Leptospira bacteria (green), coloured scanning electron micrograph (SEM). This bacterium causes leptospirosis, an infectious disease characterized by fever, vomiting, conjunctivitis and muscular pains. Jaundice and renal failure may occur in the severe form of infection known as Weil's disease. Rodents are the main carriers, also dogs and farm animals. Farmers, sewage workers and vets are susceptible to infection. Treatment is with antibiotic drugs.