A Tour around Mumps
(Date of publication 08 October 2004)

How about this for a Trivial Pursuit question - "What is the origin of the word 'mumps'?" The answer can be found at one of the sites on this tour, but in the meantime, this picture will bring back painful memories for a fair proportion of the older readership.

Classically, mumps is an acute infection of one or both parotid salivary glands, although many other organs may become involved, including the sublingual or submandibular salivary glands, testes, pancreas and meninges. If you need to brush up on the relevant anatomy, there is a good structural diagram here. The salivary glands produce mucus and digestive enzymes in different proportions; the parotid secretes mainly enzymes, the sublingual mainly mucus, and the submandibular both - as is clear from their microscopic structure.

General information about mumps, previously common in childhood, is available on the eCureMe site. The highly contagious condition spreads via salivary and respiratory secretions, but is self-limiting, usually lasting 7 - 10 days. Sufferers experience fever, malaise, swelling of the affected gland and pain upon eating. According to the University of South Carolina (below measles on this page), 30% of cases are subclinical and the disease is primarily spread via these individuals. When infection is clinically apparent, sufferers are contagious from about 7 days before the onset of symptoms until about 9 days afterwards.

One of the most illuminating articles is at eMedicine. Among the interesting facts recounted here are that humans constitute the only reservoir for the mumps virus, meningitis occurs in about 10% of cases but is not usually severe, mortality is rare, and orchitis (inflammation of the testis) affects some 20 - 35% of post-pubertal male patients.

The paramyxovirus responsible is usually roughly spherical, with a diameter of about 200 nm, but may be much larger and pleomorphic. A lipid bilayer envelope encloses a helical nucleocapsid containing single-stranded RNA. The University of Cape Town has produced some very clear black and white images by transmission electron microscopy which demonstrate that the capsid has a 'herring-bone' appearance. If virology is a particular interest of yours, there is detailed information on morphology and replication here and here, but you really do need some background knowledge. Interestingly, the genome contains just 6 - 10 genes and there is only one invariant serotype.

Although the male:female ratio mumps victims is 1:1, three times as many males as females go on to develop viral - or aseptic - meningitis. The incidence drops with age; the younger the patient, the greater the risk. A significant number of meningitis cases are asymptomatic, but patients more commonly have fever, severe headache, stiff neck, sensitivity to bright lights, drowsiness and nausea. These symptoms usually last for 7 - 10 days and complete recovery follows. The associated mortality rate is less than 1% (excluding neonatal patients) and the morbidity rate is also low. Nevertheless, a degree of controversy exists about the long term effects in children, with some studies attributing learning difficulties, neuromuscular problems and deafness to viral meningitis.

Mumps is the most common cause of orchitis. Scrotal swelling, testicular pain, fever, swollen groin, discharge from the penis and pain on urination appear between 4 and 6 days after the onset of parotitis. In most cases the condition is unilateral. Around one third of males with the condition will suffer testicular atrophy, while infertility and sterility are also acknowledged consequences. Incidentally, some of the treatment described on this page (elevating the scrotum and applying ice packs to the affected area) sounds more appropriate to a very different sort of web site! The increased vascularity resulting from inflammation can be clearly seen in the ultrasound picture on this page and in the stained section here.

A rare but particularly serious complication of mumps is acute pancreatitis, which may be life-threatening. The main symptom is abdominal pain, often accompanied by a swollen and tender abdomen, nausea, vomiting and fever. Blood levels of the digestive enzymes amylase and lipase are characteristically increased by a factor of three or more. Many patients develop hypoxia as a result of breathing problems, and other complications include kidney failure and infection.

No tour of mumps would be complete without mention of the MMR vaccine and the controversy about possible links to bowel disease and autism. The NetDoctor site points out that over 500 million doses have been administered in more than 90 countries since the early 1970s, and that the World Health Organisation states that MMR is a highly effective vaccine with an excellent safety record. A safety review conducted by the US Institute of Medicine concluded that the evidence favours rejection of a causal link between MMR and autistic spectrum disorders (ASDs), but could not exclude the possibility of a contributory effect in a small number of children. The entire document can be read online. Only last month a UK study involving over 5,000 children ruled out any link between MMR and autism, and the topic is reviewed at some length in an article from Archives of Disease in Childhood.

Finally, the answer to the question at the start of the tour. For those who missed it, 'mumps' comes from the archaic English verb 'to mump', meaning to grimace or grin, and can be found on the University of South Carolina site. Useful....probably not!

Disclaimer

OnePharm Internet excludes any warranty, express or implied, as to the quality, accuracy, timeliness, completeness or fitness for a particular purpose of this briefing. OnePharm Internet will not be liable for any claims, penalties, losses, damages, costs, or expenses arising from the use of or inability to use this briefing or from any unauthorised access to or alteration of the Briefing. OnePharm Internet makes no warranty that the contents of this briefing are compatible with all computer systems and browsers.