Giardia Lamblia Essay

Giardiasis is a disease of the lower digestive system caused by the parasite Giardia lamblia which is transmitted via a faecal-oral route. The infection is acquired when a person ingests a dormant cyst of the parasite, usually by drinking contaminated water. The disease affects around 200 million people worldwide and is especially prevalent in third world countries, where there are larger populations of people in areas with poorer sanitation and therefore a greater risk of the parasite being passed on from person to person through direct contact. However, the parasite is also zoonotic and may spread between animals and humans. After an incubation period of one to two weeks, symptoms such as severe diarrhoea, abdominal cramping, vomiting and weight loss may arise but some infected people remain asymptomatic and a carrier of the parasite. There are two assemblages of the causative agent Giardia lamblia which infects humans and other animals, except rodents. This parasite has a

Outside of the host, Giardia lamblia is an infectious but dormant cyst, which protects the parasite. This form ensures the parasites survival in harsh and variable environments which are unfavourable for the colonization and replication of the parasite. The cyst exits the host in the excreted faeces and is resistant to harsh temperature and chemicals, as it has a very strong two layered cyst wall composed of sturdy inter-chain carbohydrate (galactosamine) interactions with proteins attached. The wall of the cyst is insoluble which means the Giardia lamblia can survive in water and be transmitted easily to other hosts via a faecal-oral route. Astonishingly, as few as ten cysts are needed to cause giardiasis. This infection of other hosts then leads to more cyst production, release and eventually an increase in the number of potential waterborne parasites in the