Written By: Pavitra Sampath | Updated : July 15, 2014 4:41 PM IST
Recently China has reported that the death toll due to the H7N9 bird flu has risen to 17, and infected 87 people. The Bird flu also known as the 'Avian Flu' is known to be transmitted from poultry to human. According to the CDC (Center for Disease Control), the H7N9 virus is present in wild birds, and its transmission from wild birds to poultry is very likely. This supposition was further strengthened when the WHO found that a large number of people who were suffering from the disease had little or no contact with poultry. This particular virus is considered more virulent than other forms like H1N1 because it is a 'novel' (non-human) virus and has the potential to cause a pandemic if it were to change or mutate. Since scientists have not yet been able to find the mode of transmission of the virus, there potential for a human epidemic remains.
The H7N9 bird flu is a form of the Influenza virus A. Detecting the presence of this virus is very difficult because it does not cause illness in poultry. It is a virulent form of the H1N1 virus and has a much higher fatality rate.
In India, a number of birds have been culled in the past because they were found to have the H5N5 form of the virus. H5N5, it was found, could easily be transmitted from poultry to humans, and then from one human to another. Having experienced a form of the disease earlier, India is at as much risk as China for the disease. Here are a few facts you should know about the H7N9 virus.
What is H7N9?
H7N9 bird flu is a form of avian flu that is spread from infected poultry to humans. In the name given to the disease, the H7 stands for 'haemaglutinin' or HA. Haemaglutinin is a glycoprotein found on the surface of the influenza virus. Its main function is to cause the agglutination (clumping of particles/cells) of blood. HA has 17 different parts and they are labeled as part H1 to H17. H7 is the type of haemaglutinin found in this particular virus. The 'N7' stands for Viral neuraminidase, its main function is to help viral DNA enter the patients' cells and cause infection. Like Haemaglutinin, Viral neuraminidase also has a number of parts and N9 is the type of neuraminidase found in this particular virus.
The H7N9 bird flu is a form of the Influenzavirus A. It has been found to commonly infect people who handle poultry infected with the virus. Detecting this virus is very difficult because it does not cause illness in poultry. It is a virulent form of the H1N1 virus and the CDC and WHO(World Health Organisatiom) are still looking into its origin, the way it is transmitted and a possible vaccine for the condition.
According to the CDC and WHO the symptoms of mild avian flu are the same as having a viral fever. Symptoms include sore throat, running nose, muscle aches. Symptoms of infection by a more virulent form of the disease include severe respiratory illness, shortness of breath, difficulty breathing, pneumonia, acute respiratory distress, viral pneumonia, respiratory failure, multi-organ disease, sometimes accompanied by nausea, abdominal pain, diarrhea, vomiting, confusion, dizziness etc.
Diagnosis of Avian Flu:
The avian flu cannot be diagnosed by clinical signs and symptoms alone, there are a few basic tests that a physician is likely to prescribe in such a case. To perform the test, a lab technician will take a swab of the throat of the person. This will then be used to culture the organism in the lab. Tests usually performed are molecular analysis and culture (growing the organism) analysis. In cases where there is a severe form of the disease, the technician might take a swab from the lower respiratory tract (a region a little lower in the throat). This again will be analyzed like a normal swab. If the Influenzavirus A is still not detected, the lab may perform a test called the viral antigen detection test. This test is used to identify if the patient's body has produced antigens (fighting cells) against the influenza virus.
In the case of the H7N9 virus, the time of testing is crucial to accurate diagnosis. A person cannot be tested at the onset of the disease nor when he/she has fully recovered. This is because the virus is very rarely detected under such circumstances.
Treatment options:
The CDC and WHO has found that the H7N9 virus is sensitive to neuramidase inhibitors such as oseltamivir or zanamivir. These are drugs sold under the commercial name of Tamiflu. As a precaution doctor says that people should avoid the indiscrimate use of this drug as it could lead to antibiotic resistance in patients.
Methods of prevention:
The influenza virus A or the Avian flu can be prevented by simple measures. Firstly, people working with poultry should take adequate protection before handling them. Protective measures such as wearing a mask and gloves are the best methods. People should also ensure that they wash their hands well before eating or touching their face or nose. Currently the CDC has not been able to pinpoint the exact mode of transmission from human-to-human, but they do suggest that people should avoid contact with patients infected with the virus. It is also suggested that patients should be effectively quarantined during the time of the infection. All in all the H7N9 hasn't given the authorities much to worry about till now!
Read more about causes, symptoms, diagnosis and treatment of bird flu.
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