Human papillomavirus (HPV) is a virus from the papillomavirus family that is capable of infecting humans. Like all papillomaviruses, HPVs establish productive infections only in keratinocytes of the skin or mucous membranes. While the majority of the nearly 200 known types of HPV cause no symptoms in most people, some types can cause warts (verrucae), while others can – in a minority of cases lead to cancers of the cervix, vulva, vagina, and anus in women or cancers of the anus and penis in men. It can also cause cancers of the head and neck (tongue, tonsils and throat). Recently, HPV has been linked with an increased risk of cardiovascular disease.
More than 30 to 40 types of HPV are typically transmitted through sexual contact and infect the anogenital region. Some sexually transmitted HPV types may cause genital warts. Persistent infection with “high-risk” HPV types different from the ones that cause skin warts may progress to precancerous lesions and invasive cancer. HPV infection is a cause of nearly all cases of cervical cancer. However, most infections with these types do not cause disease.

The Human Immunodeficiency Virus (HIV) is the cause of Acquired Immune Deficiency Syndrome (AIDS). HIV can be transmitted sexually, via contaminated needles or blood transfusions, and from mother to child during pregnancy, birth or breast-feeding. The primary navigation template for this category is AIDS.

Encephalitis literally means an inflammation of the brain, but it usually refers to brain inflammation caused by a virus. It’s a rare disease that occurs in approximately 0.5 per 100,000 individuals most commonly in children, the elderly, and people with weakened immune systems. Although several thousand cases of encephalitis (also called acute viral encephalitis or aseptic encephalitis) are reported to the Centers for Disease Control and Prevention (CDC) every year, experts suspect that many more may go unreported because the symptoms are so mild.

The yellow fever virus is transmitted by the bite of female mosquitoes (the yellow fever mosquito, Aedes aegypti, and other species) and is found in tropical and subtropical areas in South America and Africa, but not in Asia. The only known hosts of the virus are primates and several species of mosquito. The origin of the disease is most likely to be Africa, from where it was introduced to South America through the slave trade in the 16th century. Since the 17th century, several major epidemics of the disease have been recorded in the Americas, Africa and Europe. In the 19th century, yellow fever was deemed one of the most dangerous infectious diseases.

Hepatitis is an inflammation of the liver, most commonly caused by a viral infection. There are five main hepatitis viruses, referred to as types A, B, C, D and E. These five types are of greatest concern because of the burden of illness and death they cause and the potential for outbreaks and epidemic spread. In particular, types B and C lead to chronic disease in hundreds of millions of people and, together, are the most common cause of liver cirrhosis and cancer. Hepatitis A and E are typically caused by ingestion of contaminated food or water. Hepatitis B, C and D usually occur as a result of parenteral contact with infected body fluids. Common modes of transmission for these viruses include receipt of contaminated blood or blood products, invasive medical procedures using contaminated equipment and for hepatitis B transmission from mother to baby at birth, from family member to child, and also by sexual contact. Acute infection may occur with limited or no symptoms, or may include symptoms such as jaundice (yellowing of the skin and eyes), dark urine, extreme fatigue, nausea, vomiting and abdominal pain.

Herpes viruses are a leading cause of human viral disease, second only to influenza and cold viruses. They are capable of causing overt disease or remaining silent for many years only to be reactivated, for example as shingles. The name herpes comes from the Latin herpes which, in turn, comes from the Greek word herpein which means to creep. This reflects the creeping or spreading nature of the skin lesions caused by many herpes virus types. There are at least 25 viruses in the family Herpesviridae. Eight or more herpes virus types are known to infect man frequently.

Rotavirus is the most common cause of severe diarrhoea among infants and young children, and is one of several viruses that cause infections often called stomach flu, despite having no relation to influenza. It is a genus of double-stranded RNA virus in the family Reoviridae. By the age of five, nearly every child in the world has been infected with rotavirus at least once. However, with each infection, immunity develops, and subsequent infections are less severe; adults are rarely affected. There are five species of this virus, referred to as A, B, C, D, and E. Rotavirus A, the most common, causes more than 90% of infections in humans. The virus is transmitted by the faecal-oral route. It infects and damages the cells that line the small intestine and causes gastroenteritis. Although rotavirus was discovered in 1973 and accounts for up to 50% of hospitalisations for severe diarrhoea in infants and children, its importance is still not widely known within the public health community, particularly in developing countries. In addition to its impact on human health, rotavirus also infects animals, and is a pathogen of livestock.

Chickenpox is a highly contagious illness caused by primary infection with varicella zoster virus (VZV). It usually starts with vesicular skin rash mainly on the body and head rather than at the periphery and becomes itchy, raw pockmarks, which mostly heal without scarring. On examination, the observer typically finds lesions at various stages of healing. Chickenpox is an airborne disease spread easily through coughing or sneezing of ill individuals or through direct contact with secretions from the rash. A person with chickenpox is infectious one to two days before the rash appears. They remain contagious until all lesions have crusted over. Immunocompromised patients are contagious during the entire period new lesions keep appearing. Crusted lesions are not contagious. It takes from 10 to 21 days after initial infection for the disease to develop.

Influenza is a viral infection that affects mainly the nose, throat, bronchi and, occasionally, lungs. Infection usually lasts for about a week, and is characterized by sudden onset of high fever, aching muscles, headache and severe malaise, non-productive cough, sore throat and rhinitis. The virus is transmitted easily from person to person via droplets and small particles produced when infected people cough or sneeze. Influenza tends to spread rapidly in seasonal epidemics. Most infected people recover within one to two weeks without requiring medical treatment. However, in the very young, the elderly, and those with other serious medical conditions, infection can lead to severe complications of the underlying condition, pneumonia and death.

The common cold (also known as nasopharyngitis, acute viral rhinopharyngitis, acute coryza, or a cold) (Latin: rhinitis acuta catarrhalis) is a viral infectious disease of the upper respiratory system, caused primarily by rhinoviruses and coronaviruses. Common symptoms include a cough, sore throat, runny nose, and fever. There is no cure for the common cold, but symptoms usually resolve in 7 to 10 days, with some symptoms possibly lasting for up to three weeks.The common cold is the most frequent infectious disease in humans with the average adult contracting two to four infections a year and the average child contracting between 6 and 12. Collectively, colds, influenza, and other upper respiratory tract infections (URTI) with similar symptoms are included in the diagnosis of influenza-like illness.