Shaun CasePublic Health Epidemiology PhD Student

Walden UniversityPUBH-8165-1

Instructor: Dr. Rebecca HeickSpring Quarter, 2010

What is meant by zoonosis, pandemic and epidemic

What is the Influenza virus

What are the types of influenza How does it infect a cell and replicate

How does Influenza mutate, or change

What is antigenic drift What is antigenic shift

How does working with animals affect risk

Some Definitions

Zoonosis: “disease of animals transmissible to humans under natural conditions”1

Influenza: “an acute viral infection of the respiratory tract, occurring in isolated cases, epidemics, and pandemics, caused by Influenzavirus A, B or C … “1 (AKA “The Flu”)

Influenza A: “A genus of viruses of the family Orthomyxoviridae containing the agent of Influenza A”1 (AKA “A type of flu”)

Pandemic: “A widespread epidemic of a disease”1

Epidemic: “Occurring suddenly in numbers clearly in excess of normal…”1

[1] Saunders (2009). Dorland’s Pocket Medical Dictionary, 28th Ed., Philadelphia: Elsevier-Saunders

Diseases can be passed between animals and humans and visa-versa1,2,3

80% of all infectious diseases known to infect humans are zoonotic4

75% of all new human diseases are attributable to diseases originating in animals2

Cause for concern in the general public

[1] Myers K.P., Olsen C.W., Setterquist S.F., et al. (2006). Are swine workers in the United States at increased risk of infection with zoonotic influenza virus? Clinical Infectious Diseases, 42, 14–20

[2] Tomley, F. M. & Shirley, M.W. (2009). Livestock infectious diseases and zoonosis. Philosophical Transactions of the Royal Society B: Biological Sciences, 364, 2637-2642

[3] Gray G.C., Trampel D.W., Roth J.A. (2007). Pandemic influenza planning: Shouldn’t swine and poultry workers be included? Vaccine, 25, 4376-4381

[4] Olmstead A.L. (2009). The First Line of Defense: Inventing the Infrastructure to Combat Animal Diseases. The Journal of Economic History, 69, 327-357

Found in domesticated animals such as swine, horses, and birds, to name a few1,2,3

Can also be carried, and spread to other animals, and humans, by feral and wild animals2,4,5

Some animals are “mixing vessels”1,3

Influenza A is the primary concern for Zoonosis

Type B is found primarily (though not exclusively) in humans and type C causes generally mild effects in humans6

Types B and C may cause epidemics but have not been known to cause pandemics6

[1] Myers K.P., Olsen C.W., Setterquist S.F., et al. (2006). Are swine workers in the United States at increased risk of infection with zoonotic influenza virus? Clinical Infectious Diseases, 42, 14–20

[2] Spencer, J.L. Guan, J. (2004). Public health implications related to spread of pathogens in manure from livestock and poultry operations. Methods in Molecular Biology, 268, 03-515

[3] Gray G.C., Trampel D.W., Roth J.A. (2007). Pandemic influenza planning: Shouldn’t swine and poultry workers be included? Vaccine, 25, 4376-4381

[4] Tomley, F. M. & Shirley, M.W. (2009). Livestock infectious diseases and zoonosis. Philosophical Transactions of the Royal Society B: Biological Sciences, 364, 2637-2642

[5] Olmstead A.L. (2009). The First Line of Defense: Inventing the Infrastructure to Combat Animal Diseases. The Journal of Economic History, 69, 327-357

[6] CDC (2005). Avian Influenza (Bird Flu). Retrieved on 25 April, 2010 from: http://www.cdc.gov/flu/avian/gen-info/pdf/flu_viruses.pdf

RNA Virus (smaller than a cell)1

Has no cell wall1

Invades other cells1

Alters the infected cell and its DNA1

[1] Webster R., Bean W.J., Gorman O.T., Chambers T.M., Kawoaka Y. (1992) Evolution and Ecology of Influenza A Viruses. Microbiological Review, 56, 152-179

Influenza A is made of 8 parts, called segments1

Those 8 segments are used to make 10 larger components called gene products1

These determine certain aspects of the virus. Include products called Hemagglutinin and Neuraminidase, or

HA and NA for short. Commonly recognized in the name of the strain of the virus, such

as “H1N1”

[1] Webster R., Bean W.J., Gorman O.T., Chambers T.M., Kawoaka Y. (1992) Evolution and Ecology of Influenza A Viruses. Microbiological Review, 56, 152-179

Control how this virus interacts with the host cell

HA: How well the virus gets along with the host cell1

Friend or foe: “Do I know you?” Come on in, make yourself at home…

NA: How well the children of the virus can detach from the inside of the host cell1 to spread to other cells Allows the children to “leave the nest” Children move in with someone else, start their own families

Why we classify the strain by the H and N variations.

[1] Webster R., Bean W.J., Gorman O.T., Chambers T.M., Kawoaka Y. (1992) Evolution and Ecology of Influenza A Viruses. Microbiological Review, 56, 152-179

Hey, look, it’s a party! (The door is open…with the right HA key…)

Mix with your friends Decide to stay (Hey, why not, the food is free, and the

party never stops?) Start talking to the other DNA segments Spread some urban myths

How about a little Antigenic Drift? Have children, (slow random genetic changes) Kick the kids out when they’re old enough (replication)

Influenza A comes in many varieties1

All originate in the avian species (birds)1

Changes in the virus make it able to infect other species, (pigs, horses, humans, etc)1

Other animals have species specific versions also1

Mixing of species specific versions causes mutations1 into strange new creatures

[1] Webster R., Bean W.J., Gorman O.T., Chambers T.M., Kawoaka Y. (1992) Evolution and Ecology of Influenza A Viruses. Microbiological Review, 56, 152-179

New arrivals from out of town

Move in and settle down

Want a little Antigenic Shift?

Mix with other members of the house Sometimes have children with others not from their town

Children are a different variety all together... They like to move to other towns and crash parties

Drift and shift happen all the time

Drift is more likely than shift1,2

Most changes are not viable, (they don’t survive)

Pandemics happen with a regular frequency1,2

Every 10 to 20 years Not all are caused by shift, not necessarily zoonotic

Epidemics happen even more frequently, (yearly flu epidemics in humans)1,2

[1] Webster R., Bean W.J., Gorman O.T., Chambers T.M., Kawoaka Y. (1992) Evolution and Ecology of Influenza A Viruses. Microbiological Review, 56, 152-179

[2] Lin J., Andreasen V., Casagrandi R., Levin S. (2003). Traveling waves in a model of influenza A drift. Journal of Theoretical Biology, 222, 437-445

Will living near or working with animals increase my risk of contracting a zoonotic influenza?

Hotly debated topic We really need more studies

Many studies show a correlation Some argue those correlations are due to other factors Correlation does not mean cause

Bansal S., Grenfell B., Meyers L.A., (2007). When individual behaviour matters: homogeneous and network models in epidemiology. J R Soc Interface, 4, 879-891

 C

DC (2005). Avian Influenza (Bird Flu). Retrieved on 25 April, 2010 from: http://www.cdc.gov/flu/avian/gen-info/pdf/flu_viruses.pdf

Donham K.J., Wing S., Osterberg D., et al. (2007). Community health and socioeconomic issues surrounding concentrated animal feeding operations. Environmental Health Perspectives, 115, 317-20

 D

onham K.J. (2000). The concentration of swine production. Effects on swine health, productivity, human health, and the environment. The Veterinary Clinics of North America Food Animal Practice, 16, 559-597

 G

ray G.C., McCarthy T., Capuano A.W., et al. (2007). Swine workers and swine influenza virus infections. Emerging Infectious Disease, 13, 1871–1878

 G

ray G.C., Trampel D.W., Roth J.A. (2007). Pandemic influenza planning: Shouldn’t swine and poultry workers be included? Vaccine, 25, 4376-4381

Lin J., Andreasen V., Casagrandi R., Levin S. (2003). Traveling waves in a model of influenza A drift. Journal of Theoretical Biology, 222, 437-445

 L

ewis, D.B. (2006). Avian Flu to Human Influenza. Annual Review of Medicine, 57:139-154

Myers K.P., Olsen C.W., Setterquist S.F., et al. (2006). Are swine workers in the United States at increased risk of infection with zoonotic influenza virus? Clinical Infectious Diseases, 42, 14–20

 O

lmstead A.L. (2009). The First Line of Defense: Inventing the Infrastructure to Combat Animal Diseases. The Journal of Economic History, 69, 327-357

 R

amirez A., Capuano A.W., Wellman D.A., et al. (2006). Preventing Zoonotic Influenza Virus Infection. Emerging Infectious Diseases, 12, 997-1000

 S

aunders (2009). Dorland’s Pocket Medical Dictionary, 28th Ed., Philadelphia: Elsevier-Saunders 

 S

hinde V., Bridges C., Uyeki T.M., Shu B., Balish A., et al (2009). Triple-Reassortant Swine Influenza A (H1) in Humans in the United States, 2005-2009. New England Journal of Medicine, 361

Spencer, J.L. Guan, J. (2004). Public health implications related to spread of pathogens in manure from livestock and poultry operations. Methods in Molecular Biology, 268, 03-515

 T

omley, F. M. & Shirley, M.W. (2009). Livestock infectious diseases and zoonosis. Philosophical Transactions of the Royal Society B: Biological Sciences, 364, 2637-2642

Webster R., Bean W.J., Gorman O.T., Chambers T.M., Kawoaka Y. (1992) Evolution and Ecology of Influenza A Viruses. Microbiological Review, 56, 152-179

CDC: Influenza websites

http://www.cdc.gov/flu/ http://www.cdc.gov/flu/avian/ http://www.cdc.gov/h1n1flu/ http://www.cdc.gov/SocialMedia/Campaigns/H1N1/

RNA Virus replication

University of South Carolina School of Medicine Virology : http://pathmicro.med.sc.edu/mhunt/RNA-HO.htm

RNA virus mutations and fitness for survival: http://www.ncbi.nlm.nih.gov/pubmed/9343347