« Prev Next »
October 30, 2015
|
By:
Julia Paoli
Health Aftereffects Plague Ebola Survivors
One of the most pressing issues is Ebola's ability to survive in immune-privileged regions of the body. Certain areas, such as the eyes, central nervous system and testes, exhibit suppressed immunity to antigens. This mechanism serves to protect sensitive areas from being damaged by powerful immune system responses. Viruses love to hide out in these regions, which makes it hard for the body to get rid of them. Ebola, it turns out, is a master at hiding in survivors' eyes and testes. A new paper published in The New England Journal of Medicine reports that Ebola virus (specifically Ebola RNA) can remain in the semen of male survivors up to nine months after the onset of symptoms and in the ocular aqueous humor (the watery fluid that flows between the eye lens and the cornea) up to 98 days after onset. These statistics hold true even for patients whose bodies have rid the virus from the bloodstream and are thus declared "Ebola-free."
Although instances of new Ebola cases are decreasing in West Africa, for the 17,000 Ebola survivors the ordeal is not over. Many survivors are now experiencing headaches, joint pain, extreme fatigue, difficulty sleeping and vision problems in "post-Ebola syndrome." The virus has even been found to remain in people's eyes and testes after they have been declared Ebola-free. The epidemic's repercussions leave survivors, health officials, and scientists a bevy of new problems to address and many unanswered questions.
Now that scientists have proved Ebola capable of lingering in semen, the question begs to be asked: can Ebola be sexually transmitted? Typically, the virus is transmitted through contact with infected bodily fluids or contaminated medical equipment, although there have been a few instances of Ebola being sexually transmitted. In 2014, a male survivor from Liberia had unprotected sex with a woman five months after he was released from an Ebola treatment center. The woman died from Ebola 20 days later. Analysis of his semen and her blood showed that the virus was sexually transmitted, on account of the near identicalness of the Ebola virus genome found in each sample (their genomes differed by only one mutation). However, virologists still view sexual transmission as a rare, although possible occurrence. In response to the Liberian case, the World Health Organization (WHO) has updated its recommendations for preventing Ebola's spread. Previously, WHO advised male survivors to just abstain from sex or use a condom for three months after recovery. Now, male survivors are encouraged to have their semen tested three months after initial infection, and those who test positive for Ebola should be re-tested every month until they test negative twice in a row. Males unable to receive testing should abstain from sex or practice safe sex for at least six months.
There are many more Ebola survivors now than there have been in all previous outbreaks combined. With new cases waning, health officials and aid workers can focus their attention on the aftereffects of recovery. Roughly a quarter of survivors currently experience eye issues, loss of vision, or complete blindness. Inflammation triggered by Ebola's presence in the eye threatens vision. Unfortunately, there are no proven treatments to rid the virus from the eye, so the best doctors can do is treat the inflammation and hope the patient's immune system kills the virus. Health officials are now worried about survivors going partially or fully blind if no treatment is available for them.
We are definitely not out of the woods in terms of the outbreak. The possibility of sexual transmission and widespread health problems afflicting survivors requires further attention and research in the coming years. Luckily, the U.S. National Institute of Allergy and Infectious Diseases and the Ministry of Health of Liberia have begun a five-year study to monitor 1,500 Liberian Ebola survivors and 6,000 of their close contacts. The project, which is the largest study to date of Ebola survivors, aims to track the long-term health effects of Ebola virus disease.
Sources:
Bichell, R. "So It Turns Out There's A Lot We Don't Know About Ebola." NPR. October 17, 2015.
Bichell, R. "How Long Can Ebola Linger In The Semen Of Male Survivors?" NPR. October 14, 2015
Shute, N. "Ebola Hides In The Eyes Of A Man Who Was Considered Cured. NPR. May 7, 2015.
Image:
September 19, 2015
|
By:
Julia Paoli
30,000-Year-Old Virus Found in Siberian Permafrost
As if from the plot of a movie, scientists recently discovered an ancient virus buried underneath the Siberian permafrost. This virus, Mollivirus sibericum, belongs to a group of other ancient viruses collectively known as "giant" viruses. Mollivirus sibericum is not unique in its discovery. In fact, since 2003 researches have found four other frozen giant viruses. Some worry that reawakening this so called "Frankenvirus" will lead to trouble but, rest assured, Mollivirus sibericum poses no real threat to humans. Of more concern is the role climate change plays in the discovery of ancient viruses.
Mollivirus sibericum is the second 30,000-year-old virus to be unearthed in the Siberian permafrost. The first, Pithovirus sibericum, was discovered in 2014 by the same set of French researchers from the French Centre National de la Recherche Scientifique. The researchers published a paper on their discovery of Mollivirus sibericum, which means "soft virus from Siberia," in the Proceedings of the National Academy of Sciences. Mollivirus sibericum is classified as "giant" because it can be viewed under a light microscope whereas most viruses can only be seen using an electron microscope. Giant viruses also contain significantly more genes than average viruses. Mollivirus sibericum for instance has more than 500 genes while the HIV virus has a measly 9 genes (Pandoraviruses, another type of giant virus can have up to 2,500 genes). 
Despite being frozen for 30,000 years, "a few viral particles that are still infectious may be enough, in the presence of a vulnerable host, to revive potentially pathogenic viruses," explains lead researcher Jean-Michel Claverie. The French team of scientists hope to revive Mollivirus sibericum from its dormancy by putting it in contact with a host organism, in this case a single-cell amoeba. Reawakening the virus poses no real threats to human health since Mollivirus sibericum only infects amoebas. To be on the safe side, researchers will first test to make sure that the virus is unable to reproduce in human and mice cells, which "they don't, of course," assures lead scientist Chantal Abergel.
Unfortunately, global warming is causing the Siberian permafrost to melt (the Arctic and subArctic regions are warming twice as fast as the rest of the world). As a result, more ancient viruses, which appear to be common in permafrost, may be liberated from their frozen state. In regards to climate change, the French team of scientists explain that "[the] fact that two different viruses retain their infectivity in prehistorical permafrost layers should be of concern in a context of global warming." Increased drilling and mining in the mineral rich Siberian region may also bring humans in contact with released ancient viruses. Theoretically speaking, the frozen viruses have the potential to cause infections once reawoken. However, the threat posed by the reawakening of these ancient viruses is of minimal concern to most virologists. Even if the viruses were revived, there is a very slim chance that they would be able to infect humans and then spread amongst us. Of more immediate worry is the impact global warming has on the geographic ranges of insects. As the world warms, insects that carry pathogenic viruses, such as mosquitoes, are able to move into previously uninhabitable regions. For example, the re-emergence of chikungunya virus in recent years is related to global warming.
Thankfully, you won't have to worry about catching a 30,000-year-old Siberian virus anytime soon. We'll leave that scenario to the movies.
Sources:
"Frankenvirus emerges from Siberia's frozen wasteland." Agence France Presse. September 8, 2015.
(Published online before print)
Vence, T. "Another Ancient Giant Virus Discovered."The Scientist. September 14, 2015.
Photo:
August 07, 2015
|
By:
Julia Paoli
New Blood Test Identifies All the Viruses to Which You Have Ever Been Infected
Scientists have already conducted VirScan tests on 569 people from the United States, South Africa, Thailand and Peru. People had on average been exposed to ten different viruses out of a possible 206 types (these ten viruses are mostly of the flu, cold and gastrointestinal illness causing sort). Some subjects demonstrated exposure to as many as 25 different kinds of viruses. The researchers also found that geography plays a role in which viruses people are exposed to. People from South Africa, Peru and Thailand had antibodies for many more different types of viruses than their counterparts in the United States. "We don't know if this has to do with genetics of the people or the strains of the viruses that are out there" explains lead author Dr. Stephen Elledge. He adds that it may have "something to do with cultural habits or sanitation." Researchers were surprised to discover that people infected with HIV displayed antibodies to a greater number of viruses than people without HIV. The researchers are not sure why this is since they expected people with HIV to exhibit "diminished" immune system responses to viral infections.
I doubt any of us can remember every single virus that we have ever contracted in our entire lives. Thanks to a new blood test dubbed VirScan, scientists can now identify all the viruses someone has ever been infected with in just one drop of blood. This new technology is able to identify prior exposure to 1000 strains of 206 different types of viruses. These 206 viruses represent almost all of the viruses known to infect humans. A team of scientists led by Dr. Stephen Elledge, professor of medicine and genetics at Harvard Medical School, published their VirScan findings this June in the journal Science.
Dr. Elledge believes that VirScan will enable scientists to "ask questions that just couldn't be asked before." For example, scientists could compare the viral histories of people with and without certain diseases to see if there are any remarkable differences between the two. This research could help scientists determine if viral infections play a role in the development of cancer, diabetes and chronic fatigue syndrome in humans. Vincent Racaniello, a microbiology and immunology professor at Columbia University (and not involved with VirScan's development), explains that "there are a lot of chronic diseases where we think a virus might be involved but we can't quite pinpoint it... ." Furthermore, Racaniello believes that VirScan "is going to be helpful" in formulating a connection between chronic disease and viruses. VirScan could also be used to help detect HIV and Hepatitis C early on since patients can go years without displaying any visible symptoms. Another potential use for VirScan is to assess the best time for children to be vaccinated. VirScan would be administered to a large population in order to determine at what age most children are exposed to various viruses.
In the next few years VirScan may become part of your yearly checkup. As of now, each blood test costs 25 dollars to perform, although the price may rise to generate profit if VirScan becomes commercially available. VirScan is not currently backed by any company but a patent for VirScan is in the works.
Sources:
Photo:
Share
Close
