Ebola: Implications and Perspectives

Abstract

The 2014 Ebola virus disease outbreak in West Africa has been the largest in recorded history. During this Ebola epidemic, the media has focused much attention to the magnitude of the problem in West Africa but has also overplayed the potential for an Ebola virus pandemic as patients have been transported for treatment to the United States and Europe causing panic and paranoia in the population. Knowledge of the epidemiology, pathogenesis, clinical presentation, treatment, and prevention of this infection will allow a better understanding of the disease and decrease irrational fear of spread.

INTRODUCTION

The possibility of an Ebola virus outbreak of global significance had not been so real until the 2014 outbreak. This outbreak started in December 2013 in Guinea and spread to Liberia and Sierra Leone (1, 2). Imported cases, in some instances with secondary spread of the disease, have thus far occurred in other African nations including Nigeria, Mali, Senegal, the United States, and some countries in Europe such as Spain (3). Previous outbreaks had occurred in isolated rural regions in Africa and the disease could be contained. During this unprecedentedly large outbreak, the disease reached large cities of countries with weak healthcare systems (4). Also contributing to the expansion of this epidemic are cultural and societal characteristics of the affected populations, high population mobility across porous country borders, and recent civil strife and war in the affected countries. The sum of such factors made it difficult to control the disease in Guinea, Liberia, and Sierra Leone, and the number of affected individuals reached unprecedented numbers during this outbreak. In short, the largest, most severe and difficult to contain Ebola outbreak in history has affected some of the poorest countries in the world creating the perfect conditions for the virus to spread to other parts of the globe in this era in which travel is ubiquitous.

The media has been instrumental in presenting very graphically to the general public what is happening in Africa. Unfortunately, they have also overplayed the potential of an Ebola virus pandemic that has caused panic and paranoia in the population (5). This has created an environment in which healthcare workers who have responded to the call for help have faced stigma, discrimination, and quarantine upon their return even though they show no signs or symptoms of infection (6). Journalists who have traveled and reported what is happening in Africa have been asked not to show up to previous commitments just because they have been where the outbreak is occurring. The lack of knowledge of how the infection is transmitted and the heightened publicity about cases that have occurred outside Africa have made the spread of fear much worse than the spread of the disease itself.

THE VIRUS

Ebola, together with Marburg, belongs to the Filoviridae family. It is an enveloped, negative, single-stranded RNA virus (7). It is one of the viruses considered in the category A bioterrorism agents as part of the hemorrhagic viral diseases (8). Zaïre ebolavirus (EBOV) is the species circulating during the 2014 outbreak (2). In addition, there are four other species: Sudan (SUDV), Tai Forest (TAFV), Bundibugyo (BDBV), and Reston (RESTV). EBOV is the species that has been implicated in most outbreaks and causes the highest mortality.

Filoviruses have a very characteristic morphology when seen under electron microscopy using negative stains. They form twisted filaments with a constant 80-nm width but lengths that range from 800 to 1,100 nm (9, 10). The RNA encodes seven proteins that have more than one function (11). The genes include the nucleoprotein (NP), the polymerase cofactor (VP35), a matrix protein (VP40), a secondary matrix protein (VP24), a glycoprotein (GP), a transcription activator (VP30), and RNA-dependent RNA polymerase (10). In addition, the gene encodes for a non-structural, soluble glycoprotein (sGP) which is secreted by infected cells and is thought to have an anti-inflammatory function (12). GP and VP40 are essential components of the viral envelope with VP24 integrated at intervals. The VP30 and NP proteins appear to be intertwined with the viral RNA while VP35 and the viral polymerase are at one end of the viral RNA. The GP attaches to an unknown host receptor and facilitates entry into the cell through endocytosis into a macropinosome, and then the virus is conveyed to an endosomal compartment (13). While in the endosomal compartment the GP must be primed, which leads to viral penetration into the host cell cytoplasm and replication of the virus. The NP, VP24, and VP35 proteins participate in assembly of the viral nucleocapsid (14).

EPIDEMIOLOGY

Ebola virus was first described in 1976 during two almost simultaneous epidemics in Zaire (now the Democratic Republic of Congo) and what is now South Sudan (7, 15). The name derives from a small river in northwestern Democratic Republic of Congo. Since then, there have been more than 20 outbreaks of the disease primarily in rural areas of equatorial Africa. The reservoir for Ebola is suspected to be in bats as serological evidence has been found in several bat species (16). Primates and other mammals are secondary hosts with substantial evidence that there is transmission between different primates such as gorillas and chimpanzees (17). The virus jumps into human populations as they get exposed to the virus from either bats or other infected animals. Although no specific activities have been found to be associated with transmission of infections from animals to humans, in 2008 tourists, a Dutch and an American, had febrile illnesses and serologic evidence of Marburg virus infection after having visited a cave in Uganda (18) and similar circumstances are suggested for Ebola virus infections. Some authors have postulated that climate changes and expansion of human populations into forested areas increase animal to human transmission.

From 1989 to 1996, several non-human primates were brought to facilities in the United States and Italy and were found to be infected with Reston Ebolavirus (REBOV) (9, 19). REBOV has been found in pigs from Philippines where the primates originated (20). Care-takers of the symptomatic REBOV-infected primates in the US facilities did not show symptoms of disease although they showed serologic evidence of exposure (19, 21). Thus, this species causes disease in non-human primates and pigs but is not known to cause symptoms in humans.

The 2014 Ebola outbreak has an R0 (reproductive number) that ranges from 1.71 in Guinea to 2.02 in Sierra Leone, which is not significantly different from previous epidemics (1). This reproductive number (R0) indicates the number of cases one case generates on average. This is an R0 much lower than other diseases such as HIV, diphtheria, or measles. Although the R0 is comparatively low, the mortality of the disease in Guinea, Liberia, and Sierra Leone is very high (approximately 70%). In addition, the burden of disease in healthcare workers or family members caring for patients with the disease is disproportionately high due to their heightened exposure. This has further depleted these countries of prepared personnel who can take care of patients when they already have a very low proportion of healthcare workers to population (22).

TRANSMISSION

Ebola virus is transmitted from human to human via direct contact with infected body fluids or indirectly by contact of contaminated surfaces (23). Yamin et al used data on daily viral load among survivors and non-survivors during the 2000–2001 Ugandan outbreak and found that non-survivors had the highest risk for transmitting the virus later in the course of the disease (24). It is also known that while the patient is not symptomatic transmission does not occur. Although there are no studies defining specifically the infective dose of EBOV, it is estimated that for viral hemorrhagic fevers the number of viral particles necessary to cause disease in non-human primates using aerosols is approximately 1 to 10 organisms (25). The information available indicates that the amount of virus needed for infection is low and transmission is highest when patients are most symptomatic being particularly high in fatal cases. Not surprising, those dealing with the bodies of infected patients are at major risk of contracting the disease.

During the Kikwit 1995 outbreak in Republic of Congo, a detailed study of risk factors showed that some patients had not had direct contact with infected patients or any secretions (26). The authors suggest that transmission through aerosols cannot be completely excluded. A study of lethality of filiviruses in interferon receptor−deficient mice showed that EBOV and Marburg can be transmitted by aerosols (27). The viral dose that caused disease was lower when performing intraperitoneal infections compared to a higher dose needed for infection to occur through the aerosol route. However, the natural creation of aerosols that could pass infection has been studied in non-human primates, showing no transmission of the EBOV through the aerosol route (28).

Taking into consideration the epidemiology and transmission risks, the use of personal protective equipment (PPE) is imperative to protect healthcare workers and those taking care of remains. In many ways healthcare workers have been taught to use gloves and other protective equipment to keep patients safe from infection whether it is in surgery suites or to prevent spread infections from patient to patient. In the case of Ebola the paradigm has changed, as we are using the equipment to protect ourselves, the healthcare workers. The Centers for Disease Control and Prevention (CDC) has a guideline and a video showing how to don and doff PPE (29). Important aspects to take into consideration include the need to have a buddy system where one person observes each step performed, hand hygiene is repeated multiple times through the process, and all body parts are covered. Also important is that N95 masks are currently recommended to protect against potential aerosolization of the virus.

CLINICAL FEATURES

Patients usually present 2 to 21 days after exposure with fever, chills, myalgias, and malaise (7, 9, 15). These initial signs and symptoms are sufficiently non-specific that early in the disease the differential diagnosis is with a variety of other infectious agents including malaria, typhoid fever, influenza, dengue, yellow fever, meningococcemia, and others. The initial presentation is followed by gastrointestinal symptoms including anorexia, nausea, vomiting, diarrhea, and abdominal pain and respiratory symptoms including nasal discharge, cough, and shortness of breath. Hemorrhagic features are only observed in the final stages of those most affected and include petechiae, ecchymosis, and bleeding from venipuncture sites and mucous membranes. Poor prognosis is associated with shock, encephalopathy, and extensive hemorrhage. In addition to the mentioned clinical findings, those patients who have been evacuated to the United States have shown increased edema due to anasarca and cardiac arrhythmias that were attributed to electrolyte derangement (30). Of note is a study of rural populations in Gabon where epidemic and non-epidemic Ebolavirus have occurred and which showed a 15% prevalence of antibodies to EBOV in people who had not been sick, indicating that there are human exposures that result in asymptomatic infections (31).

Laboratory results are characterized by dynamic changes in the blood cell counts particularly in platelets and white cells (9, 32, 33). In initial stages, as antigenemia increases, there is thrombocytopenia and leukopenia that is characterized by increased numbers of atypical lymphocytes. As the disease progresses there is an increase in neutrophils which show a left shift and toxic granulations. Also present in the blood are increased concentrations of liver enzymes (aspartate aminotransferase and alanine aminotransferase), prolongation of prothrombin (PT) and partial thromboplastin (APTT) times, hypokalemia, hypoglycemia, and hypoalbuminemia. Decreases in calcium have been associated with fatal illness.

LABORATORY FEATURES

Several considerations must be considered when seeing an infected patient or a patient in whom Ebola needs to be ruled out (34): What specimens need to be obtained? How is the diagnosis of Ebola made? What other tests need to be considered for diagnosis and to take care of the patient? How are these tests to be performed? How will we dispose of the specimen?

For the diagnosis of Ebola, the specimen of choice is blood although other specimens could be considered. However, as other diagnoses including malaria, typhoid fever, meningococcemia, and others will need to be ruled out, drawing blood will likely be necessary. Several blood specimens (whole blood, serum, and plasma) will need to be obtained as some will be tested at the facility the patient is while testing for Ebola will have to be sent to a reference laboratory. Phlebotomy needs to be performed using full PPE and the specimen that will be tested for Ebola needs to be packaged following the CDC recommendations before it is shipped to the facility that will perform the Ebolavirus test (35). Ebolavirus is a category A agent and the people packaging the specimen need to be trained in how to do this. For the rest of the testing, point of care and rapid testing is advocated (36) although the United Kingdom guidelines suggest that the specimens can be tested in the hospital laboratory if closed systems are used and as long as the specimen is retrieved and disposed of adequately (37). To assess the patient's status, testing should be kept to the necessary minimum, but will likely include complete blood cell counts, electrolytes, creatinine, liver function tests, partial thromboplastin time (APTT), prothrombin time (PT), and urine analysis. As the patient may have more than one infectious agent such as malaria when coming from an endemic region, rapid testing for malaria may be necessary, although the need to make smears (thick and thin) may be questioned. Regarding blood cultures to rule out a variety of bacterial infections, these can be obtained and placed in automated systems; however, once they become positive, the rest of the work with the blood culture bottles needs to be performed in a biosafety cabinet, preferably inside a negative pressure room (such as those present in laboratories that perform mycobacterial cultures) (37).

For Ebolavirus diagnosis, detection of viral nucleic acid using polymerase chain reaction (PCR) is specific and does not require the host to have produced antibodies providing the earliest test to become positive (38). Although detection of immunoglobulin M (IgM) antibodies against Ebolavirus using immunoassays can be used for diagnosis, the presence of antibodies usually occurs after the PCR has turned positive. As isolation procedures need to be instituted as soon as possible it is imperative to have a test that gives a diagnosis as early as possible. Thus, PCR is the method of choice. However, a negative PCR can occur even in an infected individual before symptoms have started. Other modalities of testing include viral isolation, total Ebola antibodies, and immunohistochemistry.

Specimens of Ebola-infected patients need to be inactivated before they can be disposed of as regular waste (39). Incineration, autoclaving, and chemical inactivation are considered appropriate means of disposing infected specimens. Handling of deceased patients should be kept at a minimum (40). Any lines or tubes should be left in place, the body should not be washed, and the body should be wrapped in a plastic shroud. The body should then be placed in a leak-proof bag and zipped up then placed in a second leak-proof bag. The bodies should not be embalmed and the remains should be cremated or buried promptly.

PATHOGENESIS AND PATHOLOGY

Filoviruses infect primarily dendritic cells, monocytes, macrophages, Kupffer cells, and fibroblasts (41). However, other cells have been shown to have viral particles such as endothelial cells, hepatocytes, adrenal cells, and several types of epithelial cells (42). Cells infected with Ebola virus secrete large quantities of the soluble GP which is thought to interfere with the inflammatory response (9, 43). The infected cells also produce VP35 and VP40 which inhibit interferon rendering the host incapable of an effective innate or adaptive immune response (44).

There are several studies of proinflammatory cytokines such as tumor necrosis factor α (TNF- α), interleukin 6 (IL-6), IL-8, and IL-1β in patients infected with Ebolavirus (31, 45, 46). Although some of the results appear conflicting, the proinflammatory response depends on the species infecting the patients, the time when the sample was obtained, and the host's ability to survive. One study of sera obtained from EBOV infection survivors and fatalities showed that during the initial days of the disease, the amount of antigen was similar in both groups (45). However, in survivors during the symptomatic phase TNF- α, IL-6, IL-1β, and macrophage inflammatory proteins MIP-1a and MIP-1b are observed in the plasma whereas in fatal cases TNF- α was only detected before death. The proinflammatory response with TNF-α and IL-6 has been observed in asymptomatic EBOV-infected subjects. Survivors were also able to mount an IgG response to EBOV NP, VP35, and VP40 which was not observed in deceased patients. Fatal outcomes were associated with increased amounts of IL-10 which inhibits activation of T-helper cells and neopterin which is secreted by activated macrophages. These cytokine and chemokine changes have not been observed when the infection is due to SUDV (46). In those surviving infection with SUDV, there are increased levels of interferon-α. In general, the aberrant innate immunity, characterized by secretion of multiple cytokines, is noteworthy because of the absence of interferon in patients with fatal outcomes (31).

Infected cells do not trigger an inflammatory response by neutrophils, monocytes, or lymphocytes (12). Apoptosis of large numbers of non-infected lymphocytes is a frequent observation. Observations in mice indicate that lymphocyte apoptosis is due to the Fas pathway, tumor necrosis factor−related apoptosis-inducing ligand (TRAIL), and cytochrome C efflux from mitochondria (12, 47). In fatal cases there is a decrease in T lymphocytes in particular CD8-positive and activated T cells (CD8 + HLA-DR) (33).

Animal models that recapitulate what happens in humans have been created (48). Rodent models (mice, hamsters, and guinea pigs) include the use of adapted Ebola viruses. Although some characteristics such as rash, thrombocytopenia, cytokine response, and lymphocyte apoptosis are observed in each of these models, they do not completely recreate what happens with humans. In contrast, non-human primate models (using African green monkeys, cynomolgus macaques, rhesus macaques, and hamadryas baboons) and wild-type virus show clinical and laboratory characteristics that are very similar to those found in human disease. Non-human primates usually become febrile 3 days after inoculation. As disease progresses, they become dehydrated, anorectic, and have weight loss. By day 5 they develop diarrhea, rectal bleeding, and skin rash. Blood cell counts demonstrate neutrophilia with lymphopenia and thrombocytopenia. At necropsy there is extensive lymphocyte apoptosis in vessels and lymphoid tissues. The virus is found in the liver, spleen, lungs, kidneys, adrenals, testis, lymph nodes, and pancreas (48).

Few studies of Ebola-infected human tissues are available largely due to the high infectivity of fatal infections. The largest study comprises skin and liver biopsy specimens from 18 patients that occurred during the Kikwit outbreak (49). Skin biopsy specimens have shown mild changes, primarily found in the dermis. Endothelial cells in vessels have shown various degrees of swelling and necrosis, and there is dermal edema and extravasated red blood cells. Infrequent findings included fibrin thrombi in vessels and perivascular inflammation. Liver biopsy specimens showed intracytoplasmic elongated or oval, eosinophilic viral inclusions inside hepatocytes, hepatocellular necrosis, microvesicular fatty change, and Kupffer cell hyperplasia. Viral antigens using immunohistochemistry were located throughout the dermis, around sweat glands, in hepatocytes, and Kupffer cells.

TREATMENT

Care of patients with Ebola virus disease begins with isolation of patients and use of PPE by healthcare workers to prevent nosocomial transmission of the disease. Management of waste is also important and ideally all supplies should be disposable. There are currently no approved antiviral drugs for the treatment of Ebola and the most critical part of care remains aggressive supportive hospital care with fluid and electrolyte replacement, use of blood products and oxygen as needed and management of multi-organ failure if it occurs (30). Dialysis has been performed in an Ebola infected patient with renal failure who survived (50). Many patients are also co-infected with malaria so it has been recommended that empiric treatment for malaria be given.

Among the drugs that have been used in the management of patients with Ebola during the 2014 outbreak are Zmapp (a combination of three monoclonal antibodies), brincidofovir (a derivative of cidofovir, a drug that inhibits DNA synthesis used to treat DNA viruses including herpesviruses), and favipiravir (nucleotide analog that inhibits RNA polymerase and causes lethal mutations, approved in Japan for the treatment of influenza) (51, 52). However, none of these drugs have thus far been tested in controlled clinical trials. Studies with these drugs as well as others are soon to begin in West Africa but ethical dilemmas concerning the design of these studies remain unresolved (53). Other experimental candidates in clinical development for treatment of Ebola virus disease include TkM-Ebola (a small interfering RNA that targets Ebola virus RNA polymerase L, VP24, and VP35) and phosphorodiamidate morpholino oligomers which target different proteins of Ebola virus appear to be effective in reducing mortality in animal models (51, 54).

Serum from convalescent patients that contains anti-Ebola virus antibodies has been successfully used in Africa and the United States (51). The use of hyperimmune globulins for infections such as hepatitis, rabies, and varicella-zoster has been well documented. Production of hyperimmune serum in Africa will be limited because of the infrastructure needed to produce the serum, inactivation of other possible infectious agents, and the need to use compatible blood.

VACCINES

There are currently no vaccines approved for Ebola prevention, but two promising vaccines have now entered phase 1 clinical trials. The first, developed by GlaxoSmithKline in collaboration with the NIH/NIAID has the Ebola virus GP gene presented in a replication-incompetent chimpanzee Adenovirus 3 (cAd3-ZEBOV). This vaccine proved to be reactogenic and immunogeneic in a dose-response manner in a small clinical trial (55). The second vaccine, developed by the Public Health Agency of Canada, uses a replication-competent vascular stomatitis virus with one of its genes replaced by the Ebola virus GP gene (rVSV-SEBOV) (56). Both these vaccines may eventually enter phase 2–3 efficacy trials in West Africa, but clearly the ethical challenges outlined for therapeutic studies will also apply for vaccine trials. Nevertheless we are facing unprecedented times and the size and impact of the outbreak warrant all efforts possible to control it.

CONCLUSIONS

The 2014 outbreak of Ebola virus disease is the largest and most severe that has occurred to date. The countries most affected, Guinea, Sierra Leone, and Liberia, had difficulty controlling the outbreak due to lack of healthcare infrastructure and healthcare personnel. In a sense, Ebola is a symptom of a problem: weak healthcare systems in many African countries. The few patients seen outside Guinea, Sierra Leone, and Liberia showed that even in large cities transmission can be controlled and mortality can be decreased if cases are identified and adequate supportive treatment is given. There is an urgent need to test antiviral drugs effective against Ebola and vaccines that can be used to prevent future outbreaks.

DISCUSSION

Billings, Baton Rouge: Why do they say that this is not an airborne type of situation? You said that these things that they are coughing up are absolutely loaded with virus. So why is everyone saying that this is only a body fluid contact issue and not an airborne droplet problem?

Guarner, Atlanta: I think things are being revised as we speak.

Del Rio, Atlanta: I think we are not sure. So far the evidence today has been that this is not airborne. But I think some of the data, like Jeannette showed from CDC on seeing inside the lung macrophages, has made people rethink this. The reality is nowadays we actually measure viral load in the secretions, and a lot of people are looking at that. My recommendation is that we continue thinking. When I talk to the team they say, “We don't know if it is airborne or not.” But I can tell that when we are seeing a patient and somebody all of a sudden has projectile vomiting, they can infect you. So just protect yourself if you are going to be doing any deep suctioning or anything. So I think this is in flux.

Hochberg, Baltimore: As a member of our hospital's committee which is supposed to design the strategy for what happens when we have a patient who is suspected to have Ebola — based on exposure, given travel history, or contact with someone whose had a similar travel history who comes into our emergency department — what am I going to tell the care providers in the emergency department to do other than to put the patient in a taxi and tell them to take them to Hopkins?

Del Rio, Atlanta: On Friday our Ebola team got called concerning a 19-year-old with fever and a headache from Africa, and they were very concerned. He was sick and brought into our emergency room. The person was put in isolation immediately just like you would do with somebody who may have TB; you put them in isolation. The Ebola team was immediately called. They handled the specimens. They separated the specimens. They took him down to the Ebola unit. Long story short, the person did not have Ebola. The Ebola PCR was negative. We are very fortunate we can do the testing there. The patient had malaria with 32% parasitemia and was incredibly ill. One of the problems I see is that people are so focused on Ebola and forget that there are a lot of other things that look like Ebola and can be serious. We are fortunate to have the BioFire and PCR right there, and we were able to do it. The problem you have is that if you do not have that, you will be sending a sample to the health department and the health department will be sending it to CDC. Judy Aberg from Sinai told me that when they had a rule out in New York a couple of months ago, neither Federal Express nor any other transport company would take the specimen. Sinai had to rent a private plane and pay $10,000 to transfer the specimen to CDC. So in the meantime what do you do with the patient? So they had to have the patient in an isolation area and treat him as a possible Ebola patient.

Guarner, Atlanta: Another thing we have to remember is that you can have malaria and Ebola. The nurse missionary that we received at Emory has given a nice interview that has already been published. She was not one of the people that were taking care of patients, but she obviously got contaminated. When she started having a fever, they first categorized her as a low-risk. They did malaria testing and she was positive. She was given treatment and her fever did not come down. Then they did the Ebola testing, and she was positive and eventually transferred. So the fact that you have malaria doesn't mean that you are completely Ebola-free. We know that the PCR does not come up immediately as positive. So, we are learning as we speak.

Olds, Riverside, CA: Obviously the next cases are not going to walk in the door at Atlanta or Nebraska, etc. They are going to walk into community hospitals in our country. I would point out that it is going to expose two problems that we have had historically that we have not had to deal with. You just mentioned the first one. I already know of two cases in California that were admitted for fear of Ebola that sat in an isolation room for more than two days until they discovered falciparum malaria, which could've killed them by the way. The mortality rate for falciparum malaria in United States is close to 10% because of the ignorance of our physicians. The second problem that we are going to face is that we are not doing well with infection control. Any of us that work in hospitals around C. difficile or any of the other issues know that our community hospitals — or even our university hospitals — are already handling this poorly. And this is a fairly scary scenario as was seen in Texas; poorly trained and prepared just to handle routine infection control. Faced with an actual case is really a scenario that is a little scary for those out on the field. Could you comment on the latter?

Del Rio, Atlanta: I think that Ebola is exposing the weakness in our healthcare system. The reality is that there are a lot of holes in the system. What happened in Dallas I think is a great example. The other one I was going to add is also the continuity of care and the sporadic care we deliver in our systems with hospitalists and shifts and other things. We are very, very opposed to that. We need to have a core group of individuals that manage these patients; none of this shift work. We did not involve residents, and we did not involve house staff. We wanted to maximally avoid the possibility of someone getting contaminated. A dedicated hospital team that is well-trained to take care of these patients is going to make a difference. If you put them into your regular patient flow, you're going to have a problem. In the Dallas case, the patient was in the ICU and died. His nurse was taking care of two patients and she was using vinyl powder free gloves and taking them off and going to the other patient. We have a dedicated nurse taking care of that patient. If you are doing this many times, you are going to get contaminated. There is going to be a problem. This is expensive. I don't even know what Emory has spent on this, but I can tell you the healthcare system has been incredibly valuable. They built that laboratory in no time. But I can tell you that the bill is not insignificant. So far they have been okay with all the expenses. But it is not cheap to properly care for Ebola patients.

Sullivan, Atlanta: Where we are now with our reaction to this infection is similar to the way we responded as a nation in the late 80s to the AIDS virus. Many of you remember children being excluded from school. So clearly we don't know how to handle emergencies like this very well. Your slide showed tremendous viral load in these tissues. I believe I read where the number of viral particles in fluids in patients with Ebola is much more than in other viral infections. Does this have any relationship to the health workers — not only here in this country but in countries in West Africa — where so many doctors and nurses have been infected? Is it because of the viral load that they come in contact with? What happens to this virus in nature? I understand that Fulton County initially did not want to have the water from this containment unit coming into the public water system. Finally, you mentioned incineration of the body is preferred. That is not occurring in these African countries. How long does the virus last in these bodies? Is it permanent, or is there some life span?

Del Rio, Atlanta: We need to understand a lot more about the pathogenesis and transmission of this virus. There is a lot of virus as Jeannette showed in the skin, primarily in the subcutaneous tissue and the blood vessels. But talking to my colleague, Dr Bruce Ribner, they measure viral load in the patient's skin and they have also measured viral load in the sheets, and there is no virus there. So at least it leads you to believe that direct insignificant contact will not get you infected. I believe that the people that got infected did so because they touched their eye or face or had a little break in their skin. A lot of those patients have very high viral loads. I think those of us working in HIV have known how the virus load correlates very nicely with transmission. These patients have viral loads in the millions — in the tens of millions — so the transmission is incredibly high. We still need to understand a lot about the transmission. As far as how long the virus stays in the environment, that is a different story. We do not know but probably very shortly. I would like to clarify that it was not Fulton, it was Dekalb County, and they never said don't dispose. Dekalb County just called and said we need to understand what you are going to do. But inactivation will happen very rapidly, and what we decided to do at Emory was treat all the secretions with sodium hypochlorite before being disposed.

Guarner, Atlanta: They get solidified. We put a solidifier onto the secretions and then they get autoclaved, and then they get disposed of. You need to also understand the different techniques when you are demonstrating the PCR or the immunohistochemistry; you may have a lot more antigens than nucleic acid; that's one. The other is you don't know if that virus that you are seeing there, or those remnants of the virus that you are seeing in the immunohistochemistry, are viable. Since we are not doing viral cultures we do not know how much of it is viable. I agree with the assessment of the HIV craziness and equating it to what we are seeing now. It's really funny how people don't think logically. Some of the nurses that are in the unit have decided to rotate out of being in the unit and go back to their usual duties on the regular floor. The nurses on the regular floor are up in arms saying that they don't want them to be there until 21 days after they have been away, because what if they are infected. I think that we have proven that these nurses have been absolutely excellent at doing the things that need to be done. However, their nurse mates are extremely afraid of them coming in to contact with them because they have been taking care of Ebola patients. And it's very irrational.

Del Rio, Atlanta: Rick Besser wrote yesterday in the Washington Post that he had been in Africa recently and was invited to Case Western to give a talk on crisis management. He was called by the provost to the president saying, “Don't come. If you can do it via Skype that would be fine, but we are really concerned about you speaking to our students because you are still not over the 21 days.” Read it! It's really a fascinating piece to read because it talks about how this fear… I mean this is a university president saying don't come, could you do it via Skype so we don't have you here just in case you don't bring Ebola? And he said, “No, I am not doing it.”

Katz, Boston: I want to thank you for pointing out this link between diseases like this and poverty which is something we learn over and over again with multiple diseases but somehow have trouble getting beyond it. My questions are however related to the issue of the Ebola team that you have described. I know you have talked a little bit about it, but I have some specific questions like many people in the audience. My hospital is struggling what to do with this. House staff role or not? Who should be on the team and who should not be on the team? The follow up to that is this issue of balancing limited exposure and expertise versus a larger group because this type of work must be exhausting. So you may pick 10 people to be on your team, but they are going to be overworked and overwhelmed and exhausted. There are very few diseases I can think of, or over even anywhere, where we allow providers to opt out of participation? I don't know if Emory has thought about that or looked at that.

Del Rio, Atlanta: We started with a small team. The small team was fine, but they are beginning to get tired. In fact, we have expanded our team. We are getting more people trained and we are rotating people off. In other words, as people are coming in our people are rotating off the team in order to avoid exhaustion. At this point in time, we are basing the team composition on volunteers; people that actually want to do this, people that are willing to do it and put in the time, the energy. The beauty is that most of us, thank God, went into medicine because we wanted to help others, and we wanted to make a difference. Our head nurse, Susan Grant, has a beautiful little YouTube video entitled “Why I decided to do this,” that just talks about her desire to help people and to do what is the right thing; to step up to the plate. The problem we have had honestly is sometimes with consultants who are not part of the team, who are a mess sometimes because they like to work independently. But we have done a very good job trying to get everybody aligned in doing the right thing. But this is an ongoing struggle and part of it has also been building a team, a family that supports itself. I could show you a picture of the day after the president came into town. They all went to have a beer courtesy of the Ebola team just to give them a break, just to make them feel like they are appreciated. There have been a lot of efforts from the hospital to get them recognition. There has been a lot of, “You guys are great!” kind of approach… really getting recognition out to them. But I am concerned about the long-term care. I am in charge of Emory ID and the Chief of Service in the hospital, and I am struggling; two of my attendings right now are actually on the Ebola team, the transplant attending and the general ID attending. So we have to reshuffle the attending schedules so that somebody can cover them. That means some people that didn't have service now have to have service. At some point in time that is not a sustainable model.

Guarner, Atlanta: We use a lot of consultants in the sense. You may not be directly in the team testing but you are helping with other aspects of providing the laboratory support that needs to be provided. We have a person that is basically doing all the transfusion protocols, getting the hyperimmune serum. There has been a lot of collaboration.

Falk, Chapel Hill: The case in Dallas raises the question of what happens when one of these individuals ends up in an ICU. Is it futile and dangerous to do, for example, hemodialysis on one of these patients? What is the outcome? Is it always going to be fatal, and are we only then going to expose all of our healthcare employees to the risk without any benefit? Should they ever go to an ICU?

Del Rio, Atlanta: Our units are our two rooms. There is a room with an anteroom with two rooms with bathrooms and a lab that was built outside and a shower. These rooms are ICU rooms. They are double-sized rooms, and you can manage somebody in an ICU setting. One of our patients, our latest one, was very sick; he was hemodialyzed. The renal team did a fantastic job. The patient is about to be discharged from the hospital. So I don't think it is futile. I can tell you that it saved his life. The kind of care that we can provide in the ICU is fantastic. But it required the renal team to come in and decide who was going to do it; to be very careful. We need to do what we need to do and we need to do it well. That is the key of this. We can provide outstanding care for our patients and we can do it well. So far at Emory our mortality rate is zero and we are in patient number 4, so we are pretty happy about that.

Hook, Birmingham: Jeannette I'm interested in the pathophysiologic process here. Is this macrophage activation syndrome? And while that consideration may not be absolutely relevant in Africa, as we begin to think about it and move forward, that consideration would have therapeutic implications.

Guarner, Atlanta: As you can see there is antigen in epithelial cells. There is antigen in macrophages. There is antigen everywhere. So I am not sure we can definitively pinpoint. Obviously, once the liver is affected and you have liver failure, then clotting factors go down. There is an enormous amount of cytokines that are involved. There is an interesting article that came out looking at serology and T-cell activation from a previous outbreak, and they also talk a lot about these kinds of things. I can provide it to you.

Rice, Providence: Tim Flanigan, my colleague from Providence, has been in Monrovia for 5 weeks now and has been writing a blog. One of his recent blogs — to leave some optimistic information here — shows in Lofa County (which is abutting Sierra Leone and one of the places that was most affected) there was a major uptick in new cases and suspected cases and admissions to the hospital a month ago. But it has come dramatically, dramatically down. A presentation in his blog attributes that to the general population being educated and finally recognizing that their practices are spreading the disease and also to expansion of the hospital facilities. So it may not be as bad as everybody is predicting. Last week at the IDSA meetings, several presentations showed that the presence, at least of the DNA, in different body fluids lasts for different periods of time. The one that was most memorable was in semen that lasts for as much as 3 months. I know we really love these numbers, especially early on when we really have no idea what's going on. So everybody thinks that 21 days is some magical time. What happens 6 months out? Is all the virus gone from peoples' bodies? There was a huge amount you showed there. Do we know? Does it stay latent? What actually happens to it?

Guarner, Atlanta: They get virus-free. They have been measuring viral loads. It's been interesting because the CDC was doing the viral load in serum and they were cleared before we were clearing them because we were measuring it in blood, which I guess it is not surprising if you compare it to HIV. The urine stays positive for apparently a longer period of time. It has to do in some ways because of the reservoir in the testis. Apparently some of these patients end up having a lot of neuropathy from what I am hearing, but we're learning.

Del Rio, Atlanta: The policy we are establishing in Emory is in order to get out of the unit you need to have two consecutive negative viral loads, because people would have a negative then have another positive; so you really need to have two consecutive negative viral loads. I think they probably remain virus-positive but not necessarily infectious for a period of time. We don't know enough about this disease. There probably are a fair number of people that actually are infected and asymptomatic. There was a very nice study years ago from Gabon in which they went to a population that had never seen Ebola. They took adults that never had clinical Ebola, and 15% of them were antibody-positive. So there probably is some subclinical infection that leads to immunity. Those people then don't develop disease because they are already immune. There is a big thing being made in Africa about the survivors. Some people are saying, take the survivors and actually train them and make them a healthcare worker. Those are the people you need to have in your unit taking care of the patients, since they already are immune to the current outbreak. CDC is locating those survivors and trying to employ them; trying to give them a role in this epidemic, at least at the community level.

Barish, Shreveport: You've described the extreme precision with which you need to handle these patients. It's almost like a military operation. One deviation could lead to a fatal mistake. You said there are approximately 10,000 cases expected now in West Africa — with 8 having made their way to the United States — and suggestions there could be 100,000 in the future. How do you transfer a patient to a facility like yours? What are your criteria to accept the patient in Emory?

Guarner, Atlanta: The State Department is doing that.

Del Rio, Atlanta: An American being sick — an American overseas — becomes the property of the State Department. So an American being sick overseas, the State Department then decides that it's appropriate to transfer those patients. You can use any regular ambulance service that actually the State Department uses. There is one company that they use when they transfer the patient. We at Emory are basically obligated to take them based on this biocontainment unit that we have. That was one of our commitments. It is the head of our unit, Dr Ribner, who they talk to, and he makes the decision to take the patient. But again we are talking about an expensive operation.

Barish, Shreveport: But if I had a patient in my hospital in Louisiana…

Del Rio, Atlanta: For the patient in Dallas, the call went to CDC. And CDC and NIH together with HHS made the decision to take one of the nurses. She came to Emory yesterday, and one of the other nurses is going to the NIH. When Mr Duncan was sick in Dallas, I know that Dr Ribner and the Emory team offered the Dallas hospital to transfer the patient, and they declined. But they made their offer and said, “Look, our beds are empty right now, we're happy to take your patient.”

Barish, Shreveport: So the first call is to the CDC?

Del Rio, Atlanta: Your first call is to your local health department, your state health department who then will communicate to CDC. I don't want to bypass them. The state health departments play a really important role.

Guarner, Atlanta: Not only that, they are going to be the ones that are going to be handling the testing. If they have an LRN (laboratory response network), they will be doing the testing.

Julia Sanders (wife of Bo Sanders), New Orleans: I am wondering about the dialysis equipment, the bedside dialysis equipment. What happens to that equipment? How do you decontaminate it? Nobody else would want to be dialyzed at bedside with the equipment that was used on an Ebola patient.

Del Rio, Atlanta: I will let Jeff Sands answer that. I have no idea what he has done. The one thing I would tell you though is that — again Jeannette can confirm this — we have already heard from some of the lab equipment companies saying they are not providing maintenance to the lab equipment used down there.

Guarner, Atlanta: It's not only the maintenance. When they were asked how to decontaminate whatever instruments we are using, they basically said to incinerate it. I don't know if they were joking or not. There are decontamination procedures that we use regularly with laboratory instrumentation, and the companies are the ones that do the decontamination procedures. Obviously, we process samples that include hepatitis B, hepatitis C, HIV, and we are reusing all of that equipment. Now dialysis is another issue since they are going to go back into the patient. But in the lab that is something that is done on a regular basis, wiping out stuff. In between patients they do some decontamination procedure with hydrogen peroxide fumes or something like that.

Sands, Atlanta: So when the first two patients came to Emory, a few of us had a theoretical discussion about what we do if this happened. Thank goodness it didn't on the first two. But the decision was to not use a conventional dialysis machine but the smaller continuous renal replacement therapy (CRRT) machine. At the time we weren't sure if that machine would ever get used for anyone ever again. In the case where it did need to be used it was one machine, the CRRT machine. We had to quickly get the nurses who were in the unit trained on how to actually use the machine because we did not want to have too many people going in. That machine has been treated, as has been discussed, with the decontaminants. The CDC is still not sure whether the machine can actually be reused by anyone. So the CDC has been in touch with the manufacturer. There are certain parts of the machine that they are just not comfortable will get exposed to the decontaminant or could there be micro-contamination. So at the moment that machine is still sitting in the unit under mothballs waiting for the CDC to make a final ruling. Hopefully, it will continue to sit there unneeded by the fourth patient or any future ones. Certainly that machine was never then taken from this patient and moved immediately to anyone else. And that was why the CRRT machine was used.

Del Rio, Atlanta: Thank you, Jeff. Well, maybe it will go to the CDC museum and be put right next to the iron lung and say this was the Ebola dialysis machine.

Schuster, New York: We've had poverty for a long time and I don't think there has been a sudden change in poverty. So I understand how poverty can accelerate and permit the spread. But you know there was poverty in London, and then the well got contaminated with cholera and everybody drank from the well. So other than poverty, do you have any thoughts on why this time Ebola has broken loose?

Del Rio, Atlanta: I think there are several issues and Jim Hughes could be here. But clearly we are in the process. I mean cities are growing… we're deforesting… we're invading areas where animals used to be and bats are all over the place. During middle eastern respiratory syndrome (MERS), for example, when people said, “Oh no there are no bats in Saudi Arabia” and all of a sudden you just have to be out in the desert and see that there are bats everywhere. This animal-human interaction is getting a lot closer, and that is why the “One World, One Health” phenomena. I think there are three countries that not only have poverty but have also gone through civil war and enormous social disruption. The healthcare system has been totally decimated in these three countries. So I think we are seeing the final nail in the coffin of three countries that quite frankly have been incredibly devastated. This is not the case in Nigeria, and the proof is how Nigeria very quickly was able to control it because they actually have some functioning something. There is poverty, but they have some things that function. It is a confluence of too many things — including social disruption and this animal-human interaction — that I think is really going to lead to many more diseases. We had SARS. We had MERS. Now we have this. We can go on and on and talk about the new outbreaks, but I think those of us in infectious disease have no problem continuing being employed. That's why I tell students come into ID.

Guarner, Atlanta: The other thing we need to think about is — you see on television and we've seen multiple news organizations where they show a patient that is sick — the hospital in the little town is basically closed because they don't have any more room and they send the patient back to their home. How do you expect the family not to get sick or whoever is taking care of that patient not to get sick? If the patient is already having profuse diarrhea and profuse vomiting, you know they are sick and people are walking by them.

Billings, Baton Rouge: How can I ask Jim not to speak to his boss?

Hughes, Atlanta: Well I wasn't going to speak but since he mentioned me I will just for a moment. It's important to recognize this is another zoonosis that has originated in wild life. We have seen many examples and we will see more. Delays in recognition and serious response are part of the reason that we are dealing with some of the issues that we have been talking about. The final thing is that this is the first time that an Ebola outbreak has really gotten into the big cities, the capital cities, and you see what is happening in those settings. Previous outbreaks have been in isolated rural areas and contained there.