Patient in Denmark tests positive for the Zika virus

The mosquito-borne Zika virus will likely spread across South America, Central America and North America, according to a new warning from the World Health Organization.

A health worker stands in the Sambadrome as he sprays insecticide to combat the Aedes aegypti mosquitoes that transmits the Zika virus in Rio de Janeiro, Brazil, Tuesday, Jan. 26, 2016. There is no vaccine or treatment for Zika, a close cousin of dengue and chikungunya, which causes mild fever and rash.

With Carnival celebrations just over a week away and the Olympic Games set for Rio de Janeiro in August, Brazil is poised to receive hundreds of thousands of visitors in the coming months, adding to concerns over the spread of the virus.

The CDC is advising pregnant women to reconsider travel to Brazil and 21 other countries and territories with Zika outbreaks.

US airline United Airlines also said this week it was allowing customers with reserved tickets for travel to impacted regions to postpone their trips or obtain refunds with no penalty. For example, it is not clear how common Zika infections are in pregnant women, or when during a pregnancy a woman is most at risk of transmitting the virus to her fetus. Zika infections usually do not have symptoms-but that is part of the worry say health experts. Scientists who have studied the disease say that it is unlikely that the United States will see a mass outbreak like the one in Brazil, which has been hardest hit by the virus, linked to more than 3,800 cases of microcephaly.

The ministry said laboratories are trying to determine a link between the Zika virus and microcephaly, which also can be caused by factors such as herpes, rubella and syphilis.

On Monday, officials in Arkansas confirmed a resident tested positive for the Zika virus.

The guidelines for testing infants affected by Zika infections follows CDC guidelines for caring for pregnant women exposed to Zika virus, which were first reported by Reuters.

Danish hospital officials say a Danish tourist has been infected by the Zika virus after visiting southern and central America.

A Zika virus case was also confirmed in Sweden last summer, said Sara Rorbecker of the Swedish Public Health Agency.

Health Minister Alejandro Gaviria visited the city of Ibague, a hotbed of Zika, to start a “Tour of Colombia” campaign to educate local officials on how to fight the mosquitoes.

The man in his mid-twenties suffered fever, headaches and muscle pain and was tested in the University Hospital in Denmark’s second biggest city Aarhus on Tuesday, Professor Lars Ostergaard said.

There hospital released no further details about the patient but it says that there is little risk of it spreading in Denmark because the mosquito carrying the virus isn’t found in the country.