Vaccination systems: Today's reality check
Evolution from single-site, all-in/all-out to multi-source systems has changed the way vaccination performs in today's high-throughput systems. Although commercial vaccines against production-limiting diseases almost always merit consideration, an effective program is seldom one-size-fits-all, hands-free or simple. Two cases in point demonstrate where effective vaccine products can suffer under weak systems: mycoplasmal pneumonia and erysipelas.
Mycoplasma hyopneumoniae
The move to multi-site production and severity of M. hyo-related respiratory disease brought vaccination against Mycoplasma into favor in the late '90s. But in some cases it hasn't lived up to expectations. Why?
Attempting to vaccinate piglets too young, particularly when they're coming off vaccinated sows, permits maternal antibodies to interfere with the vaccine response.
Combined infection with other organisms involved in the Porcine Respiratory Disease Complex can overwhelm the immune system, even when an M. hyo vaccine is given correctly and on time.
Vaccination programs consisting of both single and two-dose protocols have made the choice and timing more complicated.
Continuous antibiotic feeding can prevent pigs from developing an immune response by natural exposure — leaving pigs susceptible to re-exposure unless actively immunized.
Erysipelas
An increase in erysipelas outbreaks in 2001 and 2002 reminded the industry that it still recurs cyclically. Some suggested reasons:
Although investigators continue to look for antigenic drift that might account for the outbreaks, it's now believed the more likely scenario is that a broad number of mild strains exist alongside the more pathogenic Erysipelothrix. Those benign strains likely tend to help maintain herd immunity and thus suppress outbreaks until immunity weakens.
Some researchers have suggested concurrent PRRS infection may have an affect on erysipelas vaccines; however, the question is far from settled.
Evolution of management in the industry has led many to drop routine erysipelas vaccination. Combine that oversight with conventional vaccines that don't offer sufficient duration of protection, and outbreaks may increase.
Another viewpoint behind perceived vaccination failures, notes Iowa State veterinary diagnostician Kent Schwartz, is that it may reflect the higher expectations today's producer holds for vaccines. “Is 12 of 1200 sows with skin lesions disease a vaccine failure or vaccine success?” he asks.
More info
Walter D.; et. al. The effect of a metaphylactic pulse dosing in-feed antimicrobial strategy on finishing pig health and performance. Swine Health Prod 2000 8(2):65-71.
Thacker E.L.; Thacker B.J. Vaccination as a means of controlling Mycoplasma hyopneumoniae. Proc Leman Swine Conf 2000: 84-86.
Clark L.K. Mycoplasmal pneumonia control strategies. Proc Leman Swine Conf 2000:112-118.
Hoffman L.J.; Opriessnig T. Erysipelas — new serotypes or same old stuff? Proc Iowa St Swi Dis Conf 2002:111-116.
Schwartz K.J. Erysipelas: an old disease returns to the swine industry or something new? Proc AASV 2002:419-424.