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High steaks: Lone Star ticks

The Lone Star is spreading across the US, causing a range of side effects The Lone Star is spreading across the US, causing a range of side effects
11 Aug
The Lone Star tick is spreading across North America, carrying a peculiar health threat with it: an allergy to red meat

Bad news for North American carnivores: your ability to devour red meat is being threatened. The continent has seen a large increase in populations of blacklegged ticks (Ixodes scapularis) in recent years, spreading northwards as the climate warms, carrying the bacteria Borrelia burgdorferi – which causes Lyme disease – with them. Recently they have been joined in large numbers by Lone Star ticks (Amblyomma americanum), distinguishable by the white spot on their backs. These are traditionally found in small populations in southern states such as Tennessee, North Carolina and Virginia, but are increasingly being observed in more northern states, and even across the border in Canada. While these aggressive ticks are not carriers of B. burgdorferi – in fact their saliva has been observed to destroy the bacteria entirely – their bites nevertheless have an usual and potentially hazardous side-effect.

In many regions of the United States, people have increasingly reported developing seemingly random allergic reactions, experiencing everything from mild reaction such as rashes and swelling, to, in the most severe cases, full anaphylactic shocks. Research developed over the past 15 years strongly suggests that this is a red meat allergy contracted by Lone Star tick bites, also known as ‘alpha-gal’ allergy.

Dr Melody Carter, staff clinician in the US National Institute of Allergy and Infectious Diseases (NIAID) Laboratory of Allergic Diseases, confirms that both the numbers and geographic spread of diagnosed cases are growing. ‘This is most likely due to the spread of the deer habitat along with the tick population,’ she explains.

Lone Star tick bites are believed to trigger a rapid increase in the quantity of antibodies which see alpha-gal – a sugary chemical found in the tissues of mammals, such as cattle and other livestock, but crucially not in birds or fish – as a threatening invader and consequentially goes on the attack. This is the working theory for why tick bites can cause people to later develop severe reactions to eating ribs, bacon, or other barbecue gastronomy (often several hours after eating, making it harder to link the reaction to the offending meal). ‘It is important for providers to recognise the symptoms associated with this syndrome,’ says Carter, ‘but also important to take preventive measures to decrease exposure and once diagnosed avoid red meat consumption.’ 

This was published in the August 2018 edition of Geographical magazine

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