Mumps is an infectious disease commonly affecting children and characterized by non- supparative (without formation of pus) enlargement of the parotid glands (the salivary glands below the ears). The genus Paramyxovirus contains the mumps virus, which is an exclusive human pathogen.
The mumps virus possesses hemagglutinin (H), neuraminidase (N) and fusion protein (F) which are essential for their infectivity. The virus is antigenically stable and have two complement fixing antigens- the soluble (S) antigen and the ‘viral’ antigen (V).
The virus is labile, but can be easily deactivated at room temperature, exposure to formaldehyde, ether, or UV. It can be preserved by lyophilization or at -70oC.
Infection can be acquired by inhalation, and through the conjunctiva. The incubation period is about 12 – 25 days. The virus replicates in the upper respiratory tract and lymph nodes. From there, it gets disseminated through the bloodstream to various organs.
The first sign of the disease is the swelling of the parotid gland with general tiredness. First swelling occurs only on one side, later developing to the other side also. Usually accompanied by fever, local pain and tenderness. The swelling is not with pus formation, and subsides within a week.
In certain cases of post- pubertal males, the testis become swollen and acutely painful. Fever and chills may follow. Orchitis is the serious condition that may follow. It causes inflammation of the testis and the penis becomes heavier. This may result in low sperm count and even sterility.
The central nervous system is affected in some, showing symptoms of meningitis. Mumps meningitis and meningoencephalitis may resolve naturally, but may lead to deafness. Other less complications include, arthritis, nephritis, pancreatitis, thyroiditis and myocarditis.
Epidemiology
1. Mumps is an endemic disease and is less common in advanced nations due to immunization.
2. It is common among children between 5 - 15 years.
3. More prevalent in areas like army camps, where people live in groups.
4. Household spread is also common.
5. Humans are the only natural host.
6. A patient is the best source of infection.
7. No human carriers or reservoirs exist.
Infection is spread through direct contact, air droplets or fomites contaminated with urine or saliva. The infectivity attains its peak a day or two before parotitis becomes evident. The virus is also shed through urine for up to 2 weeks after the clinical symptoms begin.
One attack of mumps confers almost life long immunity, so chances of second time infection are rare. Cell mediated immunity is developed following infection.
The diagnosis may be established by isolation of the virus and other serological tests. Isolation may be from saliva, urine or CSF. Culturing may be done in monkey kidney cell cultures. Human amnion or HeLa cells are also suitable. It may take about 1- 2 weeks for its growth.
Complement fixation and hemaglutination tests are commonly employed. IgM- ELISA is useful as it prevents cross reactions.
A subcutaneous injection of the combination vaccine with MMR is given. It provides protection for about a year. No specific treatment can be prescribed, only pain relievers can be provided to relieve the tenderness and swelling of the glands.
