Viral fever: causes, symptoms, tests, treatment

Viral fever: causes, symptoms, tests, treatment

Viral fever is an illness caused by viral infections. Many times you visit your doctor and the diagnosis is viral fever. Every person gets viral fever 6-8 times a year. Most of the time you have a mild illness.

Viral fever is caused by virus infection. It can be as simple as flu or as dangerous as Covid-19 and dengue.

Here we will see viral fever symptoms, causes, tests needed and treatments. Most of the mild viral fever can be managed at home with home remedies for fever.

What causes viral fever?

Viral fevers being the most common illnesses there causes are common too. Some viruses causing this fever categories are as follows:

  • Influenza virus
  • Norovirus
  • Rota virus
  • RSV virus
  • Adenovirus
  • Dengue virus
  • Measles virus
  • Mumps virus
  • Rubella virus
  • Coxsackievirus
  • Hepatitis A virus
  • Hepatitis B virus
  • Hepatitis C virus
  • Hepatitis E virus
  • Rabies virus
  • Herpes virus
  • Varicella zoster virus
  • HIV
  • Novel coronavirus
  • Japanese encephalitis virus
  • Chikungunya virus

We can see in the above list many of those diseases are mild and some like dengue and rabies can be lethal.

How do these viruses spread?

These viruses spread by their particular ways of transmission. They can spread from human to human or from animals to humans.

Through air

Some viruses causing viral fever spread through air. When the infected person speaks, coughs, sneezes the droplets from his/her respiratory tracts are discharged in the air. The susceptible person comes in contact after inhaling them and gets infected. e.g. Influenza virus, RSV, varicella virus

Through water

Some of these viruses causing viral fever are excreted by infected persons in feces. It may pollute the drinking water and if a susceptible person drinks that water he/she may get infected. e.g. Hepatitis A virus, Hepatitis E virus, rota virus, norovirus

Through bites

Some of these viruses causing virus fever spread through bites like mosquito bites eg. dengue and Japanese encephalitis or dogs and cats e.g. rabies.

Direct contact

Some of these infections causing viral fever spread through direct contact with the infected person e.g. Varicella zoster virus causing chickenpox.

Contaminated surface

Some of these viruses causing viral fever may spread to you when you touch infected surfaces like door knobs, table surfaces e.g. Influenza virus and novel coronavirus.

Types of viral fever

Viral fever can be classified depending upon various characteristics of the fever. Following are the different types:

Depending on associated symptoms

Viral encephalitis

In these diseases patient has inflammation of brain surfaces called encephalitis. Associated symptoms are loss of consciousness, convulsions and loss of power in limbs. E.g. Japanese encephalitis, rabies, etc.

Viral haemorrhagic fever

In these diseases the clotting mechanism is damaged. Patients show symptoms of bleeding. E.g. dengue, Japanese encephalitis

Viral gastroenteritis

In these diseases symptoms of gastroenteritis like nausea, vomiting, loose motions are prominent. E.g. Rotavirus infection, norovirus infection


In these diseases liver has inflammation and jaundice with vomiting and loose motion are the main features. E.g. hepatitis A, hepatitis E


In these diseases small airways of the lungs are involved. They get inflamed and main features are difficulty in breathing, rapid breathing, cough etc.

Depending on duration

The viral fevers can be differentiated depending on the duration of symptoms. Most of the viral illnesses may present as short term infections.

Acute infection

These symptoms occur and last for some days. Within days the patient is fine or if severe may die.

Chronic infection

In these diseases patients may show symptoms for weeks to years. E.g. hepatitis B and HIV are chronic infections.

Depending on mode of spread

  • Air borne infection
  • Waterborne infection
  • Direct contact
  • From animals to humans
  • From humans to humans
  • Through contaminated surfaces

Depending on severity of symptoms

  • Mild viral infection
  • Severe viral fever

Symptoms of viral fever

In about paragraphs we have seen various causes of viral infections. Viral fever symptoms depend upon the underlying cause of infection. We will here first discuss the common symptoms occurring in these illnesses. These common symptoms are as follows:

  • Fever is the most common symptom in these illness. It can be mild grade fever and in some it can be moderate to severe grade.
  • Chills can be associated with fever, especially moderate to high grade fever and you may experience a feeling of cold and shivering.
  • Headache may occur and it can be mild to moderate grade. Generally occurs when fever is at its peak.
  • Body ache occurs with fever and presents as muscular pain or joint pains.
  • Loss of appetite is another common symptom and you may not feel like eating. Even your favourite food may feel tasteless and you can not enjoy it. Appetite may be normal when you are afebrile.
  • Fatigue is another common symptom and is maximum when fever is rising or is at its peak. Fatigue may improve when you are not febrile.
  • In children lethargy and irritability is maximum at the peak of fever and children become active and playful when there is no fever.
  • Children with a tendency of febrile convulsion may get generalised convulsion when fever is rising or decreasing.

Other symptoms are disease specific and they occur depending upon what disease you have. They may vary from very mild to very severe life threatening symptoms. They are as follows:

  • Vomiting and loose motion.
  • Sneezing, cough, running nose.
  • Throat pain.
  • Abdominal pain.
  • Difficulty in breathing, rapid breathing.
  • Loss of consciousness.
  • Convulsions.
  • Bleeding.
  • Jaundice.
  • Skin rash.
  • Conjunctivitis, red eyes.
  • Severe joint pain.

Tests needed for viral fever

Most viral fevers are mild and may not need any test if you have mild symptoms. Some diseases with associated moderate to severe infections may need tests for the confirmation of the diagnosis and detecting the underlying cause.

Urine examination

In this test urine biochemistry is examined and microscopy is done. This test helps in diagnosis of the urine infections and kidney diseases. It rules out causes of fever. 

Urine culture may detect the infections in urine in case of urinary tract infection.

Throat and nasal swabs

This test gives an idea about respiratory viral infections. In this test viral antigen is detected on swabs taken from the throat or nose. Tests which detect genetic material of specific viruses can be done on these swabs and viruses can be isolated with the help of viral cultures.

Blood tests

Various blood tests may be done depending upon the suspected cause of viral fever. Blood tests detect changes in body functions because of illness and also helps for detecting the cause of these changes.

Liver function test

This test can detect the presence of hepatitis indicated by increased bilirubin and liver enzyme levels. Further tests are needed depending upon findings to confirm the cause.

Renal function test

This test detects serum creatinine and blood urea level. Some viral infections like gastroenteritis may cause dehydration and electrolyte imbalance. This test detects serum sodium and potassium levels.

Serum antigen test

These tests help in detecting the presence of antigen in serum obtained from blood of the infected person. E.g. HBsAg in case of hepatitis B and NS1 antigen in case of dengue.

Serum antibody test

Serum antibody test helps to detect the antibody to viruses. They are ordered depending on the symptoms of the patients. E.g. anti HBs antibody, dengue IgG and IgG antibodies.

USG abdomen

With this test hepatosplenomegaly can be detected as in cases of viral hepatitis. This test also detects ascites that are collections of fluid in the abdomen. It detects urine infections like cystitis. USG abdomen helps to detect gallbladder and kidney stones.

X ray chest

Viral fever causing respiratory symptoms may need X ray chest for diagnosis of various conditions like pneumonia, pleural effusion, pneumothorax.

MRI brain

Viral fever with encephalitis may need an MRI brain. The pattern of involvement of brain indicated the possible cause. It also detects inflammation, tumour and infraction of the brain.

CSF examination

In this test the CSF fluid is collected from the lumbar region of the back. This test examines biochemistry and microscopy of the CSF. Additionally CSF culture can de done to detect possible cause. Virus isolation can be done from CSF for some diseases like Japanese encephalitis.

Please remember all these tests may not be needed in all the viral infections that are mild.

Home remedies for viral fever

Many viral fevers being mild, may get relief with home remedies. Following are a few home remedies that may help.

  • Sponging with wet cloth helps the body temperature to come to normal. Sponging should be done with water at room temperature. Do not spong if you are shivering.
  • Water is needed more in fever. Fever may cause you dehydration as your body’s demand for water is increased in fever. You should drink a lot of water.
  • Fruits and fruit juices contain a lot of water and you should eat them. They provide multiple vitamins and dietary fibres which help in digestion.
  • Adequate food should be taken in case of fever. Illness may reduce your appetite and you may not feel like eating. You should eat easily digestible food in small quantities frequently.
  • OTC medicines like paracetamol and ibuprofen may reduce your fever. You should take them in appropriate doses. 
  • You may feel fatigued by illness. You should take rest and do not do much physical activities and work. It helps your body to recover fastly. Avoid going in hot or excessively cold climate outside your house.

Treatment of viral fever

Apart from home remedies if you have severe symptoms you should rush to your doctor. Your doctor will examine you and will suggest your if tests are required and some medicines.

Viral fever is caused by multiple diseases and they may need specific treatment for them. We first see generalised treatment then will discuss specific treatments.

  • Maintaining hydration: Patients may get dehydrated because of reduced oral intake or ongoing fluid loss like in cases of loose motions and vomiting. If a patient is not able to drink an adequate amount of water, intravenous fluids should be given.
  • Antipyretics: These are drugs that reduce fever. Fever is protective and helps fighting infection but above certain limits it damages you. So fever should be decreased with medications. If a patient is not able to take orally they may need injectable medicines.
  • Antibiotics: They help to kill the bacteria that infect you. They do not work in viral infections. If you have any bacterial superinfection they may help you.
  • Other treatment depends upon symptoms like in cases of encephalitis patient may need anticonvulsants if convulsions.

Sharing Is Caring:

Leave a Reply