Infections of International Public Health Flashcards
What additional pubic health measures may be required
restricting international movement
screening travellers for fever
setting up and treatment protocols in advance
What is the West Nile virus caused by
misquote borne by West Nile virus, a member of flavivirus genes (enveloped +ve sense RNA virus; an arbovirus)
What is an arbovirus
arthropod borne virus
Who are the natural hosts of the West Nile virus
birds, transmitted by mosquitoes
When does West Nile virus most often occur
occurs in summer/fall when and just after mosquitos are active
who are dead end hosts in West Nile virus
humans as viremia is short lived and low level
How do birds infect mosquitos in West Nile virus
birds have high numbers of virus in blood so infect biting mosquitos
Why are humans and horses referred to as dead end hosts in west nile virus
because they don’t get high numbers of virus in the blood so do not infect mosquitos
What are the symptoms of WNV
60-80% are asymptomatic
fever aches and pains, headphones and malaise, up to 50% have a rash
What can severe WNV progress into
meningitis, encephalitis (inflammation of the brain), or paralysis or other neurological conditions, with risk of death
Who is the most at risk of getting severe WNV
old and immunosuppressed
Are there congenital anomalies in WNV
no. but infection can be transmitted to newborn if it occurs at time of birth in the mother
How is WNV diagnosed
serology either IgM or rising IgG titres. BUT serology can cross react with other flavivirus infections
How does encephalitis present
as fever, headache, that progresses to vomiting, confusing, and may cause coma and even death
mat be persisting brain damage after recovery
What other arboviruses can also cause encephalitis
eastern equine encephalitis (EEE), Western equine encephalitis (WEE) and others
What is the diagnosis for encephalitis
serology (serum and CSF)
What is mosquito borne caused by
dengue virus - a member of flavivirus genus (enveloped +ve sense SS RNA virus)
How many serotypes are there in dengue virus
4 serotypes, immunity to only that serotype develops after infection
Reinfection with a new serotype may cause severe disease “dengue hemorrhagic fever”
Where does dengue occur
endemic in the tropics, may cause outbreaks
What are the symptoms of dengue
many people have minimal symptoms (up to half)
dengue fever - 2-7 days high fever, myalgia, arthralgia (“break bone fever”), macular-papular rash
What are the two potential progressions of dengue
dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS)
But a small amount of people develop this
develop plasma lead and bleeding, phase lasts about 1-2 days, but life threatening
Followed by convalescent phase and recovery, may develop rash
What is the treatment for dengue
no antivirals available
Fluid replacement and intravascular fluid volume support for DHF/DSS
What is the prevention for dengue
vaccine only if previously have had dengue
- with the vaccine, subsequent infection may cause severe dengue, if no previous infection)
Avoid mosquitos
use repellents: DEET, picaridin, lemon eucalyptus
- permethrin on clothes
removal of mosquito habitat: removal of water contains habitats to prevent mosquito reproduction
What is yellow fever cause by
flavivirus
What transmitted yellow fever
aedes aegypti or hamemagogus spp. mosquitoes
Where is yellow fever predominate
in tropics, in Africa and South America
Urban yellow fever transmission
human-mosquito-human
Savannah yellow fever transmission
human-mosquitos-monkey-mosquito-human
sylvatic or forest yellow fever transmission
primarily monkey-mosquito with human spread
What is the incubation period for yellow fever
3-6 days
what are the symptoms of yellow fever
initially fever, flu like illness nausea vomiting, then recovery
viremia îs high in first few days, can infect mosquitoes
nucleic acid detection is useful in this stage
1 in 7 develop jaundice bleeding and shock: risk of death is high
What is the most common type of diagnosis of yellow fever
serology but cross reacts with other flaviviruses
What is the treatment for yellow fever
avoid aspirin (promotes bleeding)
no anti-virals
What is the prevention for yellow virus
avoid mosquitoes
vaccine - generally say and effective
What is the zika virus caused by
a flavivirus that’s an RNA virus, in the arbovirus group
How is zika virus transmitted
mosquito borne (Aedes spp),
but also person-person by sexual contact, found in semen for up to 6 months after acute infection
Where did Zika virus orientate
Africa
What are the symptoms of Zika
relatively mild: fever, rash, conjunctivitis, muscle and joint pains
What are the major risks of Zika
birth defects espically microcephaly when the babies head is too small when born
Guillain barre syndrome can occur (paralysis)
What is the diagnose for Zika
NAAT for virus in the first 14 days, resume, urine
serology (cross reacts with flaviviruses)
ultrasound for congenital defects if they get it to observe the fetus
What is the treatment for Zika
no treatment is available
no vaccine is available
What is the prevention for zika
avoid mosquitoes
- avoid travailing to risk areas
- use of DEET or other repellents
- screened windows, air conditioning, mosquito nets
- mosquito control
use of condoms if exposure to Zika is a concern, esp if pregnant
What is the Plague caused by
yersinia pestis, a bacteria of the enterobacteriaaceae
Who is the plague transmitted by
fleas and their natural hosts are rodents, esp rats but can be human
What was the Black Death caused by
plague
What are the two types of plague
bubonic (flea transmission)
pneumonic (transmitted person-person) WORSE
coughing up organism so spreading it more
Describe bubonic plague
causes painful enlarged lymph nodes (buboes) with headaches and malaise and “flu-like” illness, progresses to sepsis and DIC (disseminated intravascular coagulation) and death
Descrive pneumonic plague
aggressive pneumonia that progresses rapidly to sepsis and death
What is the diagnosis for plague
made culture of blood, discharge of bubo, sputum
What is the treatment for plague
streptomycin or doxycycline may be effective
What is ebola and viral hemorrhagic fever cause by
filoviruses, enveloped single stranded negative sense RNA viruses
Where does Ebola and Viral Haemorrhagic fever occur
in Africa can cause outbreaks
What is the natural host of Ebola and Viral Haemorrhagic fever
a bat
What are the symptoms of Ebola and Viral Haemorrhagic fever
headache, fever, lack of energy, sore throat, muscle aches; progresses to vominting blood and diarrhea, then bleeding from all oxides and internal bleeding
How is ebola and Viral Haemorrhagic fever diagnosed
by detection of viral nucleic acid
What is treatment for ebola and Viral Haemorrhagic fever occur
vaccine for ebola now, made in Canada
What virus causes rabies
lyssavirus, negative SS RNA viruses
who gets rabies
zoonosis, including; bats, skunks, raccoons, dogs in developing world, cows in Argentina
How does the rabies virus get into you
total entry may be minor wound or scratch
what is the incubation period rabies
1-2 months or longer, days if face is affected as its a lot worse because its closer to the CNS
What are the symptoms of rabies
pain at site of inoculation, progresses to headaches, malaise, seizures, hallucinations, disorientation, coma and death
What is the prevention of rabies
wash wound, rabies immune globulin, and anti rabies vaccine (4 doses over 1 month) generally effective prior to symptoms
immunization of all domestic cats and dogs; workers at risk
how is diphtheria transmitted
person to person by respiratory droplet or skin contact (cutaneous diphtheria)
When are diphtheria outbreaks most common
outbreaks occur where immunization rates fall (Yemen recently)
Endemic in tropics
most people are protected by immunization (but waning immunity in elderly)
What is diphtheria caused by
Corynebacterium diphtheriae
What are the two types of diphtheria
respiratory or cutaneous
describe respiratory diphtheria
pharyngitis with development of grey
may cause death as a result of toxin (toxic to the heart) or asphyxiation from membrane
Explain cutaneous diphtheria
skin ulcers most often seen in homeless people in western US
What is tetanus cause by
clostridium retain an anaerobic gram positive rods, produces spores found in soil
What are the symptoms of tetanus
difficulty swallowing, tight jaw muscles, prolonged muscular spasms of extensor and flexor muscles from minor stimuli
How do you become infected with tetanus
raised from wound infection by C. retain with local production of toxin - often puncture wounds, may not appear infected
Toxin inhibits CNS inhibition of peripheral nerves at the spine (paralysis)
How do you treat tetanus
wound cleaning, penicillin and tetanus antitoxin (human tetanus Ig)
