Long-term study of virus contamination of surface water in the German Democratic Republic.

Between 1 January 1970 and 31 December 1979, a study of the concentration of viruses in surface water was carried out by 4 virological laboratories in different regions of the German Democratic Republic. All these laboratories used the same methods for virus detection.Altogether 1908 samples from 30 sampling points were evaluated. The rate of virus isolation ranged from 8% to 92% with a mean of 20%. There were considerable differences in isolation rate among the sampling points, and the rate for any particular point varied from year to year.The mean value of virus concentration, determined by the most probable number technique, was 2.7 cytopathogenic units (CU) per litre, while the maximum was 22.1 CU/litre. Viruses seen throughout the 10-year investigation included poliovirus, types 1, 2, and 3, echovirus types 6, 11, and 30, and coxsackievirus B 3 and B 5; echovirus 7 and 24, coxsackievirus B 1, and adenovirus 5 were seen occasionally. The results of the study reflected the high level of use of surface waters in the German Democratic Republic.Where water is intended for human use, e.g., as drinking-water or for recreation, reasonable safety measures, such as water treatment and disinfection, should be taken, in order to ensure that the level of viral contamination is within the permissible limits.