Mumps

==Diagnosis==
In places where mumps is widespread, diagnosis can be made based on development of parotitis and history of exposure to someone with mumps. In places where mumps is less common, because parotitis has other causes, laboratory diagnosis may be needed to verify mumps infection.<ref name=who /> A differential diagnosis may be used to compare symptoms to other diseases, including allergic reaction, [[mastoiditis]], measles, and pediatric HIV infection and rubella.<ref name=davison /> MuV can be isolated from saliva, blood, the nasopharynx, salivary ducts,<ref name=cdc /> and seminal fluid within one week of the onset of symptoms,<ref name=davis /> as well as from [[cell culture]]s.<ref name=who /> In meningitis cases, MuV can be isolated from CSF.<ref name=junghanss /> In CNS cases, a [[lumbar puncture]] may be used to rule out other potential causes,<ref name=shu /> which shows normal opening pressure,<ref name=gupta /> more than ten [[leukocyte]]s per cubic millimeter, elevated lymphocyte count in CSF, polymorphonuclear leukocytes up to 25% of the time, often a mildly elevated protein level, and a slightly reduced CSF glucose to blood glucose ratio up to 30% of the time.<ref name=junghanss />

Mumps-specific IgM antibodies in serum or oral fluid specimens can be used to identify mumps. IgM quantities peak up to eight days after the onset of symptoms,<ref name=who /> and IgM can be measured by [[enzyme-linked immunosorbent assay]]s (ELISA) 7–10 days after the onset of symptoms. Sensitivity to IgM testing is variable, ranging from as low as 24–51%<ref name=davis /> to 75% in the first week and 100% thereafter.<ref name=gupta /> Throughout infection, IgM titres increase four-fold between the acute phase and recovery.<ref name=davis /> False negatives can occur in people previously infected or vaccinated, in which case a rise of serum IgG may be more useful for diagnosis. False positives can occur after infection of [[parainfluenza virus]]es{{nbs}}1 and 3 and [[Newcastle disease virus]] as well as recently after mumps vaccination.<ref name=cdc /><ref name=senanayake />

Antibody titers can also be measured with [[complement fixation test]]s, [[hemagglutination assay]]s, and neutralization tests.<ref name=junghanss /> In vaccinated people, antibody-based diagnosis can be difficult since IgM oftentimes cannot be detected in acute phase serum samples. In these instances, it is easier to identify MuV RNA from oral fluid, a throat swab, or urine.<ref name=who /> In meningitis cases, MuV-specific IgM can be found in CSF in half of cases, and IgG in a 30–90%, sometimes lasting for more than a year with increased white blood cell count. These findings are not associated with increased risk of long-term complications.<ref name=gupta /><ref name=senanayake /> Most parotitis cases have elevated white blood cell count in CSF.<ref name=junghanss />

Real-time [[reverse transcription polymerase chain reaction]] (rRT-PCR) can be used to detect MuV RNA from the first day symptoms appear, declining over the next 8–10 days.<ref name=who /> rRT-PCR of saliva is typically positive from 2–3 days before parotitis develops to 4–5 days after and has a sensitivity of about 70%.<ref name=senanayake /> Since MuV replicates in kidneys, viral culture and RNA detection in urine can be used for diagnosis up to two weeks after symptoms begin,<ref name=gupta /> though rRT-PCR used to identify the virus in urine has a very low sensitivity compared to virus cultures at below 30%.<ref name=senanayake /> In meningoencephalitis cases, a nested RT-PCR is able to detect MuV RNA in CSF up to two years after infection.<ref name=gupta />

In sialadenitis cases, imaging shows enlargement of the salivary glands, fat stranding, and thickening of the [[superficial cervical fascia]] and [[platysma muscle]]s, which are situated on the front side of the neck. If parotitis occurs only on one side, then detection of mumps-specific IgM antibodies, IgG titer, or PCR is required for diagnosis.<ref name=kessler /> In cases of pancreatitis, there may be elevated levels of [[lipase]] or [[amylase]], an enzyme found in saliva and the pancreas.<ref name=gupta /><ref name=junghanss /><ref>{{cite journal |vauthors=Skrha J, Stepan J, Sixtova E |title=Amylase isoenzymes in mumps |journal=Eur J Pediatr |volume=132 |issue=2 |pages=99–105 |date=October 1979 |doi=10.1007/BF00447376 |pmid=499265 |s2cid=28963086}}</ref><ref>{{cite web |url=http://www.labtestsonline.org.uk/understanding/analytes/amylase/test.html |title=Amylase Test |author=<!--Not stated--> |website=Lab Tests Online |access-date=30 October 2020 |archive-url=https://web.archive.org/web/20090329055737/http://www.labtestsonline.org.uk/understanding/analytes/amylase/test.html |archive-date=29 March 2009}}</ref>

Mumps orchitis is usually diagnosed by white blood cell count, with normal [[White blood cell differential|differential white blood cell]] counts. A [[complete blood count]] can show above or below average white blood cell count and an elevated [[C-reactive protein]] level. Urine analysis can exclude bacterial infections. If orchitis is present with normal urine analysis, negative urethral cultures, and negative midstream urine, then that can indicate mumps orchitis. Ultrasounds typically show diffuse hyper-vascularity, increased volume of the testes and epididymis, lower than usual [[Echogenicity|ability to return ultrasound signals]], swelling of the epididymis, and formation of [[hydrocele]]s. Echo color doppler ultrasound is more effective at detecting orchitis than ultrasound alone.<ref name=davis />