Giardia
Giardia Lamblia
This is a one celled, microscopic parasite that lives in the intestines of people and animals. It is responsible for an illness known as giardiasis. It causes severe stomach cramping, fever, vomiting and diarrhoea that can last from four to six weeks in a healthy person. This is the most common waterborne parasite. Those with weakened immune systems are particularly vulnerable to this cyst.
Consumption of contaminated drinking water is only one of several mechanisms by which transmission (faecaloral) can occur. Recreational waters, including swimming pools, are also emerging as an important source of giardiasis. However, excluding outbreaks, the most likely route of transmission is by direct contact with a human carrier. Transmission of Giardia can also occur by contact with infected animals and occasionally through contaminated food.
Giardia cysts are more resistant than enteric bacteria to chlorine but not as resistant as Cryptosporidium.
Australian Significance
Outbreaks of giardiasis in Australia often involve close communal groups. In day-care centers, for instances, as many as 20% of children may carry Giardia without symptoms (Grimmond et al., 1988). Infection is endemic and is significant among children and adults in the wider community, and sources of this information are difficult to identify.
The most publicised incident of drinking water contamination in Australia occurred in July – September 1998 in Sydney. A concerning level of Cryptosporidium and Giardia was reported for treated water, and boil-water notices were issued for 3 million residents.
Health Considerations
Infection by Giardia may reduce absorption of nutrients and cause diarrhoea. In most cases illness is self-limiting but in some cases chronic infection with intermittent diarrhoea can occur.
BRITA On Tap Filter System removes 99.99% Giardia as certified by the international National Sanitation Foundation (NSF).
