Vector-borne Diseases Flashcards
What is the life span and breeding sites of lice, ticks, fleas, flies, mosquitos, and snails?
- LICE - 1 month; beds and clothes
- TICK - 1 month to 2 years; bushes
- FLEA - 1 year; beds
- FLY - 6 weeks; decaying organic matter
- MOSQUITO - 1 month; aquatic (except adult)
- SNAIL - 1-3 years; aquatic and terrestrial
How do arthropods cause disease? Why are snails considered vectors?
drill/suck/bite into skin, drink blood, and vomit pathogens into the host body
can be herbivores or carnivores —> can eat worms and pass them on to predator that hunts them
What is the reproductive biology of snails like? What 3 habitats/breeding sites do they frequent?
hermaphrodites
- terrestrial - land snails
- freshwater
- sea
What do snails amplify? How do they compare to other vectors?
amplifiers and required for zoonotic trematode (fluke) spread, causing schistosomiasis*, angiostrongyliasis, fascioliasis, fasciolopsiasis, opisthorchiasis, paragonimiasis, or clonorchiasis
do not chase hosts and drink their blood —> direct contact or ingestion of snail is required for transmission (technically do not cause vector-borne disease)
What life stages of mosquitos, fleas, flies, lice, and ticks feed on blood?
- MOSQUITOES - adult females
- FLEAS - all adults
- FLIES - all adults
- LICE - all stages (except egg) and sexes eat several blood meals per day
- TICKS - all stages (except egg) and sexes have 1 blood meal per stage
What stages of mosquitos are aquatic?
- egg
- larvae
- pupae
NOT ADULT
What is necessary for the control of mosquito populations?
destroying aquatic breeding sites
How many times do mosquitos mate?
ONCE
What 3 genera of mosquitos are important vectors? When are they active?
- Aedes (zebra)- day
- Anopheles - dawn, night, dusk
- Culex - night, midnight (NOCTURNAL)
What do mosquitos use to bite and suck blood? Why is staying inside at night not enough to avoid mosquito-borne disease?
proboscis
30% bite during the day - Aedes
What 4 ticks are important vectors in the US? What do each of them transmit?
- Ixodes scapularis (Blacklegged tick) - Anaplasma, Borellia, Babesia
- Rhipicephalus sanguineus (Brown dog tick) - Babesia, Ehrlichia, Rickettsia
- Dermacentor (American dog tick) - Rickettsia, Tularemia
- Amblyomma americanum (Lone Star tick) - Ehrlichia, Tularemia
Where do ticks live? Where do they spend most of their time?
bushes and leafy plants - climb trees, tall grass, and shrubs to wait and jump on passing hosts
in the environment - will only go on a host up to 3 times in their life for blood meals (larva, nymph, adult)
How many times do ticks mate?
ONCE during their adult stage
What are the 3 types of lice?
- head lice
- pubic lice - jump from one individual to another during sexual intercourse
- body lice
How many times do lice mate? How many eggs are produced in their lifetime?
ONCE - produce eggs throughout lifetime
125 eggs within 1 month
On what animals are fleas found on? How many times do they mate?
mammals and birds
only need to mate once, but mate SEVERAL times to improve fertile egg production - can lay 40 eggs a day for the 4-6 months of life
What are the 4 main types of flies? What do they feed on?
- house fly (Musca) - male and female eat food and fecal matter
- sand fly (Phlebotmum) - female drinks blood
- stable fly (Stomoxys) - adult male and female drink blood
- tsetse fly (Glosinna) - adult male and female drink blood
How many times do flies mate?
ONCE
What arthropod females store sperm for the rest of their lives to fertilize tons of eggs?
- mosquitos
- flies
What are some other names of the sand fly? How do their bites compare to mosquito bites?
- biting midge
- no-see-ums
- sandflea
- granny nipper
- Chitra
much larger
What do mosquitos, sand flies, and other small flying insects not like the smell of?
citronella candle (insect repellent)
What 3 sense organs to arthropods use to locate their host?
- smell odor of host using chemosensory sensilla on feet, wings, and antennae (far distance)
- use compound eyes for site and motilty (close distance)
- palpate/touch for temperature of body heat
olfactory, visual, thermal signals
What 5 odors are arthropods attracted to? What 4 are they repelled from?
odorant compounds in breath, urine, and feces
1. CO2
2. lactic acid
3. carboxylic acid
4. ammonia
5. phenols: acetone, -ols
- DEET (N,N-diethyl 3-methylbenzamine)
- picaridin
- oil of lemon eucalyptus (para-menthane-3,8-diol)
- citronella candle
What bacteria, viruses, protozoa, and helminths are most commonly transmitted by vectors?
BACTERIA - spirochetes and Rickesttsiales
VIRUSES - Flavivirus (arbovirus)
PROTOZOA - hematozoa, like Babesia, Malaria, Leishmania, and Trypanozomes
HELMINTHS - trematodes and nematodes (filarial)
What is the pathogenesis of vector transmission of pathogens?
- tubular mouth apparatus injects pathogens into skin
- pathogen enters host, divides, and attached different tissues/organs
- induction of non-specific clinical symptoms: fever, arthritis, headache, vomiting, muscle pain, and tiredness
What are the 2 types of transmission of pathogens by vectors?
- BIOLOGICAL - pathogen divides, multiplies, develops and/or transforms itself from one stage to another within the arthropod (most common)
- MECHANICAL - pathogen does not divide and uses the arthropod as a vehicle to pass from one host to another
What 2 arthropods usually mechanically transmit pathogens? What virus, bacteria, and protozoa are spread this way?
- housefly
- cockroach
- VIRUS: hepatitis
- BACTERIA: cholera, salmonella, shigella
- PROTOZOA: amoeba, giardia
What cause most tick-borne diseases? What are 6 examples?
BACTERIA
- Anaplasma phagocytophilum - RBC attack
- Borrelia - relapsing fever, Lyme attack of blood vessels
- Coxiella burnetii - endothelial attack
- Ehrlichia phagocytophilum - WBC attack
- Rickettsia rickettsiae - Rocky Mountain spotted fever rash
- Francisella tularensis - Tularemia; attack skin, eyes, LN, and lungs
What 2 viruses are commonly transmitted by ticks? Protozoa?
- Flavivirus - encephalitis, Powassan virus
- Coltivirus (Reoviridae) - Colorado tick fever
Babesia - RBC attack
What are the most common clinical signs of tick-borne disease?
- fever
- arthritis
- headache
- vomiting
- muscle pain
- tiredness
- rash (leaky blood vessels)
What pathogens are the 3 species of mosquitos responsible for spreading?
- Aedes - viruses; Alphavirus, Flavivirus, Orthobunyavirus
- Anopheles - parasites; Malaria, lymphatic filariasis
- Culex - viruses; Alphavirus, Flavivirus, Orthobunyavirus
How do the viruses transmitted by Aedes and Culex mosquitos compare?
AEDES: blood vessel and visceral organ invasive disease causing hemorrhage, and liver or kidney disease (VISCERAL)
- Dengue, Zika, Yellow Fever, Chikungunya
CULEX: neuro-invasive disease causing encephalitis
- East/West encephalitis virus, Japanese encephalitis virus, West Nile virus
What are the reservoir hosts of neuro-invasive and viscera-invasive mosquito-borne viruses?
CULEX - farm animals, like pigs, horses, ruminants, and camels (zoonosis to humans)
AEDES - primates
How is West Nile virus transmitted? What are some clinical signs in humans? What are 4 common neurological signs?
- reservoir host = birds
- vector = Culex mosquitos
- accidental host = humans, horses
fever, arthritis, headache, vomiting, muscle pain
- encephalitis
- neck stiffness
- confusion
- seizures
What pathogen is most commonly spread by fleas? What are 3 examples? What other pathogen is commonly spread?
BACTERIA
1. Yersinia pestis - plague, Black Death
2. Rickettsia typhi - murine typhus
3. Bartonella henselae - cat scratch disease
PARASITE - Dipylidium caninum; tapeworm of dogs and cats can be swallowed by children
What pathogen is most commonly spread by lice? What are 3 examples?
BACTERIA
1. Rickettsia prowazekii - endemic typhus fever
2. Borrelia recurrentis - epidemic relapsing fever in humans
3. Bartonella quintana - trench fever, five-day fever
What 3 pathogens are sand flies known to spread? What hosts can they infect?
- Leishmania - cutaneous and visceral protozoa
- Phlebovirus
- Bartonella
What kind of transmission do stable flies (Stomoxys) do? What 3 pathogens do they commonly spread?
mechanical transmission
- Anaplasma
- Anthrax
- equine infectious anemia
What aspect of house fly (Musca domestica) anatomy aids in transmission? What pathogens do they commonly spread?
hair allows for easy mechanical transmission of enteric pathogens from the feces it feeds on
- Staph. aureus
- Salmonella
- dysentery
- cholera
- poliomyelitis
- tularemia
- leprosy
- TB
What 2 vector-borne diseases are brought to the US by Americans traveling abroad? What vector spreads them?
- Dengue
- Malaria
mosquitos
What vector-borne diseases dominate in the US? What 6 are most common?
tick-borne diseases (89%)
- Lyme disease
- Dengue (Arbovirus)
- Anaplasmosis, Ehrlichiosis
- Malaria
- Rocky Mountain spotted fever
- Tularemia
What is the leading endemic mosquito-borne disease in the USA?
West Nile virus
Where is Lyme disease most commonly found in the US? What tick transmits it there? What lesion is characteristic?
Northeast
Ixodes scapularis
ring-like skin rash around tick bite
West Nile virus is widely distributed in the US. Where does there seem to be concentrated cases?
California, Arizona, New Mexico, Utah, Colorado
How are vector-borne diseases seen by the government? What 3 are exceptions?
neglected zoonoses
Lyme, West Nile, and plague have been prioritized for One Health by US government in 2018
What are the 5 most commonly reported vector-borne zoonoses in the US?
- Lyme disease
- spotted fever group rickettsioses
- West Nile virus
- Anaplasma phagocytophilum
- Ehrlichia chaffeensis
What are the best ways to monitor mosquitos/flies, mosquito larvae, and ticks?
blue net traps that can be seen by the flying arthropods
nets over water bodies
dragging and flagging white cloth
What are the 7 methods of fighting arthropods to control vector-borne disease?
- CHEMICALS - pesticides, antimicrobials
- VACCINES - mosquito, tick, pathogen
- destroy arthropod breeding sites
- BIOLOGICAL - bacteria, fungi, birds
- trap
- birth control
- PPE - nets, long sleeves or pants, repellants, boots
What are 4 common insecticides/acaricides used to control vector populations?
- organochlorine
- organophosphates
- carbamates
- pyrethrins
kills all life stages
When should animals/breeding sites be dipped/sprayed? What is the purpose?
once in April/June and once in July/September
prevent lice, flies, mites, and ticks from attaching to skin of animals
How can infected animals and humans be treated to kill vector-born pathogens? Why do we do this?
antimicrobials (Doxycyclin!), antiprotozoals
keep infected individuals from acting as a source of infection to the public
What 2 licensed tick vaccines are used in cattle? What tick is targeted?
- TickGARD - Australia
- Gavac - Latin America
Rippicephalus microplus: Babesia, Anaplasma
What licensed vaccines are available in dogs, equids/alligators/zoo animals, and humans against vector-borne pathogens?
Borrelia burgdorferi bacterin against Lyme
West Nile virus
Dengue, Yellow Fever, Japanese encephalitis, tick-borne encephalitis
What is the double function of licensed vector-born vaccines?
immunization of animals reduces disease and zoonotic transmission to humans
What is the best ways to clean/destroy breeding sites of mosquitos, lice/fleas, flies, and ticks?
drain stagnant water and avoid dark corners
clean dirty clothes and bedding
proper disposal and cleaning of manure, filth, and dumps
pasture burning and plowing of bushes and thick, tall grass
How is birth control used to control vector populations?
sterile insect/male technique (SIT) introduced a gamma-irradiated infertile male into the field for mating
How can access of arthropods into homes/farms be controlled? What are some examples?
physical barriers
- sleep under mosquito nets
- wear long-sleeved shirts and pants with repellants
- use screens on windows and doors
- indoor farming
- fencing and plowing perimeter of grazing pastures (dehydration, predation)
How are pheromones used to control vector populations?
pheromones (acetones, octenols) are used to impregnate drags and traps to attract arthropods, leading to death by starvation or insecticides (from in the trap)
What PPE can be used to limit contact with vectors?
- long sleeves, socks, and pants
- put repellants on clothes
- repellant pheromones (DEET, picardin, oil of lemon eucalyptus, citronella)
Vector-borne disease summary:
