THE parasite Cystoisospora suis affects suckling pigs, causing severe intestinal problems such as diarrhea, but now, researchers at the University of Veterinary Medicine Vienna (Vetmeduni) in Austria have shown that antibodies against C. suis are passed from the mother to her piglets via colostrum.
Surprisingly, however, the antibodies do not seem to protect the animals very efficiently, an announcement said. The results of the Vetmeduni research are presented in the current issue of the journal Veterinary Parasitology.
Newborn piglets have poorly developed immune systems, although their resistance to disease is generally thought to be extremely important to their survival and growth. Piglets are reliant on antibodies transferred in the colostrum, and for the first few hours after birth, their intestinal walls are fairly permeable, so large proteins such as antibodies can pass into the bloodstream and be transferred to different organs.
One of the most common causes of neonatal diarrhea in piglets is coccidiosis, a severe parasitic disease of the intestinal tract caused by the unicellular organism C. suis. (According to the 2005 Merck Veterinary Manual, the genus Cystoisospora has been proposed for coccidiosis-causing organisms, but the name has not gained wide acceptance.)
Coccidiosis is associated with extensive destruction of the gut mucosa, which leads to less efficient food uptake, causing reduced weight gain and economic losses to farmers. Infection with C. suis results in heavy diarrhea and may cause fatalities if secondary bacterial infections are present, Vetmeduni said.
The issue is being tackled by a junior research group at Vetmeduni's Institute of Parasitology headed by Hanna Worliczek.
Study author Lukas Schwarz and colleagues have determined the levels of antibodies against C. suis that are transferred to piglets in the colostrum and were able to show that sows do, indeed, pass Cystoisospora antibodies on via the colostrum: Maternal immunoglobulins (Ig) A, G and M were all found in the piglets' blood within a few hours of birth.
Although high levels of the so-called IgG antibodies remained throughout the entire four weeks of the study, the other maternal antibodies disappeared within two to three weeks, by which time the piglets were producing their own antibodies, Vetmeduni said.
Adult pigs acquire antibodies against C. suis as a result of natural infections with the parasite that they are usually able to clear without showing any symptoms.
Worliczek said, "It is possible that the sows had been infected a long time ago and so no longer had sufficient levels of antibodies left to protect their piglets against the disease."
The new work suggests that IgA antibodies are involved in the immune response to Cystoisospora infection. Piglets with higher levels of maternal IgA antibodies suffered from less severe diarrhea than piglets with lower IgA concentrations, the announcement said.
The Vetmeduni researchers are optimistic that a better understanding of immune reaction against C. suis will lead to better protective measures.
"The levels of anti-Cystoisospora IgA antibodies might provide a good correlate of protection against neonatal infection with the parasite. Now, we need to find ways to boost sows' IgA levels and see whether they translate to healthier piglets," Worliczek explained.