Sexually transmitted disease (STD), also known as a sexually transmitted infection (STI), or venereal disease (VD), is an illness that has a significant risk of transmission between humans by means of human sexual behavior. While in the past these illnesses have mostly been referred to as STDs or VD, in recent years the term sexually transmitted infections (STIs) has been preferred, as it has a broader range of meaning; a person may be infected, and may potentially infect others, without having a disease.

Some STIs can also be transmitted via the use of IV drug needles after its use by an infected person, as well as through childbirth or breastfeeding. STI is a broader term than STD. Infection is a colonization by a parasitic species, which may not cause any adverse effects. In a disease the infection leads to impaired or abnormal function. In either case, the condition may not exhibit signs or symptoms. Increased understanding of infections like HPV, which infects most sexually active individuals, but cause disease in only a few has led to increased use of the term STI. The diseases on this list are most commonly transmitted solely by sexual activity.

Many infectious diseases, including the common cold, influenza, pneumonia and most others that are transmitted person-to-person can also be transmitted during sexual contact if one person is infected. However, even though these diseases may be transmitted during sex, they are not considered STDs. MultiPlex Real-Time PCR technology allows using primers and probes for several (for up to 5) DNA targets in one tube. Amplification products identification runs for each DNA target on a different optical channel.

The sensitivity of these tests is not affected by changing the number of infections. Each mono- and multiplex PCR kit contains independent Internal Control (IC) for determination of DNA extraction efficiency and PCR process. Presence of the Internal Control signal/band shows, that the DNA extraction process and amplification steps were sufficient for significant results interpretation.