Food and water-borne infectious diseases

Food and water are vital to human life. The human body can last for only three to four weeks without food and eight to ten days without water. While water and food are essential to life, we often fail to realize that the food we eat or water we drink may sometimes actually harm us.

Interestingly, food and water-borne infectious diseases are considered to be the most common of all acute illnesses. Despite this, a large percentage of these diseases are not readily recognized since most of the affected people do not seek medical help, especially when the illness is mild.

When food or water becomes contaminated, harmful organisms like viruses, bacteria, fungi or parasites may be found in them. This contamination makes food and water possible vehicles for the transmission of infectious substances. Some of the more commonly known viruses are Hepatitis A and E, noroviruses and rotavirus. Staphylococcus aureus, Clostridium botulinum, and Bacillus cereus may include the common bacteria that may cause acute gastroenteritis. Some types of bacteria can even cause damage to the gut wall and/or lead to systemic infection like Salmonella, Shigella, E. coli, and Helicobacter pylori. Common food and water contaminants also include heavy metals like cadmium, copper, lead, tin and zinc, fish toxins found in some shellfish or fishlike paralytic shellfish, plant toxins, and fungi common in green potato skins, toxic cyanobacteria (blue green algae) or red algae that overgrow in water. All of these may also cause gastrointestinal symptoms that mimick infections.

Symptoms that develop after ingestion of contaminated food or water may vary from one causative agent to another. These symptoms may be similar to symptoms of other common infections like sore throat, cough or colds, systemic viral illness, ringworms, meningitis, septicemia, and others. Such symptoms may include abdominal pain, nausea, retching, vomiting, abdominal cramps, fever, diarrhea, chills, headache, malaise, muscular pains, and even neurologic manifestations.

The severity of the illness and its complications will depend on the individual and the infective agent, and the interaction between the two. The amount of initial dose or “inoculum” of infective agent that one will ingest or will get exposed to also determines the severity of the illness. A very small amount of exposure may not even cause disease. This explains why in a group of individuals exposed to contaminated food, illness may or may not occur. Presentations may range from self- limiting and self- healing disease (such as in some viral and Staphylococcal infections) to those requiring emergency medical care (such as those caused by Salmonella and Campylobacter infections). In worst cases, longer hospitalizations and even death may occur, such as those leading to acute dehydration, metabolic acidosis and subsequent organ failure.

Coming in contact with a person or animal that is infected is one of the easiest way of transmission. This can occur in different ways: person-to-person, animalto-person and mother-to-unborn child. A good example of a person-to-person transmission is when an individual with the bacterium or virus would touch, cough on or kiss someone who is not infected. The person who passes the infectious agent may even have no symptoms of the disease (carrier). An animal-to-person transmission occurs when a person is bitten or scratched by an infected animal – like in the case of rabies.

Drinking, inhaling, or touching contaminated water, including natural salt water, freshwater or water from inadequately treated swimming pools, interactive fountains, hot tubs or spas can transmit pathogens that can cause diarrhea and vomiting. Transmission can also occur through contamination of the ears, eyes, skin, and the respiratory or nervous system. It is important that proper cleaning and maintenance of these facilities be done to avoid this situation.

There are also cases when the diseasecausing organisms are passed through indirect contact. Many infectious agents linger on inanimate objects, such as a tabletops, doorknobs or faucet handles. For example, when one touches a doorknob recently touched by someone who is ill or with the flu or a cold, one may pick up the organisms that caused these infections. Touching your eyes, mouth or nose without washing your hands enables transmission of these infection-causing organisms.

To avoid this, we should select food and water with care and caution. The general rule is that all raw foods are likely contaminated. Raw or undercooked meat, fish, and shellfish can carry various pathogens. In areas where hygiene and sanitation are inadequate, we should be advised to avoid salads, uncooked vegetables, unpasteurized fruit juices, and unpasteurized milk and milk products such as cheese and yogurt. We should eat only food that is fully cooked and served hot, and fruits and vegetables that are adequately washed with clean water and then peeled.

Raw fruits that are eaten unpeeled (such as strawberries) should be avoided. Fruits such as bananas should be eaten after being peeled using washed hands. Always refrigerate perishable cooked food within 2 hours. Cooked food that has been stored should be thoroughly reheated before serving. These recommendations also apply to eggs, which should be thoroughly cooked, whether they are served alone or used in sauces. Consumption of food and beverages obtained from street vendors has been associated with an increased risk of illness.

Tap water of unsafe origin may contain disease- causing contaminants which could be transmitted through droplets or aerosols, cause illness if inadvertently swallowed or inhaled, which can occur during showering or bathing.

We should always wash our hands with soap and water before eating, after using the bathroom or after caring for someone who is ill, and after direct contact with possibly contaminated items like animals or feces. If soap and water are not available, use an alcohol-based hand sanitizer (with ≥60% alcohol), only if hands are not soiled.

St. Luke’s Medical Center provides a complete range of laboratory services for the diagnosis of infectious diseases. Its pool of competent doctors, chemists, and clinicians are complemented with a complete line of facilities to perform bacterial, viral, and microorganisms’ isolation for study and diagnosis. Furthermore, it has instituted an improved safety program that includes stringent medication safety controls, comprehensive infection control system, and all aspects of patient, medication, and environmental safety across all points of contact in the hospital. For more information, please contact the Infection Control Department at 7230101/0301 ext 4730 /4749 (Quezon City) or 7897700 ext 5051 (Global City).

Dr. JOSEPHINE ANNE NAVOA-NG, is the Head of the Infection Control Service of St. Luke’s Medical Center in Quezon City. She is a Diplomate of the Philippine Pediatric Society, the American Board of Pediatrics, and the Pediatric Infectious Disease Society of the Philippines and a Fellow of the Philippine Pediatric Society and the Pediatric Infectious Disease Society of the Philippines. She is also a Certified Infection Control Specialist of the USA Certification Board of Infection Control and Epidemiology, Inc., and was selected as one of the Society of Healthcare and Epidemiology of America International Ambassadors in 2010. She obtained her Doctor of Medicine from the UERMMMC and completed her Pediatric Infectious Disease Fellowship at the Albert Einstein College of Medicine-Montefiore Hospital/ Children’s Hospital at Montefiore, New York, USA and her Residency in Pediatrics at the Long Island College of Medicine Hospital also in New York, USA.