Vibriosis is a venereal disease caused by the bacterium Campylobacter fetus. It affects the genital tract in cattle, Goats and Sheep causing infertility and occasional abortions. It is spread by infected bulls when they mate susceptible cows and heifers. It is considered to be the most important cause of infertility in cattle. Good vaccines are available, but it still causes losses simply because they are not used in many herds. Infection introduced into a non-exposed or non-vaccinated herd will spread rapidly during breeding.
Transmission of Vibriosis
Bulls serve as vectors of this disease. They transmit the organism from female to female during mating. Most infected bulls remain carriers for life. Immunity against vibriosis in bulls is not developed easily and they can be infected for a long time without showing any signs of illness. The bulls become infected by serving infected cows or heifers. The organism lives in the tissue surfaces of the penis and prepuce. At breeding the bacteria are passed by the bull into the vagina of the susceptible female.
Infection then develops in her reproductive organs where it may persist for 2 months or more. The initial infection may not interfere with conception but rather cause an early death of the embryo. This infection can prevent the implantation of a fertilised egg, or more commonly results in the loss of the developing embryo in the uterus. Typically, infected cows or heifers return to estrus 40 to 60 days after breeding but often with prolonged and irregular cycles.
Infertility may persist for 2 to 6 months after which an immune response reduces the infection in most females and pregnancy can be established. However, some infected females may not conceive at all, while others may conceive and then abort later. Still other cows remain infected and are able to deliver a normal calf. These silent carriers may infect susceptible bulls at mating in the following breeding season. The organism may be transmitted by Artificial Insemination (AI) of semen collected from infected bulls. Usually, AI centers and private collectors treat the semen with antibiotics before freezing or inseminating to eliminate Campylobacter.
Vibriosis is most commonly introduced to a clean herd by an infected bull. When introduced to a herd, the disease spreads rapidly, as cows and heifers in such herds have no immunity. Conception rates can then drop to around 40%. As immunity develops, the disease rate drops, but reinfection often occurs because immunity normally weakens about a year after the initial infection.
By this time, immunity against the disease has normally developed, and re-mating can result in pregnancy. When the joining period is restricted, there may be insufficient time for re-joining, with females remaining empty. Occasionally the disease results in permanent infertility.
Treatment for Vibriosis
- Vibriosis is best controlled by vaccination, which renders animals highly resistant to infection. Vaccination involves two injections 4–6 weeks apart in the first year and a single dose of vaccine each year. Vaccination should be completed 4 weeks before joining. Vibriosis vaccine is often combined with Leptospirosis in one vaccine. The use of artificial insemination is also valuable in limiting disease spread. Most A.I. organizations test the semen to assure that it is free of vibriosis and trichomoniasis.
- Antibiotic treatment of infected bulls at the time of the second vaccination is recommended because vaccination may not be curative in all cases.
- For infected animals from the third year, bulls are vaccinated annually. In many instances vaccinating and treating only the bulls can break the transmission cycle, with the disease gradually dying out in the herd