Borrelia

• Longer, wider, helical spirochaetes with a linear chromosome and linear and circular plasmids
• Obligate parasites transmitted by arthropod vectors
• Cause systemic infections in many animals and humans
• Slow growth in specialised culture media

Borrelia burgdorferi

Avian spirochaetosis

• Caused by Borrelia anserina
• Acute, endemic disease of birds in tropical and subtropical regions
• Chickens, turkeys, pheasants, ducks and geese susceptible
• Transmitted by soft ticks of the Argas family, but also via contact with infected material such as blood and tissues
• Transmitted transovarially and trans-stadially via the tick population
• Outbreaks during peak tick activity during warm, humid conditions
• Fever, anaemia and wight loss occurs, with development of paralysis later
• Immunity is serotype specific
• Diagnosis using dark-field microscopy of buffy coat smears or immunodluorescence of blood or tissues
• Giemsa-stained smears and silver impregnation of tissues
• Isolation of borreliae by inoculation of embryonated eggs or chicks
• Antibiotic treatment
• Inactivated vaccines available