We’ve all heard of bird flu but is there such as thing as bird Lyme disease? If you keep turkeys, chickens, pheasants, ducks, geese, or birds in/from the tropical or subtropical regions then you may have encountered avian spirochaetosis, a disease caused by a species of Borrelia bacteria, the same bacterial species responsible for Lyme disease.
Borrelia burgdorferi is the species of bacteria that causes Lyme disease in humans, dogs, cats, horses and other mammals. Borrelia anserina is a different species of Borrelia that is also spirochaetal, meaning that bacteria are long and slender but tightly coiled like springs. There are only six genera of spirochaetes but many of these are of vast importance for our health and the health of other animals.
Syphilis and Lyme disease are both caused by spirochaetal bacteria but the genus isn’t all bad as some species are necessary for cows and other ruminants to digest cellulose from the grass they eat.
Transmission of Avian Spirochaetosis
While Borrelia burgdorferi is transmitted via the bite of the Ixodes ticks, Borrelia anserina is spread by the Argas family of ticks (fowl ticks). The bacteria can be passed on from ticks to their offspring and can survive in a tick throughout all life-stages (trans-stadial transmission). Borrelia anserina can survive for up to two months in the droppings of birds and can be passed on directly through cannibalism if birds eat the dead carcasses of other birds or if the same needles and syringes are used to administer drugs to multiple birds.
The bacteria is vulnerable to disinfectants, however, and is less common in broiler birds than in populations of birds kept for egg production. The disease is most common at peak tick time, when conditions are warm and humid. Exotic birds are more susceptible to the avian spirochaetosis than native birds.
Symptoms of avian spirochaetosis include:
- Depressive behaviour, malaise, huddling and inactivity
- Anorexia (loss of appetite and subsequent noticeable weight loss)
- Cyanotic wattles
- Greasy, green diarrhoea
- Paresis and paralysis
Diagnosing Avian Spirochaetosis
Birds that recover from the illness may experience temporary paralysis and be emaciated and weak. Those kept for egg production usually have a vastly decreased output, making the birds considerably less viable commercially. Poultry and egg companies may decide to kill symptomatic birds and examine them for internal signs of the disease such as an enlarged and mottled spleen and liver. Some birds also have pale, swollen kidneys and have experienced hemorrhaging.
Tick bites or the presence of ticks are suggestive of spirochaetosis as the cause of the birds’ illness but clear diagnosis occurs only through the examination of blood and tissue samples under dark-field microscopy or silver impregnation. If a facility appears to have a problem with B. anserina then antibiotics including the tetracyclines, penicillin, streptomycin, chloramphenicol and tylosin are effective treatments. Chickens and other birds may be vaccinated but tick prevention is usually the most advantageous course of action using ectoparasiticides.
B. anserinas – A Possible Lyme Co-infection?
There have been no documented cases of human infection with B. anserina and the ticks responsible for spreading avian spirochaetosis are not thought to bite humans so this is not a likely co-infection with Lyme disease, despite sharing some symptoms and methods of transmission. However, it may be that studying B. anserina and avian spirochaetosis offers some clues regarding effective vaccination against Lyme disease.