Viral Fever - Symptoms, Causes, Types, Prevention, Treatment

Types of viral infections

There are various types of viral infections, depending majorly on the site infected. They are: 

• Upper respiratory infections include sore throat, sinusitis, and the common cold. 
• Gastrointestinal tract infections, such as gastroenteritis.
• Hepatitis is a group of viral infections caused by hepatitis viruses (A, B, C, D, and E).
• Neurological infections could include encephalitis, meningitis etc.
• Dermal infections by the virus can cause warts or other blemishes. Many viruses affecting bodily systems can also result in various other dermal manifestations, such as chickenpox causing rashes.
• Infections of the placenta and foetus: Few viruses, especially the cytomegalovirus, Zika virus, and the rubella virus, could infect the placenta and foetus in pregnant women.

Apart from these above-explained viruses, there are a few specific viruses which typically affect the bodily systems, such as enteroviruses and cytomegaloviruses.

Upper respiratory infections: The viral infections infecting the upper respiratory tract are a few of the most common viral infections. 

These simple viral infections of the nose, throat, upper airways, and lungs can include sinusitis, sore throat, and the common cold. Other serious viral respiratory infections include pneumonia, influenza, and SARS-CoV-2.

These viral respiratory infections are more likely to show severe symptoms in infants, the elderly, and people with a heart or lung disorder. These respiratory viruses are typically contact through with infected respiratory droplets.

In paediatrics (small children), the viruses commonly cause laryngotracheobronchitis (inflamed upper and lower airways, also called croup) and bronchiolitis (inflamed lower airways).



Influenza is one of the common communicable viral diseases which affects due to seasonal change.

Influenza viral fever

Influenza is a disease that can spread and affects both the lower and upper parts of the respiratory tract and is caused by flu viruses which can spread through the tiny droplets from an infected person's coughing, talking, or sneezing.

Influenza can be passed on before the person has any symptoms and up to 5–7 days after the infection. While healthy people need a few days to fully recover from an infection, few patient groups, such as young children, pregnant, the elderly and people with weak immune systems, may often have complications like pneumonia and death.

The flu symptoms include:

• Runny nose
• Cough
• Sore throat
• High viral fever
• Congested eyes

The body temperature during influenza viral fever could range around 103 °F to 105 °F (39.4 °C - 40.5 °C). During seasonal epidemics, the flu spreads quickly and effectively. Flu epidemics happen every fall and winter in temperate regions. They affect many adults and children, but the age groups and severity are different each season. 

Viral hemorrhagic fever - Overview

Viral hemorrhagic fevers (VHFs) are a set of serious systemic fevers caused by four virus families: Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae. The symptoms of Viral hemorrhagic fevers include coagulopathies, hemodynamic instability, changes in mental state, and, in extreme cases, death. 

Viral hemorrhagic fever causes

Most viral hemorrhagic fevers are spread by contacting infected insects or animals, as the viruses causing viral hemorrhagic fevers survive in a variety of animal and insect hosts such as rodents, bats, mosquitoes, or ticks. In some cases, it could be spread from person to person.



The causative agents of viral hemorrhagic fevers include virusus from the four virus families: Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae.

Signs and symptoms of viral hemorrhagic fever

Patients suffering from any of the various viral hemorrhagic fever could present with various generalised symptoms such as 

• Fever
• General malaise 
• Headache

Nevertheless, in severe cases and in patients with reduced immune deficiency the associated symptoms include

• Retro-orbital discomfort
• Joint aches
• Redness of the eye
• Abdominal pain
• Vomiting and nausea 
• Diarrhoea 
• Epistaxis (nose bleeds) 
• Bleeding gums

Types of viral hemorrhagic fever

These viral hemorrhagic fevers are caused by four virus families: Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae. The different types of viral hemorrhagic fevers are: 

Arenaviridae family:

• Guanarito virus (GTOV) - Venezuelan hemorrhagic fever
• Chapare virus (CHPV) - Chapare hemorrhagic fever
• Lassa virus (LASV) - Lassa fever
• Junin virus (JUNV) - Argentine hemorrhagic fever
• Lujo virus (LUJV) - Lujo hemorrhagic fever
• Lymphocytic choriomeningitis virus (LCMV) - Lymphocytic choriomeningitis
• Machupo virus (MACV) - Bolivian hemorrhagic fever
• Sabia virus (SABV) - Brazilian hemorrhagic fever

Bunyaviridae family:

• Crimean-Congo hemorrhagic virus (CCHFV) - Crimean-Congo hemorrhagic fever
• Dobrava-Belgrade virus (DOBV) - Hemorrhagic fever with renal syndrome
• Hantaan virus (HTNV) - Hemorrhagic fever with renal syndrome
• Saaremaa virus (SAAV) - Hemorrhagic fever with renal syndrome
• Puumalavirus (PUUV) - Hemorrhagic fever with renal syndrome
• Rift Valley fever virus (RVFV) - Rift Valley fever
• Seoul virus (SEOV) - Hemorrhagic fever with renal syndrome
• Sin Nombre virus (SNV)- Hantavirus pulmonary syndrome
• Tula virus (TULV) - Hemorrhagic fever with renal syndrome

Filoviridae family:

• Bundibugyo ebolavirus (BDBV) - Ebola virus disease
• Marburg marburgvirus (MARV) - Marburg hemorrhagic fever
• Sudan ebolavirus (SUDV) - Ebola virus disease
• Taï Forest ebolavirus (TAFV) - Ebola virus disease
• Zaire ebolavirus (EBOV) - Ebola virus disease

Flaviviridae family:

• Dengue virus (DENV-1-4) - Dengue fever
• Kyasanur forest disease virus (KFDV) - Kyasanur forest disease
• Omsk hemorrhagic fever virus (OHFV) - Omsk hemorrhagic fever
• Yellow fever virus (YFV) - Yellow fever 

Viral fever diagnosis 

It must be understood that since the symptoms of viral and bacterial illnesses are frequently the same, differential diagnosis can be extremely tricky, at least on the levels of preliminary physical examination. 

Before diagnosing a viral fever, a physician would usually rule out a bacterial infection. To rule out, the physician may analyse the 

• Symptoms 
• Medical history
• Samples for bacteria through necessary blood tests. 

The diagnostic pathways reticulate further depending upon the presentations: 

• In case of a sore throat, a swab test may be performed to understand which bacteria that caused it. With a negative sample, it is clear to the physician to search for likely viral infections.
• In addition, they can collect other body fluid sample to test for signs that may indicate a viral infection.

Viral hemorrhagic fever diagnosis

The diagnosis of viral hemorrhagic fevers is necessary to prescribe the exact antiviral agent, as these agents can cause various adverse effects. The diagnostics include: 

• Complete blood count 
• Comprehensive metabolic panel
• Coagulation tests
• Liver function tests
• Evaluation for bacterial infections through 
• Urinalysis
• urine culture
• Chest x-ray
• Blood cultures 
• Serological testing for virus-specific IgM and IgG antibodies 
• Diagnostic testing procedures include reverse transcriptase-polymerase chain reaction and virus isolation via cell culture. 

Is fever good for us? 

During evolution, the body has developed several defences against the microbes which try to cause infections. These defences also help in driving out influenza viruses. The defences include:

• Physical barriers, such as the skin, discourage the entry of viruses.
• Biological barriers, such as immune defences, tackle the virus after its entry.

The entry of a virus into the body activates the immune system. These defences are initiated by white blood cells, such as lymphocytes and monocytes, which learn to target and destroy the virus or infected cells. Some white blood cells can respond more quickly and efficiently to a later infection by the same virus if the body survives the initial viral assault.

The viral fever and the symptoms associated with it are developed during these internal activities. Like any other microbes, the virus intends to multiply within the body spreading disease and the body tries to counter it. Fever is an evolutionary response to counter viraemia (virus in the blood), which could be beneficial to the patient’s survival, as the increase in body temperature inhibits viral replication.

In patients suffering from a viral infection, such as influenza, a mild elevation in the temperature within the first 24 hours after the admission into intensive care unit (ICU) is associated with a better result compared to patients who have had normal temperature or hyperthermia above 104 °F (40 °C).

Elderly patients suffering from viral pneumonia who had no viral fever had a much lower chance of survival when compared to elderly patients who developed feverish reactions. 

Increased temperatures tend to increase endosomal pH, which adversely affects the entry of influenza viruses and intracellular transportation.

Nevertheless, it must be understood that the viral fever symptoms must be brought down, as they could be associated with greater organ dysfunction, prolonged hospitalisation, and prolonged periods of mechanical ventilation in intensive care units. 

When should a doctor be consulted?

In many cases, a viral fever alone is not cause for concern. Nevertheless, if the viral fever reaches 103 °F (39 °C) or higher, medical attention must be sought. In infants, medical consultation must be done if the rectal temperature reaches 100.4 °F or higher (38 °C). The doctor’s consultation for patients with varying ages are:

For infants /toddlers

• 0–3 months of age: If the rectal temperature is 100.4 °F (38 °C) or more.
• 3–6 months of age: If the rectal temperature is more than 102 °F (39 °C) and the child is irritable or sleepy.
• 6–24 months of age: If the rectal temperature is above 102 °F (39 °C), lasting for more than a day. 
• More than two years of age: If the temperature of the body is greater than 104 °F (40 °C) repeatedly.

Apart from the above, other viral fever symptoms which warrant a consultation include: 

• Rash
• Cough
• Diarrhoea
• Lethargic (being lazy) 
• Inability to maintain eye contact. 
• Fever lasting longer than three days or being non-responsive to the prescribed medication.

For adults

The doctor must be consulted if the fever of 103 °F (39 °C) or higher lasts longer than three days, being non-responsive to medication. Also, viral fevers are usually accompanied by the following viral fever symptoms, warranting prompt consultation:

• Rash
• Severe headache
• Stiff neck
• Photophobia (sensitivity to light)
• Frequent vomiting
• Breathlessness (usually due to increased mucous production)
• Chest or abdominal pain 

Viral fever treatment

In most people suffering from influenza without any co-morbidities, the infection is self-limiting (goes away on its own). There is no requirement for antiviral treatment administration. Viral fever treatment can also include symptomatic resolution. To reduce the viral fever symptoms, non-steroidal anti-inflammatory drugs (NSAIDs) may be prescribed.

Viruses, unlike bacteria, do not react to antibiotics. Most viral illnesses (usually including influenza) simply need to run their course. Keeping hydrated (by drinking fluids) or taking over-the-counter fever-reducing medications can help until the fever goes away.

The patients are suggested not to self-medicate any antibiotics for viral fevers, as apart from not bringing any positive results, the antibiotics may give outside effects. Also, taking antibiotics for viral fevers unnecessarily can increase antibiotic resistance!

Physicians may prescribe antiviral medications to treat or prevent influenza infection, particularly during outbreaks in healthcare settings. 

Viral fever prevention

The prevention of viral fever can be done if the spread of viral infection is stopped. Viral fever prevention can be succeeded by the following: 

• Frequent handwashing: Rotavirus causes diarrhoea. It can transfer the infections through contaminated human hands and non-porous inanimate surfaces. Therefore, frequent handwashing, especially before food, is necessary. 
• Maintaining distance and wearing masks: While there is an accepted notion of spreading respiratory viruses through aerosol transmission, research demonstrated that the spread occurs through contact with contaminated surfaces. Therefore, maintaining distance with infected people and wearing masks are necessary, especially in endemic areas. 
• Wiping surfaces with viricidal solutions: Viral contamination was directly implicated or for which viral agents and their spread can be reduced by treating the surfaces with viricidal solutions (such as iodine-based solutions). 
• Pasteurization: decreases virus infectivity in milk by several logs. Pasteurization is the act of heating milk to 72 °C for 15 minutes. Similarly, boiling water before drinking ensures a similar effect. 
• Prevention of mosquito bites: Mosquitoes can cause the spread of various viruses, especially that causing dengue, chikungunya, etc. Therefore, usage of mosquito nets and repellents could help prevent mosquito bites.

Frequently asked questions, FAQs

Department of General Medicine