What is the relationship between orchitis and parotitis?

Relationship Between Orchitis and Parotitis

Orchitis is a well-established complication of mumps infection, occurring in up to 38% of postpubertal males who develop mumps, with parotitis typically preceding orchitis by an average of 10 days. 1

The Mumps Connection

The relationship between orchitis and parotitis is fundamentally rooted in mumps virus pathophysiology:

• Mumps virus demonstrates specific tropism for both salivary glands (causing parotitis) and gonads (causing orchitis), making these two manifestations part of the same systemic viral infection 2
• Parotitis precedes orchitis in approximately 82-90% of cases, with the testicular inflammation typically developing 4-11 days after the onset of parotid gland swelling 3, 4
• However, orchitis can occur without preceding parotitis - clinicians must recognize that epididymo-orchitis may be secondary to mumps infection even with no history or clinical evidence of parotitis 4

Clinical Presentation Pattern

The typical sequence of mumps-related orchitis follows a predictable pattern:

• Initial phase: Bilateral or unilateral parotitis develops 16-18 days after mumps virus exposure, often preceded by fever, headache, malaise, myalgia, and anorexia 1
• Orchitis phase: Testicular inflammation develops approximately 10 days after parotitis onset in postpubertal males, presenting with marked scrotal swelling, testicular pain, and fever typically above 38.5°C 3
• Only 60-70% of mumps infections actually produce parotitis, while 15-20% are asymptomatic and up to 50% present with nonspecific respiratory symptoms 2

Important Clinical Caveats

Several critical points warrant emphasis:

• Serious complications of mumps, including orchitis, can occur without evidence of parotitis 1
• The incidence of orchitis increases dramatically after puberty - it affects up to 38% of postpubertal males with mumps but is rare in prepubertal boys 1
• Bilateral orchitis occurs in approximately 12% of orchitis cases (3 of 25 patients in one series), which carries higher risk for fertility complications 3, 4
• Sterility from mumps orchitis is thought to occur only rarely despite the high incidence of orchitis, though testicular atrophy can develop in affected testes 1

Diagnostic Approach

When evaluating a patient with orchitis:

• Obtain detailed history of parotitis or mumps exposure in the preceding 4-11 days, recognizing that absence of parotitis does not exclude mumps as the etiology 3, 4
• Viral orchitis is most frequently ascribed to mumps virus, diagnosed by IgM serology for mumps antibodies or acute and convalescent IgG serology 1
• Consider other viral causes including Coxsackie virus, rubella virus, Epstein-Barr virus, and varicella zoster virus if mumps serology is negative 1
• In men <35 years, sexually transmitted pathogens (Chlamydia trachomatis and Neisseria gonorrhoeae) are more common causes of epididymitis/orchitis than viral etiologies 1

Vaccination Impact

The relationship between parotitis and orchitis has important prevention implications:

• MMR vaccination reduces both the incidence and severity of mumps disease, including orchitis 5
• Two-dose MMR vaccine effectiveness is approximately 88%, though breakthrough infections can still occur 6, 2
• Unvaccinated postpubertal males face a 40% risk of orchitis if they contract mumps, making vaccination critical for preserving future fertility 4
• Parents should be counseled that failing to immunize their children threatens the future fertility of their sons 4