Vector Borne Disease Flashcards
What are vectors (in terms of disease)?
Anything that carries a pathogen from host to host
What phylum of organisms make up a large proportion of vectors?
Arthropods
What spreads malaria and how?
Pregnant female mosquitos
She bites a host for blood (blood provides nutrients to her babies) while she has contaminated salivary glands carrying the malaria parasite. She uses salvia to prevent the blood from clotting
Malaria has R0 value can range from <1 to over 1000, how it can it be so high
Transmission in regions with high proportions of mosquitos is super high due to frequent contact with mosquitos and recovery rate is super low as resistance takes years to develop, allowing for the presence of malaria
Thus since beta is frequency-dependent here → R0=Beta/Gamma
With high beta and low gamma, you get high R0
Malaria life cycle
- Malaria parasite inside the saliva of a mosquito
- Gets injected into the bloodstream of human where it goes to liver cells
- Divides and amplify in liver cells –> schizonts
- Schizonts move into blood and eat blood cells –> causes anemia
- Blood cells can burst & release more parasites
True or false: Sickle cells are resistant to malaria
True
Which is the most serious malaria parasite
Plasmodium falciparum
What kind of mosquitos spread malaria
-Anopheles
-Pregnant females
Which mosquito is in anthropophilic (attracted to humans)
Anopholes gambiae
Which mosquito lives well in urban environments
Anopheles stephensi
What organelles are used to be photosynthetic
Apicocomplexan/apicoplast
True or false: Malaria is like red algae
True
How do you estimate R0 for vector-borne pathogens?
You multiply the R0 of both pathways together to get the total R0.
eg.) R0(human to mosquito) * R0 (mosquito to human) = R0total
What is one of the best human mosquito vectors? Why is it that?
Aedes aegypti, it is all over the world as it is an aggressive invasive species in urban areas that specialize on human hosts
What is vector competence?
Susceptibility of a vector to a given pathogen (Ch)
What is vectorial capacity?
The expected number of infective mosquito bites that would eventually arise from all the mosquitos that would bite a single fully infectious person on a single day
What is the main vector that causes yellow fever and dengue?
Aedes aegypti
It is not as bad to get dengue once and recover, but it is not great to get it a second time… why?
Antibody dependent enhancement
-there are 4 types of different dengue
True or false ticks are parasites
True
What are hard bodied ticks called
Ixodidae
What are soft bodied ticks called
Argasidae
Ticks are vectors to what kind of disease
- Crimean Congo Hemorrhagic Fever
- Rickettsia
- Lyme Disease
What are Wilbachia symbionts
-Can change gametes in host to favor transmission
-Protect insects from viruses
-could help stop virus transmission through vectors
What is an important member of the Rickettsiales group?
Mitochondria
-came from Rickettsia bacteria
What makes it less worrying for disease transmission through ticks
Ticks only contact one host in their lifetime
What is one exception that could make disease transmission through ticks a problem?
Vertical transmission
-ticks live long and can transmit to multiple hosts
What kind of tick spreads lyme disease
Ixodes scapularis
-The deer tick
True or false: Larvae of ticks that cause lyme disease are infected
False
-Larvae are uninfected
-No vertical transmission for lyme disease
At what stage for ticks do they do the most transmission for lyme disease
Nymphs
What are ticks preferred habitat
Wildland-urban interface
-need nature
For larval ticks they infect most species the same
False
-Variation in infectiousness between species –> reservoir competence
What is the dilution effect?
Pathogen gets diluted w/ less competent hosts
What does it mean to clean ticks and what can do it
-Clean means to jill the tick
-Lizards can do this, due to protein in the blood that kills the bacteria (Borrelia burgdorferi)
Which stage of the tick would cleaning affect?
Nymph
What is sleeping sickness caused by?
Trypanosomes carried by tsetse flies
