The contamination of food and other substances by the salmonella bacteria is proving to be a major issue
The consumption of contaminated food has caused illnesses and deaths of millions of people. It has been recognized that food contamination is a global challenge and that “food contamination that occurs in one place may affect the health of consumers living on the other side of the planet.”
Salmonella bacteria are considered the primary cause of food contamination. The contamination of food by this bacteria has proven to be a serious issue among the masses causing an estimated 93.8 million cases of gastroenteritis. Out of these cases, nearly 80.3 million are food borne (Majowics et al, 2010). Fresh fruit and vegetables have been identified as the primary transmission vehicles of salmonella.
The Salmonella bacteria belongs to the family Enterobacteriaceae. This gram negative bacteria are usually motile with peritrichous flagella and are non-spore forming. They reside in the intestinal tract of animals, humans and are also found in the environment. The genus Salmonella is classified mainly as two species: “Salmonella enterica” and “Salmonella bongori” which also contain subspecies with a collective of 2700 serotypes all which can grow and survive on a large number of foods (Harris et al., 2003). Therefore in order to prevent Salmonella contamination, consumer awareness is a must.
The contamination of food and other substances by the salmonella bacteria is proving to be a major issue because it causes diseases. The salmonella bacteria may enter the food chain and disrupt its ebb and flow. It may enter at any point through crops, farming, livestock feed and food manufacturing, processing and retailing. Fresh produce, though previously thought to be safe for consumption, may be the main source of transmission of the bacteria. Therefore, no one is ever really safe from getting infected by this fast spreading, bacteria.
In order to create awareness among consumers, listed below are a few of the main food products that are commonly known for being vehicles of transmission of the bacteria: Raw and under-cooked eggs, egg products, raw milk or milk products, meat, poultry, tomatoes, lettuce bean and alfalfa sprouts, mixed salads, raw almonds, cantaloupes, fresh fish, farmed and imported frozen shrimp and many more.
These foods get contaminated by the bacteria in a variety of ways. Eggs being the number one transmitter, are contaminated at their conception. If the chicken laying the egg is infected with Salmonella, the bacteria can pass through its faecal matter and into the egg once they sit on the eggs. The process of contamination can be divided into two parts; vertical transmission (primary contamination) which occurs when the salmonella travels to the egg while it is inside the hen and before it forms its shell, and horizontal transmission (secondary contamination) which occurs when the cells migrate to the egg albumen from the outside of the shell after the egg has formed. Egg surface contamination is associated with many serotypes, while the infection is the yolk and the white are associated with S. enterititis.
Meat on the other hand is contaminated by the human touch. Meat is handled by many workers during slaughter and processing and therefore, the meat can be contaminated if the meat is bleeding, during the skinning process, or when the carcass is handled.
Fresh fruit and vegetables are also known to be transmission vehicles since contamination may occur at any of the many steps in the supply processing chain, for example, harvesting, washing, trimming, dehydrating, blending etc. The behaviour of salmonella that ensures its survival, is controlled by various ecological and environmental factors like pH (Optimum pH for growth in Salmonella is approximately neutral, with values> 9.0 and < 4.0 being bactericidal.), chemical composition, storage temperature, chemical composition, moist conditions, presence of natural or added antimicrobial compounds, processing factors such as heat application and physical handling.
Symptoms of diseases caused by Salmonella, more specifically the disease Salmonellosis, can range from minor ones like nausea, vomiting, abdominal cramps, to more extreme signs like blood in stools. Most cases of salmonellosis are mild but there are cases where the symptoms have proved to be life threatening. The severity of the disease depends on host factors as well as the serotype of Salmonella. Presently microbiology tests has advanced to greatly improve the speed at which this pathogen is detected.
Salmonella can be controlled and the contamination can be minimized by taking a few precautionary and preventive steps. Some important control measures according to FAO (2011) are: farm location, layout, equipment and clean water supply, harvesting, on farm post-harvest handling, transport of aquaculture products from farm, employee health and hygiene. Physical approaches, like proper refrigeration, cooking before consumption, irradiation. Chemical approaches are also used like the use of antimicrobial agents like chlorine which is the decontaminating agent most widely used in the seafood industry.
The vital way to ensure food safety is to make the public and all food handlers involved in the supply chain to be aware of the dangers of bacterial contamination and ensure adoption of simple precautions such as use of clean gloves, clean water when handling raw food items, proper storage land proper cooking of the food items.