how many medical treatments are tested by a phase iii study to evaluate the safety and efficacy of ganciclovir (dihydroxypropoxymethyl guanine [dhpg]) treatment of symptomatic central nervous system (cns) congenital cytomegalovirus (cmv) infections.?
(COUNT (AND medicine.medical_treatment (JOIN (R medicine.medical_trial.treatment_being_tested) m.03zbbyd)))