DID you know that worldwide, the prevalence of allergic diseases are increasing especially in low and middle income countries, our Zimbabwe included.
Not only are more allergies related cases being recorded but also the allergies are increasing in their complexity and severity especially in children and young adults. Allergic conditions range from life threatening asthma, food allergies, rhinitis, conjunctivitis, urticarial, eczema, eosinophilic disorders, including eosinophilic esophagitis, and drug and insect allergies.
According to the World Allergies Organisation (WOA), globally, 300 million people suffer from asthma and about 200 to 250 million people suffer from food allergies while a tenth of the global population suffer from drug allergies and 400 million from rhinitis.
In our previous article, Twin Palms Managing Director, Professor Elopy Sibanda who is also an Allergies, Asthma and Immunology expert spoke at length on the subject of Asthma and how best people can manage the condition through getting expert diagnosis and treatment. However, in this particular article, Prof Sibanda (Prof Sibanda) speaks to our Editor Michael Gwarisa on the subject of seasonal allergies.
WHAT ARE SEASONAL ALLERGIES?
Prof Sibanda: Seasonal allergies as the name suggests are those that occur and follow a seasonal pattern. Usually those are allergies that are associated with inhalations of certain materials which are present at certain times of the year.
WHAT ARE THE MAJOR ALLERGENS OR TRIGGERS FOR SEASONAL ALLERGIES?
Prof Sibanda: A good example of a seasonal allergen is grass. Grass is something that comes in during the rainy season and therefore people who are allergic to grass pollen will have more severe symptoms during the grass pollen season. There is also a tree pollination season which is characterised in Zimbabwe by the blooming of Jacarandas
DOES THIS MEAN JACARANDA TREES CAUSE ALLERGIES?
Prof Sibanda:. People have symptoms that occur during that time of the year when Jacarandas bloom. What I have to add however is that the Jacarandas themselves do not cause allergies. For one to have pollen allergy, the plant must be wind pollinated not insect pollinated. For a plant to be insect pollinated, an insect has to get inside the flower to get pollen whereas for a wind pollinated plant, the wind blows away the pollen. So the Jacaranda is always accused of a crime it has not committed.
WHAT OTHER CATEGORIES OF SEASONAL ALLERGENS DO WE HAVE?
Prof Sibanda: The third category of seasonal allergens are those that are caused by moulds. Moulds spores favour certain environments. There are mould spores which are predominant in the mouldy type of weather that will include the rainy season and or the winter months. There are moulds which can be easily blown away by the wind those which occur mainly in the late summer months. The forth seasonal but to an extent non seasonal allergens are those due to house dust mites. The house dust mites are there throughout the year. During winter we have this practice of closing the windows and other ventilation openings so that we stay warm. As that happens, you find that the house dust mites which are always there throughout the year appear to give us more problems during this period. So these are perennial allergens and they are there throughout the year not just one season.
WHAT ARE SOME OF THE COMMON SEASONAL ALLERGIES?
Prof Sibanda: The commonest allergies are associated with the inhalation of anything and it follows the inhalation passage. Something must pass through the nose and the destination from the nose is usually the lungs. You find that these allergens will block the nose and cause Hay fever and the mucus that you produce in the nose which is supposed to stop the allergen from getting further into the lungs at times fails and causes or worsens Asthma. Those are the allergies that are associated with a seasonal patterns. Primarily you find eye problems, nasal problems, Itchiness of the eyes and tearing of the eyes which is associated with Hay fever. At times you can find Hay fever which is associated with sneezing, itchiness of the throat and itchiness of ears.
DO WE HAVE FAMILIES OF SEASONAL ALLERGIES AND HOW ARE THEY CLASSIFIED?
Prof Sibanda: Seasonal Allergies are predominantly Hay fever, Conjunctivitis and Asthma which follow a seasonal pattern. What doesn’t follow any pattern is eczema which tends to be associated with things that we eat as opposed to things that we breathe in. Urticarial (Munyawiri) maybe not and that’s a different allergy. Mainly inhaled allergies which affects the eyes, throat and lungs constitute majority of seasonal allergies.
ZIMBABWE ONLY HAS TWO SEASONS THAT IS WINTER AND SUMMER. WHICH AMONGST THESE TWO CARRIES THE MOST SEASONAL ALLERGIES?
Prof Sibanda: It’s a tricky question that one. However, the dominant allergen is house dust mite. House dust mites affect about 50 percent of those who have allergies and those are worse during the winter months. The pollen allergies are in the region of 15 and 20 percent, they are worse in the rain and summer months. More people will have allergies to house dust mites than to pollen and by the way those house dust mites will also be affecting them in summer as well. I think it’s a difficult question to pin down because of the relative prevalence of the allergies from the two groups.
WHAT IS THE RELATIONSHIP BETWEEN CLIMATE CHANGE AND SEASONAL ALLERGIES?
Prof Sibanda: There is a theoretical correlation between climate change and allergies but I don’t have enough facts to say exactly how it correlates. The correlation that we have and that we have talked about in terms of climate is that the type of vegetation that we are exposed to changes and then we have new introduction of certain sources of allergies that were not there in your life before and people get sensitive to that. Secondly, climate change will disrupt the usual seasonal patterns. Summers become hotter In Europe and in the Southern Part of the hemisphere droughts were experienced last year and the temperatures are getting hotter.
CAN GENETICS PREDISPOSE SOMEONE TO SEASONAL ALLERGIES?
Prof Sibanda: It is true, allergies are and can be inherited. Allergies are not inherited to the extent that if you are the son of an allergic person you must have allergies, it’s not like that. Its slightly different, some people will have them, others will not. Allergies are inherited as a cluster for example Asthma is one of the cluster of allergies which includes Hay fever, Conjunctivitis (itchiness of the eye), Urticarial and all those inherited within the family tree. You find that you may have asthma and your cousin may have hay fever. So allergies are hereditary and environmental, you may go to live elsewhere not be exposed to pollen and you will never develop a pollen triggered allergy even though you have inherited the allergy.
WHAT TREATMENT AND ALLERGY MANAGEMENT OPTIONS ARE AVAILABLE FOR SEASONAL AND ENVIRONMENTALLY TRIGGERED ALLERGIES?
Prof Sibanda: I think hay fever which is triggered by pollen tends to be self-limiting because the pollen season is short so what you then try to do is to manage in the best you can during that season but if it is severe, there are options which are available which include vaccination against the allergen source so people can be immunised against whatever they are allergic to. The first rule of thumb is that if there is an allergy, you first try to identify the route cause of the allergy and then what are the accompanying causes are and then eliminating the cause for example getting rid of the carpet or dog. There is also this long term preventive prophylaxes which you can actually vaccinate the person against that which they are allergic to and they will stay free from allergies for at least seven to 11 years and we offer those vaccinations here. These are called specific immune therapy vaccinations. They are specific for what the person is allergic to and it works.