A variety of micro-organisms that can cause illness have been found in water, these can be introduced into the body by drinking and inhalation, or by exposure to skin or mucous membrane. They include bacteria, protozoa, algae and viruses. This discussion will cover the description, significance, water treatment required for elimination and health significance where applicable.

Campylobacter
Campylobacter are bacteria that require specialised culture media and incubation conditions for isolation in a laboratory. They that can grow over a temperature range of 32 to 45°C and have an optimal temperature for growth at 42°C. They have been isolated from wild birds and poultry and other domestic animals such as pigs, cattle, dogs and cats. Therefore meat, poultry products and unpasteurised milk are important sources if Campylobacter infection. Their occurrence in surface water is dependent on rainfall, water temperature and the presence of water fowl, as well as water contaminated by raw sewage.

Water-borne outbreaks have been reported world-wide. The number of people infected in each episode ranged from a few to thousands. People who drink unchlorinated or inadequately chlorinated water are at risk. Campylobacter species survive well at low temperatures, and can survive for several weeks in cold groundwater or unchlorinated tap water.

The incubation period (time from ingestion to the development of symptoms) is from 1 to 11 days, most usually 3 to 5 days. The diarrhoea produces stools with the bacteria in high levels. This would enable detection by pathology laboratory analysis. The symptoms generally persist for up to a week. Excretion of the organism continues for up to 2 to 3 weeks.

All age groups can be affected but infection is more common in children under five years of age and young adults. Elderly people and those with other medical conditions often develop more severe symptoms. Diarrhoea is the most consistent and prominent manifestation of campylobacteriosis. The faeces is often blood stained. Typical symptoms include fever, nausea, vomiting, abdominal pain, headache, and muscle pain. A majority of cases are mild and do not require hospitalisation and may be self-limited. However, the infection can be severe and life threatening. Death is more common when other diseases (e.g., cancer, liver disease, and immuno-deficiency diseases) are present. Long-term consequences can sometimes result from a Campylobacter infection.

Some people may develop a rare disease that affects the nerves of the body following campylobacteriosis. This disease is called Guillain-Barré syndrome. Although rare, it is the most common cause of acute generalized paralysis in the Western world. It begins several weeks after the diarrheal illness in a small minority of Campylobacter victims. It occurs when a person's immune system makes antibodies against components of Campylobacter and these antibodies attack components of the body's nerve cells because they are chemically similar to bacterial components.

The infective dose of Campylobacter species is considered to be small. Human feeding studies suggest that about 400-500 bacteria may cause illness in some individuals, while in others, greater numbers are required.

Provided the water has low turbidity, standard disinfection procedures are sufficient to prevent the spread of  Campylobacter  in water distribution systems.

The next BioTalk will deal with Legionella.

Source: Australian Drinking Water Guidelines - 6: 1996. National Health and Medical Research Council of Australia & Agriculture and Resource Management Council of Australia and New Zealand.  Foodborne Microorganisms of Public Health Significance. 5th Edition. 1997. AIFST (NSW Branch Food Microbiology Group. And US. FDA Foodborne Pathogenic Microorganisms and Natural Toxins Handbook.