Lecture 7 Flashcards
who can Filoviruses or filamentous viruses infect
Can infect humans as well as other primates (chimps, gorillas, macaques)
who is the natural host of the Filoviruses or filamentous viruses
Natural host appears to be the fruit bat Bats serve as a reservoir for the virus
By a reservoir, we mean that bats have developed some immunity so the virus co-exists with them without killing them
Also means that in bats, the virus isn’t rapidly changing
Early symptoms in humans are like what
Early symptoms in humans seem not so bad, kind of like a bad case of the flu
Arthritis, Backache (low-back pain), Chills, Diarrhea, Fatigue, Fever, Headache, Malaise, Nausea, Sore throat, Vomiting
what are examples of Filoviruses or filamentous viruses
Ebola and Marburg Hemorrhagic fevers
Filoviruses or filamentous viruses lat systems include
Late symptoms, however, are a different story and can include: Gastrointestinal bleeding, swelling of eyes and genitals, increased feeling of pain in the skin, rash over the entire body that often contains blood (hemorrhagic)
African strains of Ebola virus are lethal in 70-90% of cases of infection The actual percent depends on
what
- -the virulence of the infection
- -the quality of available healthcare
why is the Success of the Ebola virus in humans is limited
Success of the Ebola virus in humans is limited because it is so swift and lethal
then why was the 1918 flu so successful
Didn’t we just say that the 1918 flu was swift (albeit not quite as lethal)?
The difference is in transmission:
Ebola transmission is more difficult than influenza transmission – requires close personal contact with blood or body fluids or contact with used needles, etc
what were the traits of the Spanish flu
Easily transmissible (sneezing, etc)
Lethality came on later (and rapidly)
People could be out and about while initially contagious, before becoming very sick
Talked about 3 viruses:
“swine flu” of 2009 — highly transmissible, not especially virulent
Ebola/marburg — lower transmissibility, highly virulent
1918 spanish flu –- highly transmissible, more virulent
the recent case of ebola: how was it different than before
So what changed? Was it the virus?
The virus arrived in Sierra Leone from Guinea
–A pregnant woman in Sierra Leone fell ill after attending the funeral of an Ebola victim in Guinea
But, doesn’t appear that the severity of 2014 outbreak was a consequence of those mutations
So what changed?
Was it the virus? No. Was it the environment?
There has been a dramatic increase in the urban growth rate in Africa over the last 15 years
This growth has not yet been accompanied by a dramatic improvement in infrastructure
–clean water
—sanitation
–durable housing
–sufficient living space
–improved access to health care
One hypothesis is that the 2014 outbreak spread and was maintained because unlike previous outbreaks it was in more densely populated urban areas
how do you suppress the spread of ebola (or any other disease/virus)
1) To recognize the illness
2) To prevent the further spread by reducing contact:
–quarantine
–protective equipment
—disposal of waste
–proper burial
how do you deal with a pandemic
Monitor globally for the appearance of a virus in humans with pandemic potential:
Quickly produce a vaccine
This is a huge challenge because of the way vaccines are made and because viruses are constantly mutating
Limit exposure and transmission
Given the frequency and ease of travel, this is also a challenge
This approach is not a lost cause:
–New knowledge about viruses helps vaccine development –New methods for vaccine production being tested –Modern communication is quick (we are no longer waiting for the newspaper to get information)
But it’s definitely a challenge
This is sort of a ‘top down’ approach
Recently, there has been the introduction of a bottom-up approach
what is the bottom up approach
Nathan Wolfe and others are working on a bottom-up approach
Monitor the “viral chatter” in populations of wild animals Determine which things may be likely to become problematic i.e.
Monitoring across the globe, one example is sub-Saharan Africa
Within populations of people who rely on bushmeat as a food source
Both because of the nature of the animals (non-domesticated) and the butchering (messy) there is a reasonable probability of viral infection with a virus that humans have not encountered before
Working with hunters, try to convince them not to collect already dead animals (since they don’t know what killed them)
Get as much information as possible from the hunters about the animals they encounter
Hunters collect blood samples from the animals they kill
– Just put a drop of blood on a card
– because of modern methods, it is possible to isolate viruses from this card
This approach makes it possible to monitor
(think of how this wouldn’t work if they needed to collect blood in vials, or keep samples cold, etc)
How successful this approach is remains to be seen…
