Up to one in seven people worldwide may have had Lyme disease, according to new estimates.
For decades, researchers have been clueless as to exactly how widespread the tick-borne illness was.
The new findings could open up avenues to tackle the bacterial infection, which can cause sufferers symptoms such as headaches, muscle and joint pain and fatigue that can last for years.
Academics from China examined blood sample data from studies involving 150,000 people.
Results showed 14.5 per cent had antibodies indicating Lyme disease.
Canadian pop singer Justin Bieber (left) has spoken out about suffering from Lyme disease, while American model Bella Hadid (right) has shared that she suffers an irregular heartbeat, joint pain, and difficulty with breathing due to the condition
Lyme disease is a bacterial infection that is spread through a tick bite. It causes a round rash and can trigger flu-like symptoms but usually gets better with antibiotics within weeks or months. Pictured: stock of tick
Rates were, however, just over 20 per cent in Central Europe, an area which usually encompasses Germany and Poland.
Researchers said a ‘more accurate’ figure on the global distribution of Lyme disease would ‘identify risk factors’.
WHAT IS LYME DISEASE?
Lyme disease is a bacterial infection that is spread to humans by infected ticks.
It causes symptoms including a circle or oval-shaped rash around a tick bite, which usually appears within four weeks of being bitten, but may take up to three months to show.
Some people also get flu-like symptoms in the days after being bitten, including a high temperature, a headache, muscle and joint pain and a loss of energy.
And a few of those treated for Lyme disease continue to have symptoms, such as tiredness, aches and a loss of energy, that can last for years.
It’s not clear why some suffer from ongoing symptoms and there is no agreed treatment for the disease.
Not all ticks carry the bacteria that causes Lyme disease, but infected ticks can be found across the UK.
High risk areas include grassy and wooded areas in northern and southern England, as well as the Scottish Highlands.
People are advised to remove ticks safely and as soon as possible using tweezers.
This, they said, may ‘inform the development of public health response policies and control programmes’.
Before now, the most accurate figures suggested that around 900 Brits and 30,000 Americans were struck down every year. However, these were widely thought to be an underestimate.
Ticks are second only to mosquitos in terms of the number of harmful microbes they carry.
Some harbour Borrelia burgdorferi sensu lato, the bacteria which is responsible for Lyme disease.
The infection triggers a circular oval-shaped rash around a tick bite that can appear up to three months after being bitten.
The bacteria can also spread to other tissues and organs, potentially affecting the nervous system, joints, heart and skin for years.
But it’s not clear why some suffer from ongoing symptoms — and there is no agreed treatment for the disease.
Researchers from Kunming Medical University in China examined 89 Lyme disease studies involving 158,287 people, conducted between 1984 and 2021.
Each study looked at Lyme disease rates from blood test results because it triggers antibodies in the same way as Covid.
This means a blood sample can confirm whether a person is currently infected or has been in the past.
The team wrote their findings, in BMJ Global Health, are the ‘most comprehensive and up-to-date systematic review of the worldwide’ prevalence of Lyme disease.
A fifth of people in central Europe tested positive — the highest rate — followed by Eastern Asia (15.9 per cent) and Western Europe (13.5 per cent).
For comparison, rates were lowest in the Caribbean (2 per cent) Southern Asia (3 per cent) and Oceania (5.3 per cent).
The researchers noted that tick-borne diseases have doubled over the last 12 years. Such pathogens pose a ‘significant and growing public health problem’ and are a ‘major cause of disease and death worldwide’, they said.
Ticks have expanded globally in recent years, ‘greatly increasing the risk of human exposure’, the study stated.
This could be down to longer summers and warmer winters, animal migration and increased time spent outdoors.
A sub-analysis showed over-50s, men and those living in rural areas were most likely to have Lyme disease.
Men were more likely to be working in jobs that make them more exposed to ticks, such as farmers, police officers and soldiers.
The team said it is ‘essential’ to develop new treatments and prevention methods.
However, they noted that a third of the studies used just one type of test to confirm a Lyme disease infection.
These studies reported more cases than those using a second test to confirm a case.
This may be due to the bacteria behind Lyme being similar to other viruses, such as Epstein-Barr.
And they said that some of the studies were conducted in regions where Lyme disease is endemic and therefore had much higher rates.
So the 14.5 per cent figure may be ‘over-estimated and non-representative of the global population’, the researchers said.
A standard testing method worldwide would provide ‘great value’ in confirming the prevalence of Lyme disease, as well as information on which groups are most at-risk, the team said.