06 Viruses and Diseases Part 2 Duncan Flashcards Preview

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Flashcards in 06 Viruses and Diseases Part 2 Duncan Deck (55):
1

What are the two most common viruses causing diarrhea?

Rotavirus (<2 years of age). Norwalk virus (in older children and adults)

2

What are the general characteristics of Rotavirus?

It's a reovirus. Segmented, double-stranded RNA virus

3

What are the general characteristics of Norwalk Virus?

Small RNA calcivirus

4

What is the epidemiology of Rotavirus?

Primarily in the winter months. Asymptomatic to severe, fatal (severe dehydration). Infectious particles can remain for days on objects, for hours on hands (hygiene essential to prevent spread)

5

What is the pathogenesis of Rotavirus?

Primarily attacks and destroys intestinal cells. Vomiting a few days after infection. Diarrhea. Dehydration results

6

What is used as prevention from Rotavirus?

RotaTec given 3x prevents > 75% illnesses. It's a live, oral, pentavalent vaccine

7

What are the general features of Hepatitis Virus?

All of them infect liver cells - initial infection may be GI. Otherwise, they are very distinct types of viruses. Cause short acute illness, to persistent, latent, seemingly innocuous disease

8

What are the general characteristics of Hepatitis A Virus (HAV)?

Picornavirus (like polio, echo, coxsackie). Epidemiology: fecal-oral transmission (raw shellfish)

9

What is the pathogensis of Hepatitis A Virus?

Initially infects enteric mucosa. > 25 day latency. Elevated liver enzymes: AST, AlkPhos, LDH, Bilirubin. Liver pain, jaundice

10

What is the treatment for Hepatitis A Virus?

Passive immunization. Generally self-resolving

11

What are the general characteristics of Hepatitis B Virus (HBV)?

Hepadnavirus. DNA virus with VERY small genome (3000 bp, 4 genes). Unusual replication - involves reverse transcription (this is why it can cause cancer)

12

What is the epidemiology of Hepatitis B Virus?

Transferred via blood, body fluids (sex), needles. Initial acute infection, followed by extended latency. Hepatocellular carcinoma in later life. Very common in parts of Asia

13

What is the pathogenesis of Hepatitis B Virus?

Death of hepatic cells. Decreased cell mediated immunity. Jaundice. Fatigue, loss of appetite, dark urine. Cirrhosis of the liver, with long latency. Liver cancer, with long latency

14

What is the prevention and treatment of Hepatitis B Virus?

Passive immunization for acute infection. Vaccine is available. Interferon treatment. Various HIV agents: RT is common to both

15

What are the general characteristics of Hepatitis C Virus?

Flavivirus. Positive strand RNA virus 9.5kb in length. Newly recognized, poorly understood

16

What is the Epidemiology of Hepatitis C Virus?

Transferred via blood, body fluids (sex), needles (like HBV). Transfusion-mediated transfer was a major problem

17

What is the pathogenesis of Hepatitis C Virus?

Initial acute infection, followed by extended latency. Hepatocellular carcinoma in later life

18

What is the prevention and treatment of Hepatitis C Virus?

Screening of blood. No vaccine is currently available. Interferon alpha treatment (expensive, painful, only sometimes effective, but best alternative), combined with Ribavirin improves therapy

19

What are the general characteristics of Hepatitis D Virus?

Small, single-stranded RNA virus. Requires co-infection with HBV (lacks essential gene function, supplied in trans by HBV)

20

What is the pathogenesis of Hepatitis D Virus?

Increases the severity of HBV infection

21

What are the general characteristics of Hepatitis E Virus?

Single-stranded, positive sense, RNA virus. Related to the calciviruses. Fecal-oral transmission (like HAV). Rare in the US, prevalent in India

22

What are the general features of Herpes Viruses?

Large, enveloped, DOUBLE STRANDED DNA viruses. Cause a wide range of symptoms, from mild to severe. Cause short acute illness, leading to persistent, latent, infection. Herpes viruses include: VZV, Herpes Simplex, CMV, EBV

23

What is the epidemiology of Herpes Simplex Virus (HSV)?

Type 1: Spread by direct contact with secretions. Types 2: Spread from sexual contact. High incidence of Type 1 infection (most are asymptomatic, or cause only mild disease)

24

What are the clinical manifestations of Herpes Simplex Virus?

Genital lesions (much greater in HSV-II). Lesions above the waist: primarily HSV-I. Herpes meningitis: associated with HSV-I, and more severe, though rare, consequences

25

What is the prevention and treatment of Herpes Simplex Virus?

Several antiviral agents have good activity: Acyclovir, related agents like ganciclovir and penciclovir. Foscarnet

26

What are the general characteristics of Cytomegalovirus (CMV)?

Infected cells tend to enlarge, hence "cytomegalo". Most individuals have been infected, based on antibodies (mild infections). Pathogenicity principally an issue in immunocompromised. Low infectivity (greatest risk in CMV+ donor tissue, CMV- recipient). Treatment with ganciclovir

27

What are the general characteristics of Epstein-Barr Virus (EBV)?

Causes mononucleosis. Associated with certain cancers (rare). Most individuals have been infected, based on antibodies

28

What are the general characteristics of Herpes Virus Types 6 and 7?

Infect immune cells. Leads to lymphoproliferative disease. Most individuals have been infected by age 2, based on antibodies

29

What are the enteroviruses?

Poliovirus. Coxsackie virus. Echovirus

30

What are the general characteristics of Enteroviruses or Picornaviruses?

Small, single-stranded, positive-strand RNA virus. Many types, cause many diverse diseases

31

What is the epidemiology of Enteroviruses or Picornaviruses?

Most infections late summer, early fall. Assymptomatic infections are common. Transmission to proximate individuals varies. Transmission primarily fecal-oral (though can be aerosol)

32

What is the general pathogenesis of Enteroviruses or Picornaviruses?

Cause of (childhood) viral meningitis. Initially targets respiratory cells, then GI tract epithelial and lymphoid cells. Secondary infections of CNS (can also cause myocarditis). Immune response is usually sufficient to control infection

33

What are the general characteristics of Poliovirus?

Picornavirus. Small, single-stranded, positive-strand RNA virus (requires protease cleavage, potential therapeutic target). Rhinovirus is very closely related

34

What is the epidemiology of Poliovirus?

Paralysis - severity increases with age of infection. Cases can be so mild they are barely noticed

35

What is the pathogenesis of Poliovirus?

Specific tropism for CNS cells. Motor neurons destroyed

36

What is the prevention and treatment for Poliovirus?

Vaccine (highly effective). Inactivated virus (Salk) or Live attenuated virus (oral; Sabin). No specific (chemo-) therapy

37

What are the general characteristics of Coxsackie Virus?

Picornavirus. Coxsackie A16 is the cause of most disease. Mainly occurs in children under 10 years old. Spread by person-to-person contact. Fever --> blisters --> ulcers. Rash on palms, soles of feet. No specific treatment. Hand-foot-mouth

38

What are the Pox Viruses?

Small Pox Virus. Vaccinia Virus

39

What are the general characteristics of Variola Virus (Small Pox Virus)?

DOUBLE-STRANDED DNA virus. Highly infectious - virtually all exposed develop disease. Eradicated d/t vaccination, no reservoir

40

What are the general characteristics of Vaccinia Virus?

DOUBLE-STRANDED DNA virus. Not a cause of disease. Used in genetic engineering

41

What is the epidemiology of Pox Viruses?

Aerosol transmission from infected individuals. Incubation period: 10-14 days

42

What is the pathogenesis of Pox Viruses?

Initially infects pharynx. Spreads systemically to various organs. Skin localization leads to pustular rash. Most prominent around the face, leading to permanent scarring

43

What is the prevention and treatment of Pox Viruses?

Small pox has been eradicated via vaccination. Vaccine is based on vaccinia, a closely related virus

44

What are the general characteristics of Papilloma Viruses?

DOUBLE STRANDED DNA viruses. Cause wards and begin wart-like tumors - papillomas (genital warts have the highest chance of progressing into malignant tumors). Infection is common, usually benign. Most common sexually transmitted virus

45

What is the prevention and treatment of Papilloma Viruses?

Removal of the infected epithelial area. Recently introduced vaccines (Gardasil and Cervarix)

46

What are the Retroviruses?

HIV-1, HIV-2, HTLV

47

What are the general characteristics of Retroviruses?

Single-stranded RNA viruses. Relatively simple genome: 4-10 genes, < 10,000 bases (some, such as HIV, have accessory proteins: Nef, Tat, Rev). Replication requires reverse transcriptase. DNA copy integrates into infected cell's chromosome

48

What are the general characteristics of HIV?

HIV-1 and HIV-2. Initial mRNA transcript is a polyprotein (requires VIRALLY-encoded protease to process to proteins, target for anti-HIV drugs)

49

What is the epidemiology of HIV?

Transferred via blood, body fluids (sex), needles. Transmission rate increased if abraded skin is exposed

50

What is the pathogenesis of HIV?

Targets principally T cells and other immune cells. Leads to decreased cell mediated immunity (long latent period). Opportunistic infections appear, wasting

51

What is the prevention and treatment of HIV?

Multi-Drug therapy (Nucleoside analogue (e.g. AZT), Protease Inhibitors, much more under development). Vaccines are under development

52

What are the general characteristics of Arthropod-Borne and other Zoonotic Viruses?

Arboviruses use an insect vector. Other types have mammals as intermediate hosts. Cause a wide range of diseases from mild to severe

53

What types of diseases do Arboviruses cause?

Equine encephalitis. Yellow fever. Dengue fever (severe pain in back, muscles, joints). Insect vectors live primarily in tropical climates

54

What are the general characteristics of Prion-Based Spongiform Encephalopathies?

Very long incubation period, typically > 10 years. Results in neurological deterioration. Infectious agent appears to be a protein, called a prion (normal and infectious prion have same sequence of amino acids, but different shapes). Infectious prion protein (prpSC) can "seed" conversion of the normal (prpC) to the infectious form

55

What is the MOA of infectious prions (prpSC)?

Forms aggregates to form amyloid fibrils, that are associated with toxicity