amudu: What does Ebola actually do?

Monday, October 20, 2014

What does Ebola actually do?

Behind the unprecedented Ebola outbreak in West Africa lies a species with an incredible power to overtake its host. Zaire ebolavirus and the family of filoviruses to which it belongs owe their virulence to mechanisms that first disarm the immune response and then dismantle the vascular system. The virus progresses so quickly that researchers have struggled to tease out the precise sequence of events, particularly in the midst of an outbreak. Much is still unknown, including the role of some of the seven proteins that the virus’s RNA makes by hijacking the machinery of host cells and the type of immune response necessary to defeat the virus before it spreads throughout the body. But researchers can test how the live virus attacks different cells in culture and can observe the disease’s progression in nonhuman primates—a nearly identical model to humans.

A new study suggests the origin of the worldwide Ebola outbreak was a two-year-old African boy who passed away last year.

Image: Festa/Shutterstock

A toddler in Africa may have started the Ebola outbreak, which the World Health Organisation has now delcared an international public health emergency, according to research published in The New England Journal of Medicine.

The two-year-old boy identified as Patient Zero died on 6 December 2013 in a village in Guéckédou in southeastern Guinea in Africa. The region borders Sierra Leone and Liberia, making it an ideal entry point for an epidemic.

There have since been at least 1,779 cases of the disease, as Denise Grady and Sheri Fink explain in The New York Times, and 961 deaths - including the boy's mother, sister and grandmother.

At the time of their deaths, no one was sure what had sickened the family, despite the fever, vomiting and diarrhoea characteristic of the disease, so no special procedures were put into place when it came to treating them. And, within a few weeks, the study shows that contaminated healthcare workers who had supported the family and mourners at their funerals then spread the disease to surrounding villages and hospitals. By early March it had appeared across southern Guinea. Cases have now been reported in Nigeria, Liberia and Sierra Leone.

The international team of researchers managed to trace the disease's origins by looking at the way the new strain spread through Africa. Although the toddler and his family were never officially diagnosed with Ebola, their symptoms match the disease and, according to The New York Times, "fit into a pattern of transmission that included other cases confirmed by blood tests".

However, the scientists still aren't sure how the boy would have caught Ebola in the first place.

Sylvain Baize, part of the team that analysed the Guinea outbreak and a researcher at the Pasteur Institute in Lyon, France, told Grady and Fink at The New York Times that there might have been an earlier undiscovered case prior to the young boy.

“We suppose that the first case was infected following contact with bats,” Blaize said. “Maybe, but we are not sure.”

So how did this Ebola outbreak get so out of control, when we've generally been able to get a hold of them quite quickly in the past? Grady and Fink explain it's a combination of a lack of infrastructure and hygiene, increased travel and modernisation in Africa, and the fact that healthcare workers in West Africa simply weren't prepared to deal with the disease, and didn't know the symptoms.

Find out more about the Ebola outbreak, the virus itself and the myths about the disease.

Source: The New York Times

So there’s a case of Ebola in the US, and the disease has already killed 70 percent of those it infected in West Africa. Is this the beginning of the end for humanity? Not even close, and here’s why.

Image: Adam Cole/NPR

The US case of Ebola is the first to be identified outside of Africa. The patient, who has now died from the disease, didn’t know that he was infected straight away, so wasn’t quarantined by the Texas Health Presbyterian Hospital in Dallas for four days. This sounds like a long time to be walking around being contagious, but medical authorities have assured the public not to panic.

In fact, officials seem pretty sure that this particular case would not lead to an outbreak in the US. "I have no doubt that we will control this importation, or case, of Ebola so that it does not spread widely in this country," director of the Centers for Disease Control and Prevention (CDC) Tom Frieden told the press earlier this week.

Professor of integrative biology Lauren Ancel Meyers from the University of Texas agreed, tellingThe Huffington Post science editor David Freeman, "I think they are striking a good note in saying that most of you out there don’t have to worry. There doesn’t seem to be a real threat of a large epidemic in the United States."

The reason for Frieden’s and Meyers's confidence is a simple mathematical term known as R0. This is a 'reproduction number' used by epidemiologists to indicate how infectious a specific disease is. It tells you how many people, on average, will be infected by one patient.

"The reproduction number provides a lot of information," Meyers told The Huffington Post. "It gives us a baseline for projecting the growth of outbreaks in the absence of intervention, and it tells us how hard and how effective do our interventions have to be in order to stop an epidemic."

Measles, for example, is the most contagious disease we have, and its R0 is about 18. This means that if no one is vaccinated, an incredible 18 people can be infected by every one person who has the disease. Of course, this number drops to zero if everyone is vaccinated. For HIV/AIDS and SARS, the R0 number is between 2 and 5, and for Ebola, it’s just 2.

According to Michaeleen Doucleff at NPR, while many factors influence a disease’s reproduction number, the fact that Ebola’s is transmitted via bodily fluids, rather than the air, is probably why it’s rated so low. And because Ebola isn't contagious until the patient starts showing symptoms - at which point the Dallas patient had checked himself in to the hospital - all that needed to be done to contain the spread of the disease in the US is to isolate anyone at the hospital who might have been infected.

CNBC reports that as of yesterday, none of the 48 people who potentially came in contact with Dallas patient have developed any definite symptoms.

"Then R0 drops to zero. And Texas is free of Ebola,” says Doucleff.

Here's how medical staff figure out who might have become infected by the Dallas patient:

Researchers have discovered the world's first ‘virological penicillin’ in a molecule found in honeysuckle.

Image: Haris M/Shutterstock

The sweet-smelling honeysuckle plant (Lonicera japonica) has been used for generations in traditional Chinese medicine to treat influenza infections. While it’s been known to block the replication of the influenza virus, the mechanism and active components in the plant have remained a mystery until now.

In a new study published in Cell Research, scientists from the Nanjing University in China studied the honeysuckle plant and identified a plant microRNA called MIR2911. MicroRNAs are small molecules found in plants and animals that play an important role in influencing the pathways responsible for many diseases. In clinical trials, this molecule was able to suppress deadly influenza A viruses such as swine flu (H1N1) and bird flu (H5N1).

The scientists delivered boiled honeysuckle to the plasma and lung tissue of mice infected with the H1N1 infection. Results showed that MIR2911 quickly bound itself to the messenger RNA - the molecule containing the genetic information - of the two genes responsible for viral replication. This binding mechanism blocked the replication process, and eventually the virus was destroyed.

The trials were conducted with both synthetic and naturally occurring honeysuckle, and both proved to be equally effective.

Findings also revealed that the MIR2911 molecule suppresses the replication of influenza viruses H5N1 and Avain inluenza A (H7N9). This suggests that it has a broad-spectrum antiviral activity, and could be a potential cure for the Ebola virus. While the results are promising, the team needs to observe the molecule in human subjects before advising it as a therapeutic cure for influenza A viruses.

It was previously thought that boiling honeysuckle would degrade the beneficial molecules, but MIR2911 proved to retain its properties after boiling. This suggests that honeysuckle tea is an effective way to take the plant.

The team hopes that MIR2911 can be used as a ‘virological penicillin’ to treat deadly viruses for which there is currently no known natural cure.

“We suggest that as the first natural product to directly target influenza A viruses, MIR2911 is the ‘virological penicillin’ that serves as a novel therapeutic and preventive agent against not only influenza A, but potentially also other types of viruses," conclude the authors in the study.

Source: EurekAlert