Giardia intestinalis (also known as G. lamblia or G. duodenalis) is a cyst-producing single-cell parasite that triggers the diarrhoea disease Giardiasis. Divided into eight genetic subtypes (A-H), only type A and B are capable of infecting humans, but other mammals, amphibians, birds and reptiles can also be infected by Giardia intestinalis. Giardiasis is one of the most common food and water-borne diseases. Since 2011, however, the number of infections has been steadily decreasing.
Giardiasis that is caused by Giardia intestinalis is also referred to as classical travel sickness, as it occurs in 55 percent of cases after visits to other countries. The parasite is transmitted fecal-oral through direct contact with fellow human beings, contaminated surfaces or by ingesting food and drinking water. However, an infection can also occur through bathing in bodies of water such as lakes or rivers, or generally poorer hygiene conditions. Transmission by blood, on the other hand, not possible.
The first symptoms appear one to three weeks following infection with the Giardia intestinalis parasite. Mostly infants and rarely adults are affected, whereby males between 30 and 59 years of age predominate. An infection can be asymptomatic, but can also lead to prolonged intestinal symptoms. These include recurrent diarrhoea, flatulence, fatigue, nausea, dehydration or weight loss. There is a risk of infection as long as affected persons excrete pathogens in their stool. As a preventive measure, bed linen, towels and underwear should be washed at a temperature of at least 60 degrees Celsius.
Once excreted from the body, the Giardia intestinalis parasite can survive in the environment for weeks and months.
Special disinfectants with efficacy for parasites are required.