Paramyxo viruses (Mumps)

Paramixo virus includes:

• Mumps
• Measles
• Human parainfluenza
• Respiratory virus

Mumps

Classification

Family: paramyxoviral

Subfamily: paramaxovininae

Genus: paramyxovirus

General properties

• It is a stable virus, so we can develop measles, mumps, and rubella (MMR) vaccine.
• It is stable because it consists single stranded ss (negative sense) RNA i.e. un-segmented nucleic acid. So it doesn't cause recombination.
• Sometimes variation in a virus is due to mutation.
• If recombination has occurred, new strains may form.
• These are respiratory pathogens transmit through aerosols, droplet.
• It infects their host by a primary interaction of host cell receptor and by virus-encoded glycoprotein.
• Firstly glycoprotein present in lipid layers fuses with host cell receptors in the cell membrane which then causes infections.
• The outcome of this disease is syncytia formation or cell lysis or both.
• Syncytia formation leads to cell death and so form giant nucleus with a combination.

Morphology

• Size ranges from 150-400nm.
• Spherical and with lipid envelope which is formed by plasma membrane of a host cell.
• Lipid layer surrounds the ssRNA negative sense generated through the plasma membrane of a host cell.

Chemical properties

• All consists single strand RNA.
• Its chemical composition is proteins (69-74%), outer layer lipid of about (20-25%) and carbohydrate of about (5-6%).
• This is an infectious virus which can be removed by chemical and physical means.
• The chemical which ruptures the lipid layer of virus are:

i Organic solvent

ii Detergent

iii Formaldehyde

iv Oxidizing agents

The physical ways to rupture virus are:

i UV rays

ii Heating

iii Drying

Genomic Structure

• It consists of single stranded unsegmented RNA, negative sense (no direct function of mRNA).
• This RNA is surrounded by helical nucleocapsid.

Clinical manifestation of mumps

• One of the very much infection and occur childhood death.
• About 80% of a child (5-10 years) infected by mumps.
• When vaccine develops, rate decreases.
• Generally, paratitis that is swelling of the parotid gland.
• About 2-3 weeks after infection there is an onset of a system.
• This is systemic infection (which causes various part)
• The incubation period is 2-3 weeks.
• About 30% of infections are unsymptomatic.
• First symptoms are fever, myalgia (muscle pain) and malaise (vomit, pain) followed by paratitis.
• Paratitis is bilateral and diffuse and about 10 days it resolves itself.
• It also causes meningitis, myocardial heart disease and also kidney problem.
• Since it affects the meningitis of brain, so we can isolate virus from CSF.
• Before the vaccine, measles may cause encephalitis.
• Orchitis (swelling of testis) occurs in a male about 25% as a symptom of measles infection.
• Oophoritis (swelling of the ovary) occurs in 5% of female patients due to measles.
• Due to this virus, it may cause less production of semen from testis but no un sterility.
• From respiratory fluid, CSF and urine, renal system and cardiac system.
• It also causes a kidney infection and leads to decrease in globular filtrations and increase in protein in the urine.
• It is also associated with ECG, Myocardia, electro-cardiac glands.
• Some patients may loss hearing capacity due to measles.

Symptoms of mumps virus

Mumps is more severe in adults and it seems that cell-mediated immunity is important in recovery.

• Fever

• Meningitis:

In symptomatic meningitis, it causes stiffness of neck and headache which usually resolves in up to 10 days. .Aseptic meningitis is usually mild. In about half of patients, the meningitis is asymptomatic.

• Parotitis:

This is the most common feature of mumps causing pain and swelling of persists for 7 - 10 days. It may be unilateral or bilateral depending on which salivary glands.

• Deafness:

It is usually unilateral. Deafness is a leading problem caused by the mumps virus. Deafness may improve with time but is usually permanent.

• Orchitis:

it is the condition of inflammation of testicular in a male. Sometimes, it occurs along with parotitis. It is unilateral.

• Pancreatitis:

This is an infrequent side effect of mumps.

• Rare complications:

These include nephritis, arthralgia (joint pain) and arthritis (joint inflammation)

Epidemiology of mumps

• About 80% has an infection before vaccination.
• In rural area endemic mumps.
• About 2-7 years, there will be outbreaks of mumps in rural.
• In an urban area, it is endemic diseases.
• In 1968, 150,000 cases in US and 1993 this rate decrease and seen in 1692 patients due to an effectiveness of Mumps virus.
• Generally, MMR vaccine is used.
• If vaccine also, some patients can get mumps due to a failure of primary or secondary vaccination.

Pathology and pathogenesis

• It is systemic disease causing pancreatic infection, meningitis, myocardium and renal infection.
• Transmitted through respiratory secretion.
• Illness begins about 2-3 weeks of infection.
• Then, a virus can be isolated from a sample before 5-6 days of onset of symptoms or after 5-6 days it subsite itself.
• The virus can be isolated from blood, urine, CSF and respiratory excretory.
• Swelling of paratid, it causes viremia (virus in all part of body)
• It causes the inflammation, this cytophatic effect of virus and inflammation (due to immunity response of our body)
• After vaccine or infection, our body produce antibody i.e. IgA, IgG, and IgM.
• This antibody has memory cells so no cause reinfection because it destroys the antigen.
• Cellular immunity (T and B cells) protect from long term disease.
• But reinfection is a rare case.

Diagnosis

Diagnosis is done by the following process:

1. Antigen detection: it is done by immunology process such as immunofluorescent Assay, electrophoretic immunoassay (EIA).
2. Antibody detection: Isolate of virus up to 12 days of symptoms
3. Haemagglutination inhibition test
4. Complement fixation test
5. Neutral infection
6. Cell culture: Cell culture is done by a different technique such as Primary monkey kidney cell, Human embryonic kidney cell these gives the best result for isolation of mumps virus and other culture techniques are Human fibers test, Hep-2 cell, Hela cell, etc.

Prophylaxis and treatment

• Live virus vaccine
• Killed virus vaccine but not effective as live
• Vaccine-induced about 90% response against an antigen.

Prevention

• The attenuated vaccine virus, which is made in chick embryo fibroblasts, does not spread to contacts and gives long-term immunity.
• The vaccine usually contains three live, attenuated viruses:mumps,measles, and rubella which is given as MMR vaccine.
• It is usually as single virus preparation or may also be given as combined with the rubella vaccine.
• Normally, two doses separated by four weeks are recommended for children more than one year of age.
• Some people who have severe allergic reactions after a previous mumps vaccination should not receive the MMR vaccine.
• By the use of organic solvents such as chloroform and ether the virus is rapidly inactivated and also using physical means i.e. UV light and formaldehyde.

Treatment

There is no any specific treatment for mumps.

REFERENCE

Cheesbrough, M.Medical Laboratory Manual for Tropical Countries. Vol 2. ELBS London, 2007.

Tille, P.Diagnostic Microbiology.13th. Elsevier, 2014.

D Grenwood, Slack RCB, and Peutherer J.Medical Microbiology.Dunclude Livingstone: ELBS, 2001.