Animal Waste, Water Quality and Human Health

30Animal Waste, Water Quality and Human Healthsymptoms with severe dehydration, malabsorption, weight loss, and possiblymortality.Toxoplasma gondii RANK 3 Toxoplasmosis is caused by the protozoanT. gondii; it is one of the most common parasitic infections worldwide. It is aneconomically important cause of disease in animals and produces a variety ofclinical presentations in humans.T. gondii is an obligate intracellular parasite with felids the only definitive hosts.The life cycle is complex. There are three infectious stages of T. gondii.Tachyzoites, crescent to oval shape, are seen in the active infection andare transmitted through the placenta from mother to fetus, by blood transfusion,or by organ transplantation. Tissue cysts, containing thousands of bradyzoites,are transmitted to persons or animals that eat infected meats or organs. They areassociated with latent infection, and are reactivated in persons who lose theirimmunity. The oocyst stage, excreted only in domestic or wild cat faeces, is themost environmentally hardy form of T. gondii. It is ubiquitous in nature, ishighly resistant to disinfectants and environmental influences, and plays a keyrole in the transmission through the faecal-oral route. Oocysts in environmentalsamples are detected by means of conventional parasite concentration methodsincluding traditional mouse bioassays and by microscopy. PCR, a favouredmolecular technique, has the potential that not only provides the sensitive andspecific detection of T. gondii oocysts in water (Kourenti et al. 2004) but alsoreduces the detection time from weeks to one to two days.Water reservoirs have been implicated as a source of toxoplasmosis outbreaksfor more than two decades. In 1979, the first waterborne outbreak occurred inPanama; 39 soldiers who drank unfiltered, iodine treated water from streamspossibly contaminated by jungle cats became infected. No other identifiablecommon sources of exposure were found (Benenson et al. 1982). In 1995 up to7,718 persons became infected with toxoplasmosis from a municipal watersupply in British Columbia, Canada (Bowie et al. 1997) that used unfiltered andchloraminated surface water. The likely source of contamination was cougarand/or domestic cats faeces (Aramini et al. 1999). In Santa Isabel do Ivai,Brazil, waterborne toxoplasmosis was thought to be responsible for an outbreakinvolving 155 persons served by an underground tank reservoir deliveringunfiltered water contaminated with faeces from cats that lived on top of the site(de Moura et al. 2006). Another outbreak reported in the same year occurred inCoimbatore, India, where 178 cases of toxoplasmosis were linked to a municipalwater supply contaminated by heavy rainfall in catchment areas infested withdomestic and wild cats (Palanisamy et al. 2006). In endemic toxoplasmosis, ahigh Toxoplasma prevalence related to drinking unfiltered water was found inBrazilian communities (Bahia-Oliveira et al. 2003), and in rural Guatemalan