ICEH Resources Information Sheet

GASTROENTERITIS

Pronunciation: Gas-tro-ent-er-itis

What causes Gastroenteritis?

Gastroenteritis (gastro) is the name given to an illness where there is inflammation of the stomach and intestines caused by infections with parasites, bacteria or virus germs. Gastro is characterised by specific symptoms, namely diarrhoea (runny tummy) and vomiting.

Parasites like Giardia lamblia or Cryptosporidium parvum can cause gastro. The virus germ rotavirus is the most common cause of gastro in children under 5 years. Other viruses that cause gastro are the calicivirus, astroviruses, enteric adenovirus, toroviruses, corona viruses, picobirnaviruses and pestiviruses.

Bacteria germs that cause gastro include Bacillus cereus, Campylobacter jejuni, Clostridium perfringens, Escherichia coli, Salmonella spp., Shigella sonnei, S. boydii, S. flexneri, S. dysenteriae, Staphylococcus aureus, Vibrio cholerae, Vibrio parahaemolyticus and Yersinia enterocolitica.

Germs that cause gastro can be found in soil, water, plants and wild or domestic animals.

What does it look like?

The viruses that cause gastro are too small to be seen with a regular microscope, so too with the parasite C. parvum (0.002-0.004 mm). However, the gastro-causing parasite G. lamblia (usually 0.01-0.02 mm) can be seen using a regular microscope, as can most bacteria (usually 0.02-0.08 mm).

Gastroenteritis in Australia

Where does it occur?

The various germs and parasites that cause gastro are found worldwide. It is estimated that gastro causes between 3-5 million deaths per year worldwide, most of which occur in developing countries.

Gastro outbreaks have occurred in nursing homes, childcare centres, restaurants and hotels.

Australian / Indigenous Significance

Gastro is a significant disease because it can contribute to the death of sensitive patients like young children, the elderly, or people with poor immune systems. The disease is also of concern because outbreak investigations can be expensive as they are often labour intensive and time consuming.

Symptoms: What to look out for?

The most common symptoms of gastro are vomiting and diarrhoea (runny tummy), which may be violent and plentiful. Patients may also have stomach cramps, nausea (feel like vomiting), fever and headache. People should see a doctor if they have diarrhoea and vomiting for more than 24 hours.

Some people may have asymptomatic infections, which is when they are infected with the germs without feeling sick. These people may unknowingly pass on the illness to many people.

How do you diagnose (confirm) a case?

Stool samples (faeces) may be examined to try to find out what germ is causing the gastro.

How does it spread?

Germs that cause gastro may be passed from person to person, as well as in contaminated food and water. Specific ways in which a person may become infected include:

• Kissing or other close personal contact.
• Coming into contact with an infected person's faeces (shit).
• Touching surfaces such as tap handles or items like toys which have been contaminated with germs from infected people who have not washed their hands after going to the toilet etc.
• Eating contaminated food. Food can become contaminated if a person does not wash their hands before handling food, or if safe food handling practices are not followed.
• Drinking contaminated water. Water supplies may contain germs from faecal pollution, or germs like Giardia Lamblia can be present naturally in untreated water sources.
• Inhaling germs released into the air by a sick person vomiting, coughing or sneezing.
• Failing to wash hands after handling pets or other animals.

In most cases it is difficult or impossible to determine how a person became ill.

How does it reproduce?

Virus germs that cause gastro can only reproduce in living cells. The virus invades a cell and makes it produce new viruses, which burst out of the cell, and then infect other cells.

Bacteria germs can reproduce inside humans and animals, or in food, water or soil. Bacteria multiply by dividing in half to form 2 new cells. These cells can then divide again and again.

Gastro-causing parasites multiply in a variety of animals, people, soil, water or plants, and reproduction methods vary from parasite to parasite.

How infectious is it?

Germs that cause gastro are often highly infectious. Care must be taken when coming into contact with a person who is ill, or items they may have had contact with.

How long does it take for symptoms to appear?

Symptoms may start within hours of the germs entering the body. However it usually takes a couple of days to become ill. People often believe their last meal gave them gastro, but this is usually not true.

Who is most at risk?

Gastro is most dangerous to babies, young children, the elderly and people with other illnesses. The symptoms of vomiting and diarrhoea can make people become dehydrated (excessive fluid loss from the body) very rapidly.

How do we prevent it from occurring?

Community education on good personal hygiene practices is the main method for preventing gastro. Emphasis should be placed on the importance of:

• Washing hands to prevent ingestion of germs or contamination of items that may come in contact with the mouth after one of the following activities: going to the toilet, smoking, changing nappies, blowing their nose, gardening, or handling pets; and before handling or eating food .
• Using clean and safe water for drinking and preparing food. Water from untreated sources should be boiled vigorously for 1 minute before use.
• Washing raw fruits and vegetables in safe water prior to use.
• Disposing of human faeces in a sanitary way.
• Preventing the contamination of water supplies with faeces.
• Employing safe food handling and storage practices.
• Cleaning households regularly, especially the bathrooms, toilets and areas where nappies are changed.

How can it be controlled?

Information for Environmental Health Workers

In an outbreak, EHWs work as a team to investigate all potential sources of infection. Team investigations may involve some of the following activities:

• Inspecting the premises where the outbreak is supposed to have occurred. This may involve inspecting kitchen and food storage areas, collecting food samples, taking environmental swabs, checking water sources and reviewing plans and sewage systems of houses. Other investigation activities may involve observing cleaning methods, staff training and food safety programs, and checking for other infection sources like swimming pools or informal eating areas.
• Conducting questionnaires and interviews. This may involve interviewing sick people about their symptoms and recent meals, or giving questionnaires to food handlers at the place that could be the source of the outbreak.
• Sampling of food and water to try to determine the source of the outbreak.
• Giving advice to managers or owners of a business on control measures that can be put in place to try and stop more people from becoming ill.
• Reviewing sampling results and other data to try to work out the cause of the outbreak.
• Monitoring to see if control measures are effective.
• Discussions with all parties involved in the outbreak about how to prevent one happening in the future.

Cleaning Up

People must be careful when handling faeces, vomit, and dirty bedding or clothing of people sick with gastro. Any cuts or skin sores should be covered, gloves worn, and hands washed with warm water and soap when finished.

Bench and floor surfaces, along with items like toys, sheets and eating equipment should be washed first with hot soapy water, and can then be disinfected using methods such as:

1. Heat treatments like hot-water washing machine washes for contaminated sheets and clothes, or soaking dishes in very hot water.
2. Chemical disinfection with solutions that contain 10% formaldehyde (formalin) or 5% ammonia or chlorine (bleach). Chlorine solutions can be made up of adding 1 part bleach to 9 parts water, and should never be used with other cleaning products, especially ones that contain ammonia because it will produce a toxic gas.
3. Metal objects can be wiped over with solutions that contain +70% alcohol (methylated spirits), or placed in sunlight for several hours.

Care must be taken when disposing of contaminated items like nappies to ensure they do not come into contact with potential hosts like dogs, which may scavenge at waste disposal sites. Faeces can be disposed of into modern sewage systems without preliminary disinfection. However, plastic nappies should not be placed in sewage systems. These should be sealed in plastic bags and disposed of with household waste. The paper towels and rags used to clean up vomit should also be sealed in plastic bags before being placed in rubbish bins.

Contaminated mattresses should be washed down with warm soapy water and placed in direct sunlight.

Patient Responsibilities

People with gastro symptoms should see their local doctor to ensure they get proper treatment and advice on how to prevent spreading the disease. Sick people should not prepare or handle food that is to be eaten by other people, or share their towel, face washer, toothbrush or eating equipment.

Workers with gastro should not work with food or in childcare or healthcare settings until at least 2 days after symptoms have stopped. Children with diarrhoea should not attend school, preschool, childcare or playgroups.

Infected people should not swim in pools or swimming holes, and should not share sheets and towels with other people for at least one week after diarrhoea has stopped.

Case Study

Norwalk-like virus outbreak in Canberra (Miller et al, 2002)

During winter 2002 in Canberra, an outbreak of viral gastroenteritis occurred in two aged care facilities and one hospital. The outbreak lasted around a month, and was thought to have been caused by a Norwalk-like virus. The timeline of the outbreak is documented below.

24 June 2002 ACT Health Protection Service (HPS) notified that than an aged care facility (institution A) had 17 residents and 8 staff sick with gastro.
24 June 2002 Sick resident of institution A was moved to another aged care facility (Institution B).
27 June 2002 Sick resident of Institution A was moved to hospital aged care ward (Institution C).
1 July 2002 Patient in Institution C becomes Ill.
3 July 2002 HPS notified of 8 gastro cases in Institution B.

The HPS conducted investigations of the kitchen facilities at both of the aged care facilities. However neither of the kitchens appeared to be the cause of the outbreak. HPS also contacted all other aged care facilities after the first gastro outbreak notification to see if any had high levels of gastro illness amongst residents.

Environmental, epidemiological and microbiological investigation methods were used to investigate the outbreak. Environmental investigations involved examining kitchens and food handling practices, as well as infection control audits of aged care facilities. The hospital had infection control practitioners who were responsible for investigating this facility and liaising with other practitioners.

Epidemiological investigations were completed at each aged care facility. A case was defined as a person who lived or worked in the facilities and had vomiting or diarrhoea after 1 June. A questionnaire was given to sick staff to obtain information on when their illness started, symptoms, foods eaten, and work. Sick staff were also asked to provide stool samples for microbiological investigation. Staff identified ill patients, and senior staff completed their questionnaires. Stool samples were also collected from these patients (where possible).

In the hospital, a case was defined as a patient in an infected ward with vomiting or diarrhoea after the 1 June, or staff in the affected wards with diarrhoea after the 25 June. Infection Control Officers identified ill patients, and recorded their symptoms. Stool samples were collected from patients and those who had already checked out were interviewed by telephone. The wards involved were isolated as soon as the outbreak was identified, and no new patients admitted.

Microbiological investigations involved examining stool samples for parasites (Cryptosporidium, Giardia) and bacteria (Salmonella, Shigella, Campylobacter and Yersinia). Some samples were tested for rotavirus. Samples collected within 24-48 hours of a person becoming ill were tested for Norwalk-like viruses.

It is thought the outbreak was caused by infection control procedures not being followed properly, or by the transfer of ill residents to other facilities. The investigations found infection control procedures at the aged care facilities did not match those recommended in the National Infection Control Guidelines. Problems included:

• No protective gear worn in hose rooms.
• Limited access to spill kits.
• No procedures for cleaning shower chairs.
• Transfer of patients between institutions during an outbreak.
• Incorrect use of protective gear when working with sick residents.
• Sick staff returning to work before they had fully recovered, which was one of the reasons why the outbreak lasted so long in Institutions A and B.

Control measures put in place at the aged care facilities included:

• Wearing protective equipment when working with sick residents.
• Strict policy of hand washing between contact with each resident.
• No new admissions or transfers to other facilities.
• Grouping of sick residents away from healthy residents.

Both Institution A and B were following recommended procedures during follow up visits. The hospital had its own infection control program, which was successfully applied to control the outbreak in the infected wards.

Glossary

Resources

Community Education Flyer to print out
Available at: iceh.uws.edu.au/fact_sheets/gastro_flyer.pdf
[2 page sheet for community information, 151KB PDF file]

Chin, J., 2000, Control of Communicable Disease Manual, 17th edn, American Public Health Association, Washington DC, pp. 215-220.
[Book on infectious diseases that is often referred to in health departments (technical language)]

Gastroenteritis Fact Sheet, 2003. Health Protection Service, Canberra. Available from: www.health.act.gov.au and click on Publications
[Fact sheet on gastro, good for general community]

Gastroenteritis: cleaning up, 2000, Queensland Health, Brisbane. Available from: www.health.qld.gov.au/phs/Documents/cdu/614.pdf
[Fact sheet giving advice on how to prevent gastro spreading, good for community]

Gastroenteritis Fact Sheet, 2000. Public Health Division, Victoria. Available from: www.dhs.vic.gov.au/phd/topics/diseases.htm
[Fact sheet on gastro and how to prevent and control it, good for general community]

Gregory, J. 1999, Guidelines for the investigation of gastrointestinal illness, Public Health Division, Vic. Available from: www.dhs.vic.gov.au/phd/9902113/intro.htm
[Very clear and easy to follow publication on how to investigate gastro outbreaks]

Griffiths, O. & Henderson, H. 1997, Environmental Health for Aboriginal Communities: A Training Manual for Environmental Health Workers, Office of Aboriginal Health, East Perth, pp. 16-28.
[Training manual for Environmental Health Workers in Western Australia]

Hellard et al. 2003, ‘Cost of community gastroenteritis’, Journal of Gastroenterology and Hepatology, Vol 18, pp. 332-328
[Journal article investigating the costs associated with gastro outbreaks in Australia]

Miller et al, 2002, ‘Norwalk-like virus outbreak in Canberra’, Communicable Diseases Intelligence, Vol 26, No 4, pp. 555-561.
[Detailed journal article on how a gastro outbreak in Canberra was investigated]

NHMRC. 1996, Infections control in the health care setting: guidelines for the prevention of transmission of infectious diseases, NHMRC, Canberra.
[Australian guideline on how to prevent the spread of infectious diseases]

Viral Gastroenteritis: information for supervisors in aged care, childcare and hospitality industries, Queensland Health, Brisbane. Available from: www.health.qld.gov.au/phs/Documents/cdu/17493.pdf
[Fact sheet for managers on what to do if an outbreak of viral gastro occurs]

Thielberger, N. & McGregor, W. 1994, Macquarie Aboriginal Words: a dictionary of words from Australian Aboriginal and Torres Strait Islander languages, Macquarie Library Pty Ltd, NSW.

Wilhelmi, I., Roman, E. & Sanchez-Fauquier. 2003, ‘Viruses causing gastroenteritis’, Clinical Microbiology and Infection, Vol 9, No 4, pp. 247-262. Available from: www.health.gov.au/pubhlth/cdi
[ Journal article on gastroenteritis causing viruses and their classification (very technical)]

Created November 2003
by Margaret Davidson