BUENOS AIRES , Argentina ( CNN ) -- Argentinians planning to travel to the northern part of the country , Brazil and Paraguay were lining up for vaccinations Tuesday , because of a yellow fever breakout that has killed at least 21 people in the region . An Argentinian man receives a vaccination in Buenos Aires , Argentina . Public health officials recommend that anyone planning to travel to an affected area get the vaccine -- which is effective for a decade -- 10 days before arriving . Concern in Argentina began last month , when health authorities reported finding 17 dead monkeys in Pinalito Park , in the San Pedro Department of Misiones Province . Tests showed they had died of yellow fever . But the Ministry of Health 's Dr. Hugo Fernandez pointed out that the last documented case of yellow fever among people in Argentina was in 1841 . `` What we have had until now is death in monkeys from the transmission of the virus , '' he said . `` That put us on alert , and we have put in place all the necessary controls since January of this year . '' Watch residents line up for the vaccines » . The Ministry of Health recommended that residents and travelers to the `` high-alert '' area in northern Argentina , near the borders of Brazil , Bolivia and Paraguay , also receive the vaccine . On Monday , Paraguay 's Ministry of Health and Social Welfare confirmed 16 cases , eight of them fatal , in two areas in the center of the country -- San Pedro Department and Central Department . Brazil had tallied 13 deaths , the country 's Ministry of Health said . As of Saturday , more than half of the 2 million vaccine doses obtained by Paraguay from the World Health Organization had been administered , the government said . A team from the WHO 's Pan American Health Organization has been working in the country since February 15 . Some Paraguayans have endured long waits for vaccines in sweltering heat . `` Citizens pay taxes for our health and education , but there are no vaccines here , '' Cynthia Shaerer , told CNN last week . `` We do n't need speeches here . We need vaccines . '' People contract yellow fever from the bite of an infected mosquito . The disease causes fever , muscle pain , headaches , shivering , nausea and vomiting , the World Health Organization says . Most people improve after three or four days , but some enter a second `` toxic '' phase that causes fever , jaundice and blood in the vomit , the health organization says . About half of the people who enter the second phase of yellow fever die within 10 days . There is no treatment , so medical authorities recommend vaccinations . Yellow fever typically is found in tropical regions of Africa and Latin America . E-mail to a friend . CNN 's Carolina Cayazzo and Sanie Lopez Garelli contributed to this story .
Disease outbreak has occurred in northern Argentina , Brazil and Paraguay . The outbreak has killed at least 21 people . Health officials recommend that people need to go to affected to get help . Concern arose in Argentina last month after two monkeys died of yellow fever .