Health officials in Victoria, Australia have reported today on the fourth confirmed measles case, this case like the other three has no history of international travel and is considered acquired locally.
There is a risk of exposure to measles across metropolitan Melbourne and some parts of regional Victoria. Three of the cases were in the central business district of Melbourne between 10 — 13 June and this may represent the source of infection for those people. There are many other areas across metropolitan Melbourne where infections may have been acquired, and individuals have attended a range of public settings across Melbourne and in regional Victoria whilst infectious, including Shepparton.
Clinical features of measles include prodromal fever, a severe cough, conjunctivitis and coryza. Individuals, especially children, are typically unwell.
The most important clinical predictors are the following features:
- generalised, maculopapular rash, usually lasting three or more days, AND
- fever (at least 38°C, if measured) present at the time of rash onset, AND
- cough, coryza or conjunctivitis.
Measles is transmitted by airborne droplets and direct contact with discharges from respiratory mucous membranes of infected persons and less commonly, by articles freshly soiled with nose and throat secretions.
Measles is highly infectious and can persist in the environment for up to two hours.
The incubation period is variable and averages 10 days (range: 7 -18 days) from exposure to the onset of fever, with an average of 14 days from exposure to the onset of rash. The infectious period of patients with measles is roughly five days before, to four days after, the appearance of the rash.