Download Oct. 1

Sand Flies, Black Flies, and
Midges
Announcements
Mucotaneous Leishmaniasis
(espundia, Uta, chiclero)
• Found primarily in Brazil, Bolivia, and Peru.
Probably in Paraguay as well.
• ‘uta’ – Quechua (Inca) for the nasal/oral
disfiguration.
• Known from Incan pottery > 2,000 years old.
• Generally thought to be caused by the same
Leishmania species as in cutaneous but is
transmitted by different fly species. Different
pathogen strains likely as well.
Result with treatment
Result without treatment
Reservoirs
• Dogs & rodents are efficient
reservoirs.
• Dogs can acquire Leish.
without sand flies through
an unknown process.
sub corneal pustular dermatitis
Early Stage Canine Leish.
End Stage
Prevalence
• Prevalence increasing >500% increase in
cases in the last 10
years.
• Now endemic in 88
countries
• Increase due to:
– Expansion into new vector
habitat
– Expansion of vector range
– Coincident increase with
HIV.
Bartonellosis
• Etiological agent is Bartonella bacilliformis, a
gram-negative bacterium.
• biphasic disease
– phase 1: febrile disease
– phase 2: hemolysis and/or verrucous skin lesions
(“verrucous” = “wart-like”)
• Unique to humans, native to Andean South
America (Colombia, Equador, Peru).
• Present in Pre-Columbian times, numerous
archelological artifacts dating >3,000 years ago,
Peruvian mummies >6,000 years old show
evidence of wide-spread outbreaks.
Bartonellosis
• Historically a very confusing disease
• Numerous names
– Phase 1 (Acute phase): Oroya fever
(Peru), Guáitira Fever (Colombia).
Untreated case fatality rate 40 – 90%
– Phase 2 (Chronic phase): Verruga
Peruana, Muru Uncoy
– Carrión’s Disease. Low fatality rate.
• Phase 2 symptomology historically
confused with measles and smallpox.
• Traditionally only found between 500
m and 3,000 m elevations. Recently,
a low-elevation strain has
(re?)emerged & is typically
monophasic.
Carrións Disease named after
Daniel Alcides Carrión
• Peruvian medical
student in the 1880’s
• From Cerro de Pasco
• Outbreak of Verruga
Peruana among
railroad workers.
• Went to investigate,
with some friends …
National Hero
Carrións Disease has a restricted
distribution now.
Bartonellosis Vectors
• Higher elevation forms: Lutzomyia
verrucarum & peruensis in Peru, L.
colombiana in Colombia
• Lower elevation forms are a different strain
of the bacterium with low homology with
the others. Probably a different vector
species but it is unknown (may not be a
sand fly).
Transmission is poorly understood
• Occurs during nocturnal blood feeding of
vector
• Presumably via saliva and/or
contaminated proboscis.
• Some adults (human) carry asymptomatic,
nascent infections & act as the reservoir.
• Locals tend to react less than travelers.
Outbreaks always associated with
strangers coming into an endemic area.
Close relationship with El Niño climate event
– outbreak occurs 1 – 3 months later.
Sandfly fever
• Phlebovirus
• Non-lethal, self-limiting. Noticeable only by immigrants.
• Transmitted vertically (sandfly to egg) & horizontally to humans.
Vesicular Stomatitus – A growing
threat in Kentucky
Black Flies
• Family Simuliidae
• Larvae/pupae are aquatic
in flowing rivers/streams
• Attach to substrate, move
on silk
• Very difficult to
distinguish species
morphometrically
• See text for photos
Black Fly Bites
• Can build up in big
enough numbers that
this is a problem.
• Irritation,
exsanguination, and
toxemia all occur.
• Bites often occur where
clothing contacts skin.
• Telmophages
Main Medical Problem is
Onchocerciasis
• River Blindness caused by Onchocerca volvulus
• 99% of cases in Africa
• 3rd leading cause of infectious blindness (trachoma is #1).
Transmission Cycle
External symptoms
• Adult females clump together
& males enter to mate.
• Clumping creates visible
nodules.
Below is NOT O. volvulus. It is a Guinae Worm.
Occular involvement is the main issue
Occular Involvement
• Microfilarae migrate
throughout epidermal
tissues.
• Some end up in eye.
• Cause lesions,
cataracts, retinal
hemorrhages, corneal
opacities (right),
glaucoma.
• Involvement with a
bacterial symbiont,
Wolbachia.
Onchocerciasis Management
• Black fly control
• WHO’s OCP
(Onchocerciasis Control
Programme) and the 19country APOC (African
Programme for
Onchocerciasis Control).
• Filarial control
– Ivermectin: Paralyzes worms
but does not kill adults.
Mectizan (Merk) in pill form.
– Antibiotics: Kills the Wolbachia
symbiont
Biting Midges
• Order Ceratopogonidae
• “no-see-ums”: Very common in boggy
areas, beaches (for this they are
sometimes called “sand flies”).
• Many other names in your book (e.g.
“jejenes”).
• For humans, the main problem is
nuisance.
Biting Midges are mostly a
veterinary problem.
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Blue Tongue (BT)
Epizootic Hemorragic Disease (EHD)
Both caused by orbivirus
BT found mainly in domestic ruminants
(esp. sheep & cattle), EHD mainly in wild
ruminants (esp. white-tailed deer)
• Both transmitted by Culicoides spp.
EHD a growing threat to Kentucky
White-tailed Deer
• Population has reached a point that could
support an epidemic with large-scale sudden
die-off.
• Incidence has increased dramatically in the last
few years.
• 3,000 confirmed deaths in 2007, >4,000 in 2008.
Actual number is probably much higher.
• Not a threat to humans but symptoms very
similar to chronic wasting disease (which is a
threat). Both are present in other states (esp.
Michigan & Wisconsin). Deer are being
imported from those states to KY.