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Initiation of laboratory-based surveillance and outcome of surveillance of selected diseases, Riyadh central Laboratory.


The availability of surveillance data in time for appropriate action is very important. For certain diseases, laboratory confirmation is necessary and the laboratory will be the first place where the occurrence of these diseases is recognized.


for initiation of laboratory-based surveillance, we reviewed the Ministry of Health's list of notifiable diseases and determined which diseases are first diagnosed in the laboratory. We reviewed the laboratory reports register (culture isolates) in Riyadh Central Laboratory for salmonellosis, shigellosis, typhoid/paratyphoid and brucellosis and compared these with reports received through the surveillance system.


A total of 226 isolates for Salmonella (typhoid and non-typhoid), Shigella and Brucella were obtained during the study period (weeks 24-40, 1994). These included: salmonellosis 173 (76.5%), shigellosis 33 (14.6%), typhoid/paratyphoid 18(8.0%) and brucellosis 2 (0.9%). Of these, only 17 had been reported through routine surveillance. For these 17 cases, the median delay in reporting was 15 days. There was no reporting either from the emergency room or from the outpatient clinics. One hospital did not report many laboratory-confirmed diseases because they were unaware of the need to report salmonellosis.


A large number of important disease reports are lost in the current system. Direct reporting from the laboratory would improve both sensitivity and timeliness of surveillance.