public health, things that bite

1. What Just Bit Me?
A Short Primer on Arthropods of
Medical Importance

2. Rosmarie Kelly, PhD MPH
Public Health Entomologist
GDPH – 2 Peachtree St NW
Atlanta, GA 30303
404-657-2912 (w)
404-408-1207 (c)
rmkelly@dhr.state.ga.us
rpk8@cdc.gov
http://health.state.ga.us/epi/zvbd/
http://www.Gamosquito.org
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3. First, some background info…
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4. What is Entomology?
- the branch of zoology that deals with
the study of insects
What is Medical Entomology?
• the study of insects that carry diseases
• may also deal with other arthropods that carry disease
(ticks & mites)
• may deal with insects & other arthropods that are
considered pests by humans
A Public Health Entomologist works in the realm of public health
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5. What is a pest?
1. an annoying or troublesome person, animal, or
thing; nuisance.
2. an insect or other small animal that harms or
destroys garden plants, trees, etc.
3. a deadly epidemic disease, especially a plague;
pestilence.
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6. Arthropods that are considered pests by humans
are primarily found in 2 classes:
• Arachnida – spiders, ticks, mites
• Insecta – the insects
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7. We define pests in terms of our own standards of good and bad --
standards that are often based largely on aesthetics, economics, and
personal welfare, and shaped by cultural bias and personal experiences.
A "pest" is defined as any organism that causes annoyance or injury to
human beings, human possessions, or human interests.
The injury may be physical (bites and stings), medical (causing illness or
disease), or economic (monetary loss to goods or property). Injury may
arise directly from the pest itself, or may develop indirectly as a result of
the actions or behavior of the pest.
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8. In reality, many of the insects and other
arthropods we label as pests are essential
components of our natural ecosystem.
The species we regard as pests
usually affect us in one or more of
the following ways:
• They are an annoyance or
nuisance
• They endanger human health
or safety
• They threaten the welfare of
useful plants or domestic
animals
• They damage stored products
or structural materials
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9. Out of the 800,000 - 1,000,000 species of insects
that have been described so far, not more than
1,000 (about 1/10 of 1%) can be regarded as
serious pests, and less than 10,000 (about 1%)
are even occasional or sporadic pests.
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10. Aesthetic pests cause no damage and inflict no injury.
They may be annoying, unsightly, or disruptive (like chirping crickets that keep you
awake at night, or dance flies that swarm around your head in the spring), but their
presence will cause no injury or financial liability.
An insect is most likely to be regarded as an aesthetic pest when it inadvertently
invades a home or business establishment.
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11. Agricultural pests
• Of all the insect species now living on earth, at
least half of them (400,000 - 500,000) feed
directly on the tissues of living plants.
– Herbivores with chewing mouthparts consume a
plant directly.
– Plant tissue is also damaged by herbivores with
piercing-sucking mouthparts.
• Many insects that feed on plants also serve as
vectors of plant diseases.
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12. Pests of Medical Importance
It is impossible to measure the full impact of insects and other
arthropods on human health and welfare.
• These organisms have the capacity to inflict injury, disease, discomfort, or
distress.
• They can be a direct cause of illness, pain, and suffering through bites and
stings, infested wounds, or allergic reactions.
• They feed on blood or body tissues and they may transmit deadly pathogens
or parasites.
Economic losses associated with these pests are borne not only by the affected
individuals and their families, but also by human society in general.
• Losses include not only the direct costs of medicine and health care, but also
indirect costs resulting from stress, absenteeism, and reduced productivity.
• These are costs that are not easy to measure in dollars and cents.
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13. Many of the Medically Important Arthropods are Hematophagous
(they feed on blood)
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14. All of the arthropods that
can pierce human skin have
mouthparts that are
especially adapted for
piercing, cutting, or burrowing.
These include:
• Diptera (mosquitoes, black flies, horse flies, deer flies,
stable flies, sand flies, and various biting midges)
• Hemiptera (bed bugs, assassin bugs, water bugs)
• Thysanoptera (thrips)
• Phthiraptera (sucking lice)
• Siphonaptera (fleas)
• the class Arachnida (spiders, mites, and ticks)
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15. Salivary enzymes and other compounds, such as anti-
coagulants, anesthetics, and vasodilators also may be injected
by the mouthparts during feeding.
The localized reaction to an insect bite (pain, swelling, redness,
etc.) is usually a physiological (inflammatory) response to these
injected compounds.
Although the amount of blood taken by each insect may be
quite small, the cumulative effects of blood feeding by large
populations of hematophagous insects can be life-
threatening.
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16. Contrary to popular belief (and the internet), you can not reliably tell
what bit you by looking at the bite.
Identification of the source
of the bite is important in
order to determine whether
to seek emergency medical
attention, call your doctor,
or treat the bite at home.
The best way to do this is to
see what bit you.
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17. And now to the topic at hand…
What is a primer?
An old-fashioned school book that
contains very basic facts about a
subject.
1. An elementary textbook for
teaching children to read.
2. A book that covers the basic
elements of a subject.
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18. A is for:
ARTHROPOD
All insects are arthropods but not all arthropods are insects! 18

19. What is an arthropod?
The arthropods constitute
over 90% of the animal
kingdom and are classified in
the phylum Arthropoda.
They are distinguished from
other animals by:
• an exoskeleton (a skeleton
on the outside of the
body)
• body divided into distinct
parts
• jointed legs and
appendages
• May have wings and
antennae
• bilateral symmetry (both
sides of the body are the
same)
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20. B is for: BUGS
Another truism: all bugs are insects; not all
insects are bugs.
A “bug” is one of the 35000 or so species
in the order Hemiptera.
Many bugs are considered a nuisance,
especially in agriculture.
Some bugs are pests of medical
importance because they transmit
diseases.
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21. Hemipterans have piercing-sucking mouthparts
Hemipterans feed on
a variety of liquids,
including blood.
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22. What is that!
nymph
eggs
female male
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Bed Bugs

23. LIFE CYCLE
Female bed bugs deposit 3 to 8
eggs at a time; a total of 200-
500 eggs can be produced by
one female over her 10 month
life span.
The eggs hatch in 4-12 days.
Bed bugs go through 5 nymphal
stages before reaching
maturity. This usually takes 35-
48 days.
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24. Reactions to
Bites
The bite of a bed bug is painless.
Common allergic reactions include the development of
large welts that are accompanied by itching and
inflammation.
The welts usually subside to red spots but can last for
several days.
Blister-like eruptions have been reported in association
with multiple bed bug bites and anaphylaxis may occur in
patients with severe allergies.
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25. C is for:
COLEOPTERA
(beetles and
weevils), the
largest order in
the class Insecta.
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26. What is that!
Blister beetles receive their common
name from the ability of their
hemolymph to produce blistering on
contact with human skin.
Hemolymph is often exuded copiously
by reflexive bleeding when an adult
beetle is pressed or rubbed.
Blisters commonly occur on the neck and
arms, as the result of exposure to adult
beetles attracted to outdoor lights at
night.
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27. D is for:
• Diptera, the true flies
Flies are insects. Diptera means two wings; di =
two, ptera = wings. The hind pair of wings are
reduced to a couple of knob-like balance organs.
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28. What is that?
Psorophora ciliata (shaggy-
legged gallinipper)
This is the largest blood sucking
mosquito in the US. The larvae
are large and are predacious
upon other larvae. The adult
inflicts a painful bite.
Larval habitat: flooded fields, temporary ground pools, and ditches.
Adult habitat: fields and yards
Biting activity: Anytime of the day when disturbed.
Flight range: 1-2 miles
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29. What is that!
Myiasis is the infestation of the organs or tissues
of host animals by the larval stages of dipterous
flies, usually known as maggots or grubs.
The fly larvae feed directly on the host's necrotic or living tissue. The hosts
are usually mammals, occasionally birds and, less commonly, amphibians or
reptiles.
TYPES
• dermal, sub-dermal or cutaneous (creeping)
• nasopharyngeal
• ocular
• intestinal/enteric or urinogenital
• open wounds - traumatic
• boil-like, the lesion is termed furuncular
• bloodsucking myiasis - sanguinivorous
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30. Medical Myiasis
• Not all flies associated with myiasis are deleterious or
otherwise a nuisance to their vertebrate hosts.
• Some species of Calliphoridae (blowflies) have been
observed on infected wounds since the mid-1500’s.
• History:
– Ambroise Paré (1509-1590), the chief surgeon to Charles IX and
Henri III, discovered in 1557 during the battle of St. Quentin that
maggots often infested pus-forming wounds.
– In 1829, Baron Dominic Larrey the chief surgeon to Napoleon
found that these infestations prevented infection and hastened
healing.
• Today, these beneficial maggots serve as an adjunct to
modern medicine rather than solely as a last resort.
• They are used to treat several maladies including the foot
wounds of diabetic patients.
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31. Disease Transmission
Mosquitoes are estimated to
transmit disease to more than 700
million people annually in Africa,
South America, Central America,
Mexico and much of Asia with
millions of resulting deaths.
In Europe, Russia, Greenland,
Canada, the United States, Australia,
New Zealand, Japan and other
temperate and developed countries,
mosquito bites are now mostly an
irritating nuisance; but still cause
some deaths each year.
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32. H is for:
HYMENOPTERA
Insects - ants, bees, wasps, hornets
sting and bite
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33. Hymenoptera
• The best defense against
hymenoptera is to avoid them
• When ants, bees, wasps, or
hornets attack, run!
• Pain, redness & swelling are
normal at the sting site
• Anyone with >15-25 stings
should seek medical attention
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34. 34

35. What is that!
The European hornet,
Vespa crabro, is the
largest of the
European eusocial
wasp.
The queen measures 25
to 50 mm (1–2 in)
long; males and
workers are smaller.
European hornets are
attracted to lights at
night…
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36. What is that!
The velvet ant, or cow
killer, is a wasp.
Females are wingless
and covered with
dense hair.
The males have wings.
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37. Africanized Honey Bees
• “Killer Bees”
• Originally brought to South
America from southern
Africa in 1956 (crossbreeding
program)
• Areas of colonization: every
Latin American country
except Chile; Arizona; New
Mexico; Nevada; Texas;
California; Mississippi;
Florida; … and Georgia???
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38. I is for:
• Insect
– 3 body parts
– 6 legs
– 1 pair antennae
– 0, 1, or 2 pairs of
wings
Remember, all insects are arthropods but not all arthropods are insects!
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39. Growth & Development
• Metamorphosis
Gradual – adults & nymphs
usually eat the same food and live
in the same habitat
Complex – adults & larvae eat
different foods and live in
different habitats
• Molt to increase size
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40. L is for:
• Lepidoptera, the moths and butterflies
– Lepidoptera are insects.
– The name Lepidoptera, derived from the
Greek words "lepido" for scale and
"ptera" for wings, refers to the flattened
hairs (scales) that cover the body and
wings of most adults.
– Although many Lepidoptera are valued
for their beauty, and a few are useful in
commerce, the larvae of these insects
are probably more destructive to
agricultural crops and forest trees than
any other group of insects.
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41. Urticating (irritating) Caterpillars
• Urticating hairs can be of two distinct types
– Envenomating hairs
• Tubular
• Hold venom
– Non-envenomating hairs
• Fragile
• Irritating
• Contact - wheals and widespread rashes that
can be accompanied by a burning sensation
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42. What is it!
Moths in the genus
Calyptra are
sometimes known
as vampire moths,
a colorful name
referring to the
ability of at least
some species to
pierce mammalian
flesh and feed on
blood.
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43. M is for:
• Mites – small arthropods that can infest animals, plants, and
stored foods and include important disease vectors
• Mites are wingless, lack antennae and are flat or round
bodied
• Adults have eight legs, although the first immature stage has
only six legs
• All members have piercing-sucking mouthparts
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44. Chiggers
• Chiggers are the juvenile form
(larvae) of a mite in the family
Trombiculidae.
• Chiggers are barely visible to the
naked eye (their length is less than
1/150th of an inch).
• They are red in color and are most
easily seen when clustered in
groups on the skin.
• The juvenile form has six legs; the
(harmless) nymphal and adult mites
have eight legs.
• They do not suck blood but cut into
the skin, inject skin-digesting saliva
and suck up the liquefied skin
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45. Scabies
• Very small & rarely seen
• They burrow into the skin
• Reaction: initially, little
irritation; after about a
month, a rash appears
• Common bite areas:
skin between the fingers,
bend of the elbow &
knee, penis, breasts, and
shoulder blades
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46. P is for:
• Phthiraptera, the lice – small, wingless,
parasitic insects
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47. www.headlice.org
Head Lice (Pediculosis)
• Infestation of the hair on the scalp by Pediculus
humanus capitus, or the human head louse
• Live by biting and sucking blood from the scalp
• Problem common in schools and institutions
• 6-12 million people worldwide are infested each year
• Three forms of lice: nit, nymph, and adult
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48. What bit me!
Phthirus pubis – crab louse
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49. S is for:
• Siphonaptera, the fleas
– Fleas are insects
– As adults, all fleas are blood-sucking external parasites
– In addition to their irritating bites, fleas may also transmit
pathogens that cause disease in humans and other
animals
– Cat and dog fleas are intermediate hosts for a tapeworm
(Dipylidium caninum) that infects dogs, cats, and humans
• Ever heard of the plague?
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50. The Black Death (1347 – 1350)
The Black Death came in three forms. All forms were caused by a bacterium
called Yersinia pestis. In some cities, as many as 800 people died every day.
• bubonic plague was the
most commonly seen form
of the Black Death
(mortality rate was 30-
75%)
• pneumonic plague was the
second most commonly
seen form of the Black
Death (mortality rate was
90-95%)
• septicemic plague was the
most rare form of all
(mortality was close to
100%)
The economy was probably hit the hardest of all the aspects of Europe. The biggest problem was that valuable
artisan skills disappeared when large numbers of the working class died. This eventually lead to a change in the
society structure.
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51. T is for:
• Ticks
– Ticks are arthropods, like spiders.
– Two families of ticks, Ixodidae (hard ticks) and
Argasidae (soft ticks), are important to humans
because of the diseases or illnesses they can
transmit or cause.
• Ticks are the leading vectors of diseases to
humans in the United States, second only to
mosquitoes worldwide.
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52. Don’t Do This to Remove a Tick
• Put vaseline on it
• Put fingernail polish over it
• Put mineral oil on it
• Drench it with whiskey, wine, or
other alcoholic beverages
• Stick a lit match on it (or a
recently extinguished match)
• Especially do not combine the
above flammable materials with
the match treatment!
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53. Resources
• http://www.cals.ncsu.edu/course/ent425/text18/pestintro.html
• http://www.emedicinehealth.com/ticks/article_em.htm
• http://emedicine.medscape.com/article/769067-overview
• http://www.crcpress.com/product/isbn/9780849385391
• http://www.agius.com/hew/resource/arthrop.htm
• http://www.who.or.id/eng/contents/aceh/wsh/books/evc/evc-02.pdf
• http://lancaster.unl.edu/pest/resources/medspider006.shtml
• http://www.medicinenet.com/chiggers_bites/article.htm
• http://www.cdc.gov
• http://health.state.ga.us/epi/zvbd/
And many, many more. Be careful though. There is a lot of mis-information
out there.
Take a Disease and History class if you ever get a chance.
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54. "There was an old lady who
swallowed a spider that
wiggled and jiggled and
tickled inside her. She
swallowed the spider to
catch the fly. I don't know
why she swallowed the fly.
Perhaps she'll die."
Insects and Arthropods in Poetry and Folklore
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55. ANY QUESTIONS?
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