Lyme disease.

Lyme disease is among the most frequently diagnosed zoonotic tick-borne diseases worldwide. The number of human cases has been on the increase since the first recognition of its aetiological agent. Lyme disease is caused by spirochete bacteria belonging to the genus Borrelia, with B. burgdorferi sensu stricto (s.s.) found in the Americas, and B. afzelii and B. garinii, in addition to B. burgdorferi s.s., in Europe and Asia. Environmental factors, such as human encroachment onto habitats favourable to ticks and their hosts, reduced deforestation, increased human outdoor activities, and climatic factors favouring a wider distribution of tick vectors, have enhanced the impact of the disease on both humans and animals. Clinical manifestations in humans include, in the early phases, erythema migrans, followed several weeks later by neuro-borreliosis (meningo-radiculitis, meningitis or meningo-encephalitis), Lyme arthritis and/or Borrelia lymphocytoma. In dogs, acute signs include fever, general malaise, lameness, lymph node enlargement and polyarthritis, as well as neuro-borreliosis in the chronic form. Diagnosis is mainly serological in both humans and animals, based on either a two-tier approach (an immunoenzymatic test followed by a Western blot confirmatory test) in humans or C(6) peptide, only in dogs. Early treatment with antibiotics, such as doxycycline or amoxicillin, for three weeks usually reduces the risk of chronic disease. Tick control, including the use of tick repellents for both humans and animals, particularly dogs, is highly reliable in preventing transmission. Vaccines are not available to prevent human infection, whereas several vaccines are available to reduce transmission and the clinical manifestations of infection in dogs.