Overview

Campylobacter is a commonly found bacterium (germ) in many animals and in nature. It is one of the top 4 causes of diarrhoeal disease and the most common cause of human gastroenteritis in the world.¹ It has been reported to be the cause of about 8.4% of global diarrhoea cases, with the CDC estimating that 1.5 million people in the United States get ill from it every year² and just under 55,000 reported cases in England in 2022.³

A person can have a Campylobacter infection without showing any symptoms. The common signs of infection are diarrhoea, fever, vomiting or needing to vomit, and suffering from stomach cramps. In this article, we will discuss the sources involved in Campylobacter infection and the strategies to prevent or control it.

Importance of identifying contamination sources

Campylobacter is a zoonotic disease, meaning it can be passed from animals to humans. In this case, it is commonly passed on through consuming contaminated meat, dairy products and water. In 2015, the European Food Safety Authority reported that poultry products and meats caused about 60-80% of Campylobacter infection cases worldwide.² The sources of this infectious disease can be classified as primary and secondary, which are given below. 

Primary sources of campylobacter contamination

Eating raw or undercooked poultry meat, drinking untreated water, and poor personal hygiene are responsible for the infection. Contaminated meat or infected animals are common reasons behind Campylobacter cases. Campylobacter can be present in many animals, but it rarely causes them any symptoms or illness. Cross-contamination is one of the reasons for such infections, people have to be careful when preparing food involving raw meats. The factors responsible for the contamination are: 

Poor hygiene

Moreover, healthy chickens can have Campylobacter in their digestive systems, which can lead to the contamination of meat products. Alternatively, poor hygiene levels during slaughter can also cause infection if faeces come in contact with carcasses. Studies have reported that up to 90% of commercially available chicken meat in different regions has been identified to be contaminated by Campylobacter.⁴

Raw chicken handling

Due to high levels of Campylobacter, when handling raw chicken, the risk of cross-contamination is significant in the kitchen whilst preparing food. This can be a concern in kitchens preparing food for many people, such as restaurants. Outbreaks of campylobacter are a public health concern since it is considered a notifiable disease in England.

Raw milk

It is the second most common cause of Campylobacter cases.³ The bacteria are passed on through drinking unpasteurised milk as the pasteurisation process kills them and prevents infection. This applies to any dairy-based foods made with raw milk, such as cheese and ice cream. The milk contamination mainly occurs due to contamination with cow faeces or due to the cow suffering from mastitis (inflammation in the udders). The risk can be reduced again by good hygiene standards both in the cow's environment and during the milking process. 

Contaminated water 

This is the third possible source of Campylobacter infection. The water usually becomes contaminated by animal faeces. Avian faeces are either being passed directly into the water or through water runoff for a lot of the contamination. Water can be treated to kill the bacteria to prevent infection in consumers However, there can be events that occur to the water even after being treated. In such cases, the bacteria could still be present in broken pipes and water disinfection machines that are not functioning correctly.⁵

In addition, farms and agricultural premises must take all necessary precautions to minimise the risk of Campylobacter infection in their products. The methods to prevent contamination related to the above factors are continuously being updated with further research and scientific developments. 

Secondary sources of contamination

The risk of ingesting Campylobacter isn’t just limited to meat and water consumption. It can also be present in fruits and vegetables due to contamination by contact with infected faeces during the processing stages. In studies, the risk levels associated with such cases are much lower than those stated in other sources. It has been shown that the consumption of fruit can be more of a preventative measure against the infection rather than a risk factor.⁹  

Some less common causes of Campylobacter spread include direct transmission either from animal to human or from human to human. Transmission directly from animals can occur both in livestock and pets. This can happen when an animal infected with Campylobacter is handled by a human, and inadvertently ingests the bacteria by failing to follow good hygiene practices. 

With pets, this can happen if they are allowed to either consume directly or contaminate surfaces with bodily excretions that are not handled properly or have been used for food preparation. There is a high chance of Campylobacter infections if pets are fed on a raw diet. This may be due to the presence of bacteria in poultry. 

Campylobacter can also be transmitted via faeces, so another way to minimise the risk of infection is to clear faeces as soon as possible. It would help to reduce the potential risk of contamination via accidental contact with the faeces or intentionally in the cases of dogs that may eat faeces. The potential to reduce environmental contamination through water runoff that come into contact with faeces and transmits the Campylobacter along with it is also addressed by it. 

Pets and livestock, much like poultry, can be infected with Campylobacter without showing any signs or symptoms. This means that any contact with animals that involves a transfer of saliva or other bodily fluids can pose a risk of transmission if good hygiene practices are not followed. Although human-to-human transmission is rarer, it is still possible, especially for people who live nearby, sharing bathrooms and high-touch contact areas. Good hygiene is again vital to minimise the risks involved. 

Prevention and control strategies

Campylobacter infection is possible through so many different routes. While this bacterium can survive outside the body, it cannot replicate outside a host animal. In temperatures around 4 ̊c, it can persist in faeces, urine, saliva and meat. This is why refrigeration of raw meat and unpasteurised milk is important along with other considerable hygiene practices in preparing food.  

As mentioned above, good hygiene practice is an important tool to prevent the spread and minimise the risk factors of Campylobacter. This involves 

• Common cleaning practice: Hands should be washed with soap and water after contact with any potential risks or before contact with a person's mouth, such as eating
• Follow guidelines to handle raw meat: Food should be prepared in a way that raw meat or anything that comes in contact with it should not be used for food, but will remain uncooked as in salads. After contact with raw meat, all kitchen items should be thoroughly washed with a detergent and water. Once prepared, raw meat should be cooked to the correct temperature as this will kill any Campylobacter present, which needs an internal temperature of at least 74̊C
• Consume decontaminated fluids: Only milk that has been pasteurised should be consumed, and water that has been correctly treated from a reliable source. Taking these precautions will greatly reduce the chances of being infected

Research hasn’t yet managed to prove the precise survival time of Campylobacter in the environment. But it can be altered by several different factors, such as oxygen levels, light, temperatures and amounts of nutrients available.⁹ Further studies are required to understand its ability to survive in the environment and minimise the chances of direct contamination or cross-contamination. 

Summary

Campylobacter is an inevitable risk in many areas of life, mainly involving eating and handling raw meats, particularly poultry, and consuming unpasteurised milk or contaminated water. Therefore, taking precautions should be something that everyone has to follow to minimise individual public health risks. It is true for people who are less able to cope with the symptoms, such as the elderly population and people already suffering from conditions that reduce their ability to fight off infections, such as immunocompromised individuals.