Introduction to campylobacter

Campylobacter is a rod- or spiral-shaped bacterium that is considered the most common cause of human gastroenteritis, commonly known as the stomach flu, worldwide. There are 17 species and 6 subspecies within the Campylobacter genus with C. jejuni and C. coli being the most pathogenic species affecting humans. Those affected usually start to experience symptoms about a week after encountering Campylobacter due to its incubation period. During this period, the bacteria attach to the walls of the small intestine via the intestinal mucosa and cause disease by producing toxins and triggering the immune system, which leads to inflammation. The most commonly experienced symptoms can last between 5 to 7 days and include:¹ 

• Diarrhea
• Nausea 
• Headaches
• Fever
• Abdominal cramps 

Although infection with Campylobacter is common (with 1 in 10 people expected to be affected annually), death from this foodborne pathogen is rare. However, certain individuals are more at risk, including the elderly, immunocompromised individuals (such as those affected by AIDS), and young children under the age of 5.² In fact, the most commonly affected demographic by Campylobacter infection is children under the age of 5, with hospitalization frequently occuring, especially in developing countries.³ Reassuringly, there are several strategies that can be implemented to avoid the consumption of Campylobacter and its undesirable effects. 

Campylobacter transmission overview

Campylobacter is a zoonotic disease, meaning it is transmitted to humans through animals or the consumption of animal products. Infection is most commonly associated with the ingestion of undercooked poultry, unpasteurized (raw) milk, and contaminated water.¹ However, most infections can be easily avoided by thoroughly cooking meat, drinking clean water, and avoiding unpasteurized milk. Although less common, pets have also been identified as a significant host of Campylobacter bacteria. In the United States, specifically, 15% of Campylobacter infections can be attributed to contact with domestic animals.⁴ With over 60% of Western families owning a pet, awareness of the associated disease risks and how to prevent them is critical to avoiding infection.⁵

Campylobacter and pets

Domestic animals that commonly carry Campylobacter include dogs, cats, birds, and rabbits. Dogs, especially puppies, are the most likely carriers, with up to 49% harbouring the bacteria. C. jejuni is the species most often found in canines and is easily transmitted to their human owners.⁶ Although zoonotic infection through pets is less common, a recent outbreak of antibiotic-resistant C. jejuni traced to pet store puppies highlights the need for greater awareness of pet-transmitted infections.⁷ Pets usually contract the disease through direct or indirect contact with infected feces, digestion of raw meat or unpasteurized milk, or drinking contaminated water. Certain factors make pets more susceptible to the disease and pets with the following characteristics are more likely to be affected:⁸

• Immature pets with unexposed immune systems
• Pets living in large groups (e.g.  in shelters)
• Animals showing signs of diarrhea
• Pets on a raw meat diet

Some signs to watch for that may indicate your pet has been infected with Campylobacter include: 

• Lethargy
• Loss of appetite
• Abdominal pain 
• Watery diarrhea 

Transmission of campylobacter from pets to humans

Although Campylobacter has been isolated from pets showing signs of infection, it has also been found in many healthy pets. This means that pets can harbor and transmit the disease both asymptomatically and symptomatically.⁹ Therefore, while signs of infection should be monitored, precautions should be taken with all pets to avoid disease transmission, regardless of their health status. 

Campylobacter in pets can be transmitted to humans in various ways. The most common method of transmission is through contact with infected feces, such as when cleaning up after a pet. Infected feces may also leave traces on the pet's fur and in its living area, allowing  Campylobacter to be transmitted in this way. For example, while close and intimate interactions with our furry friends can be tempting, direct contact such as petting, cuddling, and allowing the pet to lick one's face, can increase the risk of disease transmission.¹⁰ Indirect contact, such as handling the bedding and food bowls of infected pets, can also facilitate transmission. Despite the multiple ways the disease can be transmitted, simple precautions can be taken to mitigate the risk of infection without having to forfeit cuddling your pet. 

Avoiding infection with campylobacter

Avoiding your pet obtaining campylobacter

The simplest way to avoid infection with Campylobacter from your pet is to take precautions that can prevent your pet from becoming infected in the first place.  Regular vet visits, health checks, and keeping up with your pet’s vaccinations can significantly reduce the risk of infection. It’s also important to seek veterinary help at the first signs of illness. Additionally, maintaining cleanliness in household areas frequented by your pet can reduce the risk of exposure to Campylobacter from other sources. This includes regularly cleaning litter boxes, picking up after your pet to minimise contact with feces and preventing your pet from interacting with other animals’ feces during walks.  Laundering pet bedding, cleaning general surfaces with pathogen-killing sprays, and regularly bathing your dog can also help prevent initial infection.¹¹

Hygiene practices to avoid pet-human transmission

As previously mentioned, pets can often be long-term asymptomatic carriers of Campylobacter, so general hygiene practices should be followed to avoid transmission, regardless of whether your pet shows signs of the disease. Washing hands, and ensuring children wash their hands after interacting with a pet reduces the risk of spreading the disease through direct contact. Additionally, discouraging pets from licking people’s faces can further prevent the transmission of Campylobacter. Finally, efforts to limit direct exposure to feces and potentially contaminated surfaces can further reduce the risk. Wearing gloves when picking up pet feces and cleaning cages or bedding areas is also highly recommended.¹¹

Additional precautions for at risk individuals  

If you are immunocompromised or have young children and are particularly concerned about infection with Campylobacter, additional precautions can be taken. Since young animals frequently carry the disease, adopting older pets and avoiding pets younger than 12 months old can reduce your risk of exposure.  Additionally, avoiding pets that have lived in highly dense environments, such as pet shops or shelters, further limits the initial risk.⁸ However, do not panic if you already have a pet in one of these categories or if you suspect that your pet has Campylobacter, as a simple fecal test at the vet can confirm the infection. 

Treatment of campylobacteriosis if infected 

Treatment of your pet

Most cases of Campylobacter infection will resolve naturally without the need for in-patient treatment for your pet. It is advised to closely monitor your pet, encourage hydration,  and consult a vet if symptoms worsen. At the vet, the bacteria will be confirmed as  Campylobacter through a fecal test, and antibiotics such as erythromycin or tylosin may be used for treatment in severe cases.⁶

Human treatment 

Most Campylobacter infections will resolve without the need for medical intervention. It is recommended to get plenty of rest, stay hydrated, and resist the temptation to take anti-nausea medication, as the body is trying to expel the infection. If symptoms do not improve and the patient develops a fever or bloody stool, treatment with antibiotics such as azithromycin and fluoroquinolones may be considered.¹

Summary

Infection with Campylobacter is not often severe but is very common and unpleasant, so efforts to avoid infection should be made. Although domestic pets are not the most common transmitters of Campylobacter to humans, they frequently host the bacteria and can transmit the disease regardless of whether they show symptoms. Particularly, young pets such as puppies and kittens often carry Campylobacter due to their numerous interactions with other animals and their unexposed immune systems. Despite the risks associated with pet ownership, the many physical and mental health benefits of having pets far outweigh these risks. The risk of Campylobacter infection from a pet can be significantly reduced through basic hygiene practices, such as hand washing, and by being a responsible pet owner who keeps up with regular veterinary check-ups.