Protecting you and your employees from zoonotic diseases

While all people are potentially at risk, farmers and managers should take special care to prevent zoonotic diseases among immunocompromised people.

March 26, 2019

4 Min Read

By Neil Benjamin, DVM,  Carthage Veterinary Service LTD
People who work with pigs often overlook zoonotic diseases (diseases that can spread from animals to people) as a work place hazard. That may be because farming in general is a hazardous occupation (according to the U.S. Bureau of Labor Statistics farming and ranching was the eighth most dangerous occupation in 2016) and zoonotic diseases in comparison seem like less of a risk.

The good news is that modern indoor production and disease control have mostly eliminated the risk of some diseases like trichinosis (the reason your grandmother cooked her pork well done), cysticercosis (cysts containing tapeworms) and brucellosis. Nonetheless, the risk of other zoonotic diseases remains present. While all people are potentially at risk, farmers and managers should take special care to prevent zoonotic diseases among immunocompromised people such as the elderly, young children, pregnant women and employees with medical conditions such as HIV/AIDS or cancer that attack the immune system.

On a macro level, influenza or flu is perhaps the most potentially dangerous zoonotic disease to infect swine. This is because flu viruses have segmented genomes, which can reassort to make new viruses, potentially creating a more pathogenic virus in people. The risk of this is happening in any given year is very low but over long periods of time it remains a concern. It is a lot harder to quantify the risks for individuals working with pigs. Infections are quite common in both people and pigs but viruses are typically species-specific. Transmission between species is much less common.

While the 2009 pandemic H1N1 flu was commonly called “swine flu,” that particular virus had genes from people, birds and swine and no one is certain how or where it first arose. The Centers for Disease Control and Prevention recommends that all people working with swine be vaccinated with the annual flu shot. The CDC actually recommends that everyone aged six and over be vaccinated because the normally circulating strains of human influenza are estimated to kill more than 10,000 Americans per year. Additionally workers should avoid coming to work if they have signs of flu: fever, cough, aches, chills and fatigue. Anyone suspected of having flu should seek medical attention.

Another commonly seen potentially zoonotic disease is erysipelas caused by Erysipelothrix rhusiopathiae which occasionally causes diamond-shaped skin lesions in infected swine. This pathogen causes erysipeloid in people and commonly presents as swelling and inflammation on affected body parts. Direct skin-to-skin contact between people and infected pigs can lead to infection, most frequently through a prior wound or break in the skin. Anyone handling infected swine should wear appropriate protection such as disposable gloves.

E. coli, salmonella, campylobacter and other bacterial diseases can cause intestinal discomfort and diarrhea in people occasionally leading to serious dehydration. E. coli 0157 can cause serious symptoms including kidney failure in people but is not normally found in swine. These diseases present a more serious risk to children. Good biosecurity procedures like showering in and out, wearing separate boots and clothing in barns and good handwashing practices prior to eating or smoking can help prevent transmission from pigs to people.

Farmers and veterinarians have eliminated many internal and external parasites on many farms in the United States. Nonetheless, roundworms remain ubiquitous. While human and pig roundworms have traditionally been thought of as species specific, pig round worms have been reported in people and vice versa. Cases of roundworms are rare in the United States but the total number may be underdiagnosed and human doctors may be unaware of contact with swine as a risk factor. Transmission is through ingestion of infected manure so workers should observe good hygiene to prevent transmission.

Ringworm is a fungal disease that can be contagious between animals including pigs. While clinical cases in modern swine barns are uncommonly diagnosed, rodents including mice can be carriers. A good rodent control program including mowing around buildings and baiting can help prevent this disease in both pigs and people.

Many other zoonotic diseases that a pig farmer might encounter are beyond the scope of this article from both pigs as well as wildlife and pests. Raccoon roundworms spread by raccoons and histoplasmosis from exposure to bird droppings are notable examples. Additionally, farmers working with outdoor pigs could potentially be exposed to other diseases. The good news is that the overall risk of contracting these diseases is low for most people with healthy immune systems. Common sense practices that also promote pig health such as good biosecurity and rodent control, wearing gloves and hand washing aid in prevention.  

Source: Neil Benjamin with Carthage Veterinary Service LTD, who is solely responsible for the information provided, and wholly owns the information. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.

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