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Ebola Virus

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Levi Bonnell

on 2 May 2013

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Transcript of Ebola Virus

Ebola Virus by
Katelyn Hall and Levi Bonnell Overview History Classification Epidemiology Outbreak of Ebola Hemorrhagic Fever Recent Outbreak Recent Discoveries Quiz!! MarbugVirus First outbreak in Marbug, Germany in 1967
Cases were exposed to African green monkey tissue imported from Uganda
Unusual morphology and extreme infectivity underscore the fact that this family of viruses are a serious threat to human health
Although morphologically similar to Marbug, Ebola is immunologically distinct
5 subtypes of Ebola have been discovered
4 of which are harmful to humans Ebola is a highly virulent and infective virus largely found in Africa
Named after the Ebola River in the Norther Democratic Republic of the Congo (previously Zaire)
25 total outbreaks since simultaneous discovery in Zaire and Sudan, 1976
ICD-10 code: A98.4
When discovered, scientists thought Ebola was a new strain of Marbug virus Reston Ebolavirus Apathogenic to humans
Discovered in Reston, Virginia in 1989
Since 1989 it has been found in Texas, Pennsylvania, and Italy
The outbreak that occurred in Reston started from infected Monkeys shipped in from the Philippines... Reston Ebolavirus Ebola was previously only known to be endemic in Africa before monkeys were shipped to Reston, Virginia from the Philippines Bundibugyo Ebolavirus Newest subtype found: November 27, 2007
2 epidemics since discovery
Bundibugyo, Uganda (2007)
116 cases, MR=34%
Democratic Republic of the Congo (2012)
15 cases, MR=67% Cote de I'voire (Tai Forest) Ebolavirus Discovered in Chimpanzees in Tai forest on the Ivory Coast Africa in 1994
Epidemic among chimpanzees
Western red colobus monkey was initially suspected as the natural reservoir infected (chimps food source)
One scientist infected during autopsy of chimp
Recovered within 6 weeks in Switzerland First assumed to be identical with Zaire Ebolavirus due to simultaneous discovery dates
however, later discovered to be different
Outbreak among cotton workers in 1976
Latest outbreak in Sudan in 2001
MR=53% Sudan Ebolavirus Zaire Ebolavirus Discovery of Ebola virus August 1976
318 cases 280 deaths
Average MR= 83% over 27 years
More on this outbreak later... Bioterrorism The case fatality rate is nearly 90%, second only to rabies
Ebola is easily spread from person to person via bodily fluid but not through aerosol
The CDC has classified Ebola as a level 4 biosafety agent and a category A bioterrorism agent (both of highest concern)
But, because of the limited number of outbreaks, and lack of knowledge concerning the natural reservoirs, isolation of the virus is unlikely by terrorist groups
Also, in an adequate hospital Ebola would not spread
Detecting/identifying Ebola before spread major issue Outbreak Characteristics Zaire Ebolavirus Outbreak, 1976 International Commission Bumba Zone Characteristics Yambuku Mission Hospital (YMH) Case Definition International Committee Establishes Team for Retrospective Case Study Outbreak of a new virus in Northern Zaire (now Democratic Republic of the Congo)
Bumba Zone
Outbreak started Sept. 1, 1976
Final case died Nov. 5, 1976 275,000 people live in Bumba Zone
75% live in small villages (<500 ppl)
Tropical Rainforest
Locals are avid hunters
No paved roads
Rural conditions
Endemic diseases
malaria, pneumonia, TB, Dysentery, measles ect...
One hospital YMH serves 60,000+ people
120 beds
17 staff members
~12,000 people/ month
Use 5 syringes/needles per day
Wash in warm water in between patients
Boil at end of day to reuse Formed Oct. 18th with 6 primary goals
1) Stop transmission of disease
2) Control epidemic
3) Increase surveillance
4) Clinical features and epidemiology of Ebola
5) Collect samples
6) Search for possible reservoirs Person living in the epidemic zone (Bumba Zone, Ziare), who died after one or more days with two or more of the following symptoms: headache, fever, abdominal pain, nausea and/or vomiting, or bleeding (especially gastrointestinal tract bleeding). Also patient must have received an injection from YMH or been in close contact with a confirmed case within the three weeks prior to death. Where a confirmed case had an indirect florescent antibody titre of 1:64 within three weeks of onset of symptoms. Majority of transmission ceased when the YMH closed
However, the international commission also recommended
burning clothes worn by deceased
Stop hunting wild monkeys
Stop cultural burial ceremonies/bury bodies and cadavers deeply
respirators/goggles for medical employees
isolation/quarantine Ceasing Transmission of Ebola 6 physician lead teams survey villages Nov 1-9 and again independently Nov. 15-21
91% agreeance on cases
Index case: 44 year old mission instructor
Toured in car near Sudan border Aug. 10-22
22nd bought antelope and monkey meat
26th admitted into YMH for 'malaria'
given injection
fever resolved until Sept. 1st- GI bleeding
died Sept. 8, 1976
9 other cases in first week of Sept.
All received injection from YMH
Attack rate 8/1000 people Distribution of cases/Statistics Possible Reservoirs 55/550 villages had at least one case of Ebola
64% of cases occurred in villages having 1-5 cases
85/318 injected at YMH
All died
149/318 cases by contact
43 both
13/17 YMH workers contracted Ebola
11/13 died: CFR=85%
66% of cases had melaena
Total of 318 cases, 280 deaths
Case fatality rate=88%
Secondary attack rate
5% for general public
20% among family members
55/550 villages affected
Ebola does not discriminate between gender or age
However, females 15-29 were adversely affected due to occupation Natural reservoirs caught for sampling
818 total samples of bedbugs
5 different mosquito species
10 pigs, 1 cow, 7 species of bats
123 different rodents
All tested NEGATIVE!
Nowadays it is thought, yet unproven, that the fruit bat is the natural reservoir How would you stop an outbreak of Ebola in an inadequate hospital setting? Question #1 True or False: Monkeys are the natural reservoir for Ebola virus? Question #2 Question #3 Given R0= c*q* 1/delta
is there an epidemic of Ebola in the hospital?
number of contact per unity time = 25
transmission probability of bodily fluid = .9
Duration of infectious period is = 10 days References 1) Ebola haemorrhagic fever in Zaire, 1976. Bulletin of the World Health Organization 56 (2): 271–293. 1978.
2) Ebola outbreak in Democratic Republic of Congo – update. Who.int.
3) DRC Confirms Ebola Outbreak. Voanews.com.
4) WHO: Ebola Outbreak in Uganda is Under Control : US/World. Medical Daily.
5) http://www.cnn.com/2012/08/03/health/uganda-ebola-virus/index.html
6) Growing concerns over 'in the air' transmission of Ebola, United Kingdom: BBC News, 2012, retrieved 2013-04-17
7) Heymann, D. L. (2008). Control of Communicable Diseases Manual (19th ed.). Baltimore, MD: United Book Press, Inc.
8) Murphy, F. A., Van Der Groen, G., Whitefield, S. G., and Lange, J. V.(n.d.). Ebola and Marburg Virus Morphology and Taxonomy. Centers for Disease Control and Prevention. Retrieved April 29, 2013 from http://www.enivd.de/EBOLA/ebola-18.htm
9) Public Health Agency of Canada (2010). Ebola Virus: Pathogen Safety Data Sheet- Infectious Substances. Public Health Agency of Canada. Retrieved April 30, 2013 from http://www.phac-aspc.gc.ca/lab-bio/res/psds-ftss/ebola-eng.php
10) Weingartl, H. M., Embury-Hyatt, C., Nfon, C., Leung, A., Smith, G., and Kobinger, G. (2012). Transmission of Ebola virus from pigs to non-human primates. Nature Publishing Group: Scientific Reports. Scientific Reports 2(811). doi:10.1038/srep00811 Retrieved April 29, 2013 from http://www.nature.com/srep/2012/121115/srep00811/full/srep00811.html Questions? Index Case Started showing symptoms Sept. 1, 1976
5 days earlier, admitted into YMH for malaria
Injection of chloroquine
Within 4 weeks
11/17 hospital workers dead
280 cases
hospital ordered to close
Incubation period~1 week
Duration of disease~1 week
Primary mode of transmission
injection with infected needle
secondary: non-aerosol bodily fluids Key Findings Discovery of a new virus
Natural reservoir unknown
Not monkeys
Spread by bodily fluids but not by aerosol
Highly virulent
High attack rate due to unsafe practices Host: Person Environment: Northern 'Zaire'/ Southern Sudan Agent:
Zaire Ebolavirus Indirect Vector:
Monkeys Epi Triange -> stop transmission ->
(injections) Reservoir Host Sept. 15, 2012 outbreak of Ebola hemorrhagic fever in Democratic Republic of the Congo
46 cases; 19 fatal
At time of article: still an epidemic
Active team established by the ministry of health is trying to interrupt modes of transmission and stop epidemic
Who recommends not traveling to Congo
Another on Aug. 8, 2012 in Uganda Scientists have confirmed that pigs (domestic and wild) are apathogenic to Ebola virus
possible natural reservoir?
Also, they have proved that pigs can spread Zaire Ebolavirus via aerosol to monkeys
Deadly implications Member of RNA virus family called Filoviridae
Marbug included in Filoviridae
Five subtypes: Ebola-Zaire, Ebola-Sudan, Ebola-Ivory Coast, Ebola-Bundibugyo and Ebola Reston Virus
Majority of the studies on the Ebola Reston Virus is on adult males
Need more studies on women, children, and immunocompromised Pathology So few specimens that no true pathology has been defined
There are speculated mechanisms Ebola Hemorrhagic Symptoms Diagnosis Identification by the onset of early symptoms
Testing with:
enzyme-linked immunosorbent assay (ELISA)
antigen detection tests
serum neutralization test
reverse transcriptase polymerase chain reaction (RT-PCR) assay
virus isolation by cell culture Testing is difficult due to the hazardous nature of virus Treatment No treatment
Supportive therapy: balancing the patient's fluids and electrolytes, maintaining their oxygen status and blood pressure, and treating them for any complicating infections
Several drugs being tested
Without supported therapy, outcome is likely death History
Ebola Outbreak
Recent outbreaks
Recent discoveries
Quiz Four strains of Ebolavirus: Ebola-Zaire, Ebola-Sudan, Ebola-Ivory Coast and Ebola-Bundibugyo Agent-related Factors Infective dose: 1 – 10 aerosolized organisms
Virulence: largely unknown
affects many different cells in the body Habitat suitable for monkeys and bats
Clinics or hospitals with unsanitary conditions
True reservoir unknown
fruit bats from Pteropodidae family possible reservoir
Specifically genera Hypsignathus monstrosus, Epomops franqueti and Myonycteris torquata
Pigs have been shown to be a reservoir in animal studies Hammer-headed Fruit Bat Franquet's Epauletted Fruit Bat Little collared fruit bat Humans
All ages
Incubation period: 2 to 21 days
Up to 90% fatality rate Non-human primates could be considered vectors
Animal studies have shown that pigs can transmit Ebolavirus to non-human primates specifically ZEBOV Non specific-sudden onset of fever, intense weakness, muscle pain, headache, sore throat, red eyes and a skin rash
Symptoms may also include diarrhea, dysphagia, rash, severe weakness, hemorrhagic phenomena, vomiting, impaired kidney and liver function, both internal and external bleeding, CNS involvement and shock, and multi-organ dysfunction Structure Pleomorphic
Commonly in "U" or "6" Shape Transmission Animal-Human
Contact with blood or bodily fluids from infected animals
documented transmission through the handling of infected chimpanzees, gorillas, fruit bats, monkeys, forest antelope and porcupines found dead or ill in the rainforest.
No animal vaccine
Contact will blood or bodily fluids from an infected individual
Contact with infected objects like needles
Spreads quickly in healthcare facilities where patients are treated without the use of a mask, gown, or gloves and where non-disposable needles are used
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