E coli outbreaks:

What are they and how do they affect us?

by Dr. Sujeewa GUNARATNE

The E coli outbreak reported in May 2011 in Germany, and continued during the month of June resulting in 48 deaths and 4077 cases created havoc among citizens, tourists, health administers and politicians in the country. It spread fear in neighbouring countries as well as far away countries, since trade is globalized and there is high chance for diseases to spread worldwide. The bacteria responsible for the outbreak were identified as E coli O104: H4, a strain of E coli. This article intends to add to your knowledge on E coli and help you take precautions against E coli that cause diseases.

Escherichia coli or E coli are bacteria commonly found in intestines of warm blooded animals and humans. It was first isolated by T. Escherich in 1885 and was named after him. The bacteria are rod shaped and they can live without air, for instance, inside human and animal intestines. A strain of E coli means a sub group of E coli with unique characteristics. Some E coli strains are harmless, while some other E coli strains cause multiple diseases and discomforts to their animal or human hosts.

Harmless E coli

Billions of E coli live in intestines of warm blooded animals and humans. They live in large numbers in human bodies so that one could say their numbers out do the number of cells in a human body. While living in human intestines, they protect or shield the intestines from invading harmful bacteria and fungi. Any living being has to fight for space to live, so by being present in very large numbers, these harmless and friendly E coli out-compete pathogens or the bacteria that cause diseases. Useful E coli also secrete substances that are toxic to invading bacteria and thereby inhibit (adversely affect) the growth of pathogens. Apart from protecting us from disease causing bacteria, E coli help us by secreting the vitamins, vitamin K and B12. Vitamin K involves in our body in blood clotting and bone formation. Vitamin B12 is needed for our healthy blood cells and nerve functions. Another service offered to us by friendly E coli is the formation of lactase, the enzyme that breaks down lactose, the sugar found in milk and dairy products. The presence of friendly E coli in human intestines helps us to counter lactose-tolerance, which means the inability to consume and digest lactose after the first few years of life. This account shows us that harmless and useful E coli are an essential part of human life.

Pathogenic E coli

Pathogenic E coli are just the opposite of friendly and useful E coli. They cause humans a multitude of diseases. Gastrointestinal tract disorders such as diarrhoea and dysentery, Haemolytic Uremic Syndrome (HUS), urinary tract infections, pneumonia and meningitis are some of them. let's discuss the most common diseases caused by pathogenic E coli.

Diarrhoea

Diarrhoea is the most common disorder caused by E coli. Different strains of E coli may cause diarrhoea in humans when they consume unclean drinking water, unhygienically prepared food or food contaminated with pathogenic E coli. The common symptoms are diarrhoea that lasts for many days, abdominal pain and fever. Travellers who may have consumed unhygienically prepared food or unclean drinking water may suffer from Traveller's diarrhoea caused by Enterotoxigenic E coli. This strain of E coli produces toxins once it colonises the surface cells of the small intestine. These toxins cause heavy water loss from the body by means of diarrhoea and loss of iron balance in body fluids. If not treated with antibiotics in time, even death may occur.

Haemolytic Uremic Syndrome

Haemolytic Uremic Syndrome (HUS) is considered the worst disease caused by E coli'. It is caused by the strains E coli O104:H4 and E coli O157:H7. While many previous outbreaks resulting in HUS have been caused by E coli O157: H7, the recent outbreak in Germany was caused by E coli O104: H4. According to the reports, 48 deaths and 4700 cases were reported. The non Germans who were affected, had travelled to Germany at least for a short period. The major symptoms of HUS are bloody watery diarrhoea, red skin patches due to low platelet counts and kidney failure. The bacteria can be transmitted to humans from fresh vegetables, meat, undercooked beef, raw milk, unclean water and other contaminated food. It colonises in the human gastrointestinal tract, producing a deadly toxin that kills the cells lining the tract. If not treated, the bacteria perforate the colon causing blood loss and spread the infection throughout the abdominal cavity. Ultimately blood transfusion and haemodialysis would be required to save the patient's life. Mode of transmission of E coli into humans

E coli is transmitted into human bodies rom various sources and routes. Given below are some of them.

· Drinking un-boiled or contaminated water

· Eating meat and fish products not properly cooked

· Drinking unpasteurized milk

· Eating raw fruits that are not properly washed

· Eating raw vegetables such as salad leaves, cabbage, carrots, green leaves without sufficient washing

· Inadequate cooking of vegetables

How can humans prevent food -borne diseases related to E Coli?

· Wash hands carefully with soap before cooking and eating

· Cook meat and fish products sufficiently

· Avoid slow defrosting of fish or meat in the kitchen

· Drink boiled water, pasteurized milk

· Avoid eating suspicious food (perishable food kept overnight without refrigeration)

· Take extreme care after handling baby or adult diapers, and caring for pets

· Cook green leaves and vegetables well, especially after flood periods

· Wash all fruits, vegetables and leaves under running water. Avoiding re-using water in washing bowls.

Frequency of E coli outbreaks

E coli outbreaks in the world are not uncommon. They occur in the developed world just as much as they occur in the developing countries. The Centres for Disease Control and Prevention, USA has reported more than 10 outbreaks of E coli in the period of 2006 to 2011. Most of them were caused by E coli O157: H7 contaminated from ground beef, fresh spinach, cheese and lettuce. In one outbreak which occurred in May 2010, the contaminant was E coli O145 strain which was linked to Romaine lettuce. The record keeping of diseases in developing countries is not as developed as in developed countries, and some sicknesses may even not be reported. In some other cases, the sickness is reported but the disease causing agent is not identified and recorded.

Nosocomial Infections

Nosocomial infections are infections acquired in the hospital. Though a hospital is meant to be a place providing medication and rest, due to treating many patients with infectious diseases, it is also a reservoir for disease causing bacteria such as E coli. They are known to cause urine infections, post -surgical wound infections and respiratory tract infections.

The public tends to think that it is the duty of the government and health authorities to protect them against diseases and treat when they are sick.

The public duty in preventing outbreaks

Yet, the public too can and must do their part. Given below is what the public must do in times of disease outbreaks.

· Pay more attention to personal hygiene

· Wash hands after being in public places

· Be cautious in eating out

· Report diarrhoea and fever conditions to medical practitioners immediately

· Keep sick children at home or under medical care, avoid sending them to school or day care centres

· Avoid reporting to work places while having diarrhoea or fever

· Separate sick persons from others to avoid spreading of diseases.

The writer is a Consultant Food Technologist and a Visiting Lecturer.