For people with pollen allergies, South Africa's pollen season can cause annoying runny noses, and in some more serious cases, asthma attacks. Yet, until recently, pollen levels have not been tracked systematically across the country.
Now, an ambitious new pollen tracking effort is shedding some light on how much of which types of pollen are found at different times and in different parts of the country. The new data may well help doctors and patients to manage these allergies more effectively.
What is a pollen allergy?
Individuals with pollen allergies can experience symptoms that can range from "annoying to frankly dangerous", says Paediatrician and Allergy Specialist, Professor Claudia Gray. "In general, allergies are caused by a genetic tendency for the immune system to 'overreact' to substances which should normally be harmless, for example house dust mites or grass pollens," says Gray.
"The inhaled pollens can set off an immune response in the nose, the eyes and the chest. Some people manifest mainly with a runny, itchy, sneezy or congested nose, some with itchy eyes, and some with full-blown asthma attacks. Secondary complications can also occur. An airway which is soggy and swollen from allergies is more prone to viral and bacterial infections. Also, the nasal blockage can lead to sinus and ear infections," she says.
Pollen tracking in South Africa
South Africa's pollen tracking efforts expanded in August last year, explains the Principal Investigator and coordinator of the South African Pollen Monitoring Network (SAPNET) at the University of Cape Town's (UCT) Lung Institute, Professor Jonny Peter. Before this, he says the only consistent pollen data that existed was from Cape Town.
The expansion (featured in an article in the journal Lancet Respiratory Medicine) resulted in pollen spore traps being set in Bloemfontein, Cape Town, Durban, Johannesburg, Kimberley, Port Elizabeth, and Pretoria.
"Pollen count data indicating geographical location, seasonal timing, and annual aerospora variations are now a new tool for clinicians to deliver effective diagnosis and treatment of allergic respiratory diseases in South Africa, where climate and vegetation are exceptionally diverse," the article reads.
How spore traps work
According to Dr Frank Neumann, Senior Researcher at the Evolutionary Studies Institute at the University of the Witwatersrand (Wits), the best way to track pollen is to use an ingenious machine that mimics the human body's breathing process.
Neumann, who is also part of the SAPNET team at Wits, describes the little machine, called a seven-day volumetric spore trap, as resembling a tripod. "It's located on a roof, and should be at least 3 or 4 meters up in the air. The tripod has a chamber that can rotate according to the wind," he says.
Photos of the spore trap show that it resembles a mini gas braai, with a vane (which looks like a flat fin) at the back. According to SAPNET's website, the Real Pollen Count, the machine is about 1 meter by 1 meter.
The bottom of the trap contains a drum with a slit along the side, which rotates slowly, Neumann explains.
"On the drum there is a sticky tape (or strip), and that catches the dust in the air," he says.
A little engine allows air to be sucked in through the slit in the chamber. This is where the trap mimics the human body's breathing process.
"There is something like an engine, run by electricity, that sucks in the air. Basically, the spore trap mimics our human body... the little slit will be our nose opening," Neumann says.
Once a week the strip is collected and replaced with a new one. The old strip, now filled with pollen dust, is mounted on a glass slide for microscopic analysis.
"We identify the pollen and analyse them, and then it can be calculated how much pollen you have in one cubic meter of air, and from which species," he says.
The data from this trap, and SAPNET's other spore traps, is then sent to the team at UCT, where it is analysed, after which a report is uploaded to the internet and made available on a website that is open to the public.
Why is it important to track pollen levels?
The data collected in this way can be used by people with pollen allergies, doctors and researchers working in various scientific disciplines.
Those who suffer from pollen allergies can be empowered by the data, Peter explains. "Some people don't know what they are allergic to, so being aware of it (the pollen levels) links your symptoms to what is in the air. That's the first step in getting diagnosed and treated," he says.
A more recent use is that it can also help individuals distinguish whether their symptoms indicate a pollen allergy, or something potentially more serious like COVID-19. "Another current issue is that many symptoms of pollen allergies (sneezing, blocked noses, chestiness) can mimic COVID-19 symptoms, adding to the complexity of COVID testing and isolation strategies," says Gray.
Knowing when pollen levels are rising also helps people to know when to start treatments, and to adapt their outdoor activities.
Significant burden of disease
"In South Africa, exact prevalence figures for pollen allergy are not known, but studies have estimated that between 15 and 40% of the population suffer from allergic rhinitis, and a high percentage of these would suffer from pollen allergies. So, this represents a significant burden of disease," says Gray, who is also a consultant at the Allergy and Asthma Clinic at the Red Cross Children' Hospital.
According to Gray, the country is currently experiencing high pollen levels, which is causing adverse effects for pollen-allergic patients. This places a burden on the health care system and on the quality of life of people with allergies.
"Pollen allergies can put a strain on the entire system, and with severe attacks of allergies, the sufferer can feel really unwell, tired and function sub-optimally. If not diagnosed and treated correctly, allergies can lead to poor work performance and poor school performance," Gray says.
When asked if pollen allergies can have a greater impact on people with compromised immune systems, such as people living with HIV who have low CD4 counts, Gray replies that, "in general, poorly controlled allergies can lead to an increased risk of secondary infections, which can be of particular consequence in patients with underlying immune disorders".
Changes over time
Pollen levels fluctuate for season to season for many reasons, according to Peter, making it vital to continuously monitor the levels.
The geography of an area, and the plant ecology and how people are changing the environment, for example by planting invasive plant species and removing indigenous forests, play a role in pollen levels.
Meteorological or weather parameters also play a role. Peter reveals that during the recent drought in Cape Town, the pollen levels were extremely low, but as soon as the drought broke one of the highest pollen seasons in decades was recorded.
Peter says that researchers cannot deduce much from the data collected so far, as there isn't any consistent South African data, exception for Cape Town, to compare it to. Because of this, researchers cannot yet see how South Africa's pollen seasons and levels may have been affected by climate change or predict how it will be affected in future.
Data from the Northern Hemisphere, however, paints a grim picture for the effects of climate change on pollen levels.
"The Northern Hemisphere data has generated alarming stuff about pollen, suggesting that in 20 years... pollen is going to be four times higher than it is now because of climate change," Peter says. Thus, he says, there will be seasonal variations in pollen levels, but climate change is going to be a factor in how these levels change and potentially rise. "The feeling is that these things will change and will negatively impact allergy sufferers, and the expansion of pollen will become increasingly more problematic."
Data can also help researchers and doctors
The data being collected by SAPNET will also assist scientists and researchers in different disciplines, Peter says. Uses of the data include answering scientific questions about the intersection between weather patterns and pollen and allergies, and the connection between air pollution and pollen and allergic disease.
"We're flagging up new allergens that are in the air that we haven't looked for and haven't been aware of," he adds. He recalls how the team recently identified Ambrosia, commonly known as Ragweed, through their spore traps. This plant had not been featured in a standard allergy test in South Africa until that point. He adds that information like this can help direct doctors to update what allergens they test for and when.