Simple Strategies to Prevent Infections by Food-borne Pathogens

Kaushik Bharati, PhD

It is estimated that over two million people die annually from unsafe food (WHO, 2015). In India, over 300 disease outbreaks due to food-borne pathogens were reported in 2014 alone (IDSP, Govt. of India). Since October 2013, a surveillance programme is ongoing on a pilot mode in two districts of Tamil Nadu and Gujarat to detect foodborne diseases (NCDC, Govt. of India). 

Food-borne pathogens can cause a number of serious conditions, but the most common are gastrointestinal (GI) complications, including diarrhoea, nausea and vomiting, although other systems may also be involved to varying extents. The incubation period can vary widely, depending on the infecting pathogen and the infection dose.

Common food-borne pathogens

Food-borne pathogens can cause serious infections even in apparently healthy individuals. The most common categories of food-borne pathogens include bacteria, viruses and parasites.

Bacteria are the most common food-borne pathogens and are responsible for the largest number of outbreaks. For example, Salmonella typhi causes Typhoid (also called Enteric Fever) that is characterized by very severe weakness, abdominal pain and headaches. It can spread through infected eggs, poultry and other animal products. Campylobacter jejuni causes abdominal pain, loose motions, diarrhoea, sometimes even bloody stool, which can last up to a week. It is spread by raw milk, undercooked poultry and contaminated drinking water. Enterohaemorrhagic Escherichia coli is a very serious infection that causes haemorrhagic colitis in humans that can lead to Haemolytic Uraemic Syndrome (HUS) which causes high morbidity and mortality. It can be caused by unpasteurized milk, undercooked meat, as well as fruits and vegetables. Listeria monocytogenes infection causes abortions in pregnant women or death of newborn babies. Disease prevalence is low, but when it strikes, Listeriosis is very severe and sometimes fatal, and therefore considered among the most serious food-borne infections. Listeria is found in unpasteurized dairy products and various ready-to-eat foods and can grow even in refrigerators. Vibrio cholerae causes Cholera, and is the most serious water- and food-borne pathogen. Severe abdominal pain, vomiting and profuse rice-watery stool characterize the disease. Cholera causes severe dehydration and kills within hours if not treated immediately. Food-borne diseases are also caused by Clostridium botulinum, Shigella spp., Clostridium difficile Yersinia enterocolitica, Clostridium perfringens, amongst others.

Viruses, such as the Norovirus can be found in seafood like shellfish and oysters. Norovirus infections can cause nausea, profuse vomiting, watery diarrhoea and abdominal pain. Hepatitis A virus can cause chronic hepatitis and is transmitted through contaminated food and water, including ice.

Food-borne parasites include trematodes that infect fishes. Echinococcus spp. can contaminate food through the parasite’s eggs. The parasites that enter the human food chain through water or soil and can also contaminate raw vegetables include Cryptosporidium parvum, Ascaris lumbricoides, Entamoeba histolytica and Giardia lamblia. The single-celled parasite Toxoplasma gondii causes Toxoplasmosis and can spread through raw contaminated meat.  

Moreover, fungi such as yeasts and moulds readily multiply on food such as bread, particularly in hot and humid conditions.

Strategies to tackle food-borne pathogens

Various types of preventive measures need to be taken in order to avoid food poisoning, which can manifest itself in the form of severe GI symptoms. The young, the old and those with a weakened immune system are particularly susceptible. Even healthy adults are not spared.

Personal hygiene: This is a key element in preventing the spread of food-borne pathogens. It is necessary to inculcate the habit of washing hands during food preparation. Hands should be washed before cooking and after handling raw meat, fish and poultry. An apron should be worn at all times in the kitchen. Touching food items and cooking must be avoided during colds, flu or fever. Hair should be kept trimmed and nails clipped properly. Smoking and chewing should be abstained in the kitchen.

Proper cleanliness: Cleanliness must be observed at all times in the kitchen; particularly the food preparation area should be kept clean and hygienic in order to avoid microbial contamination during food preparation. Cooking surfaces should be thoroughly cleaned before food preparation. All the cooking utensils should be washed with soap and water. Separate chopping boards should be kept for vegetables and non-veg items (meat, fish and poultry).  

Washing fruits & vegetables: Before eating fruits or cooking vegetables, they should washed in running tap water. Fruits should preferably be peeled before eating. Additionally, vegetables should be soaked in luke-warm water with some salt and vinegar for a couple of hours, in order to leach out any harmful pesticide residues that may remain on the surface, followed by thorough washing in running tap water to remove any last traces of residues.

Maintenance of correct temperature: Cooking should be done at the correct temperature and also stored at the right temperature, as otherwise there is a chance of contamination my microorganisms. Food can be kept either very cold or very hot – bacteria causing food-borne illnesses thrive at room temperature. As a rule of thumb, hot food should be kept hot and cold food cold.

The temperature of the refrigerator must be maintained at 4°C and the freezer at -15°C to -18°C. This should be checked regularly. Raw meat and poultry can be stored inside the freezer compartment. Meat can be thawed out gradually but completely in the refrigerator compartment itself, separate from other items of food. Marinating can be done in the fridge too. Once served, food should not be kept outside for more than 2 hours.

Food should be cooled rapidly before storing in the fridge. Leftovers can be reheated until steaming hot throughout, but shouldn’t be reheated again.

Precautions for cut fruits & fruit juices: Cut fruits shouldn’t be kept out in the open, and should ideally be consumed as soon as they are cut, to avoid any contamination with microbes. Likewise, fruit juices should also be consumed fresh and not stored for later consumption.

Precautions for bakery & dairy products: Bread and other bakery products like cakes, pastries and confectionery are particularly susceptible to spoilage by moulds. Therefore, care must be taken not to keep these food items exposed to humidity for long. These items should be consumed as soon as they are taken out of their air-tight packets. Since cakes and confectionery contain sugar, these are a rich source of nutrients for bacterial growth. This is another reason why these food items shouldn’t be kept out in the open for long. Care should also be exercised with milk & milk products, as these are susceptible to contamination and spoilage by microorganisms.

What about street food?

The best option is to avoid street food altogether. It is much safer to prepare food at home for consumption. If however you decide to savour street food, you should most definitely avoid golgappas, because there is no guarantee the water will be safe. In all likelihood it will be contaminated. There is always a chance of contracting water-borne diseases like cholera and typhoid in this way. Also avoid fruit juices from street vendors, as these might be kept in the open and served later, increasing chances of contamination.

Special precautions for drinking water

It is very important to keep the body well hydrated in hot and humid weather in order to avoid drop in immunity. Therefore, it is essential to drink plenty of water. Drinking water must be absolutely safe for consumption, since chances of contamination always exists. It should be noted that besides microbes, ground water can be heavily contaminated with chemicals, as these leach easily into the underground water deposits. The best way to ensure safe drinking water is to filter the water, followed by boiling, before drinking.

These simple strategies will help to keep oneself and one’s family safe from food-borne pathogens, and lead a healthy life as well as save undue health expenses.