Louping ill in man: a forgotten disease

Area of Science:

• Veterinary Medicine
• Virology
• Epidemiology

Background:

• Louping ill, a tick-borne viral encephalitis, has affected Scottish sheep for centuries.
• Human infections with louping ill virus (LIV) were first documented in 1934.
• The virus is transmitted by the sheep tick, Ixodes ricinus.

Purpose of the Study:

• To describe the clinical syndromes of human louping ill.
• To identify occupational groups at increased risk of LIV infection.
• To report new cases of human louping ill in Scotland.

Main Methods:

• Review of previously reported human louping ill cases.
• Clinical description of four distinct syndromes: influenza-like illness, bi-phase encephalitis, poliomyelitis-like illness, and hemorrhagic fever.
• Case reporting of eight new human infections, detailing their occupations and locations.

Main Results:

• Thirty-one human louping ill cases have been described.
• Infection can be subclinical.
• Eight new cases included crofters, shepherds, a general practitioner, and a butcher, primarily in rural Scotland.

Conclusions:

• Louping ill virus poses a risk to specific occupational groups in Scotland.
• Unexplained encephalitis in individuals with potential exposure should prompt consideration of louping ill.
• Continued surveillance and awareness are crucial for managing human louping ill infections.