tppa positive trust negative can not engage in the catering industry, tppa refers to syphilis is a systemic sexually transmitted disease caused by syphilis spirochete infection, in untreated syphilis patients, damage to the skin and body fluids. This includes saliva, semen and blood, which contain syphilis spirochetes and are infectious. As a result, some industries are unsuitable for people with untreated syphilis to work in, such as food and catering. Other parts, such as pre-schools, are also unsuitable for working with children. Therefore it is not possible to work in the catering industry.