Skin, Soft Tissue and Bone Infections

Virus infections of several types manifest in skin lesions. Some cause infections in the skin; others reflect generalised infections that cause skin rashes as part of the disease process. Warts are caused by the papilloma family of viruses causing formation of benign and often pigmented tumours that crop on various parts of the body. Different members of the family cause warts in different anatomical sites. They are commonly found on hands and the feet but may also be found around the anus and on the external genitalia. Women with genital warts carry an increased risk of developing cervical cancer. Verrucas are warts that occur on the feet and these can be very painful. Wart removal has a long history of folk-remedies. Even today, removal of verrucas even today is hardly a scientific process. They are commonly burned out, often using applications of liquid nitrogen to the wart and its surrounding skin. Care must be taken to ensure adequate treatment of the encircling tissues to make certain that the verrucas do not regrow.

Enterovirus infections are sometimes associated with skin rashes or reddening of the inside of the mouth. Hand, foot and mouth disease is of particular note and it is characterised by a vesicular infection of the oral cavity. Vesicles are also found over the skin but concentrated particularly on the hands, feet and buttocks. This infection is caused by strains of the Coxsackievirus A.

Chicken pox is the consequence of the primary infection of by the varicella zoster virus. This herpesvirus causes a latent infection within the central nervous system. Primary infection usually occurs in childhood and results in a crop of vesicles over the skin and mucous membranes. The fluid in each blister carries a heavy load of infectious virus particles. The skin lesions are very itchy and become pustular. It is very hard not to pick at the spots of chicken pox and almost everyone who has had chicken pox carries at least a couple of scars. When the spots disappear, the virus does not. It migrates along peripheral nerves into the central nervous system where it establishes an asymptomatic, latent infection. This silent carriage is maintained by the immune response to varicella zoster virus, preventing a second attack of chicken pox. At any time after the primary infection, but usually after a considerable time, the varicella zoster virus may reactivate. Virus infection travels down a sensory nerve and causes a crop of vesicles over the skin served by that nerve. This is shingles. The vesicles of shingles contain infectious virus particles that will cause chicken pox in a susceptible individual who has not yet had a primary infection. They do not cause shingles upon primary infection.

Herpes simplex virus type 1, the common cause of cold sores, can also cause a severe infection in young children, spreading over large areas of skin. The name of the virus derives from the Greek word herpo: to creep. Infection during childhood with other herpes viruses, human herpes 6 and 7, results in a transient skin rash that resolves, leaving a latent virus infection.

Strains of parvovirus, a very small single-stranded DNA virus, cause 'slapped cheek syndrome', so called because of the bright red rash that results from infection. This covers the face of the child suffering from this condition and it looks as if the victim has been slapped across the face. This infection is also known as 'fifth disease', being the fifth of six common rash-associated illnesses recognised by Victorian doctors.

Measles is a generalised infection, spread via the respiratory tract, associated with a characteristic skin rash. This starts to appear behind the ears and across the forehead, spreading over the face and then over the entire body. The rash is evident for about five days. In well-nourished children, the disease is generally mild but in people who are malnourished, measles is a much more aggressive infection, associated with a significant risk of mortality. Globally, more that 1.5 million children die each year from a measles infection. Patients with measles have minute white lesions covering the mucous membranes inside the mouth, referred to as Koplick's spots. These are diagnostic for measles. Rubella is another generalised virus infection characterised by a skin rash, similar to that seen in measles but often more difficult to see in the early stages of the disease. Most cases are very mild and the infection may be inapparent, revealed only after serological testing. The significance of rubella is that infection during pregnancy can lead to a devastating congenital infection.