Re-Emergence of Avian influenza A(H7N9) virus: Another Pandemic Threat

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Re-Emergence of Avian influenza A(H7N9) virus: Another Pandemic Threat

Dr. Muhammad Najeeb Durrani, Epidemiologist, District Surveillance Coordinator, District TB Coordinator (DTC), In-charge Dengue Fever Surveillance Cell, Member Global Outbreak Alert and Response Network (GOARN) Health Department ICT, Islamabad

After 2004 when Influenza appeared at global horizon it was initially localized in the migratory birds and appeared as H5N1 called the Avian Influenza later it infected the local poultry in many parts of the world. Later it became extremely dangerous when it crossed the species carrier and jumped to the human beings where it had a very high fatality rate. Globally efforts were being made to contain the disease in the poultry but the virus started affecting human being and some documented caases were recorded with human to human transmission.

The International experts, epidemiologists at that point in time in 2007 started predicting on the basis of scientific evidence and previous history of the same type of virus in 1918 that a new noval virus (H1N1)  in going to emerge from this current circulating virus H5N1 (Avian Influenza) tat would mutate after coming in contact with human and swine influenza viruses, that might change the global scenario due to mass mortality. The scientists were saying that it is expected that one fourth population of a country would be wiped off as the world had experienced in 1918 when H1N! had struck the country of Spain so much so the disease was in the history named as Spanish Flu that caused 20-40 million deaths.

And the disease appeared in April 2009 and first time it emerged in United States in Californea and Maxico at the same time, where many patients with atypical pneumonia landed at the hospitals. The WHO immediately verified and declared the emergence of the same virus being predicted. The new influenza disease was named Influenza A H1N1 2009 infection. The virus spread with a un-precedented speed and within three months it reached every country of the world. To the extent that the WHO had to declared and imposed level VI, of the epidemic, the highest for any disease due to its vast spread and virulence. The diseas affected millions of people and killed thousands globally.

The Influenza virus behaves in a strange way all the time mutating (Changing that occurs in the DNA of the virus due to shift and drift phenomenon) making itself more virulent, currently the disease has appeared at International horizon with a still a more mutated form now named as H7N9.

This Influenza A(H7N9) is one of a subgroup of influenza viruses that normally circulate among birds. Until recently, this virus had not been seen in people. However, human infections have now been detected.

As yet, there is limited information about the scope of the current form of Influenza virus, about the virus causes and about the source of exposure. The disease is of concern because most patients have been severely ill. There is no indication thus far that it can be transmitted between people, but both animal-to-human and human-to-human routes of transmission are being actively investigated.

  • Influenza is an acute viral infection that spreads      easily from person to person.
  • Influenza circulates worldwide and can affect anybody      in any age group.
  • Influenza causes annual epidemics that peak during      winter in temperate regions.
  • Influenza is a serious public health problem that      causes severe illnesses and deaths for higher risk populations.
  • An epidemic can take an economic toll through lost      workforce productivity, and strain health services.
  • Vaccination is the most effective way to prevent      infection.

Cumulative number of confirmed cases of avian influenza A(H7N9) reported to WHO, data in WHO as of 25 October 2013 at global level

137 cases and 45 Deaths

(Total number of cases includes number of deaths WHO reports only laboratory cases All dates refer to onset of illness)



Seasonal influenza is an acute viral infection caused by an influenza virus.

There are three types of seasonal influenza – A, B and C. Type A influenza viruses are further typed into subtypes according to different kinds and combinations of virus surface proteins. Among many subtypes of influenza A viruses, currently influenza A(H1N1) and A(H3N2) subtypes are circulating among humans. Influenza viruses circulate in every part of the world. Type C influenza cases occur much less frequently than A and B. That is why only influenza A and B viruses are included in seasonal influenza vaccines.

Signs and symptoms

Seasonal influenza is characterized by a sudden onset of high fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and runny nose. Most people recover from fever and other symptoms within a week without requiring medical attention. But influenza can cause severe illness or death in people at high risk (see below). The time from infection to illness, known as the incubation period, is about two days.

Who is at risk?

Yearly influenza epidemics can seriously affect all age groups, but the highest risk of complications occur among children younger than age two, adults age 65 or older, and people of any age with certain medical conditions, such as chronic heart, lung, kidney, liver, blood or metabolic diseases (such as diabetes), or weakened immune systems.


Seasonal influenza spreads easily and can sweep through schools, nursing homes or businesses and towns. When an infected person coughs, infected droplets get into the air and another person can breath them in and be exposed. The virus can also be spread by hands infected with the virus. To prevent transmission, people should cover their mouth and nose with a tissue when coughing, and wash their hands regularly.


Antiviral drugs for influenza are available in some countries and effectively prevent and treat the illness. There are two classes of such medicines, 1) adamantanes (amantadine and remantadine), and 2) inhibitors of influenza neuraminidase (oseltamivir and zanamivir). Some influenza viruses develop resistance to the antiviral medicines, limiting the effectiveness of treatment. WHO monitors antiviral susceptibility in the circulating influenza viruses.

Seasonal epidemics

Influenza epidemics occur yearly during autumn and winter in temperate regions. Illnesses result in hospitalizations and deaths mainly among high-risk groups (the very young, elderly or chronically ill). Worldwide, these annual epidemics result in about three to five million cases of severe illness, and about 250 000 to 500 000 deaths. Most deaths associated with influenza in industrialized countries occur among people age 65 or older. In some tropical countries, influenza viruses circulate throughout the year with one or two peaks during rainy seasons.

Disease effects

Influenza can cause serious public health and economic problems. In developed countries, epidemics can result in high levels of worker absenteeism and productivity losses. In communities, clinics and hospitals can be overwhelmed when large numbers of sick people appear for treatment during peak illness periods. While most people recover from a bout of influenza, there are large numbers of people who need hospital treatment and many who die from the disease every year. Little is known about the effects of influenza epidemics in developing countries.


The most effective way to prevent the disease or severe outcomes from the illness is vaccination. Safe and effective vaccines have been available and used for more than 60 years. Among healthy adults, influenza vaccine can prevent 70% to 90% of influenza-specific illness. Among the elderly, the vaccine reduces severe illnesses and complications by up to 60%, and deaths by 80%.

Vaccination is especially important for people at higher risk of serious influenza complications, and for people who live with or care for high risk individuals.

WHO recommends annual vaccination for (in order of priority):

  • nursing-home residents (the elderly      or disabled)
  • elderly individuals
  • people with chronic medical      conditions
  • other groups such as pregnant women,      health care workers, those with essential functions in society, as well as      children from ages six months to two years.

Influenza vaccination is most effective when circulating viruses are well-matched with vaccine viruses. Influenza viruses are constantly changing, and the WHO Global Influenza Surveillance Network (GISN), a partnership of National Influenza Centres around the world, monitors the influenza viruses circulating in humans. WHO annually recommends a vaccine composition that targets the three most representative strains in circulation.

WHO response

WHO, with its partners, monitors influenza globally, annually recommends a seasonal influenza vaccine composition, and supports Member States efforts to develop prevention and control strategies. WHO works to strengthen national and regional influenza diagnostic capacities, disease surveillance, outbreak responses, and increase vaccine coverage among high-risk groups.

In Pakistan

The National Institute of Health through its Influenza Project is making all possible efforts for starting surveillance of the disease to detect the virus at its earliest possible stage through awareness and capacity building of the provincial health authorities. The viral transport media has been sent in cold chain to the provinces for sending throat swab samples from any suspected cases to the National lab. The provincial authorities have been asked to exercise tight vigilance and enhance surveillance of the highly contagious disease and report any suspected case to the National Institute of Health immediately.