Flashcards in 06 Viruses and Diseases Part 2 Duncan Deck (55):
What are the two most common viruses causing diarrhea?
Rotavirus (<2 years of age). Norwalk virus (in older children and adults)
What are the general characteristics of Rotavirus?
It's a reovirus. Segmented, double-stranded RNA virus
What are the general characteristics of Norwalk Virus?
Small RNA calcivirus
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)
What is the pathogenesis of Rotavirus?
Primarily attacks and destroys intestinal cells. Vomiting a few days after infection. Diarrhea. Dehydration results
What is used as prevention from Rotavirus?
RotaTec given 3x prevents > 75% illnesses. It's a live, oral, pentavalent vaccine
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
What are the general characteristics of Hepatitis A Virus (HAV)?
Picornavirus (like polio, echo, coxsackie). Epidemiology: fecal-oral transmission (raw shellfish)
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
What is the treatment for Hepatitis A Virus?
Passive immunization. Generally self-resolving
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)
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
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
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
What are the general characteristics of Hepatitis C Virus?
Flavivirus. Positive strand RNA virus 9.5kb in length. Newly recognized, poorly understood
What is the Epidemiology of Hepatitis C Virus?
Transferred via blood, body fluids (sex), needles (like HBV). Transfusion-mediated transfer was a major problem
What is the pathogenesis of Hepatitis C Virus?
Initial acute infection, followed by extended latency. Hepatocellular carcinoma in later life
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
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)
What is the pathogenesis of Hepatitis D Virus?
Increases the severity of HBV infection
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
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
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)
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
What is the prevention and treatment of Herpes Simplex Virus?
Several antiviral agents have good activity: Acyclovir, related agents like ganciclovir and penciclovir. Foscarnet
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
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
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
What are the enteroviruses?
Poliovirus. Coxsackie virus. Echovirus
What are the general characteristics of Enteroviruses or Picornaviruses?
Small, single-stranded, positive-strand RNA virus. Many types, cause many diverse diseases
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)
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
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
What is the epidemiology of Poliovirus?
Paralysis - severity increases with age of infection. Cases can be so mild they are barely noticed
What is the pathogenesis of Poliovirus?
Specific tropism for CNS cells. Motor neurons destroyed
What is the prevention and treatment for Poliovirus?
Vaccine (highly effective). Inactivated virus (Salk) or Live attenuated virus (oral; Sabin). No specific (chemo-) therapy
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
What are the Pox Viruses?
Small Pox Virus. Vaccinia Virus
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
What are the general characteristics of Vaccinia Virus?
DOUBLE-STRANDED DNA virus. Not a cause of disease. Used in genetic engineering
What is the epidemiology of Pox Viruses?
Aerosol transmission from infected individuals. Incubation period: 10-14 days
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
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
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
What is the prevention and treatment of Papilloma Viruses?
Removal of the infected epithelial area. Recently introduced vaccines (Gardasil and Cervarix)
What are the Retroviruses?
HIV-1, HIV-2, HTLV
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
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)
What is the epidemiology of HIV?
Transferred via blood, body fluids (sex), needles. Transmission rate increased if abraded skin is exposed
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
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
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
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
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