الفهرس 
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Abstract
The actual burden of recreational waterborne diseases is unknown because of underreporting in both developed and developing countries. In countries with good epidemiological surveillance systems, a series of waterborne outbreaks have been reported in communities with adequate established measures of water quality control. Attention paid to health problems regarding recreational water is in a considerable amount attributable to the gastrointestinal disease incidence related with pathogens that are not easy to control-that is, they are difficult to detect and to eliminate from water using conventional procedures, such as viruses, and parasites. In the 1980s Giardia was considered as the most frequently isolated enteric protozoan from populations worldwide and the most common pathogenic parasite in the United States. Otherwise, nowadays, the deepest concern comes from the potential health risks associated with waterborne cryptosporidiosis. Standards for operating, disinfecting, and filtering public swimming and wading pools vary from one country to another. In Alexandria, Egypt, parasitic infections are prevalent among the inhabitants. Those citizens may bathe in swimming pools and in marine waters. Disposal of human faecal wastes into coastal waters has been a common sanitary procedure, in Alexandria, for a long time which provides a source of parasitic pollution, regulation of recreational water is determined by Ministry of Health. The public health risk of sewage discharged into coastal marine waters are derived from human population infections. The sewage contains various micro-organisms that have been shown to be pathogenic and the causative agents of several human diseases. Any illness spread either anally or orally, whose aetiological agents are found in the faecal wastes of animals and man, can theoretically be transmitted through actual contact with polluted seawater, and ingestion of seawater contaminated with pathogens. Unlike treated venues where disinfection can be used to address problems with microbiological quality of the water, contaminated marine can require weeks or months to improve or return to normal. Prompt identification of potential sources of contamination and remedial action is necessary to return bathing water to an appropriate quality for recreational use. The present work was implemented to study the parasitic contamination of recreational water in Alexandria, to compare beaches and swimming pools in relation to parasitic contamination, their counts in contaminated samples, and to correlate some physico-chemical parameters (temperature, pH, total solids and residual chlorine in swimming pools) with the presence of parasites. Accordingly, six pools and six beaches were included in the study from October 2001 through September 2002. Three water samples, each of five liters were seasonally collected from each beach, and each pool. Physico-chemical parameters were measured according to standard methods. For detection of parasites, samples were filtered using membrane filters of pore sizes 1.2?m and 5?m. Filtrate was examined by the direct and modified Ziehl- Neelsen techniques. Results of the study revealed the following : 1. Two swimming pools; Smouha’s club and Scout’s club were contaminated with parasites on more than one occasion. 2. The isolated parasites from the pools were the protozoa, Cryptosporidium parvum, Entamoeba histolytica, and Cyclospora. Toxocara eggs were isolated from Smouha club indicating that animals especially cats have free access to the pool and its surroundings. 3. Three beaches were contaminated namely Anfoushi, Sidibishr and Stanly. All three were found contaminated on more than two sampling occasions. 4. Parasites isolated from beach waters were the protozoa: Cryptosporidium parvum and Giardia lamblia, and the helminthes Ascaris lumbricoides and Toxocara sp. 5. In both Anfoushy and Sidibishr beaches more than two species were detected. (Cryptosporidium sp, Giardia lamblia, Ascaris lumbricoides, Toxocara sp). 6. The mean pH of swimming pool samples, were in the recommended range between 7.2 and 7.8 in autumn and winter. However, it was out of range in spring and summer coinciding with increased bathing activities in those seasons. Thus, violating the Minister of Health regulations. 7. As regards beaches, pH of Anfoushy beach was significantly lower than that of the uncontaminated beaches (7.6 vs 8.0). Other beaches showed no significant difference regarding pH. 8. Temperature differences in both pools and beaches coincided with climatic changes. However, YMCA pool showed a non significant higher temperature recording as it is an indoor pool. Anfoushy beach showed also a higher temperature by one degree centigrade from other beaches. 9. No statistically significant difference could be observed between contaminated and free samples of pools as regards total solids content. However, only in Sidibishr beach samples, the total solids were significantly higher than that of uncontaminated beaches. (48.99 vs. 39.83 g/L). Same was observed in Anfoushy water except that the difference was not statistically significant. 10. Residual chlorine was only estimated for swimming pools. Mean residual chlorine was less than one mg/liter in all studied pools except for Faculty of Agriculture pool. These pools violated the Ministry of Health decrees that stated that residual chlorine in pools should not be less than one mg/L. 11. In Smouha club, residual chlorine was significantly lower than all other uncontaminated pools (0.579vs 0.88 mg/L) indicating the potential hazards of using the pool as it is not disinfected sufficiently to overcome water contamination with microorganisms. 12. Disinfection of swimming pools is not adequate for recreational use. 13. Seasonal variations in water contaminations showed that it was more in autumn and summer in both pools and beaches. However, contamination was present in winter and spring also. 14. Parasite positive water samples were found in the recommended pH of 7.2 to 7.8. 15. No statistically significant association could be detected between level of total solids and presence of parasites in pool samples. However, parasitic contamination of beach samples increased when total solids were high. However, the difference was not statistically significant. 16. Cryptosporidium oocysts were higher with temperature increase in summer. However, the association was not statistically significant. Correlation of counts with temperature was significant. None of the other parameters showed a statistically significant association. 17. In contaminated pools, Cryptosporidium counts ranged between 0.2 and 0.7/L whereas 1 oocyst/L was found in Anfoushy beach. Counts for other ova or cysts were much lower (0.07/L).