[Helminth prevalence in a waste-water plant at El Rosal, Cundinamarca].

OBJECTIVE Assessing helminth egg prevalence in sludge and raw and treated wastewater from a wastewater treatment system located in the village of El Rosal, Cundinamarca. METHODOLOGY 30 wastewater and 10 sludge samples from the El Rosal plant were taken during a 10-week period. The sludge and water samples were processed according to the Bailinger and the official Mexican standard methodology, respectively. Egg viability was determined by the method described by Victórica & Galván and the Mexican official standard. RESULTS Descriptive statistics were used for analysing data. 100 % of the untreated wastewater samples showed the presence of eggs and at least one viable helminth egg/litre was found in 90 % of them. 90 % of the treated wastewater samples were positive for the presence of eggs, finding that 70 % had at least one viable egg. All raw wastewater samples being dumped directly into the stream were positive for helminths; the same situation was found at the time of the viability test. All sludge samples were positive for helminths, finding that 100 % of these had at least one viable egg. CONCLUSION Using this water for crop irrigation and using the sludge as fertiliser is a potential risk for public health. The sludge can only be used in forestry activities, as long as it does not come into contact with humans.