Emerging Viral Pathogens

Front 1

General characteristics of emerging viruses?

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-Most are zoonotic.

-Human behavior increases the probability of transfer from their endogenous animal hosts to man

-Overpopulation, overcrowding, global warming, etc.

Front 2

Examples of zoonotic viruses in exotic pets?

Back 2

Front 3

What are arboviruses?

what 3 groups of arboviruses are there?
what type of virus are they?

Back 3

-Arthropod-borne
-Transmitted by means of an infected blood-sucking arthropod.
-Virus replicates in the arthropod vector.
-Virus is usually maintained in a vertebrate host.
-Humans are usually incidental hosts; exceptions include yellow fever and dengue.
-Most arboviruses belong to the Togaviridae (alphaviruses), Flaviviridae, and Bunyaviridae families.
-All are RNA viruses.

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Back 4

Arboviruses:

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Front 6

Life cycle of arboviruses?
-1˚ and incidental hosts?
-impact of environment?

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Front 7

SPECIFIC CYCLES OF ARBOVIRUS TRANSMISSION: 3

Back 7

URBAN

SYLVATIC

ARTHROPOD-SUSTAINED

Front 8

Describe the urban cycle:
-vector
-2 disease examples

Back 8

*mosquitoes

Front 9

Describe the jungle cycle:
-vectors
-2 disease examples

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Front 10

Most arboviruses are transmitted to humans by ____ inoculation. What are some exceptions to this?

Back 10

-DIRECT

-Exception: unpasteurized milk can transmit viruses to humans.

Front 11

Describe DISEASE SYNDROMES OF THE ALPHAVIRUSES AND FLAVIVIRUSES:

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-Primary viremia may be associated with mild systemic disease.

-If sufficient virus is produced during the secondary viremia to escape immune protection and to reach critical target tissues, severe systemic disease or encephalitis may result.

-For dengue virus, rechallenge with another strain can result in severe dengue hemorrhagic fever (DHF), which can cause dengue shock syndrome (DSS).

Front 12

3 severe disease outcomes that may result from alphaviruses/flaviviruses?

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1) encephalitis
2) hemorrhagic fevers
3) non-hemorrhagic fevers

Front 13

What's an example of an arbovirus with crazy mortality?

What type of arbovirus is it?

Back 13

-EEE is an alphavirus
-Carried by mosquitoes, wild birds, horses
-50% fatality

Front 14

West Nile Encephalitis cycle:

Back 14

-Caused by a Flavivirus

-In 2004, virus was found in all states except Washington.

-Natural reservoir of the virus is birds and the virus is transmitted by mosquitoes ( Culex sp.).

Front 15

Disease course in WNV?

What determines outcome?

Back 15

-Immune status of host determines outcome.

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Dengue Virus key points:
-type of virus?
-vectors
-cycle locations
-common fever associated with it?

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-Caused by a flavivirus.

-Monkeys and humans are natural hosts, mosquitoes are the vectors.

-Has both urban and sylvatic cycle.

-Four serotypes!!

-Major worldwide problem; virus can be imported into U.S. by travelers.

-Fever, headache, rash, bone pain = “Breakbone Fever”

Front 17

Where in the world do we see dengue?

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Front 18

Describe dengue hemorrhagic fever:

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-Abs against one serotype of dengue make a horrible cross-reaction with a second serotype of dengue.

-Fc receptor binds to monocytes and facilitates entry of second serotype into cell.

-A hypersensitivity response occurs --> vascular destruction, shock.

-This is BAD.

Front 19

Back 19

dengue hemorrhagic fever!

Front 20

Rodent-Borne Pathogens:

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Hanta is key

Front 21

What vector carries the arenaviruses?

Back 21

-Rodents

Front 22

Key points about Hantavirus:
-what is its genera and why is it unique among them?
-vectors?
-transmission?
-2 bad disease outcomes?

Back 22

-No arthropod vector established; Unique among genera Bunyaviridae

-Rodent hosts--Genus and possible species specific

-Transmission by Aerosolization of rodent excretra

-Associated with hemorrhagic fever with renal syndrome (HFRS) and severe pulmonary syndrome (HPS).

~30% fatality

Front 23

Describe transmission of hanta virus?

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Front 24

Key points about Filoviridae:
-reservoir?
-2 virus examples?
-how does it damage humans?
-mortality
-transmission

Back 24

-Reservoir is unknown
-Pleomorphic; generally seen as long filamentous, enveloped particles that may be branched.

-Ebola and Marburg viruses
-Cause severe hemorrhagic fever (lysis of endothelial cells by a viral surface glycoprotein), characterized by widespread bleeding into the skin, mucous membranes, visceral organs, and GI tract.
-Mortality rate is high (60-90%)

-Can be transmitted to humans from infected monkeys and probably other animals, or by exposure to the blood or other body fluids from an infected patient.

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-Filovirus
-Unique filamentous appearance

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Pathogenesis of Ebola damage:

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-Ebola Zaire attacks every organ and tissue in the human body except skeletal muscle and bone.

-Small blood clots begin to appear in the bloodstream, and the blood thickens and slows, and clots begin to stick to the walls of blood vessels.

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-Damage from the Ebola Virus
-Attacks endothelial cells and lyses them
-"Melts" you from the inside out.