Since you confirm you have Syphilis, it also confirms you have been sleeping with the wrong people. Why do you wish to come over to Qatar with this disease? You may be infecting others. Suggest you stay away both because of your habits and that you are a carrier of terrible disease. I hope the medical authorities realize this if and when you go for medical before you apply for a visa and stop you in your country. Otherwise, sooner or later your medical issue will be discovered here and the authorities may be forced to send you home.