Human papillomavirus (HPV)

Human papillomavirus (HPV) is a virus of the papillomavirus type. HPVs infect only the keratinocytes of the skin or mucous membranes. Most HPV infections cause no symptoms in most people.

There are more than 30 to 40 types of HPV that are typically transmitted through sexual contact. Some may cause genital warts, although most cause no symptoms at all. There are other types of HPV virus - classed as "high risk" - that are different from the ones that cause genital warts, and can progress to precancerous lesions as well as invasive cancers. Nearly all cases of cervical cancer are caused by HPV. 

Human immunodeficiency virus (HIV)

Human immunodeficiency virus (HIV) is a lentivirus – a type of retrovirus – and is the cause of acquired immunodeficiency syndrome (AIDS). AIDS is a condition in humans that leads to progressive failure of the immune system, which allows infections and cancers to thrive.

HIV is one of the most widely known sexually transmitted infections in the world, and is classed as a pandemic infection by the World Health Organisation. Approximately 35 million people have HIV globally, of which 17 million are women and 3.5 million are under the age of 15. Sub-Saharan Africa is considered the area most effected by HIV/AIDS; around 6 million people are infected with HIV/AIDS, and an estimated 66% of all deaths linked to HIV/AIDS globally occurred in this region in 2009, compared with under 200,000 deaths in the US, under 600 in the UK, and 53 in Canada. Despite being a pandemic infection, the spread and morality rates associated with HIV/AIDS have declined in recent years, partly due to improvement in medication and also due to raising global awareness amongst the population. In 2010 there were 1.8 million deaths linked to AIDS, down from 3.1 million in 2001. It is estimated that around 20% of those infected with HIV/AIDS are unaware of the condition. In total HIV/AIDS has led to over 32 million deaths since it was recognised in 1981.

Herpes Simplex

Herpes simplex is a viral disease caused by Herpes simplex type 1 (HSV-1) and type 2 (HSV-2). Herpes infections are categorised into one of several disorders based on the site on infection, ranging from oral herpes (an infection of the mouth), genital herpes (an infection of the genitals), herpes infections of the hand (herpes whitlow), ocular herpes (an infection of the eye), and possibly Bell’s Palsy.

Genital infections caused by the herpes simplex virus (HSV-2) are classed as a sexually transmitted infection. Preventing the spread of HSV-2 is encouraged, and barrier protection is the most reliable method. Despite the wide availability of condoms, many people who suffer HSV-2 infections will not present with symptoms and as such will only find out about their own infection when a partner shows signs of the infection.

Crab louse

Crab louse, or pubic louse - commonly referred to as "crabs" - are a parasitic insect exclusive to humans, that feed exclusively on blood. They are typically found in pubic hair around the genitals, but can also effect other areas of the body with hair, such as eyelashes.

Crab louse can be distinguished from other species of louse by their almost-round body. Adult crab louse are typically 1-2mm long, and are smaller than the body louse and head louse. The term "crab louse" comes from their much thicker two front legs that are equipped with two large claws.

Thrush (Candidiasis)

Thrush (candidiasis) - commonly referred to as a yeast infection - is a fungal infection of any of a number of species of yeasts (candida). These yeast infections can range in severity, from simple and superficial infections of the mouth and genitals, to more severe and potentially life-threatening systemic infections.

Gonorrhea

Gonorrhea - colloquially known as "the clap" - is a common sexually transmitted infection, and is thought to be the second most prevalent STI in the US and UK.

Gonorrhea is caused by a bacterium called neisseria gonorrhoeae. It is transmitted through vaginal, anal and oral sex. The chance for men to get the infection through vaginal intercourse with an infected woman is roughly 20%, and is higher for homosexual intercourse. In women the chance of getting the infection is much higher, roughly 60-80% when having sex with an infected man. Gonorrhea, like other STIs such a chlamydia, may be passed on to babies by infected women, and can infect the infant's eyes (ophthamia neonatorum).

Arthritis

Arthritis is a joint disorder involving inflammation of one or more joints.

There are over 100 different forms of arthritis, the most common form being osteoarthritis (a degenerative joint disease caused by trauma, age or infection of the joints). Other forms of arthritis include rheumatoid arthritis, psoriatic arthritis, lupus, gout and septic arthritis.

The main signs and symptoms of arthritis are swelling and pain associated with one or more joints. Most patients complain of pain in the joints before swelling is visible, with both the pain and swelling becoming progressively worse if left untreated. Different forms of arthritis require different treatments, and many forms of arthritis are irreversible with treatment focusing on pain management.

Chlamydia

Chlamydia is a common sexually transmitted infection caused by the bacterium Chlamydia trachomatis. Chlamydia is the most common STI in the United Kingdom and the United States, and is one of the most common in the world. It is estimated that around 1 million people in the United States are infected with chlamydia.

Chlamydia can be transmitted during vaginal, anal or oral sex, and can also be passed onto babies during vaginal birth. Between 50% and 75% of all women infected with cervical chlamydia - cervicitis - do not suffer any symptoms and are not aware they are infected. In men chlamydia is usually represented by a white discharge from the penis, with or without pain during urination. If left untreated chlamydia can lead to a number of other more severe health problems.

Asthma

Asthma is a common disease effecting the respiratory system, and its prevalence has increased significantly over the last 30 years. It is estimated that as many as 300 million people globally are affected by asthma, and it is responsible for around 250,000 deaths a year.

Asthma is characterized by recurring symptoms including wheezing, coughing, chest tightness, and shortness of breathe. These symptoms are variable, and they may differ from person to person. There are different classifications of asthma, which are intermittent, mild persistent, moderate persistent and severe persistent. Diagnosis and classification is based on the symptoms present and their frequency, as well as the patients response to therapy.