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Enterovirus Infection


OVERVIEW OF Enterovirus Infection :

Enterovirus family includes a group of single stranded sense RNA viruses that commonly causes the infections especially in infants and children. They include varieties of clinical syndromes such as hand foot and mouth disease, herpangina , myocarditid, aseptic meningitis and pleurodynia.

The enteroviruses are classified into four subgroups: polioviruses, coxsackievirus A, coxsackievirus B, and echoviruses

The incubation period of the virus is 3-10 days.


CAUSES :

 Causes:

It spreads from human to human to contact. It includes spread from coughing, droplets, saliva, mucus from the nose or lungs, coughing, sneezing. Closed contact with the poop.

The disease caused by the virus:

Nonpolio viruses:

More than 90% of the infections which are caused by the nonpolio enterovirus are asymptomatic or it might leads to undifferentiated febrile illness.

 

Pleurodynia:

Group B coxsackie virus maily the B3 and B5 are the vital causes of the epidemic pleurodynia. It is characterized by the sudden onset of fever accompanied by the muscular pain in the chest and abdomen. The pain results in spasm which last for 15-30 minutes and it gets worsen by wheezing and coughing. Headache , nausea, vomiting and fever might accompany.

 

Myopericarditis:

Neonatal infections occur develop within the first week and the involvement is mainy pericardial. The typical signs and symptoms includes the shortness of breathe, chest apin and fever which lasts for 1-2 weeks following the upper respiratory tract infections. Chest pain may be dull or sharp and the pain is worsened by the inspiration and might improve with sitting and learning and leaning forward. The symptoms can be differentiated from angina by lack of response to nitroglycerin.

 

Enteroviral myocarditis can present as acute myocardial infarction associated with arrhythmias and heart failure. Some patients with myocardial infarction who have normal findings on coronary angiographic studies have been shown to have myocarditis by radiolabeled antimyosin antibody cardiac scanning. 

 

Aseptic meningitis:

The clinical symptoms include fever, chills, headache, photophobia, and nuchal rigidity. Rash and upper respiratory tract symptoms may also occur. In infants, fever and irritability are the most common symptoms.

 

Herpangina:

 Vesicular enanthem of the tonsillar fauces and soft palate appears. Vesicular eruptions which are painful is seen on the hard palate.  The posterior pharynx and tonsils may also be involved.  Most symptoms occurs in summer and symptoms might resolve within 3-4 days.

 

Encephalitis:

It is inflammatory reaction that is taking place in the brain. Clinical symptoms might include seizure, coma , lethargy, drowsiness.

 

Nonpoliovirus paralytic disease:

It can cause brainstem encephalitis, non cardiogenic pulmonary edema and unilateral oculomotor nerve palsy.

 

Hand foot and mouth disease:

Hand, foot, and mouth disease (HFMD) is a highly contagious infection. It’s caused by viruses from the Enterovirus genus, most commonly the coxsackievirus. The symptoms might include Abdominal pain and swelling ,  Diarrhoea , Loss of appetite ,  Nausea and vomiting , Sore throat with difficulty in swallowing, Swelling of the neck and neck glands.

 

 


PATHOPHYSIOLOGY :

The virus makes its entry into the oropharynx an dthen the virus replicated in the submuosal tissues of the distal pharynx and alimentary canal. the symptoms occurs when the virus particles are shed into the faeces and also when it makes it travels to the upper respiratory tract infections.  During the incubation period of the virus that is 3-10 days the virus migrated to the regional lymphoid tissues and then it replicates. Smaller amount of viraemia results which is associated with the onset of the viral symptoms and then the virus makes it  travel to the reticuloebdotheial system such as the spleen, liver, bone marrow. Spread of the virus to the distant organs and vital organs paves the way for the virus to reach the CNS(central nervous system).The major organ for it spread includes the skin and the CNS. They undergo higher rate of mutation during the replication process of the gastrointestinal tract. This lead to the prolonges excretion and neurovirulence. The nerves/neuronal destruction is mainly carried in the anterior horn of the spinal cord.

 

Immunity and immune response:

The humoral immunity plays a vital role in the control and eradication of the disease process. T lymphocytes do not help in the clearance of the disease. Humoral immunity (antibody mediated) mechanisms operate both in the alimentary tract to prevent the mucosal infection and in the blood to prevent the dissemination to the target organs.

Secretory immunoglobulin A (IgA) starts to appear in nasal and alimentary secretions within 2-4 weeks after the vaccination. The presence of IgA antibodies enhances the immunity.

Immunoglobulin M(IgM) antibodies appears as early as 1-3 days after the enterovirus exposure and it disappears after 2-3 months.

Immunoglobulin G (IgM) is generally detected 7-10 days after the infection and

Immunoglobulin G (IgG) antibodies appear as early as 1-3 days after enteroviral challenge and disappear after 2-3 months.  The subtypes of the infection includes IgG1 and IgG3 subtypes. Serum neutralizing IgG antibodies persists throughout the life after natural enterovirus infections.

Macrophage function is also a critical component of the immune response in enteroviral infections; ablation of macrophage function in experimental animals markedly enhances the severity of coxsackievirus B infections.

 


ROUTES OF TRANSMISSION :

Routes of transmission:

The main route of transmission is by faeco-oral route. The viruses such as coxsackie virus can also be spread by respiratory route. They are also shed in tears. Human to human contact is also possible with this type of virus.

 


COMMON CLINICAL SIGNS AND SYMPTOMS :

Often, people infected with non-polio enteroviruses have no symptoms, or they have only mild illness, like the common cold. Common signs of mild illness may include:

  • Fever
  • Runny nose
  • Sneezing
  • cough
  • sore throat
  • skin rashes
  • blisters
  • Body and muscle aches

 

Sometimes enterovirus infections can also cause:

  • viral conjunctivitis
  • Hand, foot, and mouth disease
  • viral meningitis(infection of the covering of the spinal cord and/or brain)
  • Viral encephalitis (infection of the brain)
  • myocarditis (infection of the heart)
  • pericarditis(infection of the sac around the heart)
  • Acute flaccid paralysis (a sudden onset of weakness in one or more arms or legs)
  • Inflammatory muscle disease (slow, progressive muscle weakness)

Infants and people with weakened immune systems are at greater risk of having these more serious complications.

 


DIAGNOSTIC :

Chest Xray:

The chest x ray predicts any abnormal area in the lungs

Computed tomography:

It reveals the slice of the lung. It uses both the combination of x ray and computer aided device.

It helps to analyse the size, shape and position of any lung tumour and also it helps in the detection of enlarged lymph nodes.

It also looks for any masses in the adrenal gland, liver, brain and other organs.

 CT guided needle Biopsy:

CT scan might be used to guide a biopsy needle into this  area to get the tissue for lung and further investigations are made.

MRI scan:

It uses the soft tissue image of the organ. It uses the both the magnet and radiowaves and aids in the view of soft tissues of the internal organs.

Immunosorbent assay- detect the virus specific IgM or IgG antibodies.

Greater than fourfold rise in titer between acute and convalescent sera  and  cerebo spinal fluid containing virus specific IgG or IgM or both are the diagnostic features.

 

Real-time polymerase chain reaction (RT-PCR)- is valuable in the early confirmation of arbovirus infections, particularly chikungunya. However, the value of RT-PCR is limited to diagnosis in the viraemic phase, with later infection requiring serology.

 

Direct immunofluorescence assay -to detect chikungunya IgM has a high sensitivity and specificity and is used in the latter stages.However, the use of these tests in the tropics may be limited by financial constraints.

 

A normal erythrocyte sedimentation rate-  it is defined as the rate of red blood cell which are termed as erythrocytes and their deposition or sedimentation rate. The normal erythrocyte sedimentation rate is 0-22mm/hr.

 Echocardiogram:

It is used to find the movements of the heart.

Electrocardiogram:

It is used to find the electrical impulses of the heart.

Lumbar puncture or spinal tap:

 The fluid is drawn from the spinal cord and further investigations are made.

 

Virus culture:

The body fluids such as saliva, mucus, urine and sputum are collected and they are sent to the laboratory for investigations.


TREATMENT AND PROGNOSIS :

Medicines used:

No antiviral medications are in current use for the enterovirus infection.

Antipyretics such as acetaminophen can be used to relieve the symptoms.

 


PROGNOSIS :

More than 90% of the non polio enteroviruses are asymptomatic .  The mortality rate for cardiovascular disease is 0-4 %.


PREVENTION :

Washing hands carefully with soap and water after contact with the blister-like lesions, after handling nose and throat discharges, and after contact with faeces such as with toileting and nappy changing.

Using separate eating and drinking utensils.

Avoid sharing items of personal hygiene (e.g. towels, washers and toothbrushes) and clothing (particularly shoes and socks).

Thoroughly wash and clean any soiled clothing and surfaces or toys that may have been contaminated.

Teach children about cough and sneeze etiquette, immediate disposal of tissues, and to wash hands afterwards.


REFERENCE :

https://www.everydayhealth.com/enterovirus/guide/

https://emedicine.medscape.com/article/217146-overview#a6

https://emedicine.medscape.com/article/217146-followup#e3