Yellow Fever may be contagious for longer than previously suspected

Wednesday, March 7, 2018 by Chris Galford

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Brazilian researchers have determined that Yellow Fever may have been underestimated, with a patient who survived the disease still showing signs of it nearly a month after infection.

Previously, scientists operated on the idea that yellow fever had a transmissibility period that roughly correlated to acute infections–a period of no more than 10 days. Most symptoms vanished after three or four days, though a small percentage of patients would enter a second phase of the disease that boasts a 50 percent death rate within 7 to 10 days. With the virus now showing up in urine and semen a month after infection, this significantly increases the danger of infection according to Paolo Zanotto, a professor at the University of São Paulo’s Biomedical Science Institute (ICB-USP).

“We don’t yet have enough samples to determine how long yellow fever virus can be detected in urine and semen, but our monitoring of the patient for 21 days after observing the first symptoms of the disease suggests the virus can be detected in these biological materials for almost a month after infection, if not longer,” Zanotto said.

Sequencing the genome of the virus isolated in their patient’s urine, researchers say this indicates yellow fever is an arbovirus–a type of virus transmitted by insects that feed on blood–and capable of being excreted through the urinary system. They do not know how long it stays with that system yet, or what the implications of it might be.

Researchers also said tests designed to detect yellow fever in urine can improve diagnosis. This is especially important given that more than half of those infected do not display any symptoms, and thus are not admitted to a hospital.

“The people who are admitted to hospital are those who have symptoms,” Zanotto said. “These are the relatively severe cases, representing the tip of the iceberg as far as the problem of infection by yellow fever in Brazil is concerned since a large proportion of those infected is asymptomatic.”

The ICB-USP conducted this study alongside colleagues from Butantan Institute, Emílio Ribas Infectology Institute, and Pontifical Catholic University of São Paulo (PUC-SP), and published their findings in the CDC journal Emerging Infectious Diseases.

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Brazil Yellow Fever Outbreak Largest in Decades; 846 Cases

Brazil's yellow fever outbreak has now infected more people than the previous one, which had been the largest in decades.

The Health Ministry said Wednesday that officials have confirmed 846 cases of the mosquito-borne disease. Of those, 260 have died.

In the 2016-2017 outbreak, Latin America's largest nation saw 777 cases and 261 deaths.

Large swaths of Brazil have long been at risk for yellow fever. But the previous outbreak and the current one are happening in areas not previously considered at risk for the disease and where vaccination rates were low. The current outbreak is hitting the populous states of Sao Paulo and Minas Gerais hard and encroaching on major cities.

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In response, Brazil has launched a campaign to vaccinate more than 23 million people.

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CDC: Limited Availability of Alternative Yellow Fever Vaccine, march 2018

The Centers for Disease Control and Prevention (CDC) has released a list of clinics stocking the yellow fever vaccine, Stamaril (Sanofi Pasteur). They have also created an interactive map allowing travelers and clinicians to easily search locations with the vaccine that are nearest to them. The map will be updated periodically to include any updates to clinic locations.

The distribution of Stamaril is due to the total depletion of YF-Vax, the only licensed yellow fever vaccine in the U.S. Sanofi Pasteur has stated they expect YF-Vax to be available again by the end of 2018. 

Stamaril, which is manufactured in France, received approval through the Food and Drug Administration's investigational new drug (IND) program (despite the name, the vaccine is not investigational or experimental and has been used in Europe for years). It is comparable to YF-Vax in safety and efficacy.

As part of the IND program, only a limited number of clinics will be provided Stamaril.  

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Brazil battles yellow fever — and a ‘dangerous’ anti-vaccination campaign

By Anna Jean Kaiser February 18

RIO DE JANEIRO — With cases of yellow fever multiplying in Brazil, Paula Muniz, a 42-year-old accountant, was considering whether to get vaccinated. Then she saw a viral Facebook post about a teenage girl’s supposedly fatal reaction after receiving the vaccine, and she decided it was a firm no for her, her 14-year-old son and her husband.

“I’m very afraid of that vaccine. I don’t trust it,” said Muniz, who lives in Sao Paulo. “I got scared when I saw the post and thought, ‘Thank God my family hasn’t taken it yet.’ Now we’re not going to.”

Brazil is suffering one of its worst outbreaks of yellow fever, a potentially lethal mosquito-borne virus. The surge of cases comes after the country suffered an epidemic of Zika, another insect-borne virus that caused severe birth defects in hundreds of babies in 2015 and 2016.

The yellow fever outbreak started at the end of 2016. The number of cases dropped during the Brazilian winter, when mosquitoes are less plentiful, but has surged at alarming speed since the beginning of this year in the country’s southeast. So far, the virus is being carried only by rural-dwelling mosquitoes, but cases are appearing dangerously close to three of the country’s largest metropolitan areas — Sao Paulo, Rio de Janeiro and Belo Horizonte.

Sao Paulo state, home to 45 million people, has experienced the most dramatic increase. In 2017, the state had 53 cases and 16 deaths, but in just the first six weeks of 2018, it logged 133 cases and 49 deaths. In Rio state, 27 cases and nine deaths were registered last year, and 47 cases and 21 deaths occurred in January alone this year.

People wait in a long line to receive the yellow fever vaccine in Sao Paulo. (Miguel Schincariol/AFP/Getty Images)

The escalation has prompted a chaotic rush to vaccinate tens of millions of people through the public health system. Officials are administering partial doses of the medication, to stretch the supply, while still protecting patients for eight to 10 years. But even as the vaccination campaign expands, so does an anti-vaccine movement fueled by Internet rumors.

“We’re seeing fake news about yellow fever spread at an alarming rate on social networks,” said Igor Sacramento, a health communication researcher at Fiocruz, one of Brazil’s largest scientific institutes.

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While millions of people have camped out overnight and stood in lines that wrapped around the block to get vaccines in recent weeks in Sao Paulo and Rio, some Brazilians are opting out.

The Facebook post that alarmed Muniz was shared more than 300,000 times and was accompanied by dozens of comments from people saying they would not receive the vaccine.

But the account of the teenager dying from side effects of the vaccine was false. Officials from the town where the young woman lived confirmed that she had died but said that the cause of death was bacterial pneumonia, not the vaccine.

The yellow-fever vaccine has been used for decades, and side effects are generally mild and include headaches and low-grade fevers. There have been reports of rare cases, however, in which people have life-threatening allergic reactions or develop diseases affecting the nervous system and internal organs. Five deaths were caused by the vaccine in Brazil last year, according to the Health Ministry.

A health agent vaccinates a child on the street in a neighborhood where the risk of infection is high during an emergency campaign against yellow fever in Sao Paulo. (Paulo Whitaker/Reuters)

“One in a million people have side effects from this vaccine. That means there will be bad reactions if we’re vaccinating millions of people at the same time,” said Carla Domingues, the coordinator of the federal government’s National Immunization Program.

Facebook groups have become forums where mothers and other worried Brazilians seek information and exchange tales about yellow fever and vaccines. A group called “The Dark Side of Vaccines” has nearly 10,000 members and refers to American anti-vaccination sites such as LearnTheRisk.org and NaturalNews.com as well as translating posts from U.S.-based Facebook groups like Vaccine Resistance Movement.

Sacramento, the researcher, said the anti-vaccine movement is growing in Brazil, but is still less articulated and political than in the United States or Europe.

“This movement is very dangerous,” said Pedro Tauil, an epidemiologist and professor emeritus at the University of Brasilia. “We need to show people that vaccination is the best prevention — because it’s not just about individual protection, it’s also about preventing the virus from spreading to a full-blown epidemic.”

Domingues, the federal official, said the phony Internet rumors are “a new thing we have to learn to deal with and combat.” However, she said, she is not concerned about fake news affecting the number of people getting vaccinated, citing the long lines that have formed during the vaccination campaign.

The reach of social-media posts in this country of over 200 million can be staggering. A Facebook account listed as belonging to a Christian nonprofit organization posted a video, which was viewed 4.5 million times, showing a tearful woman detailing what she called her son’s near-fatal allergic reaction to the yellow fever vaccine.

“We need to understand if all these people are dying because they actually had yellow fever, or if it’s because of a reaction” to the vaccine, she says. The text accompanying the post says, “Vaccines kill . . . share this so that people become aware that their biggest enemy is not an animal, but actually is the state itself, driven by powerful, hidden forces.”

WhatsApp, the country’s most popular messaging app, has also been used to convey fake information. In January, an audio message circulated on WhatsApp with an unidentified woman claiming to be a doctor at a well-known laboratory warning that the yellow-fever vaccine is dangerous.

A rumor has also made the rounds on WhatsApp claiming that drinking a blend of fruits and vegetables every day immunizes people against yellow fever. “The vaccine is not safe. Share this recipe so that more people will be immunized from yellow fever,” the message says.

Muniz said she and her family have received vaccines before. But access to social media changed her calculations. “Maybe I would have taken this one if I didn’t have Facebook and WhatsApp,” she said.

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