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.
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:
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.
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:
Sometimes enterovirus infections can also cause:
Infants and people with weakened immune systems are at greater risk of having these more serious complications.
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.
More than 90% of the non polio enteroviruses are asymptomatic . The mortality rate for cardiovascular disease is 0-4 %.
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.
