Mycotoxins in swine: Overlooked driver of vaccination failure

In pigs, exposure to mycotoxins can reduce vaccine efficacy by interfering with the activation of the immune system.

Anawach Phuengkasem

Regional Technical Manager, Southeast Asia PATENT CO DOO. Misicevo, Serbia.
E-mail: [email protected]

As the global demand for pork increases, pig farming has become more intensive.

This means that farmers need to rely heavily on vaccines to control diseases and prevent major financial losses. However, sometimes, even with a perfect vaccination schedule, vaccines do not work as expected.

Understanding why these failures occur is critical for farmers who constantly face threats from swine diseases.

While many factors can affect a vaccine’s effectiveness, those that weaken a pig’s immune system are a major reason why an otherwise good vaccine might fail to protect the animal (Augustyniak y Pomorska-Mól, 2023).

A vaccine can fail for several reasons…

Sometimes, the issue lies with the vaccine itself—such as being stored at the wrong temperature or administered incorrectly. Other times, the problem is related to the pig, including factors like age, genetics, or diet.

However, a particularly serious concern arises when something actively suppresses the pig’s immune system, making it unable to build protection even with a wellformulated vaccine (Augustyniak y Pomorska-Mól, 2023).

One of the most common—and often overlooked—causes of this immune suppression is hidden in the animal’s daily feed: mycotoxins.

THE HIDDEN CHALLENGE: MYCOTOXINS

Mycotoxins are a natural defense mechanism produced by certain types of molds—such as Aspergillus, Fusarium and Penicillium, which are common in agricultural settings.

Mold contamination is a global problem: the Food and Agriculture Organization (FAO) estimates that at least 25 % of the world’s crops are affected each year (Thapa et al., 2021; Bracarense et al., 2011).

These mycotoxins—including aflatoxins (AF), deoxynivalenol (DON), zearalenone (ZEN), fumonisins (FB), and ochratoxin A (OTA)– can develop on crops in the field or during feed storage (Bulgaru et al., 2021).

While consuming a large dose of mycotoxins can make a pig visibly sick, a more frequent and costly problem arises from the ingestion of low levels of these toxins over a prolonged period.

At such levels, mycotoxins weaken the immune system.

This immune impairment reduces pigs’ resistance to disease, slows their growth and productivity, and—most importantly—undermines the very health programs designed to protect them, such as vaccination (Pierron et al., 2016; Oswald et al., 2005).

HOW DO MYCOTOXINS WEAKEN THE IMMUNE SYSTEM?

A healthy immune system is a dynamic network of cells that are constantly working and replicating to protect the body.

⇒This continuous activity makes it particularly vulnerable to toxins that interfere with fundamental cellular functions.

Mycotoxins exploit this vulnerability to disrupt the animal’s natural defenses (Pierron et al., 2016; Oswald et al., 2005).

General mechanisms of immune disruption

Mycotoxins impair the immune system through several interconnected pathways:

Specific consequences for immune function

These mechanisms result in functional impairments across various components of the immune system.

WHEN PROTECTION IS DISRUPTED: THE LINK TO VACCINATION

When a pig’s immune system is weakened, it is no surprise that vaccines cannot perform their role effectively.

The purpose of vaccination is to train a healthy immune system to recognize a pathogen and remember how to fight it.

Mycotoxins interfere with this learning process at every stage (Augustyniak y Pomorska-Mól, 2023).

Why vaccinations may be less effective with mycotoxins

There is a wide array of mycotoxin-induced effects on the immune system can lead to vaccination failure.

Clinical signs of reduced vaccination efficacy

At the farm level, this issue may manifest as multiple production challenges:

STRATEGIES FOR RESTORING BALANCE AND ENHANCING PROTECTION

Protecting the investment in vaccination requires an integrated and proactive approach to mycotoxin risk management.

The goal is to minimize exposure to these toxins while supporting the animal’s natural resilience, thereby creating conditions in which vaccines can achieve their full effectiveness.

In conclusion, the correlation between dietary mycotoxin contamination and vaccination failure is a critical concern for swine production.

Mycotoxins can weaken immunity and compromise the protection normally provided by vaccines.

By recognizing this risk and implementing a comprehensive management strategy, farmers can safeguard animal health and ensure that vaccination programs achieve their intended effectiveness.

References

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