viral infection of RBCs

Question 1

illustrate Pathogenesis of VHFs (viral hemorrhagic fever)

Answer 1

• Virus at site of entry → local LNs → multiplies → blood → viremia → liver, spleen, kidney, BM, LNs
• vascular permeability
• DIC
• Hepatic involvement
• Hypotension
• Multisystem organ failure
• Shock, circulatory collapse & death.

Question 2

African Hemorrhagic Fevers =…………&………….

Answer 2

Marburg & Ebola HFs

Question 3

what’s African Hemorrhagic Fevers?

Answer 3

Severe & highly fatal diseases caused by viruses, from the Filoviridae family
ss RNA, enveloped, -ve sense.

Question 4

about MARBURG & EBOLA HFs
1. Among the ………….pathogens known to infect humans
2. Both are clinically almost …………
3. are, but may cause dramatic outbreaks with high …….

Answer 4

1. most virulent
2. indistinguishable
3. fatality

Question 5

about Reservoir & MOT of MARBURG & EBOLA HFs :

1. Highly ………..
2. Transmitted to man ………..
3. ………… may be the reservoir
4. ………… are susceptible to infection but are Not considered viable reservoir hosts
5. MOT: ………………
   mainly by: …………….
6. Fatality:
   * Ebola up to……… & Marburg up to…..

Answer 5

1. communicable
2. accidentally
3. Bats
4. Monkeys
5. Person to Person transmission
   by: intimate contact
   (Direct contact with infected blood, secretions, organs or other body fluids of infected persons)
6. Ebola up to 50% & Marburg up to 25%

Question 6

what’s the laboratory diagnosis of MARBURG & EBOLA HFs ?

Answer 6

Laboratory Diagnosis
* Based on Symptoms
* Demonstration of filoviruses in blood:
ELISA & PCR

Question 7

illustrate both treatment &prevention of MARBURG & EBOLA HFs

Answer 7

Treatment
* Supportive care involves fluid & electrolytes, sometimes anticoagulants
* No antiviral drug

Prevention
* Vaccine have been developed that protect monkeys

Question 8

enumerate other viruses that may be presented by hemorrhage

Answer 8

1. Flaviviruses:
   Yellow Fever & Dengue Fever
2. Bunya viruses:
   Rift Valley Fever & Hantavirus associated syndromes.
3. Arenaviruses:
   The most significant is Lassa Fever virus

Question 9

enumerate other viruses that may be presented by hemorrhage

Answer 9

1. Flaviviruses:
   Yellow Fever & Dengue Fever
2. Bunya viruses:
   Rift Valley Fever & Hantavirus associated syndromes.
3. Arenaviruses:
   The most significant is Lassa Fever virus

Question 10

about Yellow Fever
1. It is an acute, febrile, mosquito-borne illness that occurs in Africa & USA
* It is caused by………………

Answer 10

1. Yellow fever virus.

Question 11

(About yellow fever)
-Reservoir & MOT:
Two major epidemiologic cycles of
transmission of yellow fever:
1……
2……

Answer 11

1.Jungle YF
2.Urban YF

Question 12

according to Jungle YF:
1. Primarily a disease of …………
2. Monkey-to-monkey by……….
3.Man is ………. on visiting the jungle

Answer 12

1. monkeys
2. forest Aedes mosquito
3. accidentally infected

Question 13

according to Urban YF:
1. Person-to-person by ………
2. When an infected person from the …… returns to …….

Answer 13

1.domestic Aedes mosquito
(Aedes aegypti)
2. jungle/urban areas

Question 14

illustrate Clinical manifestations of yellow fever

Answer 14

1. Mild or so severe & fatal.
2. Fever, headache, dizziness, myalgia &
   backache followed by recovery or may develop jaundice (hence yellow fever) & renal dysfunction.
3. In severe cases, hemorrhagic manifestations appear. Patients have black vomitus with high mortality rate (20% or more).

Question 15

illustrate Lab diagnosis of yellow fever.

Answer 15

Detection of:
* viral antigens in the blood by ELISA
* Viral nucleic acid detection by PCR

Question 16

illustrate Treatment & prevention of yellow fever

Answer 16

-Treatment
* Supportive, depends on system affected.

• Prevention
  1.Mosquito control .
  2.Vaccine (17D vaccine) :
• live attenuated.
• to travelers & residents of endemic areas.
• Single SC dose → immunity for 10 years

Question 17

about Dengue fever
1.DF & DHF are caused by one of …. closely related, but………….., DF virus serotypes …………..

2. Infection with one serotype provides
   immunity to ……….

3.so persons living in a dengue endemic area can have……… during their lifetime

4. • ………. is the reservoir host.
   • Person-to-person transmission
     occurs by ……….

Answer 17

1.
- four
- antigenically distinct
- (DEN-1, 2, 3 & 4)

2. only that serotype for life
3. more than one dengue infection
4. • Man
   • domestic Aedes mosquito
     (Aedes aegypti)

Question 18

discuss the clinical manifestations of dengue fever

Answer 18

1. Classical DF:
   -high fever, headache, sever myalgia & arthralgia
   - maculopapular rash
2. Dengue HF:
   - A potentially deadly complication of dengue.
   - It appears to be an immuno-pathological consequence (?) 2ry infection with a different virus serotype
3. Dengue shock syndrome DSS:
   - Skin hemorrhages such as petechiae & purpura.
   - Most patients develop thrombocytopenia & hemoconcentration.
   - If not immediately corrected → profound shock
   & death

Question 19

discuss the following with dengue fever:
1.Diagnosis
2.Prevention
3.Treatment

Answer 19

1.Diagnosis
* Antigen detection in blood

2.Prevention
* Mosquito control is the most important strategy

3.Treatment
No specific treatment is available

Question 20

Bunya viruses
- Rift Valley Fever (RVF) is …………..

Answer 20

A mosquito-borne zoonotic disease

Question 21

illustrate Reservoir & MOT of rift valley fever

Answer 21

1. Pathogenic 1rly for sheep, cattle, buffaloes, goats & camels → hepatitis, abortion & death
2. Humans are 2ndly infected during the course of epizootics in domestic animals by bite of an infected mosquito
3. exposure to blood or other body fluids of infected animals

Question 22

illustrate Clinical Pathology of RVF

Answer 22

• Mostly asymptomatic or flu-like illness
  with complete recovery.
• A small proportion of patients may develop:
  -retinitis with visual loss
  -meningoencephalitis
• hemorrhagic fever.

Question 23

discuss Prevention of RVF

Answer 23

sustained program of animal vaccination
(Live attenuated & killed)