Module 9b Black, Tsetse Flies and Myiasis Flashcards Preview

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Flashcards in Module 9b Black, Tsetse Flies and Myiasis Deck (19):

black flies taxonomy and characteristics

Family Simuliidae
require flowing water (lotic)
3rd biggest arthropod vectors of disease
swarming nature


black fly anatomy

suborder Nematocera (long antennae)
well developed compound eyes (male's touch)
telmophage but don't penetrate very deep
only females bite
short mouthparts


black fly larva

larvae have distant head with pair of labral fans for filter feeding when attached to rocks in moving water


black fly life cycle

adults live less than a month, but must mate, sugar feed, locate a host, blood feed, and lay eggs
larval stage is the longest


behavior of adult black flies

notorious human biters
females bite only exposed skin
blood-engorged females must rest until blood meal is digested
anautogenous (need blood meal)



"River Blindness"
parasite: Onchocerca volvulus (nematode)
vector: Simulium spp (black fly)


onchocera transmission cycle

1. female black fly acquires microfilaria
2. it penetrates gut of fly - thorax - fly's mouthparts
3. feeds again and deposits microfilaria under host's skin
4. adults form nodules where mating occurs
5. microfilaria migrate into skin (eyes, lymph nodes, groin)


onchocerciasis control programme (OCP)

WHO initiated control program in 1975
-breeding areas (river) dosed weekly w/ insecticide
-drug to kill the microfilariae (ivermectin)
-maintaining vectors at low number


tsetse fly taxonomy and characteristics

Suborder Brachyacera
Family Glossinidae
Genus Glossina (tongue fly)
obligate hematophagous, solenophage
found mostly in tropical Africa


tsetse anatomy

short antennae
long mouthparts that are held in front
hatchet cell in wing, help on top of each other
single larvae that immediately pupates (pupivarious)


african sleeping sickness or african trypanosomiasis

parasite: trypanosoma bruci
(t.b. gambiense: west african tryp.)
(t.b. rhodesiense: east african tryp.)
vector: Glossina spp (tsetse fly)


african sleeping sickness transmission cycle

1. tsetse fly acquires parasite from infected blood meal
2. develops from bloodstream - midgut - salivary glands
3. also transmitted from mother to child, lab accidents, or blood transfusions
4. deposited in new host thru saliva


tsetse control and prevention

IPM: treatment of humans and animals, insecticides, removal of breeding sites, sterile insect technique*



invasion of living vertebrate animal by fly larva by:
1. accidental - contaminated food
2. facultative - larva is parasitic (wound invasion)
3. obligatory - larva require host for development (i.e. maggots)


families of importance in myaisis

1. family Calliphoridae: blow flies and screwworms
2. family Oestridae: bot flies (human bot fly: Dermatobia hominis)



serious livestock pest
females deposit 200-300 eggs
eradicated in US in 1960s using sterile male technique


bot fly transmission cycle

egg deposited on skin by the fly itself or by hijacking a mosquito
bot fly never comes into contact with us
human bot fly: dermatobia hominis


blow flies

used in maggot therapy
bucilia sericata (green bottle blow fly)
-used during wars
-eggs treated w/ antiseptic before use
-no need for anesthesia


benefits of maggot therapy

1. removes necrotic skin
2. promotes wound healing
3. produces habitat less conductive for bacterial growth
4. healing is very rapid w/ less scarring