Leukemia (Blood Cancer)

 

Mumps is a disease caused by the mumps virus, which is a member of the paramyxoviridae family. This is actually a large family of viruses which includes measles virus and parainfluenza viruses, and all of these tend to affect children the most. Mumps only affects humans and is spread by tiny respiratory droplets that are small enough to be carried short distances in the air, so the mumps virus is extremely contagious and anyone near a person with mumps is at risk for getting the disease as well.

The mumps virus has a single strand of RNA and a viral polymerase enzyme surrounded by a phospholipid bilayer envelope studded with viral proteins hemagglutinin-neuraminidase, or HN protein, and fusion or F protein. The HN protein allows the virus to stick to a potential host cell, cut itself loose if necessary, and the F-protein fuses the viral and cell membranes together, allowing the mumps virus to enter the cell. Once mumps enters a cell, the single-stranded RNA, which is a negative sense, gets transcribed by the viral polymerase enzyme, into a complementary positive sense strand of mRNA, which can then be translated by the host cell ribosomes into new copies of the envelope proteins and the viral polymerase, which get assembled into new viruses.

What also ends up happening with these, though, is that those HN and F-proteins on the cell surface now bind other cells, so they actually end up binding epithelial cells to one another, which forms a clump of connected cells called a multinucleated giant cell or a syncytium. Mumps enters the body and first infect the epithelial cells of the nasopharynx, where it starts replicating and causing local damage to the tissue. From there, it can cause viremia or virus in the blood, and reach various organs and tissues.

The mumps virus has tropism, or preference for, the parotid salivary glands, and the most classic finding in mumps is swelling of parotid salivary glands either on one side or on both sides, sometimes with an associated earache. The swollen parotid gland lifts the earlobe up and out and obscures the angle of the jaw, and can sometimes cause trismus which is a spasm of the muscles of mastication or chewing. Mumps also has an affinity for the central nervous system and can cause meningitis, which is an infection of the lining of the brain, as well as encephalitis, which is an infection of the brain tissue itself.

These infections can cause symptoms ranging from those that feel like the common cold, like headache and neck stiffness, as well to more severe symptoms like difficulty with balance and hearing loss, but in general, the infection is self-limited and symptoms go away as the body recovers. In boys, usually adolescents and young men, mumps can infect the testicles and epididymis, and cause orchitis and epididymitis, respectively, most often on just one side. This can cause testicular atrophy in some men, as well as a decrease in sperm count and sperm motility, but rarely does this cause infertility. Less commonly, mumps can infect the kidneys, and cause glomerulonephritis, which eventually leads to hematuria and proteinuria—blood and urine in the urine. It can also affect the joints, causing arthritis, usually in the large joints like the hips, knees, ankles, and shoulders. And it can affect the heart causing myocarditis, as well as the pancreas, causing pancreatitis. As a final note, pregnant women with mumps are not at an increased risk of having a baby with congenital defects.

Alright, like a lot of other viruses, diagnosis is done by looking at antibody titers, though for treatment there aren’t any effective antivirals for mumps. For prevention, Individuals with mumps, particularly young children, are usually kept isolated for 5 days after the onset of symptoms to prevent it from spreading. Best of all for prevention, though, is the mumps vaccine which is about 90% effective at preventing the disease in the first place. The vaccine is a live attenuated vaccine, which means that it’s a weakened mumps virus that is not infectious but still stimulates the immune system to generate a solid response to prevent future infection from the actual wild-type mumps virus. The mumps vaccine has reduced the occurrence of mumps dramatically, with outbreaks happening most often in areas where children aren’t vaccinated.

Alright, as a quick review, mumps is very contagious and spread through the air by respiratory droplets, and most classically infects the salivary parotid glands, causing them to become swollen, but can also cause meningitis, encephalitis, orchitis, and epididymitis. Luckily, there is a mumps vaccine that is safe and effective in preventing nearly 90% of cases.

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