Tick bites and allergic reactions to red meat

Allergy to red meat is believed to be rare. However, in the eastern parts of the USA there have been interesting findings suggesting that meat allergy may be more common in that country than previously thought, and that tick bites may be the cause of the allergy in many cases.

This problem is also believed to be an issue in South Africa. A few cases have been reported in the UK.

This article is written for anyone who believes this may be a problem for them. If you are one of those affected, our key advice is to seek medical advice, initially through your GP, who is likely to refer you to an allergy clinic for expert guidance.

The theory is that when the person is bitten, the tick triggers the production of an antibody to a protein known as galactose-alpha-1,3-galactose (abbreviated as alpha-gal). This protein can be found in the meat of animals, so when the person affected eats meat a reaction occurs.

It was back in 2009 that researchers in Virginia reported a novel form of delayed anaphylaxis to red meat eaten 3-5 hours previously. They found this to be related to antibodies to alpha-gal. Most of these people had tolerated meat for many years previously.

Subsequently the researchers went on to investigate possible causes of this allergic response, focusing on evidence related to tick bites, which are common in the region of the USA where these reactions commonly occur.

Studies on allergic antibodies (known as IgE) in three people following tick bites showed an increase in IgE to alpha-gal of 20-fold or greater. The researchers also found evidence that these IgE antibodies are common in areas where the tick Amblyomma americanum is prevalent.

They concluded: “The results presented here provide evidence that tick bites are a cause, or possibly the only cause, of IgE specific for alpha-gal in this area of the United States.”

It is important to remember that not all allergy to red meat is caused by tick bites, but if you have been bitten by ticks and later find you can no longer tolerate red meat, the bites may have been the cause.

In South Africa, an investigation into this issue is under way. There are some rural communities in Cape Province with a very high prevalence of red meat allergy. The investigation currently in progress seeks to understand the triggers, which may be ticks but also could be other insect bites or parasitic infestation.