Health protection – guidance

Giardia: guidance and data

The symptoms and epidemiology of giardiasis.

Giardia is a parasite which can grow in the intestines of infected humans or animals and cause giardiasis. Diarrhoea is the most common symptom of giardiasis. Other symptoms include abdominal cramps, bloating and flatulence.

More information about giardiasis is available on NHS choices.

Transmission

Giardiasis can be transmitted by direct contact with infected animals or humans, or by consumption of water, food or beverages contaminated by the faeces of infected animals or humans. People may also be infected by swimming in contaminated water (for example in lakes or rivers). Many cases are associated with foreign travel.

The incubation period - the delay between infection and the appearance of symptoms - is 5 to 25 days.

Epidemiology

Giardia lamblia Laboratory reports: all identifications reported to the Health Protection Agency (now Public Health England) in England and Wales from 2000 to 2013.

Year Total
2000 4020
2001 3540
2002 3281
2003 3460
2004 3209
2005 2938
2006 2959
2007 3032
2008 3407
2009 3471
2010 3804
2011 3708
2012 3896
2013 3624

Data source: 2000 to 2013 Labbase2

Giardia lamblia laboratory reports: all identifications reported to the Health Protection Agency England and Wales from 2000 to 2013