MAP Vaccination - Should It Be Part of Your Johne’s Program?

Johne’s Disease (JD) is a disease that is a real challenge to control on dairy farms since it is easy for susceptible animals to become exposed to the organism (Mycobacterium avium ssp. paratuberculosis, MAP) that causes JD. Infected cows that are shedding can have extremely large concentrations of organisms in their manure and can quickly contaminate the environment. On occasion, calves may even be born infected, or may be exposed to the organism in colostrum or milk. Once infected, it takes a long time before an animal can be diagnosed as being infected, and the tests that are commonly used are not very good at differentiating between infected and uninfected animals.

Reducing the amount of JD infected animals on a farm primarily involves reducing the exposure of susceptible animals to infectious organisms. This is done by maintaining a clean calving environment, employing effective neonatal calf management practices, and paying strict attention to biosecurity protocols designed to keep young, susceptible animals from being exposed to adult cattle manure. (Of course, these protocols and best management practices will also help reduce the diseases due to other pathogens!)

Vaccination is a management practice that can be considered for use in an on-farm Johne’s Disease control program in Pennsylvania (not all states permit vaccination). However, it is not a ‘cure-all’ or ‘silver bullet’, and it is definitely not a
substitute for good calving management and biosecurity protocols!

The vaccine that is available for use in the United States is a killed product that must be administered to animals before 35 days of age. The effect of the vaccine is quite long-lasting, and elevated serum antibody titres are usually found if blood samples are taken from vaccinated animals - even when they are mature. (For this reason, fecal culturing must be used to detect infected/non-infected animals in vaccinated herds.) It appears that the vaccine, even when properly used, does not significantly reduce the number of new infections that occur (that’s why other management practices are still so important!). Instead it causes a change in the progress/development of the disease in vaccinated animals so that a reduction in the number of cows with clinical JD is observed. The amount of shedding of the MAP organism is also reduced.

Any use of the MAP vaccine in PA must be authorized by the PA Department of Agriculture, and there are a number of regulatory guidelines that apply to its use. For example, specific tattooing and identification requirements exist and vaccination report forms must be submitted within 45 days of calves being vaccinated. Herds must also do a TB (tuberculosis) test on all adult animals before beginning on a MAP vaccination program, and are required to participate in the official PA Johne’s Program while vaccinating.

Vaccination is not for use in uninfected herds and will be most economically beneficial in herds that have a high level of infection and where cases of clinical JD are frequently observed. However, if other management practices to reduce the number of new infections are not put in place concurrently with vaccination it is very unlikely that the vaccine alone will have a significant long-term effect on the infection rate. Herds that are interested in pursuing a Johne’s Disease ‘testnegative’ status will need to stop using the vaccine once the infection rate is reduced.

(It should be noted that there may be a significant risk to people who accidentally get injected or pricked by a needle that has the vaccine in/on it - immediate medical attention should be sought if this happens).

In summary, MAP vaccination is not something that the vast majority of infected herds will need to use in order to control and reduce the level of JD. However, it is a tool that can be considered in highly infected herds that frequently have animals with clinical JD - as long as other management practices are put in place and used to reduce the number of new infections in the herd.

If Johne’s Disease is a concern to you, talk to your herd veterinarian about implementing an effective Johne’s Disease control and management program, and whether or not vaccination is something that you should consider using.

Ernest Hovingh, Dairy Science Extension Veterinarian