June 21, 2017

Continuing the battle against swine diseases: Merck



At World Pork Expo in Iowa, US earlier this month, Dr. Brad Thacker of Merck's  swine technical services shared with eFeedLink how disease control on a global basis is becoming increasingly important as diseases evolve.

"In recent years we have seen the spread of PED into the US, and we also had to deal with small but important changes in circovirus strains such as PCV2d which occurred about four to five years ago. And we have responded to such threats through the surveillance of pathogens beyond our borders, prepare for eventualities should pathogens come in, or even do some things in countries which could be a source of those pathogens," Dr. Thacker highlighted.

He however cited some examples of how disease concerns could be quite different in different world regions. "For example, Brazil is PRRS-free, and the virulence of PRRS strains is different in different world regions."

Merck's recent vaccine developments take into account both the global nature of diseases, and local market differences. One is the recent introduction of a ready-to-use single shot vaccine in Europe that protects piglets against porcine circovirus type 2 (PCV-2) and Mycoplasma hyopneumoniae. The vaccine in Europe is exclusively developed and manufactured at and distributed from MSD Animal Health's Boxmeer site in the Netherlands (Merck Animal Health is known as MSD Animal Health outside the US and Canada). Merck has similar vaccine products for the US market which are developed and manufactured at their Kansas site or other sites for regulatory reasons, according to Dr. Thacker. "For the US market, we have two flexible dose options. One is a single, 2cc dose which it given at three weeks of age or greater; the other is a dual, 1cc dose with the first dose given as early as three days of age. Compared to Europe, there is a tendency for the PRRS situation in the US to be more severe on farms, so there is still a market need for the two-dose option," explained Dr. Thacker.

Another recent vaccine development is introduction of the first injectable vaccine that offers a 20-week duration of immunity for control of ileitis caused by Lawsonia intracellularis. For the European market, the vaccine is produced at the Boxmeer facility, and Merck has licensed a similar product in the US for over a year and a half. While there was initial market scepticism whether the product would work, Dr. Thacker admitted, it has proven to work in the field very well after all. "There was initial scepticism that as a mucosal disease, whether ileitis could be controlled by an injectable vaccine. Previous vaccine products in the market were modified live vaccines administered orally. The initial scepticism was eventually overcome through our vaccination challenge and immunity studies and customer experiences. Regardless of the underlying immune mechanisms, the science of the immune cells and antibodies and all that, at the end of the day, what is most important is whether a vaccine works in the field," stressed Dr. Thacker.

He had some ending advice for disease management on farm. "From a disease standpoint, one thing which might be overlooked as we control disease is that diseases tend to fight back, and what we think works today might not work two to three years from now, so it is important to remain vigilant. We also need to keep reinforcing the message that disease is detrimental to profitability, and that farm staff need to exercise due diligence in their treatment and vaccination protocols, as disease control is a day-to-day battle."