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What is Genital ulcer and explain in detail?
A genital ulcer is an open sore located on the genital area, which includes the vulva, penis, perianal region, or anus. Genital ulcers are most commonly caused by infectious agents (fungal infections, secondary bacterial infections, or sexually transmitted diseases such as genital herpes, syphilis or chancroid). However, this is not always the case, as a genital ulcer may have noninfectious causes as well.

Overview
A genital ulcer may be located on the vulva, penis, perianal region, or anus. Globally, the incidence of genital ulcers is estimated to be approximately 20 million cases annually. The most likely cause of a genital ulcer varies depending on the characteristics of a population and location. The most common cause of genital ulcers in the United States is herpes simplex infections, with syphilis the second most common cause, and chancroid the third. These common causes of genital ulcer disease (HSV-1, HSV-2 and treponema pallidum) can all be efficiently transmitted through oral sex.Important signs associated with genital ulcers that may assist in the diagnosis of the cause of the genital ulcer may include the presence of tender or non-tender enlarged lymph nodes in the groin area, a painful or non-painful genital ulcer, or the presence of vesicular lesions, which are small, painful, elevated blisters.The most common causes of a genital ulcer include infectious agents, with sexually transmitted diseases being the most common, but which can also include fungal infections and secondary bacterial infections. While infectious agents are the most common cause, a genital ulcer may also be the result of non-infectious causes such as Behcets syndrome, lupus, or psoriasis.Since it is difficult to determine a cause of a genital ulcer from history, examination, and population characteristics alone, further testing is often needed. The most common diagnostic tools used are targeted towards the most common etiologies of genital ulcers: syphilis (syphilis serology, PCR testing, or dark-field examination), herpes simplex virus (PCR, culture, or type specific HSV antibodies), and haemophilus ducreyi (culture on special media currently not widely available in most hospital systems) if the individual is in a known endemic region. Further diagnostic tools such as a biopsy or culture are often utilized if ulcers appear unusual or do not respond as expected to therapy.Since genital ulcers are often infectious in origin, there is an increased risk of acquiring HIV in a HIV negative patient through viral introduction through the open sore Conversely, there is an increased risk of HIV transmission through increased shedding of viral HIV in the presence of a genital ulcer in a patient with a history of HIV. The CDC recommends testing for HIV in any individual presenting for a genital ulcer who does not already have a history of HIV.

Infectious sexually transmitted causes
Risk factors for sexually transmitted genital ulcers are similar to the risk factors for most sexually transmitted diseases which include multiple sex partners, alcohol, illicit drug use, homelessness, poverty, inmates, men who have sex with men, sexually active teenagers, sexual contact without contraceptive use, and unstable housing.                      
The most common cause of genital ulcers in the North America and Western Europe are the result of HSV or syphilis infections, while the most common cause in other parts of the world is chancroid. Most sexually active adolescents with genital ulcers have a herpes simplex virus infection, more commonly type 2. Meanwhile, according to 2017 CDC reports, syphilis is more common in men who have sex with men populations although rates of syphilis have been rising in heterosexual men and women in the United States. Following syphilis and genital herpes infections, a chancroid is the third most common cause but tends to occur in focused outbreaks over time. While rates of H. ducreyi infection seem to be declining according to a 2017 report, it is possible this may be due to lack of testing since H. ducreyi requires a very specialized culture medium which is not commonly available. Less common causes include lymphogranuloma venereum, which is more common in men who have sex with men, and granuloma inguinale, which is more common in tropical regions globally. rather than in the United States.

Non-infectious causes
Genital ulcers are not strictly a sign of a sexually transmitted illness, although non-infectious sources are significantly more infrequent in comparison. The most common non-infectious sources of genital ulcers are first Behcets disease, and second drug reaction.Behcets syndrome is a chronic systemic vasculitis infection that is defined by recurrent oral and genital aphthous ulcers but can also affect many other organ systems, such as the eyes, ears, nervous system, heart, lungs, joints, and intestines