EBOLA People Carrying Ebola, in Some Cases, May Be Free of Symptoms/2000

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This is an older article but thought it might be relevant ..I'm going to see if I can find the original Lancet articles.

People Carrying Ebola, in Some Cases, May Be Free of Symptoms


By LAWRENCE K. ALTMAN
Published: June 27, 2000
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The Ebola virus, which has caused deaths from high fever and bleeding in African outbreaks, can also infect without producing illness, according to a new finding by African and European scientists.

The possibility of asymptomatic infection was only suggested in earlier studies, they said in last week's issue of The Lancet, a medical journal published in London. Now they said they had documented such infections for the first time. They found that the Ebola virus could persist in the blood of asymptomatic infected individuals for two weeks after they were first exposed to an infected individual. How much longer the virus can persist is unknown.

All outbreaks of Ebola have been controlled by standard infection control measures such as effective body disposal, destroying or sterilizing contaminated equipment and appropriate use of gloves. But if people can be carriers without showing symptoms, it means control might be more difficult.

''This degree of containment would be virtually impossible if symptom-free carriers posed a significant threat of infection,'' Dr. Alan G. Baxter of Newtown, Australia, wrote in an editorial in the same issue of The Lancet.


Scientists have known that Ebola usually spreads from an infected person to another individual and through contamination in clinics or hospitals. The new finding suggests that some cases may result from healthy carriers. How often is unknown. The finding could help scientists in their long-term quest to develop effective therapies to treat the virus or perhaps even a vaccine to prevent infection.

But an immediate effect is to raise the need to reasses health policy about one of the most virulent viruses known and to determine how often healthy carriers transmit it, said the scientific team headed by Dr. E. M. Leroy of Franceville, Gabon.

One concern is transmitting Ebola through blood transfusions. Dr. Thomas G. Ksiazek, an expert in Ebola at the Centers for Disease Control and Prevention, a federal agency in Atlanta, said that such concern would be much greater in Africa than in the United States, where blood banks usually ask people who have been in Africa in recent months not to donate because of the threat of transmitting malaria.

Dr. Leroy's team said another public health concern was transmission of Ebola virus from healthy carriers through sex. Other scientists have detected Ebola in semen.

About 70 percent of people with symptoms of Ebola have died in widely publicized outbreaks in the central African countries of Gabon, the Democratic Republic of the Congo and Sudan.

Illness often begins abruptly, from 5 to 10 days after exposure to Ebola virus, with symptoms like fever, headache, vomiting and diarrhea. Then bleeding can occur internally or ooze from needle sites and through the nose and mouth. Death usually occurs from five to seven days after the onset of illness.

Dr. Leroy's team studied 25 individuals who never developed symptoms although they lived with family members and cared for them without using gloves and other precautions in two outbreaks in Gabon in 1996.

Using standard virologic techniques, the scientists from Gabon, Germany and France said they could not detect the virus in the blood of the healthy contacts. But Dr. Leroy's succeeded by using a technique known as polymerase chain reaction to grow the tiny amount of virus present.

http://www.nytimes.com/2000/06/27/w...la-in-some-cases-may-be-free-of-symptoms.html

 

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New York Times: Some May Carry Ebola Without Showing Any Symptoms

Posted on October 6, 2014 by WashingtonsBlog

Is the “Conventional Wisdom” All Wrong?

The New York Times reported in 2000:

The Ebola virus, which has caused deaths from high fever and bleeding in African outbreaks, can also infect without producing illness, according to a new finding by African and European scientists.

The possibility of asymptomatic infection was only suggested in earlier studies, they said in last week’s issue of The Lancet, a medical journal published in London. Now they said they had documented such infections for the first time. They found that the Ebola virus could persist in the blood of asymptomatic infected individuals for two weeks after they were first exposed to an infected individual. How much longer the virus can persist is unknown.

***

If people can be carriers without showing symptoms, it means control might be more difficult.

“This degree of containment would be virtually impossible if symptom-free carriers posed a significant threat of infection,” Dr. Alan G. Baxter of Newtown, Australia, wrote in an editorial in the same issue of The Lancet.

***

An immediate effect is to raise the need to reassess health policy about one of the most virulent viruses known and to determine how often healthy carriers transmit it, said the scientific team headed by Dr. E. M. Leroy of Franceville, Gabon.

***

Dr. Leroy’s team studied 25 individuals who never developed symptoms although they lived with family members and cared for them without using gloves and other precautions in two outbreaks in Gabon in 1996.

Using standard virologic techniques, the scientists from Gabon, Germany and France said they could not detect the virus in the blood of the healthy contacts. But Dr. Leroy’s succeeded by using a technique known as polymerase chain reaction to grow the tiny amount of virus present.

Here is the study published in Lancet. And here is the editor’s comment.

The Lancet study does not warn of an apocalyptic scenario where any casual contact could cause infection. It is more focused on contagion through sex or blood transfusions.

But Western governments and scientists have repeatedly said that Ebola carriers can only infect others if they are showing symptoms. So they need to adjust their strategies to account for potential contagion from people who aren’t showing any symptoms.

Aerosol Transmission

Two national experts on infectious disease transmission – both professors in the School of Public Health, Division of Environmental and Occupational Health Sciences, at the University of Illinois at Chicago – report that Ebola can be transmitted by aerosols … i.e. fluids mixed with air (footnotes omitted):

We believe there is scientific and epidemiologic evidence that Ebola virus has the potential to be transmitted via infectious aerosol particles both near and at a distance from infected patients, which means that healthcare workers should be wearing respirators, not facemasks. [Aerosols are liquids or small particles suspended in air. An example is sea spray: seawater suspended in air bubbles, created by the force of the surf mixing water with air.]

The important points are that virus-laden bodily fluids may be aerosolized and inhaled while a person is in proximity to an infectious person and that a wide range of particle sizes can be inhaled and deposited throughout the respiratory tract.

***

Being at first skeptical that Ebola virus could be an aerosol-transmissible disease, we are now persuaded by a review of experimental and epidemiologic data that this might be an important feature of disease transmission, particularly in healthcare settings.

***

Many body fluids, such as vomit, diarrhea, blood, and saliva, are capable of creating inhalable aerosol particles in the immediate vicinity of an infected person. Cough was identified among some cases in a 1995 outbreak in Kikwit, Democratic Republic of the Congo, and coughs are known to emit viruses in respirable particles. The act of vomiting produces an aerosol and has been implicated in airborne transmission of gastrointestinal viruses. Regarding diarrhea, even when contained by toilets, toilet flushing emits a pathogen-laden aerosol that disperses in the air.

***

There is also some experimental evidence that Ebola and other filoviruses can be transmitted by the aerosol route. Jaax et alreported the unexpected death of two rhesus monkeys housed approximately 3 meters from monkeys infected with Ebola virus, concluding that respiratory or eye exposure to aerosols was the only possible explanation.

Zaire Ebola viruses have also been transmitted in the absence of direct contact among pigsand from pigs to non-human primates, which experienced lung involvement in infection. Persons with no known direct contact with Ebola virus disease patients or their bodily fluids have become infected.

***

Experimental studies have demonstrated that it is possible to infect non-human primates and other mammals with filovirus aerosols. [Ebola is a type of filovirus]

Altogether, these epidemiologic and experimental data offer enough evidence to suggest that Ebola and other filoviruses may be opportunistic with respect to aerosol transmission. That is, other routes of entry may be more important and probable, but, given the right conditions, it is possible that transmission could also occur via aerosols.

In other words, these two infectious disease experts believe that Ebola is already – in its current form – transmissible via aerosols. They therefore urge all doctors and nurses working with Ebola patients to wear respirators.

We need to understand how Ebola is really spread, and then take appropriate counter-measures.

Ebola Is Mutating

In addition, Ebola is mutating. The discoverer of the disease (Dr. Peter Piot) said last week:

It is clear that the virus is mutating.

Indeed, top doctors say that – unless contained – it could eventually mutate to become airborne.

And the Washington Post notes that terrorists could use Ebola as a bio-weapon. The longer the outbreak rages, the more likely such a scenario becomes.

We Need a World War 2, Marshall Plan or Moon Landing Level Effort to Stop This

According to American nurses, the U.S. healthcare system is woefully unprepared to handle Ebola.

We need an effort on the scale of World War 2, the Marshall Plan or the moon shot to contain and eradicate this modern plague.


http://www.washingtonsblog.com/2014/10/new-york-times-may-carry-ebola-without-showing-symptoms.html



HERE"S THE STUDY

E M Leroy and S Baize designed the scientific project, did the technical studies, and wrote the paper. E M Leroy and S Baize contributed equally to this work. A J Georges and M-C Georges-Courbot were responsible for epidemiological investigations during all Gabonese Ebola outbreaks, and for instigating this research project at CIRMF. J Lansoud-Soukate was responsible for coordinating the activities of the Gabonese public-health authorities during these outbreaks as co-director of the national Epidemic Control Committee. J Lansoud-Soukate contributed also to epidemiological investigations. S Fisher-Hoch and J McCormick contributed to the design of the study, and gave advice on the paper. P Debré and M Capron gave advice on the paper. V E Volchkov advised on sequencing the VP24 gene and on the paper and gave us the purified Ebola antigens.

http://www.thelancet.com/journals/lancet/article/PIIS0140-6736(00)02405-3/fulltext

 

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Sanjay Gupta talking to a Dr. Charles Haas saying the incubation period might be longer....


DREXEL STUDY QUESTIONS 21-DAY QUARANTINE PERIOD FOR EBOLA

October 15, 2014
Ebola in Uganda
Quarantining individuals who might have been exposed to Ebola for a period of 21 days has been a standard procedure recommended by the Centers for Disease Control and Prevention, but it might not be long enough.

As medical personnel and public health officials are responding to the first reported cases of Ebola Virus in the United States, many of the safety and treatment procedures for treating the virus and preventing its spread are being reexamined. One of the tenets for minimizing the risk of spreading the disease has been a 21-day quarantine period for individuals who might have been exposed to the virus. But a new study by Charles Haas, PhD, a professor in Drexel’s College of Engineering, suggests that 21 days might not be enough to completely prevent spread of the virus.

Haas’s study “On the Quarantine Period for Ebola Virus,” recently published in PLOS Currents: Outbreaks looks at the murky basis for our knowledge about the virus, namely previous outbreaks in Africa in 1976 (Zaire) and 2000 (Uganda) as well as the first 9 months of the current outbreak.

In both cases, data gathered by the World Health Organization reported a 2-21 day incubation period for the virus –meaning that after 21 days if the individual hasn’t presented symptoms they are likely not to be infected or contagious. This is likely the genesis of the Centers for Disease Control and Prevention’s 21-day quarantine period, but there is little indication from the CDC as to what other considerations played into this policy.

“Twenty-one days has been regarded as the appropriate quarantine period for holding individuals potentially exposed to Ebola Virus to reduce risk of contagion, but there does not appear to be a systemic discussion of the basis for this period,” said Haas, who is the head of the Civil, Architectural and Environmental Engineering Department at Drexel.

Haas suggests that a broader look at risk factors and costs and benefits should be considered when setting this standard. With any scientific data of this nature there is a standard deviation in results –a percentage by which they may vary. In the case of Ebola’s incubation period the range of results generated from the Zaire and Uganda data varied little. This might have contributed to the health organizations’ certainty that a 21-day quarantine period was a safe course of action.

But looking more broadly at data from other Ebola outbreaks, in Congo in 1995 and recent reports from the outbreak in West Africa, the range of deviation is between 0.1 and 12 percent, according to Haas. This means that there could be up to a 12 percent chance that someone could be infected even after the 21-day quarantine.

“While the 21-day quarantine value, currently used, may have arisen from reasonable interpretation of early outbreak data, this work suggests reconsideration is in order and that 21 days might not be sufficiently protective of public health,” Haas said.

Haas, who has extensive background in analyzing risk of transmitting biological pathogens, explains that these quarantine periods must be determined by looking at the cost of enforcing the quarantine versus the cost of releasing exposed individuals. Looking at the potential tradeoff between costs and benefits as the quarantine time is extended should guide public health officials in determining the appropriate time. Obviously, with more contagious and potentially deadly diseases the cost of making a mistake on the short side when determining a quarantine is extremely high.

“Clearly for pathogens that have a high degree of transmissibility and/or a high degree of severity, the quarantine time should be greater than for agents with lower transmissibility and/or severity. The purpose of this paper is not to estimate where the balancing point should be, but to suggest a method for determining the balancing point.”

- See more at: http://drexel.edu/now/archive/2014/October/Ebola-quarantine/#sthash.JEK2Ntbx.dpuf