HPV diagnosis isn't always easy for doctors. There are a lot of reasons for this, namely because most cases of HPV are completely asymptomatic, meaning that there are no symptoms to be noticed by the patient. In fact, in almost all cases, the body handles HPV completely on its own and is able to eliminate the virus from the body within about two years. The two cases where this is not true are when a patient has the very rare type of HPV that either causes genital warts (less than one percent of Americans commonly experience this) or the type that causes cancer, which is also very rare. If a patient has visible warts, a doctor will be able to diagnose HPV just from looking. In these cases, patients can be given medication or just wait to see if warts go away on their own, as they often will.
In the case of cancer causing forms of the virus, things get a little more serious. Because the vast majority of cases of HPV are symptomatic, and because the types that cause cancer are completely asymptomatic until the signs of cancer actually present themselves, it can be difficult to diagnose HPV. The fact of the matter is that most of the cancers caused by HPV, cervical cancer being the most common, while other types are very dangerous but also extremely rare, reveal no symptoms until the cancer is in a very late stage. For this reason, doctors recommend regular screening for sexually active women to test for cervical cancer, and in fact, beyond seeing genital warts, HPV can only really be tested for by performing cervical cancer screenings. These screenings consist of either tests on cells in a woman's cervix to test for signs of cancer. A pap smear can also tests for some early warning signs of cervical cancer, although the pap smear alone has proven to sometimes provide unclear results. A pap smear positive for "pre-cancer" signs does not necessarily indicate that a patient will develop cervical cancer, but only indicates that it is possible if treatment is not provided.
All of the available tests to find out if patients do indeed have HPV are actually just screening for the signs of cervical cancer, but as mentioned above, since most patients who have HPV are completely unaffected by the virus, this doesn't really do too much harm for most people. Still, it is important to keep in mind that it is always possible to pass on the virus, even if you present no visual symptoms.
In the absence of a truly effective diagnosis for the types of HPV which truly affect people (cancerous and wart causing), there is an available vaccine for both men and women for HPV to lower the incidence of HPV. For men, there is a vaccine called Gardasil which protects against the most common forms of wart-causing HPV. This vaccine is available for women as well to the same effect, but there is also a second vaccine for women called Cervarix which has been shown, in concert with Gardasil, to prevent most types of HPV which are known to cause cervical cancer.
If you think you may have contracted HPV, contact a doctor to go through available screening methods and to get yourself on a schedule for continual monitoring. Remember, doctors recommend periodic screening for all sexually active women to help prevent cervical cancer, especially in those women who were never treated with the recently developed vaccines. Just because there is not an effective HPV screening does not mean doctors can't help, and just because the body naturally eliminates most incidences of HPV, even those which cause warts, it doesn't mean that leaving a known case of HPV untreated is the best course of action. Consult a doctor if you believe you may have HPV.