Monday, 27 August 2012

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.

Most herpes infections cycle through periods of activity and inactivity. During active periods the virus “sheds”, presenting as blisters and sores of the affected area, which can last from 2 to 21 days before going into remission. Genital herpes is general asymptomatic, although shedding may still occur. Once infected with herpes simplex, the virus spreads along sensory nerves to cell bodies, where it will reside in a latent state for life. It is not known what leads the virus to become active again, although some potential triggers have been identified, including immunosuppressant drugs. When the virus becomes active again, it multiplies new viral particles which them spread along the neurons to nerve terminals in the skin, where they are released. Episodes of recurrence reduce over time in both frequency and severity.

When one type of HSV-1 infection is contracted, the immune system will create antibodies to prevent a breakout of that type occurring in other parts of the body. For example, an oral herpes infection will lead to the production of antibodies that will prevent outbreaks of ocular herpes, genital herpes and herpes whitlow by HSV-1. These antibodies also reduce the chances of contracting HSV-2 infections, although it is still possible.

Herpes simplex is spread through close and body-to-body contact during periods of shedding, or through the body fluid of an infected person. Barrier protection – such as condoms – are the best method to protect from spreading, although they only reduce the risk and don’t eliminate it.

There is currently no known cure for herpes. Once infected the virus will remain in the body for life, and result in recurring periods of activity and inactivity over time, especially in those persons with deficient immune systems, such as in patients with HIV and cancer-related immunodeficiency. Over time – usually over the course of several years – patients will experience less frequent and less severe outbreaks, with many patients becoming perpetually asymptomatic, although they may still pass the virus on to others.

There is debate amongst medical practitioners as to whether HSV-1 infections are responsible for cases of Bell’s Palsy, a type of facial paralysis. The theory has been contested, as HSV-1 antibodies are not found in high quantities in patients suffering from Bell’s Palsy, and many people infected with HSV-1 never suffer from facial paralysis.

There is also reason to believe that HSV-1 may have a role to play in the development of Alzheimer’s disease. When certain genetic variations are present, HSV-1 appears to be far more damaging to the central nervous system, which can increase the likelihood of developing Alzheimer’s disease. Without these genetic variations the opposite is true, with no neurological damage being caused.

Signs and Symptoms

HSV infections are separated out into several disorders based on the site and severity of infection. The most common form of herpes simplex infection occurs in the mouth, either through infecting the skin or mucosa, where they will present during periods of activity with blisters and sores around on the skin. The same is true of genital herpes and herpes of the hand (herpetic whitlow). Infections of the eye (ocular herpes) are more severe in that they can result in permanent damage to the eye, and infections of the centre nervous system can leads to permanent damage of the brain (herpes encephalitis). Patients with diminished immune systems, such as transplant recipients, newborns and AIDS patients are prone to severe and potentially life threatening complications from HSV infections. HSV has also been connected to cognitive disorders such as bipolar disorder and Alzheimer’s disease, although these connections are dependent on genetics. There is also a possible link between HSV infections and Bell’s Palsy.

For oral herpes, symptoms include blisters and sores on the lips and skin surrounding the mouth. Genitals herpes displays with similar papules and vesicles on the outer surface of the genitals. Similarly, herpes whitlow displays with blisters on the fingers and hands, but can also lead to an infection of the face, ears and neck called herpes gladitorium, which can result in similar blisters as well as fever, headache, sore throat and swollen glands. Herpes gladitorium – as the name suggests – mostly effects those people who participate in full contact sports such as wrestling. Herpes esophagitis (of the throat) presents in similar blisters and papules as other types of HSV infection, and is mostly associated with those that suffer deficient or suppressed immune systems.

In cases of herpesviral encephalitis (HSE), it is thought that a reactivation of the latent herpes virus spreads to the brain. Whilst rare, it is estimated that around 1 in 500,000 people will develop the disorder every year. This disorder often presents as alterations in the infected persons levels of consciousness, as well as marked changes in personality, fever and seizures. Roughly 70% of cases of HSE that are left untreated will result in rapid death, and around one third of those that receive treatment will still die. Almost half of all survivors of HSE will suffer serious neurological damage, and only around 2.5% of sufferers will regain completely normal brain functioning.

People that contract HSV-2 most often show no symptoms, and are described as have subclinical or asymptomatic herpes.

Diagnosis and Treatment

Diagnosis of oral and facial herpes is relatively straight forward, especially during periods of activity, due to the unique display of sores, presenting as round, superficial oral ulcers. Doctors and medical professionals will often make a simple observational examination before a diagnosis is given.

In cases of HSV-2 genital infections, diagnosis is complicated by the fact that the majority of those infected rarely show any classical symptoms. There are also several other conditions that are similar to genital herpes, such as fungal infections and urethritis. In cases of HSV-2 infections laboratory testing is often used to confirm a diagnosis before pursuing treatment. Laboratory tests may include culturing, DFA tests, or skin biopsies. Laboratory tests are however rare due to their high cost and time demands. Modern serological testing can now distinguish between HSV-1 and HSV-2 infections, as well as the antibodies produced to fight them, and may be clinically preferred and encouraged over other methods of diagnosis.

Once diagnosed, treatments range from antiviral drugs to topical antiviral creams. The most commonly prescribed antiviral drugs include acyclovir, valacyclovir, famciclovir, penciclovir. Both acyclovir and valacyclovir are available in generic forms. Topical treatments are effective in cases of herpes labialis have proved effective, and include acyclovir (in topical form), penciclovir, and docosanol.


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