Zoonotic Disease Transmission : Ebolavirus in Africa

Antoinette RiveraBaldwin-Wallace College

Senior SeminarJanuary 22, 2010

Zoonotic Disease: Cross species transmission of an infection.

▫Endemic: usual rate of disease within a certain area.

▫Epidemic: unusually high rate of disease within a certain area.

▫Host, Carrier: Animal, insect or plant that carries the infection (viral, bacterial, parasitic).

▫Vector: Any living thing that humans receive a disease from.

▫Reservoir: Animal that carries the infection that occurs naturally but is not affected by it.

Places Zoonotic Diseases affect (1940-2004)Global trends in emerging infectious diseases

Kate E. Jones, Nikkita G. Patel, Marc A. Levy, Adam Storeygard, Deborah Balk, John L. Gittleman & Peter Daszak

Blame Apportioning and the Emergence of Zoonoses over the Last 25 YearsS. B. Ca’ceres and M. J. Otte

Ebolavirus (EBOV) Classification

Family Filoviridae

Genus Filovirus

Species Marburg &

Ebola

Ebola Subspecies-

Zaire, Sudan,

Bundibugyo, Reston,

Ivory

Filovirus Virus Structure

•Branch with folded Nucleocapsid containing the RNA. •Negative-Sense ssRNA, 19,000 RNA bases.

• Humans: 3 billion (3 x 109) base pairs in DNA.

•Encodes for ~7 proteins.

Filovirus- Ebola

http://phene.cpmc.columbia.edu

Branch

Branch

Nucleocapsi

d

Nucleocapsi

d

Ebola Infection

•Direct contact with:

▫Infected blood, organs, tissues and other secretions

▫Handling of infected wildlife

▫Plants

Ebola Attack on immune system

Primar

y

•Mucosal Epithelium

•Skin: Cut, Abrasion

Secondary

•Lung

•Liver

•Spleen

Targeted

Cells

•Dendritic Cells

•Macrophage

•Endothelial

Hemorrhagic Fever• Incubation: 1st week

▫Fever▫Weakness▫Muscle pain▫Headache▫Sore throat▫Vomiting▫Diarrhea

• Late symptoms: 2nd-3rd weeks▫Bleeding (eyes, ears, nose, mouth, rectum)▫Eye Inflammation▫Genital Swelling▫Rash over entire body (hemorrhagic)▫Seizures▫Coma

Mortality rate: ~50-90%

Vaccine/Cure

How Ebola and Marburg viruses battle the immune system. Mansour Mohamadzadeh, Lieping Chen, and Alan L. Schmaljohn*

http://www.nsrc.org/AFRICA

Major Ebola

Outbreaks

Ebola in Africa

Year Place # Cases # Dead Mortality Rate

1976 Sudan,Congo

284318

151280

53%88%

1994 Gabon 57 30 53%

1995 Democratic Republic of the Congo

315 250 79%

1996 Gabon 60 45 75%

2000 Uganda 425 224 53%

2001-2003 Gabon +Democratic Republic of the Congo

302 254 84%

Total Deaths up until 2003

1850 1200 65%

Africa and Ebola

Year Place # Cases # Dead Mortality Rate

1976 Sudan,Congo

284318

151280

53%88%

1994 Gabon 57 30 53%

1995 Democratic Republic of the Congo

315 250 79%

1996 Gabon 60 45 75%

2000 Uganda 425 224 53%

2001-2003 Gabon +Democratic Republic of the Congo

302 254 84%

Total Deaths up until 2003

1850 1200 65%

Africa and Ebola

1 person=10 people 185 People

EBOLA

1 person=10 people 65 People

Pathway for Transmission

Reservoir

Carriers

Humans

Potential Reservoirs

Mammal Other Vertebrate

Arthropod Plant?

Potential Mammalian Filovirus Reservoirs

A. Townsend Peterson, Darin S. Carroll, James N. Mills, and Karl M. Johnson

Which mammals?

•Reviewed all mammal species in the world.

•Deletions of genera based on 5 rationale criteria were made.

•Reviewed previous studies that tested African mammals for the virus.

Study Rationale1. Previous studies that suggest mammals.

2. Size.

3. Virus known to have a long-term evolutionary relationship with the reservoir species.

4. Range.

5. Non-commensal animals.

Families and Sub-families Fitting all rationale points

CrocidurinaePotamogalinaePteropodinaeMacroglossinaeEmballonuridaeMegadermatidaeRhinolophinaeHipposideridaeKerivoulinaeVespertilionidaeMiniopterinaeMolossidaeNycteridae

Procaviidae

SciurinaeMuridaeCricetomyinaeDendromurinaeGerbillinaeAnomaluridaeZenkerellinaeGraphiurinaeThryonomyidaeLeporidae

http://farm1.static.flickr.com

http://www.nwtrek.org/

http://thewebsiteofeverything.com

Bats seem to be focal point

•Of the 24 families and subfamilies of mammals, 11 are bats.

•Other studies have tested bats for antibodies to the virus; 3 fruit bat species were positive.

•Further research has a focus on probable species.

Pathway for Transmission

Host

Carriers

Reservoir

? ?

Humans

Apes As Carriers and Hosts of Ebola

•Apes are considered carriers and hosts because:

▫Infect other animals in the area.

▫Succumb to the disease (90-95% ape mortality).

▫Can be transmitted between ape species. (Gorillas, Chimpanzees, Humans)

Apes and Ebola

•Gabon and the Congo hold ~80% of the world’s great apes.

•Between 1983 and 2000 ape populations have declined by half due to hunting and Ebola.

•Deaths of gorillas, from Ebola, in the area of Gabon were tallied to be approximately 5000 individuals by 2000.

Gorillas and Chimpanzees

Western Lowland Gorilla (Gorilla gorilla gorilla)

http://www.cleverbadger.net http://www.apetag.orgg

Common Chimpanzee (Pan troglodytes)•Live in Cameroon, Equatorial

Guinea, Gabon, Republic of the Congo, DRC

•Eat pith, leaves, shoots and fruit

•Live in Cameroon, Congo, Gabon, Nigeria, and DRC

•Eat fruit, tree seeds, flowers, soft pith, galls, resin and bark

Potential for Ebola Transmission Between Gorilla and

Chimpanzee Social Groups

Peter D. Walsh, Thomas Breuer, Crickette Sanz, David Morgan, and Diane Doran-Sheehy

Is there potential for infection to pass between ape populations?

•Researchers used the fruit bat as an assumption, referencing previous study.

•Surveyed fruit trees.

•Analyzed feeding periods of both species.

Which fruit tree?•Apes are very picky about fruit.•Both apes leave bodily secretions on the fruit,

tree or surrounding (Urine, feces, saliva).•Types of trees: Nauclea pobeguinii (African

Peach), Ficus

http://www.ethnopharmacologia.org/

http://arbresvenerables.free.fr/ArbresVenerables

Findings: Gorilla-Gorilla Transmission

•15 total social groups (units) eating in 37 African Peach trees.▫4 Solitary silverbacks, 11 groups of 2+

•# of Cases:▫56: pair of units fed in same trees on the same

day, using same paths.▫13: gorilla(s) from one unit fed in the same tree

on the same day as another had.

Gorilla –Gorilla Foraging Overlap

Findings- Gorilla-Chimpanzee

•Observed 4 different communities of chimpanzees in Ficus.

•5 out of 75 days (once for every 15), Chimpanzees and Gorillas foraged in the same tree at the same time.*▫Lasted for ~47 minutes: ~10 Chimpanzees, ~4

Gorillas

*True Rates of occupancy might have been higher.

Pathway for Transmission

Host

Carriers

Reservoir

Chimpanzee

Humans

Human contact with non-human primates

Exposure to Nonhuman Primates in Rural CameroonNathan D. Wolfe, et. al. 2004

Habitat

Savanna

Gallery Forest

Forest

% R

ep

ort

ing

Beh

avi

or

Keep pet NHP

Butcher NHP

Hunt NHP

Eat NHP

Avg

. n

o. N

HP

Meals

per

mon

th

Cameroon

Gabon

Congo

Dem. Rep. of Congo

Uganda

Sudan

http://files.posterous.com/forestpolicy/

Wild Animal Mortality Monitoring and Human Ebola Outbreaks, Gabon and Republic of Congo,

2001-2003

Pierre Rouquet, Jean-Marc Froment, Magdalena Bermejo, Annelisa Kilbourn, William Karesh, Patricia Reed, Brice Kumulungui, Philippe Yaba, Andre Delicat, Pierre E. Rollin, and Eric M. Leroy.

Sampled Carcasses•August 2001- June 2003, 98 carcasses

( Gorillas, Chimpanzees, and Duikers)

•Found carcasses using field GPS locations and villager sightings.

•Liver, spleen, muscle, skin and bone samples.

•2 Peaks of animal death: Nov-Dec 2001, Dec 2002-Feb2003.

Lab tests on samples

Testing For Antigen (Viral Coat)

Viral RNA Visual Confirmation of Virus

Test Used ELISA PCR- DNA Amplification

Immunohistochem Staining & Microscopy

•If one test was positive, the carcass was labeled infected.

* 21 carcasses sampled, 14 tested positive.

Carcass peaks coincide with human outbreaks

• Nov• Dec

2001• Oct• May

2001-02

• Dec• Feb

2002-03

• Dec• Apr

2002-03

Human Outbreak

Carcass Peak

Carcass Peak

Human Outbreak

51 Carcasses

20 Carcasses

92 Cases 70 Dead

143 Cases

128 Dead

Pathway for Transmission

Host

Carriers

Reservoir

Chimpanzee

Carcasses

Ebola is a problem without a solution…•Complicated pathways.

•Research each level and inhibit transmission.

•Find an alternative means of food and income for native Africans.

•One strain of Ebola has been in the U.S. another could possibly come and infect thousands of Americans.

•Continue work on a vaccine as well as treatment for humans and apes.

Thank You!!!•Family•Friends•Sisters•Teachers

▫Dr. Barratt▫Dr. Melampy

•Zoo Influences▫D’Edra Thompson▫Terry Joyce▫Dr. Kristen Lukas

http://media.photobucket.com/

http://farm2.static.flickr.com/

Any Questions?

http://i30.photobucket.com

ReferencesCaceres, S B., and M J. Otte. "Blame Apportioning and the Emergence of Zoonoses over the Last

25 Years." Transboundary and Emerging Diseases 56 (2009): 375-79. Web. 22 Nov. 2009.Jones, Kate E., Nikkita G. Patel, Marc A. Levy, Adam Storeygard et al. "Global trends in emerging

infectious diseases." Nature 451 (2008): 990-94. Web. 22 Nov. 2009.Mohamadzadeh, Mansour, Lieping Chen, and Alan L. Schmaljohn. "How Ebola and Marburg

viruses battle the immune system." Nature 7 (2007): 556-67. Web. 22 Nov. 2009. Peterson, A. Townsend, Darin S. Carroll, James N. Mills, and Karl M. Johnson. "Potential

Mammalian Filovirus Reservoirs." Emerging Infectious Diseases 10.12 (2004): 2073-81. Web. 10 Dec. 2009.

 Rouquet, Pierre, Jean-Marc Froment, Magdalena Bermejo, Annelisa Kilbourn et al. "Wild Animal Mortality Monitoring and Human Ebola Outbreaks, Gabon and Republic of Congo, 2001-2003." Emerging Infectious Diseases 11.2 (2005): 283-90. Web. 22 Nov. 2009.

 Walsh, Peter D. "Catastrophic ape decline in western equatorial Africa." Nature 422 (2003): 611-14. Web. 22 Nov. 2009.

 Walsh, Peter D., Thomas Breuer, Crickette Sanz, David Morgan et al. "Potential for Ebola Transmission between Gorilla and Chimpanzee Social Groups." The American Naturalist 169.5 (2007): 684-89. Web. 15 Dec. 2009.

 Wolfe, Nathan D., A. Tassy Prosser, Jean K. Carr, Ubald Tamoufe et al. "Exposure to Nonhuan Primates in Rural Cameroon." Emerging Infectious Diseases 10.12 (2004): 2094-99. Web. 22 Dec. 2009.