What possessed me to choose such an unsavory organism? It started off as a joke-I’m presenting on Valentine’s Day so I’ll choose an STD. Then, it became a future professional question-what will my future clients come in with? I knew very little about animal STDs and thought it would be interesting to explore this.
Treponema cuniculi is very close to the same syphilis that affects humans, T. pallidum. T. cuniculi is not zoonotic to humans but T. pallidum can infect rabbits with similar symptoms. Both are spirochetes, spiral-shaped bacteria, that stain Gram-negative. Although they are not Gram positive, they are still treatable with forms of penicillin, due to differences in their cell walls as compared to other Gram negative microbes. Symptoms include lesions around the face and genital area that develop within 3-6 weeks of exposure. Even with treatment, it may take 2-3 months for the immune system to fully respond. If untreated, the rabbits may remain carriers after symptoms have cleared. Also, extensive prolonged infection may result in sterility.
T. cuniculi is spread in two ways: sexual contact and passing from mother to offspring. Breeders often utilize buck exchange with other breeders to maintain genetic diversity. However, they may also be spreading this rabbit syphilis, also known as vent disease or venereal spirochetosis.
To confirm the presence of this disease, there are several options for today’s veterinarian. There are antigen “card” tests that contain all the reagents necessary to run the test. Another option is to send off about 0.25 mL of serum to any number of diagnostic labs that will perform an ELISA assay to determine the presence of the spirochete. Also, the microbes can be sampled from the skin or lymph nodes, and visualized with dark-field microscopy or a silver stain.
Apparently, researchers were exploring the possibility of using T. cuniculi to evoke an immune response that would be effective in vaccinating against T. pallidum in humans. They actually found a volunteer that allowed them to inject him with live T. cuniculi in one arm and a killed strain in the other arm as a control. The volunteer developed small patches of erythema, the killed strain taking about five days to clear, while the live strain took 24 days to clear. Due to the slow immune response of the volunteer, the researchers did not think a vaccination was a viable option at this time. No discussion of the strength or weakness of the volunteer’s individual system was discussed.
Microorganisms are everywhere and while some are a benefit, others are more of a parasite. A lot of research is targeted towards those microbes that harm humans. However, I think it is important to also fight those afflicting other animals, as their decline may affect our food supplies and on a bigger scale, our economic system.
References:
Baker D. Natural Pathogens of Laboratory Mice, Rats, and Rabbits and Their Effects on Research. Clinical Microbiology Reviews; 1998, 11(2):231-266.
Graves S, Downes J. Experimental Infection of man with rabbit-virulent Treponema paraluis-cuniculi. British Journal of Venereal Diseases; 1981, 57(1):7-10.
Harkness J. The Biology and Medicine of Rabbits and Rodents. Philadelphia: Lea & Febiger; 1977, p 115.
Merck Veterinary Manual-online edition. Treponematosis. Available via the internet:
(http://www.merckvetmanual.com).Stahl R. Rabbit Vent Disease (Syphilis) or Hutch Burn? Available via the internet:
(http://islandgems.net).
*Disclaimer - This report was written by a student participaring in a microbiology course at the Missouri University of Science and Technology. The accuracy of the contents of this report is not guaranteed and it is recommended that you seek additional sources of information to verify the contents.
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