Influenza, commonly known as the flu, has hit with full force this season. An increasing number of cases are being reported from across the country, with a simultaneous increase in reports of flu-related fatalities.

World Health Organization Pakistan (WHO) and the National Institute of Health (NIH), the leading multidisciplinary authority on public health-related issues, have taken note of the cases and are conducting investigations into flu deaths in Multan, which seems to have been hit harder than other cities in Punjab.

As an epidemiologist and a practicing paediatrician with expertise in infectious diseases, I believe it is imperative that information about this seemingly deadly infection is provided to the public in an unbiased and objective manner.

Routine testing for flu was commonly unheard of in Pakistan before 2009, when the first case of swine flu was reported. That year, there were reports of a new type of flu, H1N1 (swine flu), which was a mutant form of the Swine Influenza Virus (SIV) in pigs, being observed in humans.

This mutation in the old flu virus seen in pigs was alarming because it was associated with increased reports of severe lung infection or pneumonia that had not been previously reported.

######Since 2009, Pakistan gets its season of flu every year, which peaks in January and February and tapers in March.

A number of these cases are comprised of the previously intimidating H1N1, especially this year, which according to NIH, has seen hundreds tested positive for it in Rawalpindi, Islamabad, Multan, Peshawar, Sargodha and Karachi, with an increasing number of cases resulting in death.

Whether this is a routine phenomenon occurring each year, or the start of an alarming epidemic is an important question to ask because it has public health implications both locally and globally.

The signs of a flu epidemic

There are several clues that we need to look at to identify that something is amiss with the flu season and there is reason to believe that this is an outbreak getting out of hand:

Clue 1

The first clue to a flu epidemic would be a change in the usual pattern of flu-like illnesses and flu-related deaths. We know now that flu has a known seasonality associated with increasing flu-like illnesses and deaths from flu-like illness that occur from January to March.

This is the usual pattern that epidemiologists, the scientists who study disease and its determinants, follow throughout the year, every year, to detect a global outbreak.

In fact, the 2009 swine flu outbreak was detected when experts were alerted to the unusual change in the seasonal pattern of predictable flu-like illness.

Clue 2

The second clue that alerts experts is if there are an increased number of infected persons who died. Flu causes its fair share of mortality annually, but there is reason to be alarmed if the number of deaths is disproportionate to what is usually reported annually.

This change can only be detected if there is a systematic surveillance of flu and flu-like illnesses conducted over many years in a constant setting.

Clue 3

The third clue to a flu outbreak would be if there was an increased severity of disease or deaths in an unusual group of patients, for example healthy adults.

Immunity from flu virus arises because of prior infection, which allows our immune systems to recognise the virus proteins.

However, if these virus proteins change due to mutation, for example as seen with H1N1 in 2009, healthy adults or those thought to be protected, start exhibiting an increased severity of illness and increased deaths.

Remember that common symptoms of flu are cough, runny nose, fever, and generalised fatigue. Presentation is usually only severe in the very young and very old, and in those with decreased immunity due to diseases such as diabetes, or smoking.

However, if the flu virus mutates, immunity is not shown and even healthy adults are at risk of severe outcomes such as pneumonia and death.

All the above clues are causes to be alarmed and suspect that there may be a flu outbreak that could get out of hand.

Is there a flu epidemic in Pakistan?

The current outbreak of flu in Pakistan is caused majorly by H1N1, which now circulates throughout the year causing an increase in cases in January to March.

This season is not different from the ones in the previous years with regards to the types of flu virus.

Similarly, reports from the Aga Khan University Laboratory, a leading CAP-certified laboratory in Pakistan, show that there is no increase in rates of flu positivity from previous years, and that the current trends in positivity of samples indicates the usual flu activity in the country.

######Although there have been an increased number of samples coming in for testing, there is no observable change in the percentage of positive cases from previous years.

It’s important to keep in mind that the flu test is very expensive, on average costing Rs7,000 per test, and not offered in most labs in the country. Testing is therefore only done on the severely ill and on patients who can afford it.

This itself biases the reporting of flu cases in the country, where one may get a false impression of the severity of the disease and the mortality rates, because testing is primarily being done on very ill hospitalised patients.

Routine surveillance of flu-like illnesses and deaths from pneumonia and flu is non-existent in Pakistan. Experts have to depend on the interest and ability of the hospitals to do testing and report positive cases.

Therefore, in the absence of sufficient data on the annual rates of flu-like illnesses and pneumonia deaths, it is not possible to confidently assume that the epidemic may get out of hand.

Thus, there is not enough compelling evidence to indicate that we are sitting on a flu epidemic that can go amiss and lead to scores of severe disease cases and increased mortality rates. We do not have enough evidence to cause us to feel alarmed.

Actions need to be taken

This flu season is a very good opportunity to reflect on public health policies in this country, and on the practices of disease surveillance and prevention of diseases such as the flu.

The flu is here to stay. We will continue to have annual rises in the number of cases in these particular months. Flu deaths will occur among the oldest and the youngest, and those with decreased immunity.

More robust means of surveillance are required, for which NIH can take a leading role.

There are protective and preventive measures that can be taken at the individual level, such as hand washing, avoiding large gatherings — especially for the elderly and children — and using tissue paper while coughing and sneezing.

If severe flu is suspected, the patient should be immediately referred to a tertiary care hospital.

Physicians and health care workers need to be equipped with the knowledge and the drugs required for treatment of severe flu.

The role immunisation plays in preventing severe forms of flu is an established fact, but currently only indicated for those with decreased immunity and healthcare workers.

However, no such recommendations exist in Pakistan’s public health policy.

Are you a medical practitioner involved in public health issues? Share your insights with us at blog@dawn.com