The outbreak of yellow fever in Brazil, which moves from the less populated rural areas to the cities, may pose another Zika-like health threat to the Americas, including the United States.

U.S. health officials have urged a close surveillance after the advancement of the outbreak in the most populous country in South America.

"Although it is highly unlikely that we will see yellow fever in the continental United States ... it is possible that travel-related cases of yellow fever could occur," Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, and Dr. Catharine Paules, in an essay published in the New England Journal of Medicine on March 8, said.


The team said dengue, chikungunya, and Zika had demonstrated how Aedes aegypti mosquitos can infect populations and spread rapidly due to human travel.

The outbreak of the fever in the United States is considered unlikely, but with Zika, the infections acquired through travel could easily get into the Aedes aegypti population, especially in warmer regions.

"In an era of frequent international travel, any marked increase in domestic cases in Brazil raises the possibility of travel-related cases and local transmission in regions where yellow fever is not endemic," the team wrote.

The Gulf Coast states with warmer temperature are most vulnerable. It is in these areas where Aedes aegypti mosquitoes are rampant.

Dangerous Among The Five

As the yellow fever advances, it is feared that it will be the fifth insect-related virus to hit the country since the 1990s. The other four were dengue, West Nile fever, chikungunya, and Zika virus.

Among the five, the yellow fever is considered the most deadly, Fauci and Paules said.

In the Brazilian outbreak, 80 people have died from the 234 documented cases.

Vaccine Not Enough

Health authorities are no strangers to the dangers the yellow fever outbreak can bring. The vaccine against the epidemic has been formulated way back in 1937.

What made its outbreak alarming is that the current supply of the vaccine is limited.

During the 2015 outbreak in Angola and Congo, health officials were constrained to administer to each infected person only a fifth of the normal dose.

Fauci noted that it takes a long time to produce additional doses of the vaccine. Only a handful of companies manufactured it.

Given the limited stockpile of the vaccine, Fauci and Paules said public health management and prevention programs are important to prevent the spread of the virus.

These preventive measures include early identification of cases, mosquito control, and vaccination.

Not Yet Critical

At present, only 371 cases were confirmed out of more than 1,000 persons suspected to have been infected with the virus.

"It's not critical yet in Brazil," Fauci said.

Fauci warned, however, it would be worrisome if the fever will reach the cities of Sao Paolo, Rio de Janeiro, or places far from the less populated areas there is an outbreak.

It is important, he said, to put yellow fever on the "radar screens" of all public health officials and physicians.

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