Know your zoonoses

Worldwide, it is estimated that approximately 60 per cent of infectious diseases are zoonotic, meaning they can be transmitted between animals and people. There are a number of different ways zoonoses can be spread between humans and animals, including direct and indirect contact, foodborne, inhalation, and vector borne.

You may be familiar with some of these diseases and methods of transmission already.

• Lyme and West Nile are vector borne by ticks and mosquitos.
• E. coli infections most commonly occur by eating undercooked meat or raw, unwashed vegetables.
• Airborne transmission is common with H1N1 “swine” flu.
• Direct and indirect contact is strongly discouraged if an animal dies of anthrax.

Regional factors

Some zoonoses are specific to certain geographic areas and species. The Canadian climate discourages many of the parasitic and vector borne zoonoses present in subtropical and tropical climates. Some zoonotic diseases have been practically eliminated in both cattle and people (brucellosis, tubercolosis), and others, like variant Creutzfeldt-Jacob disease (vCJD), have never been contracted in Canada. Milk pasteurization has been crucial in reducing the transmission of bovine disease to people.

About 75 per cent of bovine-specific zoonoses have potential wordwilde distribution, although some have been eradicated from certain regions, such as cowpox. Some are quite mild and/or easily treated in humans, such as ringworm or pseudocowpox (milker’s nodules), while others can have up to 100 per cent mortality if not treated early (rabies).

Yes, cows can get rabies. Although Alberta hasn’t had a case of bovine rabies in over 30 years, there have been eight cases in the last five years in Manitoba. Early signs of rabies in cattle can include excessive salivation (frothing), trembling limbs, reluctance to eat, an appearance of choking, bellowing, and aggression.

Stay safe this calving season

As calving season approaches, many producers will be spending increased time in close contact with their cattle, whether that be winter feeding, late night checks, assisting with difficult calving, or treating sick calves. This can increase the risk of being exposed to something that can make you or your family sick.

Scours

While most calf scours are caused by rotavirus or coronavirus (which can be vaccinated against), E. coli, Clostridia, Salmonella, and Campylobacter are bacteria that can be involved, and spread to humans causing varying degrees of gastrointestinal distress. Serious cases in people can result in hospitalization or death.

Cryptosporidium is a protozoan parasite similar to Coccidia that causes calf scours by destroying the inner lining of the intestine, so milk passes through essentially undigested. Often crypto will be mixed with other scour-causing organisms, but it is often unresponsive to standard scour treatments.

People can contract crypto by coming into contact with the feces from infected calves. Most people with healthy immune systems will recover on their own, after about two weeks of vomiting and diarrhea, but about 10 per cent of cases require hospitalization.

Q fever

Q fever has most commonly been association with sheep and goats; however, cattle can contract and carry the disease. Q fever is caused by bacteria that is shed in feces, urine, milk, and birthing fluids/membranes. Generally, Q fever infection won’t cause any identifiable symptoms in cattle, but can cause abortions in sheep and goats.

The bacteria that cause Q fever can become airborne when an animal gives birth, and that’s how people most commonly become infected. Only about 50 per cent of people exposed to Q fever will actually get sick, but if symptoms are going to develop, this happens about 2-3 weeks after exposure. Symptoms are similar to the flu with fever, chills or sweats, fatigue, muscle aches, etc. Women infected during pregnancy may be at risk to miscarry or deliver early. Most people will recover without any antibiotic treatment, but about 5 per cent may develop chronic Q fever. This is a very serious condition that infects one or more heart valves (endocarditis), and is fatal without several months of antibiotic treatment.

Leptospirosis

Leptospirosis is caused by bacteria and can infect cattle at any age. Infected animals usually shed the bacteria in their urine, placental fluids and milk, but it can also be spread through sexual activity. The most common symptom is infertility and/or mid- to late-term abortions, but cattle can be vaccinated.

In humans, Lepto causes fever and flu-like symptoms two to four weeks after exposure, for about a week. A second phase of illness may follow one to two weeks later with jaundice, reduced kidney function, irregular heartbeat, and red eyes as common symptoms. Without treatment, hospitalization is often required to treat complications like kidney failure.

Mitigate your risk of contracting zoonoses

Protect yourself and your family from bovine zoonoses by ensuring sound biosecurity protocols are in place.

• Limit access of young, old, pregnant, and immunocompromised people to sick cattle.
• Wear personal protective equipment (gloves, masks, goggles, waterproof coveralls/apron) as appropriate.
• Isolate sick animals and visit them last.
• Use separate equipment to work with sick versus healthy animals.
• Stay up to date on vaccinations.
• Disinfect and cover any scratches or broken skin thoroughly.
• Wash your hands well and frequently.
• Let your doctor know you work with animals.