sure to keep children away from
sick and dead animals; keep animal species separated as much as possible; and
report immediately to local authorities any cases of sick and dead animals.
Sick or dead animals should not be butchered and prepared for food.
11. Is there a
vaccine for the influenza A(H7N9) virus?
No vaccine for the prevention of influenza A(H7N9)
infections is currently available. However, viruses have already been isolated
and characterized from the initial cases. The first step in development of a
vaccine is the selection of candidate viruses that could go into a vaccine.
WHO, in collaboration with partners, will continue to characterize available
influenza A(H7N9) viruses to identify the best candidate viruses. These
candidate vaccine viruses can then be used for the manufacture of vaccine if
this step becomes necessary.
12. Does treatment
exist for influenza A(H7N9) infection?
Laboratory testing conducted in China has shown that the
influenza A(H7N9) viruses are sensitive to the anti-influenza drugs known as
neuraminidase inhibitors (oseltamivir and zanamivir). When these drugs are
given early in the course of illness, they have been found to be effective
against seasonal influenza virus and influenza A(H5N1) virus infection.
However, at this time, there is no experience with the use of these drugs for
the treatment of H7N9 infection.
13. Is the general
population at risk from the influenza A(H7N9) virus?
We do not yet know enough about these infections to
determine whether there is a significant risk of community spread. This
possibility is the subject of epidemiological investigations that are now
taking place.
14. Are health care
workers at risk from the influenza A(H7N9) influenza virus?
Health care workers often come into contact with patients
with infectious diseases. Therefore, WHO recommends that appropriate infection
prevention and control measures be consistently applied in health care
settings, and that the health status of health care workers be closely
monitored. Together with standard precautions, health care workers caring for
those suspected or confirmed to have influenza A(H7N9) infection should use
additional precautions (http://www.who.int/csr/resources/publications/swineflu/WHO_CDS_EPR_2007_6/en/index.html).
15. What
investigations have begun?
Local and national health authorities are taking the
following measures, among others:
• Enhanced surveillance for pneumonia cases of unknown
origin to ensure early detection and laboratory confirmation of new cases;
• Epidemiological investigation, including assessment of
suspected cases and contacts of known cases;
• Close collaboration with animal health authorities to
determine the source of the infection.
16. Does this
influenza virus pose a pandemic threat?
Any animal influenza virus that develops the ability to
infect people is a theoretical risk to cause a pandemic. However, whether the
influenza A(H7N9) virus could actually cause a pandemic is unknown. Other
animal influenza viruses that have been found to occasionally infect people
have not gone on to cause a pandemic.
17. Is it safe to
travel to China?
The number of cases identified in China is very low. WHO
does not advise the application of any travel measures with respect to visitors
to China nor to persons leaving China.
18. Are Chinese
products safe?
There is no evidence to link the current cases with any
Chinese products. WHO advises against any restrictions to trade at this time.
Other resources for
information about avian influenza:
references:
.JPG)
