The pathophysiology of rubella is not completely understood. Viral replication in the respiratory epithelium occurs following transmission of the virus via contact with droplet secretions from an infected person. Viremia subsequently ensues, with the onset of the rubella rash occurring at the peak of viremia.^[1][2]

• Rubella is transmitted primarily through direct or droplet contact with nasopharyngeal secretions of infected persons.
• Humans are the only natural host.
• Rubella infection usually occur during late winter and early spring.
• The average incubation period of rubella virus is 17 days, with a range of 12 to 23 days.
• People infected with rubella are most contagious when the rash is erupting.

The pathophysiology of rubella infection is not fully understood.^[1] The pathophysiology of rubella infection involves the following processes:^[1][2][3]

• The transmission of infection is via person-person spread through droplets that are shed from respiratory secretions of infected persons.
• Viral replication occurs in the respiratory epithelium, with subsequent spread of the virus to the regional lymph nodes.
• Viremia ensues and subsequent seeding of viremia to multiple organs may occur (including the placenta in pregnant women, which results in congenital rubella syndrome).
• The onset of viremia is usually between 8-9 days after exposure, peaking at 10-17 days.
• The onset of rash often occurs 16-18 days after exposure (around the peak of viremia).
• Approximately 10 days after infection, viral shedding from the nasopharynx begins.
• Viral shedding may continue 1 week before the rash appears to about 5-14 days after the disappearance of the rash.
• The infected patient is contagious 5 days before the onset of the rash to 6 days after the appearance of the rash.