Even after the symptoms have stopped, you may still be able to infect other people, so personal hygiene is most important. The symptoms include fever and raised temperature, loss of appetite, nausea and vomiting, stomach pains or cramps and diarrhoea, sometimes with blood or mucus. As the main cause of spread is by the faecal-oral route, contamination of food by the food handler is the most common cause. It may also be spread directly by handling soiled clothes, bedding or nappies etc and indirectly by hand to mouth contact with infected objects such as door and toilet handles etc. Flies may also carry the cysts on to food from faecal material.
Giardiasis is the most common gastro-enteritis parasite of man in the west.
Although many infections may have been acquired through travel abroad, there is a substantial number of people who have acquired the infection without travel. Giardiasis is caused by the protozoan Giardia Iamblia which infects the small intestine. The parasite is found in contaminated water. Giardiasis is spread by drinking untreated water or eating food that has been contaminated by sewage, or by person to person contact. About two thirds of those infected have no symptoms, however when symptoms do occur, they begin 1-3 days after the parasite has entered the body.