<span>overall, around twenty million teenagers contract an STI (sexually transmitted infection) each year. </span>(The half of them are from U.S.)<span>
A sexually transmitted infection (STI) is an infection that is transmitted between partners during different forms of sexual intercourse. This infection can lead to an infectious disease, formerly called venereal disease (the name comes from Venus, goddess of love)All sexual practices that involve mutual genital or oro-genital contact with another person, or genital fluids, are considered to carry a risk of transmitting an STI. Each STI has a different risk and severity. </span>
This either attaches the virus to the host cell or dissolves the membrane letting the virus into the host cell. The viral enzymes(enzymes are again chemical compounds) multiply the viral dna copies and viral protiens. These are new viruses. These new viruses breakout of the cell to infect other cells.
"severe weather conditions" are the only things than can be reasonably well predicted with the help of science. Of course the accuracy of these predictions varies greatly. <span />
