Viral fever refers to a broad spectrum of conditions where viral infections are associated with elevations of body temperature. The term encompasses a wide variety of viral infections, some of which can be clearly identified by their symptoms and signs. These viral infections may show generalised symptoms, but may target specific organs.
Headaches, body aches and a skin rash characterise most of these viral fevers. They may affect any age group, and are seen world-wide. They require only symptomatic treatment. Some are highly contagious. Most of them are not dangerous and self-limited, but some can progress rapidly leading to death.
Cause and Pathogenesis
Most viral infections are spread by inhalation of aerosolised particles, by intake of contaminated water or food, or by direct contact. Infection then spreads locally and thereafter 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 clinically is usually a consequence of the virus multiplying at a specific site. Even though the fever comes down, in some infections the virus continues to multiply and cause persistent infection.
Symptoms and Signs
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 prodromal phase of fatigue, malaise and body and muscle aches that may lead to the onset of fever. The fever may be low grade or high grade and remittent. Inflammation of the pharynx, a running nose, nasal congestion, headache, redness of the eyes, cough, muscle and joint pains and a skin rash could be present.
The fatigue and body pain could be disproportionate to the level of fever, and lymph glands 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, can cause a bleeding tendency, which results in bleeding from the skin and several other internal organs and can be fatal.
Investigations and Diagnosis
The diagnosis and management of viral fevers is based more on the clinical presentation than by laboratory investigations. Since these infections are commonly self-limited, investigations are unnecessary. 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) is not elevated. Confirmation is by culture of virus from the relevant specimens such as nasal swabs, and skin rash or by increase in antibody levels in serial blood samples.
Treatment and Prognosis
Treatment of viral fever is purely symptomatic with antipyretic and analgesic drugs. 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. Only in cases of super-infection do antibiotics need to be prescribed. It is important that antibiotics are NOT routinely used for prophylaxis.
Complications of viral infections like pneumonia (viral or super-infection by bacteria) need to be addressed specifically by clearance of respiratory secretions and utilising ventilator assistance if hypoxia is severe. 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.
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 several sub-groups of viruses with different forms of antigenicity, all of which cannot be covered with a single vaccine. Fortunately since most infections are mild and self-limited, we can be assured of a full recovery.