Everything You Need to Know About the Yellow Fever Vaccine

Article source: http://www.travelandleisure.com/trip-ideas/yoga-wellness/yellow-fever-vaccine

The Yellow Fever Virus

Yellow fever, a viral hemorrhagic disease caused by the yellow fever virus, affects roughly 200,000 people a year. Though the disease got its start in Africa, outbreaks have occurred as far away as the Yucatan Peninsula and even Philadelphia, where 5,000 people were wiped out during a single epidemic in the 18th century.

Related: What You Need to Know About Vaccines

Typically, yellow fever causes, chills, nausea, vomiting, muscle pain, and — of course — a fever. It’s certainly not a pleasant way to spend any part of your trip. While most people recover after 3 or 4 days, some experience a second wave of afflictions, which can bring jaundice (hence the name), abdominal pain and vomiting, and bleeding from the mouth, nose, and eyes. In cases where yellow fever has developed past this point, the risk of death is about 50 percent.

Back in the day, yellow fever was no joke. A single outbreak had the power to annihilate huge groups of people in small areas, though the cause of the illness eluded doctors. It wasn’t until the 1900s that they determined yellow fever was transmitted by mosquitoes.

The Yellow Fever Vaccine

Per the Centers for Disease Control and Prevention, there is no cure for yellow fever. Instead, patients are treated based on their symptoms (described above), and on their recent travel history.

While a vaccine is recommended for any travel to Africa or South America, other important prevention methods include mosquito nets, wearing clothes that cover the entire body, and using a strong insect repellent with DEET.

The yellow fever vaccine was developed by Max Theiler in the United States, and he won the Nobel Prize for this life-saving contribution. Unlike other vaccines, the yellow fever vaccine is a one-time deal: a single dose provides lifetime immunity. (Travelers who frequently visit at-risk areas should get a booster shot ever 10 years.)

The vaccine can be given to infants as young as 9 months, and is recommended for anyone traveling to certain areas in Africa and South America.

As with most vaccines, an amount of time is needed for the vaccine to work its way through your body, and it’s recommended that you schedule the vaccine appointment 10 days prior to traveling.

The yellow fever vaccine is only offered at designated vaccination centers, and can cost between $150 and $350, depending on availability. Certain countries, including Ghana, Liberia, and Sierra Leone, even require a proof of vaccination from all travelers when they arrive — and that certificate is obtained from your doctor after being given the shot.

Zika: The Untold Story

Every pathogen has a history. Here is an excellent piece from NOVA on Zika’s origin and evolution.

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Human antibody for Zika virus promising for treatment, prevention

Researchers have determined the structure of a human antibody bound to the Zika virus, revealing details about how the antibody interferes with the infection mechanism — findings that could aid in development of antiviral medications.

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From Purdue University:

The new findings also suggest the antibody might be especially effective because a lower concentration than expected is needed to inhibit a key mechanism of infection, making it more potent than previous antibodies studied. The research was performed by a team from Purdue University, Vanderbilt University Medical Center and the Washington University School of Medicine.

The human antibody was isolated by the Vanderbilt and Washington University researchers, who reported their findings earlier this year. Those findings showed that the antibody, which was isolated from a person previously infected with Zika virus, neutralizes Zika strains that belong to African, Asian and American lineages and is able to reduce fetal infection and death in mice.

“However, until now what remained unknown was the mechanism of neutralization of Zika infection by the antibody and the structural basis for neutralization,” said Michael Rossmann, Purdue’s Hanley Distinguished Professor of Biological Sciences.

The findings are being reported today (March 16) in the journal Nature Communications.

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This color-coded image depicts the surface view of the Zika virus bound to fragments of a human antibody, shown as red knobs. Researchers have determined the structure of the antibody bound to the virus, findings that could aid in development of antiviral medications.
Credit: Purdue University image/S. Saif Hasan

The research team was led by Rossmann and Richard Kuhn, both professors in Purdue’s Department of Biological Sciences, and senior postdoctoral scientist S. Saif Hasan. Research to isolate the antibody was led by James E. Crowe Jr., a professor of pediatrics, pathology, microbiology and immunology at Vanderbilt, and Michael S. Diamond, the Herbert S. Gasser Professor at Washington University.

Zika belongs to a family of viruses called flaviviruses, which includes dengue, West Nile, yellow fever, Japanese encephalitis and tick-borne encephalitic viruses.

In the new findings, researchers determined the combined three-dimensional structure of the Zika virus while attached to a key binding site on the antibody known as the antigen binding fragment, or a Fab molecule.

“It has potential to be a therapeutic neutralizing human antibody” said Kuhn, director of the Purdue Institute of Inflammation, Immunology and Infectious Disease (PI4D).

The genome of the Zika virus is housed inside a protective shell that includes 60 repeating units, each containing three envelope proteins, or E proteins. As the virus attaches to a host cell’s outer membrane a difference in pH, or acidity, in the membrane causes these “trimers” to expose “fusion peptides,” leading to the transfer of the viral RNA genome, a step critical to infection. The new findings show the antibody’s binding to Zika inhibits this pH-triggering mechanism, neutralizing the virus by “cross-linking” the E proteins, tying them up and preventing their reorganization into “fusogenic” trimers.

“This hypothesis is supported by pre- and post-neutralization assays of Zika infection, showing the antibody is able to significantly inhibit infection,” Rossmann said. “This approach should provide broad-range protection against virtually all strains of Zika.”

Moreover, considering that the surface of Zika is made of 60 copies of three E proteins, it would be expected that 180 copies of the antibody’s Fab molecules would be needed for neutralization.

“However, one antibody binds for six E proteins, so only 30 are needed,” Hasan said. “Therefore, you don’t need a high concentration of antibodies to achieve neutralization.”

The findings primarily will aid in the development of antiviral drugs but also will help researchers identify important sites on the virus for human antibodies to hook onto, which could be useful in developing vaccines down the road, Kuhn said.

The researchers determined the structure at a resolution of 6.2 Ångstroms using a technique called cryo-electron microscopy.

The Zika virus has been associated with a birth defect called microcephaly that causes brain damage and an abnormally small head in babies born to mothers infected during pregnancy. The virus also has been associated with the autoimmune disease Guillain-Barré syndrome, which can lead to temporary paralysis.

“Given the severity of the symptoms caused by Zika infection in humans, it is crucial to understand the immune response elicited by the infection to develop neutralizing anti-Zika therapies,” Rossmann said. “In contrast to other flaviviruses that are spread mainly by insects, recent evidence suggests that Zika can be transmitted sexually and from mother to child in addition to transmission by mosquitoes.”

The first major outbreak of the Zika virus was recorded in 2007 in Micronesia and then in 2013-14 in Oceania. The latest outbreak, which started in Brazil in 2014-15, has spread to other countries in South America, North America and the Caribbean. Four cases of fetal deformities were reported in December 2016 in New York City.

Read article here.

 

If you have been diagnosed with Zika, you might be eligible to donate a blood specimen and earn money. Visit www.plasmamedpatients.com for more info.

What is Japanese encephalitis?

The number of fatalities from Japanese encephalitis is estimated to be between 13,600 and 20,400 a year.

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Japanese encephalitis is a mosquito-borne viral infection. It is the leading cause of viral encephalitis in Asia. Humans can get the disease when they are bitten by a mosquito that carries the virus. Japanese encephalitis virus cannot be transmitted from one person to another.

The Japanese encephalitis virus (JEV) is related to the viruses of St. Louis encephalitis and Murray Valley encephalitis, to the West Nile virus and to dengue and yellow fever.

Encephalitis is an inflammation of the brain which can cause fever, headache, confusion, seizures, and, in some cases, death.

mosquito

When mosquitoes infect an animal, the animal can become a carrier of the virus. When other mosquitos feed on these newly infected animals, they take up the virus and can go on to infect other animals or humans.

People in rural areas where the virus is common are at highest risk. Japanese encephalitis does not usually happen around towns and cities.

It is more likely to affect children, because adults in areas where it is endemic generally become immune as they get older.

Read article here.

If you know anyone diagnosed with Japanese encephalitis, they might be eligible to donate plasma or a blood specimen and earn $600 or more. Visit www.plasmamedpatients.com for more info or call/text 561-962-5065.