Arbo, Bunya, Arenyaviruses

Question 1

VEE, WEE, EEE, chkungunya all belong to what family of arboviruses?

Answer 1

togaviridae: alphavirus

Question 2

Dengue, yellow fever, japanese encephalitis, west nile, St. Louis, and Russian spring summer encephalitis all belong to what family of arboviruses?

Answer 2

flavivirus

Question 3

• enveloped RNA viruses
• positive polatiry
• 5’ methylated cap but no polyA tail

Answer 3

alphavirus and flavivirus

Question 4

alphavirus vs. flavivirus genomic organization, which has structural then non-structural proteins?

Answer 4

alpha: non-structural –> structural
flavi: structural –> non-structural

Question 5

epidemiology of alpha and flavi virus:

• who is at risk?
• geography/season?
• modes of control?

Answer 5

• people who enter ecological niche of arthropod vector
• endemic regions determined by habitat of vector, disease more common in summer months
• mosquito breeding sites should be eliminated, live attenuated vaccine for yellow fever

Question 6

alpha and flavivirus can be maintained in nature by replication in _______ of mosquitoes

Answer 6

salivary glands

Question 7

dengue virus and urban yellow fever use what transmission cycle?

Answer 7

man-arthropod-man, where reservoir may be in man or arthropod vector

Question 8

Japanese encephalitis, EEE,WEE, Jungle yellow fever use what transmission cycle?

Answer 8

animal-arthropod-man, where reservoir is animal other than humans, man becomes infected incidentally

Question 9

how does encephalitis occur from arbovirus?

Answer 9

mosquito bite –> primary viremia –> infect macrophages, liver, spleen, lymph nodes –> secondary viremia –> virus infects endothelial cells to cross BBB –> virus infects neurons resulting in cell death

Question 10

diseases caused by arboviruses?

Answer 10

fever and rash
encephalitis
hemorrhagic fever

Question 11

• biggest arbovirus problem in the world today (390 million infections each year)
• severe cases present with hemorrhagic fever or shock syndrome
• found in SE Asia, Africa, Caribbean, South america
• 5 serotypes, transmitted by Aedes mosquitos
• human-mosquito-human cycle

Answer 11

Dengue Fever

Question 12

phases of Dengue pathogenesis?

Answer 12

1. febrile phase: sudden fever, headache, muscle pain, rash with petechia called breakbone fever
2. critical phase: fever resolves, plasma leakage leading to fluid in chest and abdominal cavity, bleeding in GI tract, shock
3. recovery: fluid is reabsorbed, accompanied by severe itching and slow heart rate

Question 13

Dengue fever:

• diagnosis made by ______
• antiviral therapy?
• prevention depends on __________

Answer 13

serology
no therapy
mosquito eradication

Question 14

risk factors for DHF/DHS:

• risk greatest for which strain?
• higher risk with two serotypes circulating simultaneously known as?
• pre-existing antibodies may lead to ____________ of disease

Answer 14

• DEN-2
• hyperendemic transmission
• antibody dependent enhancement

Question 15

• found in West Africa and South America
• urban and jungle forms, where jungle is natural reservoir in cycle involving non human primates and forest mosquitos, urban from transmitted b/w humans by Aedes mosquito

Answer 15

Yellow Fever virus

Question 16

• Yellow fever presents with chills, fever, and headache, general myalgias
• after _____ days, more severely ill patients experience bradycardia, jaundice, hemorrhagic manifestations
• 50% of patients with Frank yellow fever develop fatal disease characterized by?

Answer 16

• 3-4 days

- severe hemorrhage, oliguria, hypotension

Question 17

diagnosis of yellow fever?
antiviral treatment?
vaccine?

Answer 17

• serology
• no antiviral treatment
• live attenuated vaccine for persons living in or traveling to endemic areas

Question 18

• 80% of infections in humans asymptomatic
• 20% of infected humans develop west nile fever
• less than 1% of infected humans develop West Nile neurologic disease
• of those with WNND, 40% develop meningitis and 60% develop encephalitis
• small percent causes polio like acute flaccid paralysis
• most common in elderly

Answer 18

west nile virus

Question 19

• causes nonpurulent conjunctivits, facial exanthema, maculopapular rash on the trunk
• fetal microencephaly

Answer 19

Zika virus

Question 20

• largest family of viruses
• depend on wild animals for persistence
• 5 genera
• human to human transmission generally does not occur

Answer 20

bunyaviridae

Question 21

• enveloped, pleomorphic, have two envelope glycoproteins

- 3 segments of ssRNA, negative

Answer 21

bunyaviruses

Question 22

• perpetuated in rodent populations
• enveloped ssRNA virus, virions in square grid like structure
• genome has 3 RNA segments

Answer 22

hantaviruses

Question 23

subtypes of Hantavirus that cause disease in humans?

Answer 23

• hantaan, porrogia
• seoul
• puumala
• sin nombre

Question 24

highest mortality rate of hantaviruses?

Answer 24

sin nombre

Question 25

hantaviruses: rodents shed virus in _______, trasnmitted to people through _______

Answer 25

urine, droppings, saliva aerosolization

Question 26

5 phases of hantavirus?

Answer 26

1. febrile phase 2. hypotensive phase 3. oliguric phase 4. diuretic phase 5. convalescent phase

Question 27

febrile phase of hantavirus: abrupt onset of severe flu like illness with erythematous rash after incubation period of?

Answer 27

2-3 days

Question 28

hypotensive phases of hantavirus begins at day?

Answer 28

5

Question 29

oliguric phase of hantavirus begins at day ____, patient may develop acute renal failure and shock, hemorrhages confined to petechia

Answer 29

9

Question 30

diuretic phase occurs between days?

Answer 30

12-14

Question 31

convalescent phase of hantavirus may require how long?

Answer 31

up to 4 months

Question 32

majority of deaths occur during what 2 phases of hantavirus disease?

Answer 32

hypotensive and oliguric phases

Question 33

- damage to capillaries occur predominantly in lungs rather than kideny - shock and cardiac complications may lead to death - majority caused by sin nombre virus - micrograph: interstitial pneumonitis, intra-alveolar edema

Answer 33

hantavirus pulmonary syndrome

Question 34

treatment of HVD and HPS?

Answer 34

supportive measures, oxygen if hypoxic, vasopressors

Question 35

effective treatment against HFRS but not HPS?

Answer 35

ribavirin

Question 36

- transmitted by mosquito culex pipens - can be spread to umans by contact with tissue or blood, transcutaneous - formalin inactivated vaccine, not licensed for humans - outbreaks directly correlated with rainfall

Answer 36

rift valley fever

Question 37

rift valley fever: - incubation period? - influenza like illness with abrupt onset of fever and assoc'd symptoms - fatal cases experience what symptoms?

Answer 37

- 2 to 6 days | - liver necrosis with hemorrhage, retinitis, meningoencephalitis

Question 38

treatment for rift valley fever?

Answer 38

ribavirin

Question 39

sandfly fever: - ______ fever - incubation? symptoms?

Answer 39

phlebotomous 2-6 day incubation, rapid onset fever, complete recovery

Question 40

-enveloped virus, round or pleomorphic, ssRNA genome in 2 segments, ambisense orientation

Answer 40

arenaviridae

Question 41

arenaviruses associated with disease?

Answer 41

lassa, junin, machupa, guararito, sabia, LCMV

Question 42

small round objects in lasse fever virus are what?

Answer 42

ribosomes

Question 43

- no arthropod vectors, persist in rodent species - persist in nature by congenital transmission - interhuman transmission rare except with lassa fever

Answer 43

arenavirus infections

Question 44

high rate of moratlity in arenaviruses except for?

Answer 44

LCMV

Question 45

- natural reservoir is rat - man to man transmission can occur - incubation 3-5 days, patchy or ulcerative pharyngeal lesions, severe cases (myocarditis, pneumonia, encephalopathy, hemorrhage, shock) - high mortality rate

Answer 45

lassa fever

Question 46

- appears during early convalescence - not related to severity of illness - occurs in 1/3 cases - may be unilateral or bilateral - may persist for life

Answer 46

sensorineural deficits with lassa fever

Question 47

treatment for lassa virus?

Answer 47

ribavirin, must be given early