Occurrence of Cryptosporidium spp oocysts and Giardia spp cysts in sewage influents and effluents from treatment plants in England

Abstract

Cryptosporidium parvum and Giardia duodenalis can cause severe diarrhoea in infected individuals and their transmissive stages, oocysts and cysts, are voided in large numbers with the faeces of infected hosts. Contaminated sewage effluents are recognised as a potential source of waterborne (oo)cysts. In this investigation methods optimised for the recovery of both from a range of wastewaters were used to determine the occurrence of these organisms in influents, effluents and sludges from seven sewage treatment works in England. The data indicated the presence of small numbers of oocysts both in sewage influent and effluent samples whereas cysts were detected more frequently and at higher concentrations in both influents and effluents. Whilst sludge samples from 1/5 sites contained oocysts, cysts were detected from all five sites. These investigations indicate that discharge of sewage effluents into a watercourse, which may be used for potable water abstraction, can contaminate that watercourse with potentially infectious oocysts. In addition, the application of sludge to land can be responsible for contaminating watercourses with (oo)cysts following run-off or leaching.

Occurrence of Cryptosporidium hominis in pigeons (Columba livia)

“…In mainland Spain a similar prevalence was found by Montemayor et al (2005). In other European countries fewer samples presented oocysts, such as UK (Bukhari et al 1997) with the 63.3% of raw sewage were positive. However, the data on the annual occurrence of Cryptosporidium sp.…”

“…Molecular studies have shown that the majority of human cases are caused by C. hominis and C. parvum (Anonymous 2000, McLauchlin et al 2000. The oocysts of this parasite can be readily found in sludge, raw sewage, sewage effluents, drinking water and recreational waters (Bukhari et al 1997, Fayer et al 2000, Robertson et al 2000, Caccib et al 2003, and may represent a public health risk in developed and developing countries (LeChevalier et al 1991a, b).…”

Giardia Cysts in Wastewater Treatment Plants in Italy

“…1, an increase in Giardia cysts was observed three times during the purification process in the plants. As Giardia does not reproduce outside the host, this was probably due to the fact that the aggregated protozoa desegregated before sedimentation, thus increasing the concentration of free parasites in the sample, as also observed by other authors (6).…”

Persistence, Transmission, and Virulence Characteristics of Aeromonas Strains in a Duckweed Aquaculture-Based Hospital Sewage Water Recycling Plant in Bangladesh

“…The growing interest also seems to be due to the potential cost recovery through the use of duckweed as animal feed (13,35). However, sewage water recycling may constitute a health hazard, since sewage waters are known to be potential reservoirs of pathogenic and/or drug-resistant bacteria and other pathogenic organisms (5,28) that may persist in the sewage treatment system, be recycled through the reuse of treated sewage water, and possibly spread to humans through the food chain (23,40).…”