Genital warts are caused by Human Papilloma Virus and it is just a symptom of infection. From the test results, it is evident that you are already contracted with the virus. But in your case the presence of virus is just asymptomatic (without showing symptoms of presence). That is why there are no visible marks or warts. But the virus will stay dormant in the superficial squamous layer of cells. This layer of squamous cells is present in various parts of body including skin, genital areas, and larynx and so on. Skin to skin contact will help in the spreading of virus. But certain type of HPVs are seen causing warts in genital areas and hence called genital warts. As your body is immune to HPVs now, you can take Gardasil vaccine to prevent an outbreak of warts in body. Gardasil vaccine is to be taken in 3 doses with a six month interval in between each dose. Gardasil vaccine will help preventing 4 main types of HPV infection including two types which cause genital warts. For a lifetime protection you need just 3 doses of vaccine. Condoms can also be used to prevent the transmission of virus but their efficiency is limited as a condom break will cause spreading of HPV. So, using condoms cannot guarantee you safety from HPV. I hope your query is answered well. Take care always.