Experts say that Clostridium perfringens type A infection is one of the leading causes of diarrhea in neonatal swine today. Still, it remains difficult to reproduce experimentally and it lacks distinct diagnostic lesions.

Although it’s been recognized by the swine industry for more than 15 years, a “piecemeal” system of intervention treatments, sanitation and autogenous vaccines continues to be used for controlling this disease.

C. perfringens type A ranks near the top in causes of diarrhea in swine 1 to 7 days of age. “Our last survey results show that in pigs less than 1 week of age, 35 percent of the pigs tested positive for C. perfringens type A,” reports Karen Post, a veterinary bacteriologist at the Rollins Animal Disease Laboratory in Raleigh, N.C. “That makes it the second highest agent after C. difficle.”

 

Clostridium perfringens type A infection is one of the leading causes of diarrhea in neonatal swine today.

While C. perfringens type A mortality rates are low, high morbidity rates are costly, experts say. “There’s a loss in potential weaning weights in addition to the fallouts -- the two or three pigs in the litter that never catch up,” points out Mark Wagner, DVM,  a swine veterinarian with the Fairmont Veterinary Clinic in Fairmont, Minn.

A moving target
One of the big challenges in effectively controlling C. perfringens type A is its unpredictability.

“For some herds, it can be chronic, while other herds can go for several months without problems before C. perfringens type A expresses itself,” says Wagner, who reports seeing it consistently for the past four years. “It’s very sporadic in nature and the exact triggering agent isn’t always obvious, but we do know it is related to the pig’s environment.”

Another unique characteristic that often overrides acclimatization strategies is that C. perfringens type A infections affect sows of all parity levels.

“It seems to have a seasonality on some affected farms, occurring more often during cold weather,” reports Doug Baird, staff veterinarian, Pork Group, a division of Tyson Fresh Meats. “A few farms have a more chronic problem,” he adds.

Post says that while several companies are in the process of trying to get licensed commercial vaccines, vaccine development is complicated because it is difficult to develop good assays and toxins for C. perfringens type A.

“The disease itself is difficult to reproduce,” points out Glenn Songer, PhD, a professor at the University of Arizona. “Attempts to reproduce type A enteritis in swine have met with minimal success, so we have few host animal studies to guide us,” says Songer, an internationally recognized swine enteric disease expert. “Furthermore, type A is a normal component of gut flora.”

Environment
“One trigger for a C. perfringens type A outbreak seems to be colder weather when farrowing rooms have lower ventilation rates and higher humidity levels,” reports Baird.

 

The environment in the crate is directly linked to outbreaks of C. perfringens type A, so keeping crates clean prefarrowing has a big impact in controlling the disease.

Keeping neonatal piglets warm and dry while receiving adequate colostrum and avoiding unnecessary contact with manure helps reduce C. perfringens type A disease pressure.

“We’ve found that using drying agents to powder the crates prior to and after farrowing helps lower the bacteria counts in the baby piglets’ environment at ground level,” says Wagner. “By keeping them dry we’re able to reduce the chance of chilling.”

Another key factor involves reducing the manure present in the crate during farrowing.

“Keeping the crates clean prefarrowing has a big impact in controlling C. perfringens type A,” points out Baird. “Scraping the back of crates reduces the amount of organisms the newborn pig comes in contact with. The environment in the crate is directly linked to outbreaks.”

“The sow provides inoculum for the pigs,” agrees Songer. “The pigs come in contact with manure and act as an enrichment vessel for the disease.”

Disinfectants, foaming agents and drying time won’t prevent outbreaks of C. perfringens type A, but they do play an important role in reducing them. Researchers and veterinarians recommend a combination of foaming agents to remove dry, caked-on manure followed by Virkon (disinfectant) at two to three times the recommended level for its sporicidal effect.

“Sanitation plays a role in reducing the number of C. perfringens organisms in the environment,” agrees Songer. “But the organisms enter the farrowing room inside the sow, and no amount of washing or sanitation will change that.”

Strategies
Just like the sporadic nature of the disease itself, management strategies come with a variety of options.

In herds experiencing chronic problems with C. perfringens type A, veterinarians often turn to autogenous vaccines. “Our chronic herds use a prefarrow vaccine with a C. perfringens type A isolate eight and four weeks prefarrow, and they get good coverage,” reports Wagner. Baird relies on an autogenous vaccine containing an E. coli series, C. perfringens type A and type C isolates derived from the affected farms.

Another control option is BMD fed at 250 grams per ton to suppress clostridial shedding by the sow, says Post.

In farms with sporadic cases, intervention or self-recovery is often the answer. “When we do address neonatal scours due to type A with an antibiotic, it’s very hit and miss,” acknowledges Wagner. “Sometimes an antibiotic injection helps and sometimes it makes it worse. There’s not a specific antibiotic that works every time.”

 

A clean, dry environment with humidity levels at 50 to70 percent and good zonal heating is necessary from the pig’s first day.

While Wagner recommends manure feedback for neonatal scour issues, Songer doesn’t recommend feedback if C. difficile is a problem. Careful diagnostics are required, he emphasizes.

“Manure feedback given four weeks prefarrow can be very effective in controlling rotavirus and E. coli, which are often found in conjunction with type A,” notes Wagner. “By improving the sow’s immunity to those agents it can help reduce type A symptoms as well.”

“The pig’s environment, from the minute it hits the ground, is key when dealing with C. perfringens type A,” stresses Baird. “A clean, dry crate, humidity rates of 50 to 70 percent and adequate colostrum intake are all critical.”

Education and training of workers also is a necessity. “For more and more farm workers, this is just a job and they don’t want to spend the time needed to keep the crates clean,” says Baird.  “We need a better -- yet simpler -- approach to sanitation.”

Natalie Knudsen is a freelance writer from Mankato, Minn.

Clinical hallmarks of C. perfringens type A

To help in diagnosing C. perfringens type A, here are some of the classical signs:

  • Scours beginning on day 1 to  day 2.
  • Subtle lesions on histopathology
  • Low mortality, high morbidity.
  • Possible co-infection with C. difficile, rotavirus or E. coli.

Managing for C. perfringens type A

Because neonatal scours offer a host of diagnostic possibilities, the first step in successful management of Clostridium perfringens type A is an accurate diagnosis.

“A lot of labs now run PCR genotyping to determine if C. perfringens isolates are pathogenic,” reports Karen Post, a veterinary bacteriologist at the Rollins Animal Disease Laboratory in Raleigh, N.C. These labs include Iowa State University, University of Minnesota, South Dakota State University and the Rollins Animal Disease Laboratory.

The key to treating any disease is knowing what you’re up against. The following guidelines can help with diagnosis and management of Clostridium perfringens type A:

  • Be careful about making assumptions -- C. difficile and C. perfringens type A usually appear together.
  • Seek good diagnostic help to rule out other causes of diarrhea.
  • Intervention strategies include drying powders, electrolytes and antibiotics.
  • Scrape crates prefarrowing.
  • A clean, dry environment with humidity levels at 50 to70 percent and good zonal heating is necessary from the pig’s first day.
  • Disinfection regimes, including foaming and sporicidal agents.