Saskatchewan’s ministry of agriculture is warning livestock producers that weather conditions in some areas of the province may have coaxed anthrax spores up out of the soil.
Anthrax was confirmed Aug. 29 as the cause of sudden death in seven animals in the Rural Municipality of Chester in the province’s southeast. The RM is roughly 100 km south of Melville and 125 km north of Estevan.
Anthrax was also identified Aug. 9 as the cause of death of at least two cattle out of a group found dead in Billings County in southwestern North Dakota, according to ag officials in that state.
Anthrax, caused by the bacteria Bacillus anthracis, survives in spore form for decades in soil and can build up on pastures during periods of change in soil moisture, from flooding and drying.
Spores can concentrate in sloughs and potholes, and risk of animal exposure to anthrax increases in drier years when these areas dry up and become accessible, or when an area sees “excessive” runoff, or when ground is excavated, the province said.
Heavy rain in the affected area of North Dakota may have contributed to the disease’s appearance in that particular pasture, state officials said.
Anthrax spores also require alkaline conditions to survive, so locations that naturally have alkaline soils are at a higher risk, the Beef Cattle Research Council said.
The “perfect storm” for an anthrax outbreak, the BCRC said, is a heavy rain or flooding in spring to bring spores to the surface, then a drought later on which cause cattle to graze close to the ground and pick them up.
“Together these conditions increase anthrax prevalence, but either a drought or a flood is enough to increase the presence of spores, and producers should take precautions during these weather patterns,” the council said on its website.
Livestock are infected when they eat forage contaminated with spores. Ruminants such as bison, cattle, sheep and goats are “highly susceptible” and horses can also be infected, the province said. Affected animals are usually found dead without any apparent signs of illness.
Swine, birds and carnivores are more resistant to infection, but farm dogs and cats should be kept away from carcasses.
Anthrax can be prevented by vaccination, the province noted, and producers in regions that have experienced previous outbreaks are “strongly encouraged” to vaccinate susceptible livestock each year.
A 2006 study in Saskatchewan found the timing of vaccination after the first observed case in an RM — in cattle herds that were not previously vaccinated — affected herd survival rate.
“As can be expected, the sooner that herds were vaccinated, the lower the death loss on farm,” the BCRC said.
Photo: An animal infected with anthrax. Photo courtesy North Dakota Department of Agriculture.