3 September 2018

GPs brace for thunderstorm asthma season

Allergies General Practice Respiratory

It’s been almost two years since a freak weather event whipped up ryegrass pollen and blew it into Melbourne, leaving 10 people dead and thousands more seeking emergency assistance.

With just under one month to go until the official start of the pollen season on 1 October, GPs across Victoria will be making sure their at-risk patients are better protected this time around.

To help GPs brush up their knowledge, Melbourne’s PHNs are hosting free educational events in Whitehorse, Monash, Brimbank, Greater Dandenong, Wyndham and Casey over the next few weeks.

Melbourne hasn’t see a repeat of the devastating 2016 thunderstorm asthma episode, “thank goodness”,  Professor Amanda Barnard, a GP and the chair of the National Asthma Council Australia’s Guidelines Committee, said. But that was no reason for complacency.

There were two types of thunderstorm asthma, Professor Barnard said. There was the “huge episodic event that stretches the system to its limits and beyond”, and then there were smaller asthma incidents triggered by similar weather patterns, she said.

Springtime thunderstorms can cause severe asthma when air-borne pollen particles fill with water and degranulate, casting very fine particles to the wind, which can be breathed in.

“The message for GPs is talk to all your patients who have asthma or who have allergic rhinitis and see what the seasonal pattern of their symptoms is,” Professor Barnard said. “See if they are at risk of their asthma being triggered by a thunderstorm.”

With the coroner’s inquiry into thunderstorm asthma deaths drawing to a close, the public were taking a renewed interest in the topic, she said.

This year a spotlight should be on people with an Asian or Indian background, particularly people who have recently moved to Australia, as these groups were at greater risk of thunderstorm asthma.

“It really important that those messages get out to the communities and to the doctors who look after the people in those communities,” Professor Barnard said.

A study published in The Lancet Planetary Health journal in June found that migrants from India, Sri Lanka and south-east Asia comprised 36% of the hospital admissions during the thunderstorm asthma event on November 21, 2016. Six out of the 10 people who died that day were originally from India or south-east Asia. (These ethnic groups only make up 25% of Melbourne’s population.)

“And we don’t exactly know why,” Professor Barnard said.

Twenty-year old studies show that people with an Asian background living in Australia have a higher rate of seasonal allergic rhinitis and asthma, which increases in prevalence over time.

Up to 60% of south-east Asian immigrants developed hay fever after 10 years in Australia, while 15% developed asthma symptoms over that period.

“One theory is that people who migrate from those countries haven’t been exposed to the ryegrass pollens from early ages and they get exposed later in life and develop significant hay fever symptoms,” Professor Barnard said.

Resources on thunderstorm asthma for GPs are available on National Asthma Council Australia’s website at http://bit.ly/2oqlF7j.