Viruses that cause haemorrhagic fever Flashcards
haemorrage is fluid leakage from what?
capillaries- thinner vessels, allows access to mosquitos
- single layer of endothelial cells, this barrier is maintained by PERICYTES
what is haemorrhage?
the escape of blood from any blood vessel in body
what does viral haemorrage cause?
- severe multi-system syndrome characterised by diffuse vascular leakage
- often bleeding (may/may not be life threatening)
give examples of viral haemorrage effects?
- bruises
- conjuctival inf (esp Dengue)
- epistaxis (nose bleed)
- petechie (nose bleed, esp Dengue)
- edema
give 2 examples of haemorrhagic blood borne viruses?
- Ebola
- Marburg
FILOVIRUSES
give an example of haemorrhagic airborne viruses?
Lassa virus
ARENAVIRUSES
give an example of haemorrhagic arthropod-borne viruses?
Dengue
FLAVIVIRUS
what is the family and genus of Ebola virus? what is the family and genus of Marburg virus?
Family Filoviridae
Genus Ebolavirus, Maburgvirus
what is the tropism of Ebola and Marburg?
immune cells (macrophages), hepatocytes, endothelia cells (then can cause haemorrhage)
what type of infection is caused by Ebola and Marburg? is there persistence?
- severe acute infection
- persistence can lead to future disease
what are the treatments/vaccines for Ebola/Marburg? Are there any?
no treatments/vaccines
how did Marburg end up in Germany?
where is Marburg virus found?
research using non human primates from Africa which carried Marburg virus found in Germany
- found normally in Angola, DRC recently in Uganda
where is Ebola found?
what is the most common Ebola?
Sudan, DRC
- most common is Zaire Ebola
Reston ebola is found where?
Philippines
why does the Ebola virus change from the original virus?
mutations cause evolution
what is the enzootic (wildlife) cycle for Ebola and MArburg?
animal reservoir in Pteropodiae
fruit BATS, megabats
what is the epizootic (wildlife) cycle for Ebola and MArburg?
how does this spillover to humans ?
infects non human primates (gorillas) and antelopes (Duikers)
at this point it can spillover into humans (go to forest for Bushmeat)
how is ebola transmitted?
how long is the incubation period?
- via body fluids (blood and others) (living and dead people) - sexual contact - contaminated surfaces INCUBATION PERIOD: 2-21 days
how does ebola progress and what symptoms does it cause?
day 7-9= headache, fatigue, muscle soreness
day 10= sudden high fever, vomiting blood, passive behaviour
day 11= bruising, brain damage, bleeding from nose, mouth anus
dau 12= FINAL STAGES
loss of consciousness, seizures, massive internal bleeding DEATH
what is the death rate for Ebola?
7 days after onset of symptoms =30% chance of surviving
3 weeks after symptoms= 90% chance of surviving
where can Ebola persist and what does this cause?
areas the immune system cannot reach TESTES- can enable sexual transmission EAR- hearing loss EYE- retro orbital pain, blurred vision BRAIN/CNS- meningitis UTERUS- transmission to fetus, stillbirth MUSCLE/JOINT- myalgia
how does Ebola cause haemorrage via cytokines?
immune distruption–> infects immune cells–> i.s responds by producing cytokines (POSITIVE FEEDBACK LOOP)—> HIGH levels of VASODILATORY cytokines—> allows opening up of vasculature to allow immune cells to enter tissues—> but the level of vasodilatory cytokines are too high O blood leakage—> haemorrhage
what are 2 other ways (other than cytokines) that ebola can cause haemorrhage?
1) direct infection of ENDOTHELIAL cells
2) infection of LIVER, this disrupts production of coagulase factors for clotting
3) infection of ADRENAL glands and KIDNEY, dirupts balance of blood pressure
in airborne viruses, do large or small droplets travel further?
small (>10m)
