People showing erythema migrans, the characteristic skin rash associated with Lyme disease, can be diagnosed without the need for blood tests, NICE says in new guidance.

Lyme disease is an infection transmitted by the bite of a tick. Prompt diagnosis and early treatment helps reduce the risk of further symptoms developing.

Laboratory tests check for antibodies in the blood however Lyme disease antibodies may first appear six to eight weeks after a person has been bitten by a tick. Early laboratory tests may not detect the disease and could slow diagnosis.

Erythema migrans is a skin rash associated specifically with Lyme disease and is present in approximately two-thirds of all cases. It is a spreading red rash that usually appears one to four weeks following a tick bite and can have a bull’s-eye like appearance. When there is no rash, lab tests can be used to guide a Lyme disease diagnosis, the guidance says.

Professor Gillian Leng, deputy chief executive and director of health and social care at NICE, said: “For most people with Lyme disease, a course of antibiotics will be effective, so it is important we diagnose and treat people as soon as possible.

“A person with Lyme disease may present with a wide range of symptoms, so we have clear advice for professionals about the use of lab tests for diagnosis and the most appropriate antibiotic treatments. If a characteristic bull’s eye rash is present, healthcare professionals should feel confident in diagnosing Lyme disease.”

In the absence of erythema migrans and presentation of other symptoms, an initial ELISA laboratory test can be used. If this initial test is carried out too early for antibodies to have developed, people may have a negative result and the ELISA test may need to be repeated.

If the ELISA is positive or symptoms continue for 12 weeks or more, a more specific test called an immunoblot test should be used to confirm Lyme disease.

Veronica Hughes, CEO, Caudwell LymeCo Charity, said: "I hope the new quality standard will increase the number of doctors who feel confident diagnosing a Lyme disease rash on sight and treating the infection right away.

“Caudwell LymeCo Charity hears regularly from people whose doctors have diagnosed an erythema migrans but decide to check with a blood test, not realising that the rash is the more reliable of the two. Waiting for blood test results always delays treatment; when a patient has the rash, this delay is unnecessary and reduces the likelihood of total cure."

After a diagnosis of Lyme disease, a person will receive an appropriate course of antibiotics based on their symptoms.

This Lyme disease draft quality standard is out for consultation until the 12th March 2019.