Helminth eggs and protozoan cysts were enumerated in raw and treated wastewater in Tunisia in order to determine their removal by wastewater treatment and to provide quantitative data for developing regulations for wastewater quality that are currently lacking. Raw and treated wastewater samples were collected from 17 plants in Tunisia during 2006-2007 and analyzed for parasites using the modified Bailenger method. Two groups of parasites, namely, Ascaris sp., Entamoeba coli, Enterobius vermicularis, and Taenia sp. (group 1) and Entamoeba histolytica/dispar, Giardia sp., and Taenia sp. (group 2) could statistically be distinguished according to their removal by wastewater treatment. Group 1 parasites were removed by 1.1 log(10) (92.4%) and group 2 parasites by 0.61 log(10) (76%). The ubiquitous presence of parasitic protozoa in Tunisian wastewater and ineffective wastewater treatment lead to their proliferation in surface waters with a high probability of exposure of human and animals to these parasites and consequent adverse health effects, as is apparent from epidemiologic data as well. This study provides a quantitative basis for risk assessment studies and development of mitigation strategies, such as improving wastewater treatment efficiency.

The microbial diversity of wastewater used for irrigation and fertilization was assessed using specific polymerase chain reaction (PCR) assays to detect and genotype several pathogenic protists including internal transcribed spacer sequences of E. bieneusi originating from wastewater at the 18 treatment plants showed a similar genetic diversity, regardless of the geographical location. The identification of these parasite species and genotypes and of host-specific Eimeria species indicates that the microbial quality of wastewater was impacted by humans, livestock and rodents. Given the public health risks that some of these parasites represent, guidelines on wastewater usage are needed to minimize human exposure to these pathogens.

The present study aimed to: (i) identify helminth eggs and protozoan cysts in wastewater samples to which both human and animals could be exposed when they are reused in agriculture; and (ii) evaluate the efficiency of their removal by two wastewater treatment systems (activated sludge and lagoon). For these purposes, 234 wastewater samples (117 raw, 117 treated) were collected from 20 wastewater treatment plants (WWTPs) in Tunisia over a one-year sampling period. Parasitic load was enumerated by the modified Bailenger method. The results showed that helminth eggs found were Nematodes mainly represented by Ascaris sp. (95%), Hookworm species (50%), and Enterobius vermicularis (45%). For Cestodes, species identified were Taeniid eggs (85%), Hymenolepis nana (70%), Hymenolepis diminuta (55%) and digestive Strongyles. Among protozoa, Giardia sp., Entamoeba histolytica/dispar/moshkovskii and Entamoeba coli cysts were found in 100% of raw wastewater samples. The overall removal efficiency of helminth eggs and protozoan cysts in the treatment plants ranged from 56.5 to 100% and from 50.4 to 95.5%, respectively. The result from Multiple Correspondence Analysis (MCA) shows that the close clustering of the parasitic mean removal levels indicates that there is little difference in wastewater treatment processes between the WWTPs examined.

Limited access to safe water enhances poverty, hunger and diseases. This study evaluated the drinking water quality stored in home-based systems, located in rural areas of Tunisia. Water management was also documented as an improvement of good practice as most of the water contamination could be related to behavioral patterns. Thirty-nine water samples from five different sources (rainwater, truck cistern, mix, etc.) were screened for enteric parasitic contamination with the modified Bailenger technique. This technique allowed the detection of three protozoa: Giardia spp.; Entamoeba histolytica/dispar/moshkovskii; Entamoeba coli and one helminth specie: Ascaris spp. The overall prevalence of these intestinal parasites was approximately 97% with a relatively high frequency of protozoa over helminths and more specifically E. histolytica/dispar/moshkovskii. This incidence could be correlated to the lack of hygiene practices, sanitation and education. This situation requires the need for frequent monitoring of the water quality and management in these areas.