Mumps is predominantly a childhood disease with a high rate of subclinical infection. It is caused by a paramyxoiurus. It is spread by droplet infection, by direct contact or through fomites Humans are the only known natural hosts. Mumps is characterized by Inflammation of salivary glands, and less frequently, of testis, meninges, and pancreas.
STRUCTURE AND COMPOSITION OF MUMPS VIRUS
Mumps virus belongs to the famity Paramyxoviridae. Like other paramyxovimses, it is composed of singlestranded RNA genome. The molecular weight of RNA is 5 to 6 x 106 .The genome is of negative configuration. The genome is surrounded by a nudeocapsid that has a helical symmetry. Surrounding the nucleocapsid is the viral envelope derived from the host cell. There are two glycoprotein on the surface at the envelope: a glycoprotein mediating neuraminidase and hemagglutinin activity, and the other gtycoprotein is responsible for cell fusion and hemolysis.
Mumps virus can be cultivated in embryonated hen eggs; after several passages in eggs the virus loses it virulence for man and monkey. There is only one antigenic type of this virus. The immunity developed during infection is life long.
PATHOGENESIS
Mumps is primarily a disease of school-aged children and young adults, though there is no age exempt. It is spread by droplet infection. The virus is transmitted via saliva on respiratory secretions and enters the host via the Upper Respiratory Tract. After initial entry the virus replicates totally in the upper respiratory tract and local tymph nodes, Replication is followed by viremia that leads to the dissemination of virus to the target tissues such as salivary glands, kidney, or CNS. It is noteworthy that viremic condition develops several days prior to the onset of the clinical symptoms. It is possible that the virus will initiate its replication in the target tissues followed by a second phase of viremia.
CLINICAL MANIFESTATIONS
The incubation period averages 18 days, range being 12-29 days. The prodromal symptoms are nonspecific and include fever, malaise headache and anorexia. This is followed by acute onset of pain and swelling in one or both parotid glands. The swelling reaches a maximum in 2 or 3 days and then subsides. The enlarged parotid glands obscure the angle of the mandible and may elevate the ear lobe. Trismus due to pain is common at this stage. Occasionally other organs, such as the thyroid glands, may be involved. Orchitis is very rare.
COMPLICATIONS
A number of complications may arise in a patient of mumps. Some of the important complications are given in the following.
* CNS. Involvement of the CNS is the most common extrasalivary gland manifestation of mumps. Clinical meningitis, encephalitis, myelitis, and polyneuritis are some of the complications of CNS.
* Urogenital system. Epididymitis and orchitis may develop in one third of mumps cases. Bilateral testicular involvement results in sterility in a few of these patients. A very rare complication is the involvement of the ovarian glands leading to oophoritis.
* Pancreas. Mumps virus can involve pancreas of the patient causing pancreatitis. This complication is recognized by abdominal pain and vomiting.
* Other complications. Myocarditis, nephritis, matatitis, hepatitis, arthritis, thyroiditis, thrombocytopenic purpura, polyarthritis, and pneumonia may also occur.
IMMUNITY
Immunity against mumps is dependent upon the development of specific antibodies in response of viral surface antigens. The antibodies appear between 2 to 3 weeks after the onset of disease, reaching maximum titers by 4 to 6 weeks. These antibodies provide a life long immunity. The role of cell-mediated immunity is not well documented.
LABORATORY DIAGNOSIS
Diagnosis of mumps is based solely on the clinical features. However, laboratory diagnosis can be performed by isolating mumps virus from the saliva, throat swab, urine, and cerebrospinal fluid. The inoculations can be made on susceptible cell cultures. Viral antigens in infected cultures can be detected by immunofluorescence or hemadsorption. Serologic diagnosis is based on the demonstration of a fourfold rise in complement fixing antibodies by complement fixation or hemaggiutination inhibition tests. For this purpose soluble nucleocapsid (S)
antigen and viral antigen (V) of envelope are used.
THERAPY
There is no specific chemotherapy available tor mumps infection. Attention should be given to adequate nutrition and mouth care. Analgesic should be used to relieve the pain.
PREVENTION
Mumps infections can be effectively prevented by active immunization . Mumps Iive virus vaccine is highly recommended for immunizing children. This vaccine is also available in combination with measles and rubella vaccines in MMR vaccine. The vaccine should not be used in immunosuppressed individuals, during pregnancy, or in those with febrile illness. lmmunity developed as a result of vaccination is lifelong.
