Risk Assessment for Giardia in Environmental Samples

Giardia is a gastrointestinal parasite that causes infections in humans worldwide. In developing countries, giardiasis is an emerging infection because it plays an important role in diarrhea outbreaks linked to water and food consumption affecting the population in general. Giardiasis is referred to as zoonosis because its biological etiological agent is transmitted to humans through animal reservoirs by oral-fecal route. Detection and occurrences of Giardia cysts have been documented in water, food, soil, and air. The principal risk factors for developing giardiasis include environmental contamination associated with malnutrition and immunosuppression. The small size of cysts and their environmental resistance together with the small infection dose to produce the disease allow giardia dissemination especially in marginalized populations; however, parasitism is present in all countries and at different economic levels. This zoonotic illness contains several species of Giardia duodenalis, infecting mammals and humans with eight serotypes, of which A and B are of public health importance. Quantitative microbiological risk assessment (QMRA) is a methodology used for predicting health risk to establish regulations for permissible Giardia risk in water and food. This chapter focuses on worldwide reviews of Giardia incidence in environmental samples including giardiasis prevalence, serotypes, risk factors, and finally options for cyst reduction in the environment,emphasizing on QMRA.