EBOLA VIRUS INFECTION: BRIEF REVIEW

 

The Centers for Disease Control and Prevention on Wednesday ramped up its response to the expanding Ebola outbreak, a move that frees up hundreds of employees and signals the agency sees the health emergency as a potentially long and serious one (NBCNews.com, 2014). 

The CDC’s “level 1 activation” is reserved for the most serious public health emergencies, and the agency said, according to NBCNEWS, the move was appropriate considering the outbreak’s “potential to affect many lives.” The CDC took a similar move in 2005 in the aftermath of Hurricane Katrina, and again in 2009 during the bird-flu threat.

The Ebola outbreak is believed to have killed 932 people in the African nations of Liberia, Sierra Leone, Nigeria and Guinea. Two American aid workers sickened by the disease were flown back to the U.S. for treatment at a medical facility in Atlanta.

The CDC is deploying additional staff to the four affected countries, and said 50 more disease-control experts should arrive there in the next 30 days. It also issued instructions to airlines that may come into contact with passengers from the affected countries designed to minimize the chance of infection (NBCNews.com, 2014).

Ebola Virus Infection:

Ebola virus is one of at least 30 known viruses capable of causing viral hemorrhagic fever syndrome. Although agents that cause viral hemorrhagic fever syndrome constitute a geographically diverse group of viruses, all those identified to date are RNA viruses with a lipid envelope, all are considered zoonoses, all damage the microvasculature resulting in increased vascular permeability, and all are member of one of the following families: Arenaviridae, Bunyaviridae, Flaviviridae or Filoviridae (King, 2013).

The genus Ebolavirus is one of three members of the Filoviridae family (WHO, 2014) currently classified into 5 separate species such as Sudan Ebolavirus, Zaire Ebolavirus, Tai Forest (Ivory Coast) Ebolavirus, Reston Ebolavirus, and Bundibugyo Ebolavirus (King, 2013).

According to John W King, there are recognized two type of exposure: Primary (involves travel to or work in an Ebola endemic area) and Secondary (refers to human to human exposure, primate to human exposure, or personal who collect or prepare bush meat for human consumption.

The natural reservoir host of ebolaviruses remains unknown (Centers for Disease Control and Prevention , 2014). However, on the basis of available evidence and the nature of similar viruses, researchers believe that the virus is zoonotic (animal-borne) with bats being the most likely reservoir.

Ebola Hemorrhagic Fever is one of numerous Viral Hemorrhagic Fevers; it is severe, often fatal disease in humans and nonhuman primates such as monkeys, gorillas, and chimpanzees. The physical finding depends on the stage of disease at the time of presentation. With African-derived Ebolavirus infection, there is an incubation period typically 3 to 8 days in primary cases and slightly longer in secondary cases (King, 2013), symptoms occur 4-16 days after infection with fever, chills, headache, myalgia, and anorexia (Dambro, 2001). Later findings may include expressionless facies, bleeding from intravenous puncture sites and mucous membranes, myocarditis and pulmonary edema, in terminally ill patients, tachypnea, hypotension, anuria and coma.

Diagnosis:

Ø  Basic blood test: CBC with differential, bilirubin, liver enzymes, BUN, Creatinine, ph.

            The early phase of infection is characterized by thrombocytopenia, leukopenia, and a pronounced lymphopenia. Neutrophilia develops after several days, as do elevations in aspartate aminotransferase and alanine aminotransferase. Bilirubin may be normal or slightly elevated.

           With the onset of anuria, blood urea nitrogen and serum creatinine increase. Terminally ill patients may develop a metabolic acidosis that may contribute to the observation that these patients often have tachypnea, which may be an attempt at compensatory hyperventilation.

Ø  Studies for isolating the virus: tissue culture, reverse-transcription polymerase chain reaction assay.

Ø  Serologic testing: ELISA for antigens or for immunoglobulin M and immunoglobulin G antibodies.

Ø  Other studies: immunochemical testing of postmortem skin, Electron microscopy has been used to identify filoviruses in tissue but has obvious limitations as a diagnostic modality in the areas where human outbreaks have occurred (Geisbert & Jahrling, 1995).

Management (King, 2013).

General medical support is critical and should include replacement of coagulation factors and heparin if disseminated intravascular coagulation develops. Such care must be administered with strict attention to barrier isolation. All body fluids (blood, saliva, urine, and stool) contain infectious virions and should be handled with great care.

Maintaining  oxygen status and blood pressure and treating them for any complicating infection are the standard on the management of supportive Ebola therapy (Centers for Disease Control and Prevention , 2014). Because early symptoms such as headache and fever are nonspecific to ebolaviruses, cases of Ebola may be initially misdiagnosed.

Currently, no specific therapy is available that has demonstrated efficacy in the treatment of Ebola hemorrhagic fever. Surgical intervention generally follows a mistaken diagnosis in which Ebola-associated abdominal signs are mistaken for a surgical abdominal emergency. Such a mistake may be fatal for the patient and for any surgical team members who become contaminated with the patient’s blood.

There are no commercially available Ebola vaccines. However, a recombinant human monoclonal antibody directed against the envelope GP of Ebola has been demonstrated to possess neutralizing activity. This Ebola neutralizing antibody may be useful in vaccine development or as a passive prophylactic agent. Work on a vaccine continues.

Summary of General principles of care:

Supportive therapy with attention to intravascular volume, electrolytes, nutrition, and comfort care is of benefit to patient.

Such therapy must be administered with strict attention to barrier isolation; all body fluids contain infectious virions and should handled with great care

No specific therapy is available that has demonstrated efficacy in the treatment of Ebola hemorrhagic fever

There are no commercially available Ebola vaccines; however, neutralizing antibodies have been studied that may be useful in vaccine development or as passive prophylactic agents.

Prevention:

The CDC states that the Ebola’s prevention presents many challenges because it is unknown how exactly people are infected with the virus. As pointed out by the CDC when cases appear, there is increased risk of transmission within health care setting. Therefore, health care workers must be able to recognize a case of Ebola and be ready to employ practical viral hemorrhagic fever isolation precautions or barrier nursing techniques, and also have the capability to request diagnostic test or prepare samples for shipping and testing elsewhere. (Centers for Disease Control and Prevention , 2014).

As we know, Ebola is transmissible from person to person via direct contact with an infected patient’s blood or other fluids. Moreover, Dr King (2013) explains that the airborne transmission of Reston ebolavirus is known to have ocurred among primates; thus, although most cases in humans occur after contact with a patient or their blood or body fluids, transmission of Ebola virus via the airbone route connot be dismissed.

Infection control inside and outside of medical facilities relies on the following barrier nursing or protection techniques: (Centers for Disease Control and Prevention , 2014) (King, 2013).

Ø  Wearing of protective clothing: mask, gloves, gowns, goggles

Ø  The use of infection control measures: complete equiment sterilization and routine use of desinfectant

Ø  Isolation of Ebola patients from contact with unprotected persons

The CDC emphasizes on the aim of all of thouse techniques is to avoid contact with the blood or secretion of an infected patient, also they points out if a patient with Ebola dies, it is equally important that direct contact with the body of the deceased patient be prevented.

Bibliography

Centers for Disease Control and Prevention . (2014, Aug 5). cdc.gov. Retrieved from Ebola Hemorrhagic Fever: http://www.cdc.gov/vhf/ebola/about.html

Dambro, M. R. (2001). Griffith's 5 minute clinical consult. Philadelphia: Lippincott Williams & Wilkins.

Geisbert, T., & Jahrling, P. (1995). Differentiation of filoviruses by electron microscopy. Virus Res, ;39(2-3):129-50. Retrieved from Differentiation of filoviruses by electron microscopy.

King, J. W. (2013, Aug 19). emedicine.medscape.com. Retrieved from Ebola Virus Infection: http://emedicine.medscape.com/article/216288-overview#a0101

NBCNews.com. (2014, Aug 7). NBCNEWS. Retrieved from http://www.nbcnews.com/storyline/ebola-virus-outbreak/paramedics-take-us-inside-ambulance-ride-ebola-victims-n174456

WHO. (2014, April). who.int. Retrieved from World Health Organization: www.who.int/mediacenter/factsheets/fs 103/en/

Other:

Infection Control for Viral Haemorrhagic Fever in African Health Care Setting by World Health Organization and U.S Department of Health & Human Services (online source http://www.cdc.gov/vhf/abroad/pdf/african-healthcare-setting-vhf.pdf)