Today will find many of us out and about, gardening, walking and if we are lucky with the weather, on the beach. Our paths may cross bees, wasps, other insects and jellyfish. For an unfortunate few, this will end in a sting.
Mostly, this will result in a sharp pain, a local area of warmth with redness and swelling and in the case of an insect bite, the tell-tale puncture mark with or without the sting present. The irritation and ache may last for up to 24 hours, but usually resolves with no serious effects. However, for a minority, an insect sting can produce an allergic reaction. If the reaction is severe it is termed anaphylaxis and can be fatal.
Tony McGuire, the Co Mayo born owner of a London based construction firm, died on the floor of his home on July 14th less than five minutes after being stung by a wasp.
Calling for an awareness campaign to educate the public about anaphylaxis, his widow Lynn said her husband was in the garden near a flower-box when stung. Significantly, she said her husband suffered a slight swelling when stung on the hand by a wasp a few years ago, but added that she had no idea he would be in danger if stung again.
Anaphylaxis affects one in 10,000 people a year. It is a severe allergic reaction affecting the whole body. With any allergic reaction, the body's immune system releases histamines and other chemicals which make the blood vessels leak (causing swelling), cause low blood pressure and narrow the breathing tubes in the lungs. But with anaphylaxis, this defence mechanism spirals out of control and causes inflammation throughout the body. As blood leaks out of the vessels there is less available for the heart to pump to vital organs such as the lungs, liver, kidney and brain, resulting in medical shock.
However with quick treatment, the person's life can be saved.
McGuire's death illustrates the phenomenon of sensitisation. It is likely that when he was originally stung some years ago, his immune system developed specific antibodies to wasp venom. And when he was stung again, his sensitised immune system went into overdrive in its attempt to fight off the venom, which it "recognised" from before.
Sensitisation to wasp venom can occur after a single sting. But it appears that the phenomenon can wane over time, so that even after a severe reaction, a subsequent sting may produce a lesser reaction, no reaction at all or another severe generalised allergic response.
It is because of this variable and unpredictable outcome that a person who has had an allergic reaction to an insect sting should see an allergy specialist. While there is no blood test that will reliably predict how a patient will react to a further sting, it will be possible to make a clinical assessment of the risk.
When someone has a severe allergic reaction, the possibility of death is related to three things: the speed of symptom onset, the severity of symptoms and whether or not the sufferer receives adrenaline treatment within the first 30 minutes. Because of this short time frame, people with a history of a moderate or severe reaction are supplied with syringes pre-loaded with adrenaline (Epipen or Anapen). They, or in the case of a child, the parents, are taught to inject the drug into the thigh muscle in the event of a further wasp sting. Early self treatment is highly effective and the reaction can usually be stopped.
Having bought time with the self-administrated adrenaline, the patient must seek further medical treatment. In about 10 per cent of cases a second severe reaction can occur six to eight hours after the first.
Galway-based allergy specialist, Dr Joe Fitzgibbon says that simple means of avoiding stings are also valuable: "Do not wear light yellow or blue colours [which attract insects], always wear a hat outdoors, do not picnic beside waste bins, never swim in a lake or river and wear shoes and long-sleeved tops and trousers to make sure your skin is less vulnerable".
Symptoms of Anaphylaxis
a) Difficulty swallowing or speaking (swollen throat and mouth)
b) Swelling of the face or lips
c) Breathing difficulties
d) Large hives anywhere on the body
e) A sudden feeling of weakness (due to a drop in blood pressure)
f) Heart rate which is faster or slower than normal
g) Collapse and unconsciousness
Further information on anaphylaxis: The Anaphylaxis Campaign, PO Box 4373 Dublin 18. Could it be an Allergy? by Dr Joe Fitzgibbon, Newleaf Books.
E-mail Dr Muiris Houston, Medical Correspondent at mhouston@irish-times.ie or leave a message at 6707711, ext 8511.