Giardiasis is caused by Giardia intestinalis, a protozoal parasite in the family Hexamitidae. This organism is also called Giardia lamblia, Lamblia intestinalis and Giardia duodenalis. The creatures isolated from humans, domestic animals and most wild animals look to be alike conversely, it is probable that G.lambia is really a composite of numerous various species or subspecies. Humans are believed to be the key reservoir of infection. Interspecies communication of G.intestinalis has been established, and zoonotic transmission is believed to happen. But, the importance of animal reservoirs for human disease is debatable. Other species of Giardia are established in rodents, birds, reptiles and amphibians. These entities are not known to be zoonotic importance. Giardia muris is observed in rats, birds and reptiles. Giardia agilis happens in amphibians.
Two stages of the parasite are
1) cysts 2)trophozoites
Giardiasis is communicated by cysts through the feco-oral path. The cysts can be spread openly among hosts or on fomites comprising polluted water and sometimes food. Ingested cysts discharge one or two trophozoites in the enteric route (small intestines), where multiplication of trophozoites occurs. Several of the multiplying trophozoites are approved toward the colon, and cyst formation alongside the way. The cysts are infectious when they are emitted in the feces or in a moment afterward. Presence of Trophozoites may also be seen in the feces mainly in diarrhea. Cysts can live for extensive interval in the atmosphere under moist conditions and remain sustainable for many months in cold water. They have been revealed to persist in water at 8°C for 60 days and 30 days at 20.9°C. Some cysts has ability to survive at –13°C for 14 days. Cysts of Giardia are liable to dryness and straight sunlight.

G. intestinalis cysts and trophozoites are liable to 0.5-1.5% sodium hypochlorite, 1.5-2.5% glutaraldehyde or quaternary ammonium used as disinfectants. They can also be destroyed by boiling for at least 60 seconds.
Clinical signs
Numerous infections of human are asymptomatic, but particular people progress severe digestive signs. The common arrangement is a rapid beginning of diarrhea with bad smelling stools. Greasy appearance feces or stool are commonly observed, but blood is infrequently perceived. The diarrhea can be characterized by abdominal spasms, inflating, gassiness, nausea and exhaustion. Losses in weight or dehydration can also see. Vomiting and fever are not common. The infection frequently lasts for 7-14 days, but then chronic infections of months to years have been documented. Chronic infections can be realized in both immune poor and immune competent persons and are categorized by periodic symptoms that may lead to malabsorption syndromes, shortages of vitamin, weight loss and debilitation. Urticaria has also been seen in this problem. In adding, around 21-41% of patients develop disaccharide intolerance, mainly lactose intolerance during the contamination and up to 180 days later.
Diagnostic Tests
Giardiasis is diagnosed by direct surveillance of the trophozoites or cysts in the faecal sample. Frequent sample may be required in cases with little planes of creatures or irregular shedding. The flagellated trophozoite with “eye drop” structure, having two nuclei at the anterior end and falling motility. The cyst is approximately 13 μm long and ovoid having two to four nuclei. Immuno fluorescence technique is also be used to see the creature, ELISA can identify antigens of giardia. Serological procedures have been utilized in epidemiologic inquiries and PCR may be presented good result in the diagnosis purpose. In case of research culture method is only used.
Many drugs are used for treatment purpose comprising metronidazole, tinidazole and ornidazole. Asymptomatic carriers may not essential cure. Chronic problems can be resistant to cure, and protracted cure with mixture of drugs may be essential. The reappearance of signs may be due either to resistant infections, reinfection or post-giardia lactose intolerance.
To avoid this problem, unprocessed water from ponds, canals, springs or bores should not be offered. In regions where the supply of water may not be harmless, untreated intake of water or ice should not be offered for drinking purpose. Methods that can be used to treat potentially contaminated water include boil the water for at least one minute, water filtration by using a filter having an complete hole size of minimum 1 micron. Washing of vegetables or fruits in clean water before eating. Adopt good hygienic measures including hand washing, cleanliness of water, vegetables and fruits can help in stop infection. People suffering from this problem should not bath in entertaining water for at least 14 days even the signs end.

This article is collectively authored by Dr. Muhammad Mohsin*,Aqeel Nawab, Dr. Rao Zahid Abbas Dr. Muhammad Tahir Aleem and Dr.Asghar Abbas. Department of Parasitology, University of Agriculture, Faisalabad.