Diagnose Lyme disease from ‘bull’s eye’ rash, doctors told

Doctors should not wait for blood test results to diagnose patients with Lyme disease if they have a “bull’s eye” rash, health officials have said.

Early laboratory tests may not detect the infection and potentially slow diagnosis and the start of treatment, new draft guidance published by the National Institute for Health and Care Excellence (Nice) states.

However, erythema migrans, a red skin rash linked to the disease which can resemble a bull’s eye, is present in around two-thirds of cases.

“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,” Professor Gillian Leng, director of health and social care at Nice, said.

“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.”

Lyme disease is an infection transmitted by infected ticks and a circular rash usually appears between one and four weeks after someone is bitten.

Tests can check for antibodies in the blood, however these may not appear until up to eight weeks after the patient is bitten.

It is hoped the new draft guidance will increase the number of early diagnoses and allow patients to receive treatment immediately, reducing the risk of further symptoms developing.

When there is no rash present and symptoms are unclear, doctors will be advised to carry out blood tests.

Professor Saul Faust, chairman of the guideline committee, said: “Lab tests are necessary when a person’s symptoms are unclear, but they are not needed if a person presents the characteristic red rash, erythema migrans.

“Doctors should feel confident to prescribe antibiotics immediately for those with erythema migrans.”

Veronica Hughes, chief executive of Caudwell LymeCo, a UK charity for patients with Lyme disease, said: “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.”

The draft guidance will be under consultation until March 12.