What is viral fever?
Viral fever refers to a broad spectrum of conditions where viral infections are associated with elevation of body temperature. In medical terms, any fever caused as a result of viral infection is a viral fever. These viral infections may show generalised symptoms, but may target specific organs. The course and duration of the fever does not follow any set pattern and is frequently accompanied by, though not always by all of them, generalised body ache, running nose, cough, shivering, skin rash and irritability. Viral infections may affect any age group, and are seen worldwide. They require only symptomatic treatment. Some are highly contagious. Most of them are not dangerous and are self-limited, but some can progress rapidly leading to death.
What is the cause?
Most viral infections are spread by the intake of contaminated water or food, or by direct contact. The infection then spreads locally and, thereafter, enters into the blood stream or lymph channels. Some of the viral infections can be transmitted sexually or by direct inoculation into the blood stream. The duration of the primary infection may vary from days to several weeks. Manifestation of the disease is usually a consequence of the virus multiplying at a specific site.
What are the symptoms?
Once the virus enters the body, there is an incubation period when the virus multiplies to a level high enough to cause infection. This is followed by a phase of fatigue and body and muscle aches that may lead to the onset of fever. The fever may be low grade or high grade. Inflammation of the throat, a running nose, nasal congestion, headache, redness of the eyes, cough, muscle and joint pains and a skin rash could be present. Fatigue and body pain could be disproportionate to the level of fever, and lymph glands in the neck may swell up. The illness is usually self-limited but the fatigue and cough may persist for a few weeks. Sometimes pneumonia, vomiting and diarrhoea, jaundice or arthritis (joint swelling) may complicate the initial viral fever. Some viral fevers are spread by insects, for example, arbovirus, and can cause a bleeding tendency, which results in bleeding from the skin and several other internal organs and can be fatal.
How is it diagnosed?
The diagnosis and management of viral fevers is based on the clinical presentation rather than on laboratory investigations. The diagnosis is made by the typical history of fever with severe muscle and joint pains. Skin rash and lymph gland swellings have to be specifically looked for. Laboratory investigations are undertaken to rule out other bacterial infections rather than to confirm viral fever. Blood tests will not show any increase in the white blood cells, which typically occurs with bacterial infections. The numbers of lymphocytes may be increased. The erythrocyte sedimentation rate (ESR) may be elevated. Confirmation of the fever is done by a culture of virus from the relevant specimens such as nasal swabs, and skin rash or by increase in antibody levels in serial blood samples.
What is the treatment and prognosis?
Treatment of viral fever is purely symptomatic. Medicines are given to lower temperature and relieve body aches. Bed rest and adequate fluid intake is advised. Nasal decongestants may be beneficial. Specific antiviral therapy is not routinely recommended. Steroids are not advised as it may lead to bacterial super-infection. Complications of viral infections like pneumonia need to be addressed specifically. Symptoms of gastroenteritis should be managed with anti-motility agents. Most viral fevers recover completely in a week although fatigue may persist for a few weeks.
How to prevent the fever?
Viral fevers are difficult to prevent. They occur as epidemics of infection depending on their mode of spread. Vaccines have been tried targeting the respiratory and gastrointestinal viruses with little success due to the presence of several sub-groups of viruses, all of which cannot be covered with a single vaccine. Fortunately, since most infections are mild and self-limited, one can be assured of a full recovery.