The British government has made a public request asking all airlines flying from Zika-affected areas to spray their planes with insecticide before coming back to the U.K.

"Spraying insecticide is a highly precautionary measure to reduce the risk to passengers during flights to the U.K.," the British public health minister Jane Ellison said in a statement.

The mosquito-borne Zika virus has spread to roughly 30 countries and territories in the Americas, and the World Health Organization expects that millions of people will be infected this year. A number of travelers coming back from these areas have contracted the virus.

Most people with the virus have no symptoms, or experience only mild symptoms like fever, headache and rash. However, the World Health Organization declared Zika was a "public health emergency of international concern" because it has been linked to severe birth abnormalities.

Some pregnant women infected with the virus have given birth to babies with microcephaly, a disorder which leads to severe developmental issues and can be fatal.

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The government's insecticide request shouldn't be difficult for airlines to accommodate, since many airlines flying from the region to the U.K. already use insecticide to protect passengers against malaria.

France, South Africa and a number of other nations require some inbound flights to use insecticide before takeoff. It's more unusual for flights in the U.S. to do so.

Flight attendants generally spray insecticide throughout the cabin after passengers have boarded the plane and the doors have been shut.

"It's just a straightforward part of the journey," said a British Airways spokesperson.

Spain's minister of health confirmed on Thursday that six people in the country were infected with the virus after traveling to Zika-affected areas.

According to the World Health Organization, Pan American Health Organization and the Centers for Disease Control, the Zika virus is currently circulating in the following countries and territories: Barbados, Bolivia, Brazil, Colombia, Puerto Rico, Costa Rica, Curacao, Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Mexico, Nicaragua, Panama, Paraguay, Saint Martin, Suriname, U.S. Virgin Islands, American Samoa, Samoa, Tonga and Cape Verde.