Up to ten million Americans may be suffering from an allergy to red meat triggered by tick bites, estimates suggest — but many cases go undiagnosed because it can take up to 12 hours for symptoms to develop.
Alpha-gal Syndrome is normally sparked by bites from the lone star tick — identified by the white spot on its back — which lives in wooded areas across the eastern United States. But bites from other ticks may also cause it.
Dr Jonathan Oliver, a public health expert at the University of Minnesota, told DailyMail.com that the bug’s saliva contains molecules that appear to be similar to those from red meat. It means that when the immune system attacks the saliva, it also develops cells that target molecules from red meat — triggering the allergy.
Most tick bites do not lead to the condition, Oliver said, but he warned that getting bitten more often raises the risk of developing the condition.
Sufferers experience symptoms several hours after eating red meat including hives, severe stomach pain and swelling of the lips. In severe cases it can also trigger anaphylactic shock or a severe immune reaction, which can be fatal.
Treatment focuses on avoiding being bitten by ticks and taking medication to manage allergic reactions.
The AGS awareness campaign says that up to three percent of Americans — or about ten million people — in some areas may be sufferers, but that the vast majority are un-diagnosed.
Scientists have linked many cases to the lone star tick (left), which lives in wooded areas across the east of the U.S. and is identified by the white spot on its back. They fear molecules in its saliva may look like those from red meat, triggering the allergy
Other ticks may also cause the disease. Scientists are investigating whether the black-legged tick (left) could be behind some cases. It has a wider ranger than the lone star (right)
Pictured above is the lone star tick (left), which is linked to most cases of AGS. Other tick species including the black-legged tick (right) may also trigger the condition, it has been suggested
Alpha-gal Syndrome: The disease that makes you ‘allergic’ to red meat
Alpa-gal Syndrome (AGS) is an allergy to a molecule found in red meats including beef, pork and venison.
Up to three per cent of Americans have the condition, or 10million people, estimates suggest.
What triggers AGS?
The allergy has been linked to bites from the lone star Tick, identified by a white spot on its back, which lives in wooded areas on the East Coast. Other tick species are still under investigation.
Its saliva contains molecules which can look similar to those from red meat.
It means that when the immune system attacks the saliva, it may also develop cells that start attacking molecules from red meat.
What are the symptoms?
Sufferers experience the following about two to six hours after eating red meat, or in some cases being exposed to its fumes:
- Hives or itchy rash;
- Nausea or vomiting;
- Heartburn or indigestion;
- Cough, shortness of breath, or difficulty breathing;
- Drop in blood pressure;
- Swelling of the lips, throat, tongue or eyelids;
- Dizziness or faintness;
- Severe stomach pain;
Is the condition fatal?
The CDC says in some cases it can trigger anaphylaxis — a severe allergic reaction which can be fatal if not treated quickly.
How is AGS diagnosed?
Doctors carry out blood tests to check for specific antibodies that attack the molecule from red meat.
How is AGS treated?
Patients are advised to avoid any products that contain the molecules that trigger the allergy.
This includes red meats, and other foodstuffs using animal products including cow’s milk and gelatin.
Can I prevent the condition?
Doctors say people should avoid grassy, bushy or wooded areas where ticks may be found.
After coming inside they also recommend showering and performing a thorough ‘tick check’ to ensure they have not been bitten.
An article investigating AGS published last year in the Frontiers in Cellular and Infection Microbiology also says up to three percent of the population has the condition.
Less than a million cases have been diagnosed in the U.S. to date.
Oliver — who studies tick-borne diseases — said that more people with the allergy were being spotted every year as awareness around the allergy rose.
‘Often there is a real delay between when you eat red meat and when you get sick, maybe eight to 12 hours,’ he explained.
‘So people often don’t make the connection that they are reacting to red meat that they ate the night before or much earlier in the day.’
He said the vast majority of cases appeared to be linked to the lone star tick, which lives in ‘high densities’ in woodland.
But there are also clusters outside its natural range which may be down to a deer tick species called the black-legged tick.
Other tick species are still under investigation, and in separate countries different species have been blamed for the allergy.
Most bites do not trigger the allergy, Oliver said, although it is best to avoid being bitten if possible.
‘There are certainly many many times more Lone Star tick bites every year, so the probability of getting it from any individual bite is pretty low,’ he said.
‘But the people at higher risk are those getting bitten by ticks more regularly.’
Scientists are not yet sure what is causing the condition, although it appears to be linked to a reaction to molecules in tick saliva.
Oliver explained they could look like those from red meat to the immune system, triggering the allergy, saying: ‘it is not like many allergies where you are getting exposed to [what causes it].
‘Instead, it is like a whole class of compounds that are somehow triggering this.’
People with the allergy can still eat fish and chicken.
Symptoms of the condition include hives or an itchy rash, nausea and swelling of the lips, throat, tongue or eyelids.
In rare cases it can also lead to anaphylaxis, a potentially fatal condition where a severe allergic reaction occurs.
The CDC recommends people can avoid the condition by avoiding tick bites.
This means steering clear of grassy, bushy or wooded areas where the insects may lurk, and thoroughly checking themselves for ticks after coming inside.
Sufferers are advised to steer clear of red meats that could trigger their condition, and avoid animal products such as cow’s milk and Haribo that could also spark an allergic reaction.
Oliver said: ‘There is so much that is unknown about this disease, really knowing what combination or proteins causes AGS knowing whether infection with other tickborne diseases is altering the allergy and so on.
‘We also need to identify other tick species that are capable of inducing this and finding out under what conditions they do induce it.
‘There is a ton of work that needs to be done.’
The allergy was discovered in 2001 when Dr. Thomas Platts-Mills, a medicine professor at the University of Virginia, was working on a monoclonal antibody drug when he noticed it causing anaphylaxis in a few patients.
After failing to treat a person with the drug, called Cetuximab, an investigation found the antibodies were being attacked by separate ones inside the body.
Further investigation revealed the drug’s antibodies had AGS in them because they were grown using animal cells.
Perhaps the most famous person to publicly acknowledge suffering from AGS is mystery writer John Grisham, who caught it after a tick bite and no longer eats meat.