EBOLA VIRUS DISEASE

Dr. Bharat KalidindiMPH 1st SEMPadmashree School of Public Health. Bangalore

OVERVIEW

• Ebola is a disease of humans and other primates caused by ebolaviruses, is a severe, often fatal illness in humans.

• The average EVD case fatality rate is around 50%. Case fatality rates have varied from 25% to 90% in past outbreaks.

• The 2014 Ebola outbreak is the largest Ebola outbreak in history and the first in West Africa.

BACKGROUND

• Ebola virus disease (EVD) first appeared in 1976 in 2 simultaneous outbreaks, one in Nzara, Sudan, and the other in Yambuku, Democratic Republic of Congo. The latter occurred in a village near the Ebola River, from which the disease takes its name.

• The current outbreak in west Africa, (first cases notified in March 2014), is the largest and most complex Ebola outbreak since the Ebola virus was first discovered in 1976. There have been more cases and deaths in this outbreak than all others combined. It has also spread between countries starting in Guinea then spreading across land borders to Sierra Leone and Liberia, by air (1 traveller only) to Nigeria, and by land (1 traveller) to Senegal.

• The most severely affected countries, Guinea, Sierra Leone and Liberia have very weak health systems, lacking human and infrastructural resources, having only recently emerged from long periods of conflict and instability.

• On August 8 2014, the WHO Director-General declared this outbreak a Public Health Emergency of International Concern.

• A separate, unrelated Ebola outbreak began in Boende, Equateur, an isolated part of the Democratic Republic of Congo on 24th August 2014.

STORY OF ORIGIN• August 26, 1976 in Yambuku, a town in the north of Zaïre. A 44-year-old school teacher returned from a small hike. He went to the doctor and because of his high fever they gave him a quinine shot which is good against malaria.

• A week later, he had uncontrolled vomiting, bloody diarrhea, trouble breathing and then bleeding from his nose, mouth, and anus.

• He died ~14 days after the onset of symptoms.

• The first outbreak of Ebola (Ebola-Sudan) infected over 284 people, with a mortality rate of 53%.

• A few months later, the second Ebola virus emerged from Yambuku, Zaire, Ebola-Zaire (EBOZ). EBOZ, with the highest mortality rate of any of the Ebola viruses (88%), infected 318 people.

• Despite the tremendous effort of experienced and dedicated researchers, Ebola's natural reservoir was never identified.

• The third strain of Ebola, Ebola Reston (EBOR), was first identified in 1989 when infected monkeys were imported into Reston, Virginia, from Mindanao in the Philippines.

• Fortunately, the few people who were infected with EBOR (seroconverted) never developed Ebola hemorrhagic fever (EHF).

• The last known strain of Ebola, Ebola Cote d'Ivoire (EBO-CI) was discovered in 1994 when a female ethologist performing a necropsy on a dead chimpanzee from the Tai Forest, Cote d'Ivoire, accidentally infected herself during the necropsy.

Non-human primates, like gorillas and chimpanzees, have been cited by the World Health Organization as possible infection sources for humans, but experts have realized that they are not the source of the problem. The apes have been deemed “accidental hosts,” meaning that they catch the disease and then pass it along but are not the initial “reservoir” source that produces the virus.

The virus kills gorillas and chimpanzees and other monkeys. Because it kills apes in such high percentage – they are not likely to be its natural host.

EBOLA TAXONOMYScientific Classification

Order: Mononegavirales Family: Filoviridae Genus: Ebola like viruses Species: Ebola Subtypes

• Ebola-Zaire, Ebola-Sudan, Ebola-Ivory Coast disease in humans

• Ebola-Reston disease in nonhuman primates

• Most mysterious virus group

• Pathogenesis poorly understood

• Zoonotic virus – bats the most likely reservoir, although species unknown• Spillover event from infected wild animals (e.g., fruit bats, monkey, duiker) to

humans, followed by human-human transmission

EBOLA VIRUS TRANSMISSION• Virus present in high quantity in blood, body fluids, and excreta of symptomatic

EVD-infected patients

• Opportunities for human-to-human transmission• Direct contact (through broken skin or unprotected mucous membranes) with

an EVD-infected patient’s blood or body fluids• Sharps injury (with EVD-contaminated needle or other sharp)• Direct contact with the corpse of a person who died of EVD• Indirect contact with an EVD-infected patient’s blood or body fluids via a

contaminated object (soiled linens or used utensils)

• Ebola can also be transmitted via contact with blood, fluids, or meat of an infected animal

• Limited evidence that dogs become infected with Ebola virus • No reports of dogs or cats becoming sick with or transmitting Ebola

HUMAN-TO-HUMAN TRANSMISSION

• Infected persons are not contagious until onset of symptoms

• Infectiousness of body fluids (e.g., viral load) increases as patient becomes more ill

• Remains from deceased infected persons are highly infectious

• Human-to-human transmission of Ebola virus via inhalation (aerosols) has not been demonstrated

virus enters a cell through a mechanism that has yet to be determined

Once inside the host cell's cytoplasm, the filovirus uncoats itself and releases transcriptase, which is contained in the virion

Transcriptase transcribes the viral -ssRNA into the complimentary +ssRNA

RNA will then be used as the template for the new viral genomes

Soon after the infection, the cell develops cytoplasmic inclusion bodies that contain the highly structured viral nucleocapsid

After the nucleocapsid has been formed, the new virus will self-assemble and bud from the cell membrane stealing some of the membrane for its

envelope.

The Filoviridae Journey

EBOLA PATHOGENESIS

• Direct infection of tissues

• Immune dysregulation

• Disseminated intravascular coagulation (DIC) and coagulopathy

• Hypovolemia and vascular collapse• Electrolyte abnormalities

• Multi-organ failure, septic shock

INCUBATION PERIOD

• Patients with Ebola virus disease typically have an abrupt onset of symptoms 6 to 12 days after exposure (range 2 to 21 days).

• There is no evidence that asymptomatic persons still in the incubation period are infectious to others.

• All symptomatic individuals should be assumed to have virus in the blood and other body fluids, and appropriate safety precautions should be taken

Early Clinical PresentationAcute onset; typically 6 – 12 days after exposure

(range 2–21 days)Signs and symptoms

• Initial: Fever, chills, myalgias, malaise, anorexia• After 5 days: GI symptoms, such as nausea, vomiting, watery diarrhea, abdominal

pain• Other: Headache, conjunctivitis, hiccups, rash, chest pain, shortness of breath,

confusion, seizures• Hemorrhagic symptoms in 18% of cases

Other possible infectious causes of symptoms• Malaria, typhoid fever, meningococcemia, Lassa fever and other bacterial infections

(e.g., pneumonia) – all very common in AfricaCommon signs and symptoms reported from the 2014-2015 West African outbreak include fever, fatigue, headache, vomiting, diarrhoea, and loss of appetite. Reports have also described weakness, myalgias, as well as a high fever accompanied by relative bradycardia as seen in typhoid fever.

CLINICAL FEATURES

• Nonspecific early symptoms progress to:• Hypovolemic shock and multi-organ failure• Hemorrhagic disease• Death

• Non-fatal cases typically improve 6–11 days after symptoms onset

• Fatal disease associated with more severe early symptoms• Fatality rates of 70% have been reported in rural Africa• Intensive care, especially early intravenous and electrolyte management, may increase

the survival rate

CLINICAL MANIFESTATIONS BY ORGAN SYSTEM

IN WEST AFRICAN EBOLA OUTBREAKOrgan System Clinical Manifestation

General Fever (87%), fatigue (76%), arthralgia (39%), myalgia (39%)

Neurological Headache (53%), confusion (13%), eye pain (8%), coma (6%)

Cardiovascular Chest pain (37%),

Pulmonary Cough (30%), dyspnea (23%), sore throat (22%), hiccups (11%)

Gastrointestinal Vomiting (68%), diarrhea (66%), anorexia (65%), abdominal pain (44%), dysphagia (33%), jaundice (10%)

Hematological Any unexplained bleeding (18%), melena/hematochezia (6%), hematemesis (4%), vaginal bleeding (3%), gingival bleeding (2%), hemoptysis (2%), epistaxis (2%), bleeding at injection site (2%), hematuria (1%), petechiae/ecchymoses (1%)

Integumentary Conjunctivitis (21%), rash (6%)

EXAMPLES OF HEMORRHAGIC SIGNS

Bleeding at IV Site Hematemesis

Gingival bleeding

LABORATORY FINDINGS• Thrombocytopenia (50,000–100,000/mL range)

• Leukopenia followed by neutrophilia

• Transaminase elevation: elevation serum aspartate amino-transferase (AST) > alanine transferase (ALT)

• Electrolyte abnormalities from fluid shifts

• Coagulation: PT and PTT prolonged (These changes are most prominent in severe and fatal cases.)

• Renal: proteinuria, increased creatinine

viremia

3

IgM

ELISA IgM

0 10

IgG

IgM: up to 3 – 6 months

ELISA IgG

IgG: 3 – 5 years or more (life-long persistance?)

days post onset of symptoms

RT-PCR

Critical information: Date of onset of fever/symptoms

Fever

EVD: Expected Diagnostic Test Results Over Time

27

EBOLA VIRUS DIAGNOSIS• RT – PCR Used to diagnose acute infection

• More sensitive than antigen detection ELISA• Identification of specific viral genetic fragments• Performed in select CLIA-certified laboratories

• RT-PCR sample collection• Volume: minimum volume of 4mL whole blood• Plastic collection tubes (not glass or heparinized tubes)• Whole blood preserved with EDTA is preferred

• Whole blood preserved with sodium polyanethol sulfonate (SPS), citrate, or with clot activator is acceptable

OTHER EBOLA VIRUS DIAGNOSTICS• Virus isolation

• Requires Biosafety Level 4 laboratory; • Can take several days

• Immunohistochemical staining and histopathology • On collected tissue or dead wild animals; localizes viral antigen

• Serologic testing for IgM and IgG antibodies (ELISA) • Detection of viral antibodies in

specimens, such as blood, serum, or tissue suspensions

• Monitor the immune response in confirmed EVD patients

LABORATORIES• CDC has developed interim guidance

for U.S. laboratory workers and other healthcare personnel who collect or handle specimens

• This guidance includes information about the appropriate steps for collecting, transporting, and testing specimens from patients who are suspected to be infected with Ebola

• Specimens should NOT be shipped to CDC without consultation with CDC and local/state health departments

Packaging & Shipping Clinical Specimens to CDC for Ebola Testing

INTERPRETING NEGATIVE EBOLA RT-PCR RESULT

• If symptoms started ≥3 days before the negative result EVD is unlikely consider other diagnoses Infection control precautions for EVD can be discontinued unless clinical

suspicion for EVD persists

• If symptoms started <3 days before the negative RT-PCR result Interpret result with caution Repeat the test at ≥72 hours after onset of symptoms Keep in isolation as a suspected case until a repeat RT-PCR ≥72 hours

after onset of symptoms is negative

DIFFERENTIAL DIAGNOSIS• Malaria• Typhoid fever

In addition to the conditions listed in the differential diagnosis, other problems to be considered include the following:• Acute surgical abdomen (as distinct from abdominal signs of

Ebola hemorrhagic fever)• Crimean-Congo hemorrhagic fever• Marburg hemorrhagic fever• Other hemorrhagic fevers

Hemorrhage is a less common and less clinically important aspect of the syndrome. Thus, the term "Ebola virus disease" is now being used, rather than the

earlier name "Ebola hemorrhagic fever.“

CLINICAL MANAGEMENT OF EVD: Supportive, but aggressive

• Hypovolemia and sepsis physiology• Aggressive intravenous fluid resuscitation • Hemodynamic support and critical care management if necessary

• Electrolyte and acid-base abnormalities • Aggressive electrolyte repletion• Correction of acid-base derangements

• Symptomatic management of fever and gastrointestinal symptoms• Avoid NSAIDS

• Multisystem organ failure can develop and may require • Oxygenation and mechanical ventilation• Correction of severe coagulopathy• Renal replacement therapy

Reference: Fowler RA et al. Am J Respir Crit Care Med. 2014

INVESTIGATIONAL THERAPIES FOR EVD PATIENTS

• No approved Ebola-specific prophylaxis or treatment• Ribavirin has no in-vitro or in-vivo effect on Ebola virus• Therapeutics in development with limited human clinical trial data

• Convalescent serum• Therapeutic medications

• Zmapp – three chimeric human-mouse monoclonal antibodies • Tekmira – lipid nanoparticle small interfering RNA• Brincidofovir – oral nucleotide analogue with antiviral activity• Favipiravir – oral RNA-dependent RNA polymerase inhibitor

• Vaccines – in clinical trials• Chimpanzee-derived adenovirus with an Ebola virus gene inserted• Attenuated vesicular stomatitis virus with an Ebola virus gene inserted

PATIENT RECOVERY

• Case-fatality rate between 50-70% in the 2014 Ebola outbreak • Case-fatality rate is likely much lower with access to intensive care

• Patients who survive often have signs of clinical improvement by the second week of illness

• Associated with the development of virus-specific antibodies• Antibody with neutralizing activity against Ebola persists greater than 12 years after

infection

• Prolonged convalescence• Includes arthralgia, myalgia, abdominal pain, extreme fatigue, and anorexia; many

symptoms resolve by 21 months• Significant arthralgia and myalgia may persist for >21 months • Skin sloughing and hair loss has also been reported

Detection of Ebola Virus in Different Human Body Fluids over Time

INITIAL ASSESSMENT FOR EBOLA VIRUS DISEASE

Determining the risk of exposure 

• The risk of exposure to Ebola virus helps to guide the evaluation and management of both symptomatic and asymptomatic individuals.

• Patients are at risk for Ebola virus disease if they had an exposure that occurred within 21 days before the onset of symptoms. However, the level of exposure risk ranges from high to low to no known identifiable risk. For healthcare workers, the level of exposure risk can vary depending upon the intensity of the epidemic at their work site (i.e., the risk of exposure is greater in areas of widespread Ebola virus transmission).

• The level of risk defined below is consistent with CDC recommendations, which take into account uncertainty about the extent of Ebola virus spread in some urban areas in West Africa.

EVD Risk Assessment

• **CDC Website

HIGH-RISK EXPOSURE

Percutaneous (e.g., needle stick) or mucous membrane exposure to blood or body fluids of a person with Ebola while the person was symptomaticORExposure to the blood or body fluids (including but not limited to feces, saliva, sweat, urine, vomit, and semen) of a person with Ebola while the person was symptomatic without appropriate personal protective equipment (PPE)ORProcessing blood or body fluids from an Ebola patient without appropriate PPE or standard biosafety precautionsORDirect contact with a dead body without appropriate PPE in a country with widespread transmission or cases in urban areas with uncertain control measuresORHaving lived in the immediate household and provided direct care to a person with Ebola while the person was symptomatic

SOME RISK EXPOSURE

In countries with widespread transmission or cases in urban areas with uncertain control measures:• Direct contact while using appropriate PPE with a

person with Ebola while the person was symptomatic or with the person’s body fluids

OR

Close contact in households, healthcare facilities, or community settings with a person with Ebola while the person was symptomatic• Close contact is defined as being for a prolonged

period of time while not wearing appropriate PPE within approximately 3 feet (1 meter) of a person with Ebola while the person was symptomatic

EVD Risk Assessment (continued)

• **CDC Website

LOW (but not zero) RISK EXPOSURE

Having been in a country with widespread transmission or cases in urban areas with uncertain control measures within the past 21 days and having no known exposuresORHaving brief direct contact (e.g. shaking hands) while not wearing appropriate PPE, with a person with Ebola while the person was in the stage of diseaseORBrief proximity, such as being in the same room for a brief period of time, with a person with Ebola while the person was symptomaticORIn countries without widespread transmission or cases in urban settings with uncertain control measures: direct contact while using appropriate PPE with a person with Ebola while the person was symptomatic or with the person’s body fluidsORTraveled on an aircraft with a person with Ebola while the person was symptomatic

NO IDENTIFIABLE RISK EXPOSURE

Contact with an asymptomatic person who had contact with person with EbolaORContact with a person with Ebola before the person developed symptomsORHaving been more than 21 days previously in a country with widespread transmission or cases in urban areas with uncertain control measuresORHaving been in a country with Ebola cases, but without widespread transmission or cases in urban settings with uncertain control measures, and not having any other exposures as defined aboveORHaving remained on or in the immediate vicinity of an aircraft or ship during the entire time that the conveyance was present in a country with widespread transmission or cases in urban areas with uncertain control measures and having had no direct contact with anyone from the community

EVD CASES (UNITED STATES)• EVD has been diagnosed in the United States in four people, one (the index patient) who

traveled to Dallas, Texas from Liberia, two healthcare workers who cared for the index patient, and one medical aid worker who traveled to New York City from Guinea

• Index patient – Symptoms developed on September 24, 2014 approximately four days after arrival, sought medical care at Texas Health Presbyterian Hospital of Dallas on September 26, was admitted to hospital on September 28, testing confirmed EVD on September 30, patient died October 8.

• TX Healthcare Worker, Case 2 – Cared for index patient, was self-monitoring and presented to hospital reporting low-grade fever, diagnosed with EVD on October 10, recovered and released from NIH Clinical Center October 24.

• TX Healthcare Worker, Case 3 – Cared for index patient, was self-monitoring and reported low-grade fever, diagnosed with EVD on October 15, recovered and released from Emory University Hospital in Atlanta October 28.

• NY Medical Aid Worker, Case 4 – Worked with Ebola patients in Guinea, was self-monitoring and reported fever, diagnosed with EVD on October 24, recovered and released from Bellevue Hospital in New York City November 11.

Practical Considerations for Evaluating Patients for EVD in the

United States

• CDC encourages all U.S. healthcare providers to• Ask patients with Ebola-like symptoms about travel to West Africa

or contact with individuals with confirmed EVD in the 21 days before illness onset

• Know the signs and symptoms of EVD• Know the initial steps to take if a diagnosis of EVD is suspected

• CDC has developed documents to facilitate these evaluations

EVD Algorithm for Evaluation of theReturned Traveler

Symptomatic patients with identifiable risk

• Clinical findings that are consistent with Ebola virus disease include fever and/or severe headache, weakness, muscle pain, vomiting, diarrhoea, abdominal pain, or unexplained hemorrhage. Infection control precautions should be used for all symptomatic patients who have an identifiable risk for Ebola virus disease.

• Such patients should be isolated in a single room with a private bathroom and with the door to the hallway closed, and all healthcare workers should use standard, contact, and droplet precautions (Eg, gown, facemask, eye protection, and gloves).

• In patients who are suspected of having Ebola virus disease, phlebotomy and laboratory testing should be limited to tests that are essential for care.

• Certain hospitals may be designated as "Ebola assessment hospitals," which are prepared to evaluate and care for patients with possible Ebola virus disease until a diagnosis can be confirmed or ruled out. Such patients who have confirmed Ebola virus disease should be transferred to specialized Ebola treatment centers.

Asymptomatic individuals with identifiable risk 

• Monitoring for symptoms and signs of Ebola virus disease should be performed for asymptomatic persons who have had an exposure to Ebola virus at any risk level (i.e., high, some, or low risk).

• Such individuals should be monitored for 21 days after the last known exposure and should immediately report the development of fever or other clinical manifestations suggestive of Ebola virus disease.

• The type of monitoring (Eg, self-monitoring and reporting versus direct observation by a designated health official), as well as the need for travel restrictions, restricted movement within the community, and/or quarantine depend, in part, upon the exposure risk level, and are described in detail in the CDC guidance for the monitoring and movement of persons with Ebola virus exposure.

• Local authorities may also have specific regulations for man monitoring and movement of persons with Ebola virus exposure management of asymptomatic individuals with Ebola virus exposure.

Patients with no identifiable risk

• If after initial evaluation, patients are determined to have no identifiable risk for Ebola virus infection, monitoring or diagnostic testing for Ebola virus disease is not warranted.

• However, if patients have fever and other signs or symptoms of infection, they should be evaluated for other causes of febrile disease (Eg, malaria, Lassa fever, influenza).

• Appropriate infection control precautions will depend upon the patient's clinical findings, as well as the specific pathogens that are being considered.

Interim Guidance for Monitoring and Movement of Persons with EVD

Exposure• CDC has created guidance for monitoring people exposed to Ebola virus but

without symptomsRISK LEVEL PUBLIC HEALTH ACTION

Monitoring Restricted Public Activities

Restricted Travel

HIGH risk Direct Active Monitoring Yes Yes

SOME risk Direct Active Monitoring Case-by-case assessment

Case-by-case assessment

LOW riskActive Monitoring for some; Direct Active Monitoring for others

No No

NO risk No No No

Ebola virus disease (EVD) cumulative incidence* West Africa, December 17, 2014

* Cumulative number of reported EVD cases to WHO

3/1/

14

3/7/

14

3/13

/14

3/19

/14

3/25

/14

3/31

/14

4/6/

14

4/12

/14

4/18

/14

4/24

/14

4/30

/14

5/6/

14

5/12

/14

5/18

/14

5/24

/14

5/30

/14

6/5/

14

6/11

/14

6/17

/14

6/23

/14

6/29

/14

7/5/

14

7/11

/14

7/17

/14

7/23

/14

7/29

/14

8/4/

14

8/10

/14

8/16

/14

8/22

/14

8/28

/14

9/3/

14

9/9/

14

9/15

/14

9/21

/14

9/27

/14

10/3

/14

10/9

/14

10/1

5/14

10/2

1/14

10/2

7/14

11/2

/14

11/8

/14

11/1

4/14

11/2

0/14

11/2

6/14

12/2

/14

12/8

/14

12/1

4/14

12/2

0/14

12/2

6/14

1/1/

15

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Total Cases, Guinea

Total Cases, Liberia

Total Cases, Sierra Leone

2014 Ebola Outbreak Reported Cases in Guinea, Liberia, and Sierra Leone

This graph shows the cumulative reported cases in Guinea, Liberia, and Sierra Leone provided in WHO situation report beginning on March 25, 2014 through the most recent situation report on December 17, 2014.

Reporting Date Total Cases Confirmed Cases Total Deaths

Guinea 16 Dec 14 2,453 2,164 1,550

Liberia 14 Dec 14 7,819 3,021 3,346

Sierra Leone 17 Dec 14 8,759 6,856 2,477

United States 24 Oct 14 4 4 1

Mali 23 Nov 14 8 7 6

Nigeria** 15 Oct 14 20 19 8

Spain** 27 Oct 14 1 1 0

Senegal** 15 Oct 14 1 1 0

TOTAL 19,065 12,073 7,388

EVD Cases and Deaths*

*Reported by WHO using data from Ministries of Health **The outbreaks of EVD in Senegal, Nigeria, and Spain were declared over on October 17, October 19, and December 2 respectively.

MEASURES CARRIED OUT TO REDUCE OUTBREAK

• More than 150 national and international staff are now working on the outbreak in Sierra Leone.

• Beyond medical treatment, controlling the outbreak will require the deployment of large numbers of people to train health care personnel in infection control measures, to follow up with and trace cases and their contacts, to set up an epidemiological surveillance network, and to promote public health messages

• By setting up treatment centers and transit units close to affected villages, MSF can treat patients quickly and reduce the risk of infection in local hospitals and the community.

• Ebola creates fear inside communities, and sick people are often stigmatized. Psychological support is provided to patients and their families. The health workers organize participatory health promotion activities with healed patients. To reduce fear, they are also conducting sensitization campaigns to inform people how the virus spreads. As such, they are encouraging people to report suspected cases of haemorrhagic fever, to avoid contact with people sick with the virus, and to avoid touching the dead body of someone who had been ill with Ebola.

India’s First Ebola Patient Has Been Quarantined

• An Indian resident who tested positive for Ebola—and was cured—has landed in Delhi from Liberia.

• The 26-year-old man is being isolated in a facility at Delhi’s Indira Gandhi International airport.

• The man had already been treated for Ebola in West Africa, currently does not have symptoms and tested negative for the virus before he flew. However, his semen tested positive for the virus.

• Semen can test positive after clinical clearance for up to three months, according to the CDC.

• The patient in India is being kept in isolation in a health facility at the airport until his semen tests negative.

REFENCES

www.google.comcdc.org/ebola

Who.org/ebolaTimes IndiaIndia Today

Lancet. Mar 5, 2011; 377(9768): 849–862WHO Ebola Response team. NEJM. 2014

en.wikipedia.orgwww.nlm.nih.gov/medlineplus

www.mayoclinic.org/diseases-conditions/ebola-viruswww.nhs.uk/conditions/ebola-virus/pages/ebola-virus

www.webmd.comwww.dnaindia.com

www.sciencedirect.comwww.ncdc.gov.in

8Qiu, X et al. Nature 2014; www.sciencemag.org

www.nature.comwww.viprbrc.org

archpedi.jamanetwork.comwww.theguardian.com/world/ebola

www.virology.ws/ebolavirusOestereich, L et al. Antiviral Res. 2014.

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