The United States is on high alert after yellow fever in rural Brazil turns into an outbreak. Yellow fever in the country has now claimed the lives of 220 people and the number could still rise over time. With international travel more accessible and more frequent than ever, travel-related cases of yellow fever may happen in the U.S.

Experts say that the yellow fever outbreak in Brazil could spread just like the way Zika virus did, CNN reported. Zika started in Brazil in 2015 and has spread to about 60 countries. The United States also had the worst Zika outbreak with Florida being the most affected. The yellow fever in Brazil started in December 2016 and reports said that the very first victims were from the rural areas of the country along the states of Espirito Santo, Sao Paulo and Mina Gerais.

According to the Pan American Health Organization, there are 326 confirmed cases of yellow fever in Brazil with 916 suspected cases. The PAHO also said that the fatality rate is around 33% for confirmed cases and 11% for suspected cases. Aside from areas in rural Brazil, there are clustered cases in Rio de Janeiro which is the busiest and the most highly-populated city in the country.

Although there is a vaccine for yellow fever it is not given as a routine vaccination program in Brazil, the Pittsburgh Post-Gazette reported. With the recent outbreak, Brazilians health workers are now urging people to get vaccinated right away. Officials also said that they are worried about infected people coming from the jungles of Brazil. These people are infected by jungle-dwelling mosquito species and may travel to the city and spread the virus.

The Word Health Organization and the Centers for Disease Control and Prevention are closely monitoring the outbreak. According to officials, the entire state of Espirito Santo has been considered for yellow fever transmission. CDC reiterated the importance of quickly detecting and controlling outbreaks to reduce the illness, death and prevent the spread of the disease to other regions.