Insect vectors

Question 1

propagative

cyclo-developmental

cyclo-propagative

Answer 1

Propagative: pathogen multiplies in the arthropod vector (ex. - arboviruses)

Cyclo-developmental: pathogen changes form, but does not multiply (ex. - filarial worms)

Cyclo-propagative: pathogen changes in form and multiplies (ex.- malaria, Leishmania)

Question 2

culicidae family

Answer 2

mosquitoes

most medically important group of arthropods

wings with scale and moutparts for sucking i

mmature stages are aquatic

Question 3

anopheles mosquitoes vs culex mosquitoes vs aedes mosquitoes

Answer 3

A –> malaria, filariasis

larvae rest parallel to water and lack siphon

adult has long palps and 45 degree posture

C –> west nile, WEE,VEE, JE, st louis encephalopathy

larvae have long siphons and eggs in rafts

adult with blunt abdomen

Aedes –> dengue, yellow fever, CA, filariasis

temporary pools/containers;single eggs

Question 4

mosquito with palps that are as long as proboscis or longer are

Answer 4

anopheles malaria carriers!! ** if short palps, not anopheles

Question 5

sand flies carry what

virus?

bacteria?

protozoa?

Answer 5

biting pest

viruses = sand fly fever

bacteria = bartonellosis

protozoa = leishmaniasis (cutaneous, mucocutaneous or visceral)

Question 6

black flies/simuliidae

Answer 6

fast moving water (filterfeeders on rocks/vegetation)

vectors of onchocerciasis (river blindness, filarial worms)

Question 7

tsetse fly

Answer 7

glossinidae family

**affects african economic development

feed only on blood; produces 1 young at a time

major vectors: glossina palpalis and G. morsitans

central/west african trypanosomiasis = T brucei gambiense (chronic)

east african trypanosomiasis = T brucei rhodesiense (acute)

*T = trypanosoma

Trypanosomiasis - african sleeping sickness

Question 8

AFRICan sleeping sickness

Answer 8

Question 9

vector of chagas disease

Answer 9

order hemiptera, family reduviidae (kissing bugs or conenoses)

• TRIATOMA*
• bite actually causes little or no pain
• vectors of Chagas disease (American trypanosomiasis)
• trypanosomes passed in bug feces (stercorarian) and rubbed into the bite site, wounds, nose or eyes

Question 10

common lice and their classifications

Answer 10

• Pediculus humanus humanus – body louse
• Pediculus humanus capitis – head louse
• Pthirus pubis – crab louse

order = phthiraptera

Question 11

pediculus humanus humanus

what is it?

how does it transmit?

what 3 diseases ?

Answer 11

BODY LOUSE

ALL STERCORARIAN TRANSMISSION (fecal origin)

• Epidemic typhus Rickettsia prowazekii
• Louse-borne relapsing fever Borrelia recurrentis
• Trench fever Bartonella quintana

Question 12

fleas

Answer 12

order siphonaptera

• Wingless flat ectoparasites of mammals and birds
• Cause allergic reactions
• Oriental rat flea (Plague, Murine typhus)

Question 13

plague

vector? pathogen?

Answer 13

Xenopsylla cheopis (Oriental rat flea)

pathogen = Yersinia pestis

Question 14

murine (endemic) typhus

vector and pathogen?

Answer 14

Xenopsylla fleas

transmit Rickettsia typhi

Question 15

tungiasis

Answer 15

•Chigoe or jigger flea burrows into the feet of humans causing “tungiasis”

Question 16

cockroaches

Answer 16

mechanical vectors of enteric diseases

significant contributors to allergens causing allergic asthma

Question 17

most significant allergen-producing species in multi-family dwellings?

Answer 17

•German cockroach populations

In asthmatics, allergies to cockroaches is second only to house dust mites.

Question 18

filth flies

Answer 18

•house flies, blow flies, flesh flies

Breed in filthy habitats; transmit >100 disease agents

•Transmission = Regurgitation (liquids from crop), Contamination (sticky feet), or Defecation (probably most important!)

Question 19

myiasis

Answer 19

Diptera larvae invade tissue and feed on the host’s tissue

Very painful, SINGLE, boil-like lesion with sensation of movement

•caused by human bot fly (Dermatobia hominis)

›Females lay eggs on blood sucking insects e. g. mosquitoes

Question 20

tick lifecycle

Answer 20

2 years to complete

• eggs hatch into uninfected larvae during the summer
• molt to nymphs the following spring
• molt to adults in the fall of the same year
• the activity period of nymphs precedes that of larvae during any given year. As a result, nymphs have the opportunity to feed upon and infect an array of small mammals that will serve as hosts for larvae 6 - 8 weeks later. This phenomenon is largely responsible for the inordinately high infection prevalence of Lyme disease spirochetes in nymphal and adult blacklegged ticks.

Question 21

lyme disease and borrelia burgdorferi

Answer 21

The feeding tick is basically a blood-sucker. It must keep its host’s blood from clotting in order to continue sucking so it is able to regurgitate assorted enzymes to keep the blood flow liquid and smooth. It is during this regurgitation process that the Lyme spirochete is brought up from the tick’s mid-gut to its mouthparts. This process requires a minimum of 48 hours which means
that if the tick is removed within 48 hours of attachment, the spirochete cannot be transmitted and the host will not get the disease.