Health Stream Literature Summary - Issue 50 - June 2008

First investigations into the prevalence of Cryptosporidium and Giardia spp. in Hungarian drinking water
Plutzer, J., Tako, M.H., Marialigeti, K., Torokne, A. and Karanis, P. (2007) Journal of Water & Health, 5(4); 573-84.

The presence of Cryptosporidium spp. oocysts and Giardia spp. cysts in water is an increasing problem worldwide. Drinking water sources may become contaminated by the introduction of infected faeces from wild and/or farm animals or from sewage flushed into surface waters. There have been a number of outbreaks reported throughout the world due to a combination of chlorine resistance of the dormant parasite and inadequate water treatment. It is unusual to find these parasites in boreholes or deep well water unless fissures are present and allow surface water into the source. In Hungary, 95% of the water supplies originate from groundwater (confined aquifers and karst water) with riverbank filtration (RBF) and surface water treatment plants making up the remaining 5%. This study investigated the public drinking water systems in Hungary to gain information on the distribution of Giardia cysts and Cryptosporidium oocysts and to estimate the efficacy of applied water treatment techniques.

From 2000 to 2005 suspected contaminated drinking water resources were examined on an irregular basis taking into account particular events such as heavy rains or/and dry seasons. Three springs and three karats were examined. In all cases the water is used without treatment or treatment by chlorination or in the case of the one spring, the water is stored in an open pool. There is extensive animal husbandry in the vicinity of the karst wells and 2 springs. Two groundwater wells were sampled several times however as no protozoa were detected in these samples they are not included in this report.

Source water and finished water was tested near all of the 16 treatment plants abstracting surface water from lakes and rivers for drinking in Hungary. Water was tested a minimum of two times during the study period, in different seasons or after rainfalls. Six surface water treatment plants were in contact with effluents from sewage treatment plants located 1 to 40 km away, 3 surface water treatment plants took water from a forested area containing abundant wild animals and 2 surface water treatment plants received source water from agricultural areas.

Samples were also taken from riverbank filtration wells servicing the city of Budapest and its suburbs. There are 700 riverbank filtration wells located 20-100m from the River Danube, mainly on the Island Szentendrei and on the Island Csepel. On the Island Szentendrei, water flows through sand and gravel layers and is directed to the drinking water system after chlorination. On the island Csepel, water is filtered through muddy layers and after treatment is directed to the water distribution system. During 2004-2005, the River Danube in Budapest was investigated once per week at the 1,656 km point along with its riverbank filtered water.

There were 236 water samples (31 raw water, 45 drinking water, 87 river water and 70 post RBF samples) collected and investigated for the presence of Cryptosporidium oocysts and Giardia cysts. Two Giardia cysts/100L were found in one spring, while in another spring 4 Cryptosporidium s oocysts and 3.5 Giardia cysts/100 L were detected once, in this last case drinking water was stored for a long time in an open pool. The raw water of 10 treatment plants was contaminated with both protozoa with Giardia cysts ranging from 0.3-1,030 per 100L and Cryptosporidium oocysts ranging from 5 to 50 per 100L. Higher oocyst densities were associated with source water receiving effluents from sewage treatment plants or originating from a forest environment. The final water of 8 water treatment plants was contaminated with Cryptosporidium oocysts and Giardia cysts varying between 0.1-3 oocysts and 0.2-63.6 cysts/100L.

In approximately 60% of surface river water samples no Cryptosporidium oocysts were detected. In those samples contaminated with oocysts, values ranged between 0-50/100 L. Giardia was detected more frequently with cyst numbers ranging within 0-500/100L in about 90% of the river water samples, with 1% of samples containing more than 1,000 cysts/100L. The highest Giardia levels were found in January to April in both 2004 and 2005 with a second peak in November 2005. The lowest Giardia levels were found in July and August each year. Cryptosporidium levels were found to peak in March and April 2004. No Cryptosporidium oocysts and Giardia cysts could be found in the distribution system of drinking water from riverbank-filtered sources, suggesting the effectiveness of RBF as a purification method. The results found here confirm the need to examine water treatment technologies concerning Giardia and Cryptosporidium inactivation/removal efficacy in Hungary.