Like Kryptonite hidden from Superman until it was too late, a similar foe hides from dairy producers only to strike when little can be done to stop it.
This dairy assailant is Cryptosporidium parvum (C. parvum), a parasitic protozoan and primary cause of scours. With four other common causes of scours, many producers often skip testing sick calves and try to manage the symptoms.
Multiple research studies have shown that up to 92 percent of calves younger than four months test positive for C. parvum and are shedding the C. parvum organism, with or without clinical signs of disease. It is found in all calf-housing systems and in all regions.
C. parvum is transmitted through ingestion of oocysts, or protozoan eggs. Hutches, water and feed supplies can be carriers of C. parvum oocysts, allowing the disease to spread within herds.
Researchers have tried to find cures for C. parvum, but most treatments only focused on one stage of the disease.
“In the past, researchers focused solely on the oocyst, which is the end infectious stage of protozoans like C. parvum,” says Mark Welter, president of Oragen Technologies Inc. in Des Moines, Iowa. “Oocysts are shed by the animal in their feces. So they tried using oocysts as an antigen to make vaccines, but that didn’t work... C. parvum has many life cycle stages, so focusing on one stage is insufficient.”
It’s not just the calves that are in danger from C. parvum, it is also a threat to humans.
The Centers for Disease Control and Prevention says, "Cryptosporidium has become recognized as one of the most common causes of waterborne disease (recreational water and drinking water) in humans in the United States. The parasite is found in every region of the United States and throughout the world."
“The best defense against this disease is to prevent the oocyst,” says Welter, who has been working on a vaccine for C. parvum for close to 18 years. “That's what gets into watersheds and infects humans. Since bleach and other filtration systems do not work against C. parvum, it has to be controlled at the source.”
A new scientific breakthrough is poised to give producers control of this persistent parasite. Similar to the flu vaccine, Welter has developed and patented a process to generate killed C. parvum proteins in every stage of its life cycle. The killed C. parvum proteins are delivered in a liquid form that can be mixed with milk replacer and fed to calves. It allows the calf an opportunity to produce an immune response without being attacked by the parasite. Then when the parasite is present, the calf will be primed to fight it.
Soon producers will be able to prevent C. parvum induced scours, rather than just react to the symptoms. Preventing the spread of this highly infectious disease will not only help calves stay healthy and strong, but the humans around them too.
Welter has been working in the virology field for nearly 40 years. He developed the first Rotavirus vaccine for swine. To date, he has developed 12 federally licensed vaccines for swine and cattle.