The three California state hospitals for mentally retarded persons have been having a severe problem with amebic and
bacillary dysentery and with other
infectious diseases of the gastrointestinal tract. At Sonoma, the oldest of these hospitals, this problem is known to have existed for many years. Improved medical and nursing staffing and the use of
antibiotics and other effective drugs developed in recent years have greatly lowered morbidity and mortality rates in these institutions. However, in themselves these measures have not been effective in lowering the incidence of
infection. Studies have demonstrated that mass treatment of cottage groups known to have a high incidence of amebic
infection has resulted in control of this disease where such mass treatment was followed by adequate laboratory follow-up, with isolation and
retreatment of treatment failures. Where mass treatment of such groups has been carried out without such laboratory followup, there was a rapid return to the previous high incidence of
infection. Statistics show that these diseases are a serious threat to employees working in these institutions. Increasing attention is being paid to the potential threat to the surrounding communities and the state as a whole from the focus of
infection present in these hospitals.