besnoitia antibodies in spain

Foreign diseases are just a plane or trailer ride away. Case in point: Spanish researchers have found subclinical (not causing signs of disease) besnoitiosis, a chronic and debilitating illness caused by a protozoan parasite mostly found in the Americas, in a “surprising” number of randomly screened equids in southern Spain. And while the animals aren’t yet showing signs of disease, scientists believe clinical cases could soon occur in Europe.

“In the near future new clinical cases could be expected to be reported (in Europe),” said Gema Álvarez-García, PhD, of the Animal Health Department in the Complutense University Faculty of Veterinary Sciences, in Madrid. “Surveillance should be implemented, and harmonized diagnostic procedures and standardized techniques are needed in order to get comparable results and infer reliable conclusions.”

Álvarez-García and her fellow researchers tested blood samples from 553 horses, 85 donkeys, and 83 mules across Andalusia, which is home to more equids than any other region in Spain. They tested the animals for antibodies against Besnoitia bennetti, a single-cell protozoan that creates cysts. They also tested for two other cyst-generating protozoan species: Sarcocystis neurona and Neospora hughesi, which are responsible for causing equine protozoal myeloencephalitis (EPM). These protozoa are abundant in North, South, and Central America, but have historically been rare other parts of the world.

They found that 7.1% of the tested equids were positive for the presence of antibodies against Besnoitia. Furthermore, 6.4% of the animals were positive for Neospora antibodies and 2.8% for Sarcocystis antibodies, Álvarez-García said. Although the animals didn’t show clinical signs of disease, the positive results indicate that the animals had been exposed to the pathogens at some point.

“We were surprised concerning the number of seropositive animals detected,” she said. “We reported 51 seropositive animals among 721 animals tested. This result contrasts to other previous epidemiological studies carried out in our country in other ungulate species, such as wild ruminant species, where clinical cases are known to occur, and only two seropositive animals were found among 4,893 animals sampled.”

Certain subspecies of Besnoitia have been affecting cattle and wild ruminants in Europe for years, she said. But those subspecies are not the kind that usually affect horses, donkeys, mules, and zebras.

In the U.S., besnoitiosis is an emerging equine disease that principally affects donkeys. However, it’s important to note that it’s not limited to donkeys, Álvarez-García said.

“The disease has been reported in different equid species, such as donkey, horse, mule, and zebra,” she said. “However, the clinical disease has been more frequently diagnosed in donkeys.”

In their study, they found more positives in the donkey and mule population than in the horse population, she added. But that doesn’t mean these equids are more susceptible to the disease. It could be related to how donkeys and mules are managed compared to horses.

The only known case of besnoitiosis in a European equid occurred in a horse in northern France in 1922. However, scientists suspected the disease in a herd of donkeys in more recent years in southern Spain, Álvarez-García said. Researchers have not yet determined the origin of the protozoa’s presence in Europe, but they have theories.

“There are two feasible explanations,” she said. “Animal trade from areas where the disease is endemic or scattered cases from a ruminant species origin (as whether Besnoitia species infecting ruminants can also infect equids and vice versa remains to be elucidated).”

The percentages revealed in the study underscore a need for scientists and veterinarians to be more aware of the pathogen and its disease risks in Europe, said Álvarez-García.

“As it happened with bovine besnoitiosis in the past, the disease might be underestimated, taking into account that there is a suspicion of the presence of the disease (at least in our country) and that skin lesions associated with this parasitic disease might be confused with other skin diseases,” she said.

“Thus, our recommendation is to carry out surveillance of this parasitic disease by including equine besnoitiosis in the differential diagnosis of skin diseases and conducting serosurveys (blood screenings) at least in those countries where bovine besnoitiosis is present, since it is not known whether this species might infect equids,” Álvarez-García said. “Surveillance might help to detect clinical cases that are needed to isolate and genotype the parasite in order to clarify the numerous epidemiological gaps.”

The study, “A serosurvey of selected cystogenic coccidia in Spanish equids: first detection of anti-Besnoitia spp. specific antibodies in Europe,” was published in BMC Veterinary Research.