Heated versus unheated sera in the hemagglutination treponemal test for syphilis

Sera (920) were tested to evaluate the use of heated versus unheated sera in the hemagglutination treponemal test for syphilis. The heated and unheated samples were tested on the same day with the hemagglutination treponemal test for syphilis kit according to the manufacturer's protocol. Agreement of results between the heated and unheated sera was 99.2%. The reading pattern of agglutination was clearer and more distinct with heated sera; therefore, based solely on our preference for the reading patterns, we suggest that heated sera be used in the hemagglutination treponemal test for syphilis.