Vector Born Diseases Flashcards
what are vectors?
organisms that transmit infections from one host to another (but are not infected themselves).
They are Asymptomatic carriers of parasites and pathogens that attack humans or other animals.
_______ is a leading cause of illness and death in the tropics and subtropics. As many as 100 million people are infected yearly
Dengue infection
are there vaccines for dengue? what about the most effective treatment?
There are not yet any vaccines to prevent infection with dengue virus (DENV) and the most effective protective measures are those that avoid mosquito bites
what is dengue caused by?
any one of four closely related dengue viruses
DENV 1, DENV 2, DENV 3, DENV 4
All are Flavivirus family members
In the Western Hemisphere, the _____ _______ _______ is the most important vector of dengue viruses
Aedes aegypti mosquito
what is a characteristic symptom of dengue?
Muscle and bone pain (“Breakbone Fever”)
what is a sever form of Dengue fever ?
DHF is a more severe form of dengue infection, with more severe bleeding
Can be fatal if unrecognized and not treated in a timely manner
With good medical management, mortality due to DHF is
< 1%
is serology helpful for dengue?
NO
overall treatment for dengue is what?
all are SELF-LIMITED - so txt is supportive (as long as theyre not hemorrhagic- if so they NEED IV fluid)
Dengue is easily confused with what other disease? what is the major difference?
chikungunya but this one has no hemorrhagic form
what are prevention methods for dengue?
Avoid times of high mosquito activity in endemic areas (dusk, dawn)
Use DEET, long sleeves and pant legs
chikkungunya is carried by what organism?
carried by Aedes aegypti and Aedes albopictus mosquitos (same as dengue)
Zika virus: similar to dengue, but ____ _____.
Similar to Dengue, but less severe, often asymptomatic
what are the symptoms of zika?
often asymptomatic
what is the vector for Zika?
Aedes egyptii mosquito
What is the major concern with Zika?
Appears to cause microencephaly of developing fetuses, and is now considered to be a major public health risk
Zika can be transmitted from who?
infected males
how long to wait if you want to get pregnant or have unprotected sex but were exposed to Zika?
Wait 2 mo if female only is exposed, 3 mo if male or both
lyme disease: what is it and what environments does it prefer?
Spirochete: prefers viscous environments. (oral cavity, gut)
what is the common reservoir for lyme disease ?
white footed mouse (wild mouse)
what is the Most common vector borne disease in USA?
Lyme disease
lyme disease invades …
blood and tissues of warm blooded animals
what are the vectors for lyme disease ? (weeds maybe…)
Vector: Ixodes ticks, I. scaularis (E), I. pacificus (W), I. ricinus (Europe)
what size ticks have lyme?
VERY small ones - highest rate of viral transmission
ticks with lyme must stay attached for __ to ___ hrs to infect
Must remain attached for 36-48 hr to infect
characteristic sign of lyme disease - early stage
Erythema Migrans, non-puritic, “target/bullet rash”
what is the secondary stage of lyme disease show?
more severe constitutional symptoms : high fever, meningismus, headache, pain
what type of complications does lyme disease cause? (what particular body systems)
neuro and cardiac
late stage lyme disease occurs __ to ___ after the bite
weeks to months
what three complications occur with late stage lyme disease
Lyme arthritis: monoarticular large joints
Cardiac: Heart block, check an EKG
Neurologic: psych, CNS, encephalopathy
Dx for early, secondary and late stage lyme disease?
early lyme disease - dont see good serology
secondary- EIA and western blot
late stage - IgG +
Post- exposure prophylaxis for lyme disease
PEP (post-exposure prophylaxis): maybe single dose of doxycycline within 72 hr
treatment for lyme disease (actual disease with rash)
about 2-3 wks of oral Tx
Encephalopathy/itis or severe neural involvement: what is the treatment? (maybe weeds)
IV therapy x 30 d (longer than 2-3wks)
overall: early or late stage lyme disease, what is the treatment?
2-3 wks abx
agent for rocky mountain spotted fever?
Agent:Rickettsia rickettsii gram negative intracellular bacteria
what does spotted mountain spotted fever cause?
Thrive within cells that line small- to medium-sized blood vessels ( vasculitis which leads to vasculitic rash (which means it wont blanch))
what is the vector for rocky mountain spotted fever?
ticks: Dermacentor variabilis (American dog tick), and
D. andersoni (wood tick)
characteristic sign of rocky mountain spotted fever
vascular rash
Dx of rocky mountain spotted fever: what two things do you need ?
Rash in < 3 days since tick bite (90% of people)
Indirect immunofluorescent antibody (IFA)
how long is the incubation period before symptoms (other than rash) of rocky mountain spotted fever ?
one week
treatment for rocky mountain spotted fever ? what about pregnancy?
Treatment:: Doxycycline 100 mg PO/IV BID for at least 5-7 d, including 3 d after fever is gone
In pregnancy: Still doxy (concern for bone and tooth enamel formation- but the risk is low for this)
how many cases/yr of malaria worldwide ?
300-500 million cases/yr worldwide
what are the agents that cause malaria?
protozoan- 4 kinds
which is the worst (most deadly, can be rapidly fatal) of the 4 agents that cause malaria?
protozoan Falcifparum
what is the vector for malaria?
Anopheles mosquitoes
what is the reservoir for malaria?
Humans are only known host (the reservoir and the target)
malaria: Symptoms triggered by ____ _____, mediated by ____, _____, ____ and _____
schizont rupture;mediated by TNF, cytokines, pyrogens (IL-1,6), and cellular debris
for malaria, ___ is different for different regions
drug resistance
what are some drugs for malaria treatment?
- malarone
2. quinine sulfate + Clindamycin, Tetracycline or Doxycycline
what are the three parts to malaria prevention?
Vector control
Permethrin treated bed nets
Insect repellent (DEET)
what can you do for chemoprophylaxis of malaria?
Malarone, start it before you travel to exposed area and continue taking when you get back (for a period of time)
what is the rabies virus? agent, family, genus, and type of virus
Agent: Rabies virus
Family Rhabdoviridae
Genus Lyssavirus
Enveloped, single stranded RNA
what are the vectors for rabies? (5)
Infected corneal grafts
Animal saliva on open skin
Inhalation of bat secretions (any casual contact with a bat)
Bites of infected animals: Dogs, cats, foxes, coyotes, skunks, raccoons, jackals, wolves, and bats
rabies cases:
In 3rd world, __% by dogs.
N. America, Europe __% by dogs.
In 3rd world, 90% by dogs.
N. America, Europe 5% by dogs.
post exposure prophylaxis for rabies: 2 part
- human rabies immunoglobin
2. Vaccination
what is the dosage for the rabies vaccine for PEP?
1 ml vaccine IM on days 0, 3, 7 14
what does arboviral mean?
Arboviral = “arthropod-borne viral”
what are the agent, vector, and vaccine for arboviral encephalitis?
Agent: Alphavirus, Togaviridae
Vector: Multiple mosquito species, sometimes ticks
Usually no vaccines (for people)
arboviral enchephalitis is most common in what animal?
horses
what are two major syndromes of arboviral encephalitis?
West Nile Encephalitis and Yellow Fever
what is the treatment for all syndromes of arboviral encephalitis?
supportive, no anti-virals available
vector for yellow fever
Aedes mosquitoes
vector for west nile enceph.
culex mosquitoes
West Nile Encephalitis: Most infections are ________ (__%), more severe in _____ ______
Most infections asymptomatic (80%), more severe in older persons
what are the hosts for west nile?
birds
Dx of west nile
IgM antibody to WNV
IgM doesn’t cross BBB
incubation and possible symptoms of west nile (maybe weeds)
Incubation 2-14 days
Can cause motor weakness, respiratory difficulty, GI complaints common
agent, vector and host of yellow fever
Agent: Flavivirus
Vector: Aedes aegypti mosquitoes
Host: nonhuman primates
which is the most lethal of the arboviruses?
yellow fever
what organs are most damaged by yellow fever?
Liver, Kidneys show most damage
incubation and possible signs of yellow fever (maybe weeds)
Incubation 3-6 days
Fever, severe HA, myalgias, nausea, short “remission phase”
pathology of the toxic phase of yellow fever (maybe weeds) (6parts)
High fever, severe pain, vomiting Hepatic jaundice, coagulopathies Hemorrhages, “black vomit” Bradycardia, acute tubular necrosis CNS symptoms, lethargy, coma Death
how do you Dx yellow fever?
Diagnosis: Serum (IgM) ELISA
how do you treat and prevent yellow fever?
Treatment: None
Prevention: Yellow fever vaccine
(YF-VAX) is a live, attenuated virus vaccine
what type of disease is typhus? what is the usual vector?
A rickettsial disease, usual vector is an arthropod (tick, flea, mite, lice )
Rickettsial Disease: Symptoms vary but ____, _____ and _____ are common.
HA, fever, malaise
Dx and Txt of rickettsial Disease
Diagnosis by specific antibodies
Treatment by antibiotics, no vaccines
which rickettsial diseases have the human louse as the vector?
what are the agents for each of these? (weeds)
Epidemic Typhus
Agent: R. prowazkeii
Trench Fever
Agent: B. quintanta
what are unique symptoms to epidemic typhus and trench fever? (weeds maybe )
confusion and photophobia
Agent and vector for Murine Typhus
Murine Typhus
Agent: R. typhi
Vector: Rat fleas
Vector for Cat-Flea Rickettsiosis
Cat-flea Rickettsiosis
Agent: R. felis
one Txt option for Rickettsial Disease? (maybe weeds)
Doxycycline 100mg po bid x 7 days
where can you look for reccomendations on travel vaccines?
CDC yellow book
