US health officials are warning travellers they may have been exposed to measles after three infected children arriving from New Zealand visited two states.
In a statement on Monday, the Los Angeles County Department of Public Health said it was investigating three cases involving non-residents.
The LA department said the three of them had gone through Los Angeles International Airport (LAX), and warned that others present at the time may be at risk.
The risk involves those present at Terminal 4 and 5 on 11 December, between 6.50am and 12pm.
On the same day, Denver's Tri-County Health Department released a statement saying three children visiting Colorado from another state tested positive for measles "after travelling to a country with an ongoing measles outbreak".
The department said people who were at Denver International Airport on 11 December or the Anschutz Campus Emergency Department on 12 December may have been exposed to measles.
The children are now being treated at Children's Hospital Colorado.
The Denver Post on Tuesday reported federal health officials confirmed the children were travelling from New Zealand to LAX before arriving in Denver last week.
New Zealand has been dealing with its own outbreak of the disease, and earlier this month the Ministry of Foreign Affairs and Trade (MFAT) confirmed it was the likely source of Samoa's epidemic, which has left 76 people dead so far.
LA's public health department said there have been 20 measles cases among residents in 2019, as well as 14 non-resident cases that travelled through the region.
"The majority of cases to date were unimmunized or did not know whether they had ever been immunized."
Measles facts and what you need to know
- Measles is a highly-infectious viral illness spread by contact with respiratory secretions through coughing and sneezing.
- People are infectious from five days before the onset of the rash to five days after the rash starts.
- Infected persons should stay in isolation - staying home from school or work - during this time.
- The best protection from measles is to have two MMR vaccinations. MMR is available from your family practice and is free to eligible persons.
- People are considered immune if they have received two doses of MMR vaccine, have had a measles illness previously, or were born before 1969.
- Anyone believing they have been exposed to measles or exhibiting symptoms, should not go to the ED or after hours' clinic or general practitioner. Instead, call the GP first.