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Sri Lanka on alert for any new flu strain
Sri Lanka is on the alert for any virulent flu strain, assured a health expert as a red flag went up on a strain identified in pigs in China with scientists warning that it may have the potential to cause a pandemic.
Dr. Jude Jayamaha
“There is no cause for alarm yet because it is too early to determine whether this flu (influenza) strain could trigger a pandemic,” said Consultant Medical Virologist Dr. Jude Jayamaha who heads the National Influenza Centre of the Medical Research Institute (MRI).
Identified as the G4 virus in a study published in ‘Proceedings’ of the National Academy of Sciences, United States of America, researchers point out that this version of the swine flu does not spread between people. However, it could potentially adapt to become transmissible between humans and if that happens could cause a global outbreak. It is not an immediate threat but the world needs to keep an eye on it.
The G4 virus has blended characteristics of the H1N1 virus that triggered the 2009 flu pandemic; the 1918 influenza pandemic; and a North American H1N1 flu strain containing genes from avian, human, and pig influenza.
Explaining that in Sri Lanka, the Influenza Preparedness Committee chaired by the Director-General of Health Services, Dr. Anil Jasinghe, meets every month, Dr. Jayamaha said that all stakeholders, around 19, are part of it including the Epidemiology Unit, the MRI and the Veterinary Research Institute.
“We have an active surveillance system with more than 300 samples being collected once a month from sentinel sites such as hospital outpatient departments (OPDs) as well as patients suffering from Influenza-Like Illness (ILI) and Severe Acute Respiratory Infection (SARI). We carry out typing, sub-typing and cultures on these samples to check whether there is any change in the flu viruses circulating in the country. If we find any odd ones, we send them for deep sequencing to the World Health Organization’s Collaborating Centre for Reference & Research on Influenza in Melbourne, Australia,” he said.
Dr. Jayamaha reiterated that Sri Lanka’s hospitals are also prepared for such an emergency.
He himself is in touch with China’s Centre for Disease Control & Prevention and vigilant about any new flu strain so that Sri Lanka’s National Influenza Centre could obtain PCR primers and probes promptly, like it did in the case of the new coronavirus long before the countries in the region got activated.
Chinese researchers had collected and evaluated more than 30,000 nasal swab samples from pigs in slaughterhouses and veterinary teaching hospitals between 2011 and 2018 in China, as pigs are considered ‘mixing vessels’ for pandemic flu viruses, as they make great hosts for multiple viruses to recombine with one another and produce a new strain.
The team had identified 179 swine flu viruses in the pigs and even though many had dwindled over the years, one strain had kept popping up, increasing year after year. This was the G4 virus. They had found a handful of people who contracted this virus directly from infected pigs.
In 2009 and 2010, ‘swine flu’ (A/H1N1pdm09 or H1N1) caused a pandemic, originating from Mexico and spreading worldwide. The misnomer of swine flu came about as it is similar to flu viruses that affect pigs. The outbreak did not turn out to be as serious as originally predicted, largely due to many older people being immune to it.
The H1N1 outbreak was declared a global pandemic by the WHO on June 11, 2009, but on August 10, 2010, this status was changed.
According to the Centres for Disease Control & Prevention in America around 700 million to 1.4 billion people contracted the illness worldwide with around 151,700 to 575,400 deaths.
H1N1 primarily affected those over 65, children younger than 5, children with neurodevelopmental conditions (such as cerebral palsy, muscular dystrophy or developmental delays), pregnant women (especially during the third trimester) and people of any age with underlying medical conditions such as asthma, diabetes, obesity, heart disease or a weakened immune system.
The symptoms, similar to the common flu, include fever, cough (a dry cough usually), headache, muscle or joint pain, sore throat, chills, fatigue and runny nose. Diarrhoea, vomiting and neurological problems had been reported in some cases.
The regular flu vaccine usually protects people who are at a higher risk of becoming severely ill.
| All about influenza | |
| Focusing on the main types of influenza viruses, Dr. Jude Jayamaha said there are four types – A, B, C and D.Usually pandemics are caused by Influenza A viruses when a new and very different virus emerges and infects people, while spreading rapidly between people, he said, explaining that Influenza A viruses are divided into subtypes based on two proteins on the surface of the virus: hemagglutinin (H) and neuraminidase (N). There are 18 different hemagglutinin subtypes (H1 through H18) and 11 different neuraminidase subtypes (N1 through N11). While there are potentially 198 different influenza A subtype combinations, only 131 subtypes have been detected in nature. The current subtypes of influenza A viruses that routinely circulate in people include: A(H1N1) and A(H3N2), it is learnt. Looking closely at Influenza A, Dr. Jayamaha says that it can infect mammals (humans, pigs, horses, cats, dogs and even whales) and also birds. The problem arises when the virus mutates and jumps species. The virus can mutate or change in two ways, says this Virologist. They are: Antigenic Drift – small changes in the genes of the virus that can lead to changes in the surface proteins of the virus: HA (hemagglutinin) and NA (neuraminidase). Such an antigenic drift does not cause major illness in people. But these small changes can accumulate over time and bring out a virus that is very different to which people are not immune to and have no protection. Drifts happen frequently. Antigenic Shift – this is an abrupt, major change in the virus, resulting in new HA and/or new HA and NA proteins. This can cause a new influenza A subtype in humans. It could happen when an influenza virus from an animal species gains the ability to infect humans. Such animal-origin viruses can contain an HA or HA/NA combination that is so different from the same subtype in humans that most people do not have immunity to the new (novel) virus. This was the ‘shift’ which occurred in 2009, when an H1N1 virus with genes from North American swine, Eurasian swine, humans and birds emerged to infect people and quickly spread. Shifts happen less frequently. Influenza type A viruses undergo both antigenic drift and shift and are the only influenza viruses known to cause pandemics, while influenza type B viruses change only by the more gradual process of antigenic drift, Dr. Jayamaha added.
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