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1. CockroachesCockroaches
And Disease

2. Basics
• Order: Blattaria
• 4000 species worldwide
• 57 species in the U.S.
• 18 species have become serious domestic pests
• The most important medically are:
– Blattella germanica (German cockroach)
– Blatta orientalis (Oriental cockroach)
– Periplanta americana (American cockroach)
– Supella longipalpa (Brown-banded cockroach)

3. Biology
• Like warmth (climate plays a role)
– Cold Climates
– Warm Climates
• Nocturnal
• Omnivorous
• Live for 5-10 weeks without water
• Live many months without food
– Not a limiting factor
– Nymphs often die 7-10 days

4. Life Cycle
• Hemimetabolous
• Eggs are laid encased in a capsule called an ootheca
– Typically 18-40
– Deposited or cemented to surfaces
– 4-90 ootheca
• Nymphs
– Hatch after 1-3 months
– Wingless
– Number of nymphal stages and length varies with species.
• Adults
– 2 year lifespan or more

5. “Medical” Importance
• (1) Get into our food supplies
• (2) Odor (Some stink!)
• (3) They feed on humans
• (4) Allergies
• (5)Transmit pathogens?
• We tend to call cockroaches insects of sanitary
importance.
• Synanthropic species

6. American Cockroach
Periplaneta americana
• Originally from Africa.
• Like damp environments.
• Sewers, around pipes,
ships.
• Basement or first floor in
buildings.
• Nymphal stage 10-14
months long.

7. German Cockroach
Blattella germanica
• Most common
species in WY.
• Originally from Africa.
• Smaller than
American.
• Basement and first
floors in buildings.
• Carries egg capsule.
• Nymphal stage 2-3
months long.

8. Oriental Cockroach
Blatta orientalis
• Shiny black,
common in WY.
• Found in sewers,
likes basement.
• More tolerant of
cooler temps.
• Males have short
wings, females are
long.
• Nymphal stage 12-
15 months long.

9. Brown-Banded Cockroach
Supella longipalpa
• Originally from Cuba.
• 2 broad bands across
dorsum.
• All rooms in house.
• Likes high places
versus low.
• Big problem in the
Southern U.S.
• Glue eggs to things.
• Often ships in with
Furniture.

10. Control
• Be clean!
• Insecticidal spraying
– E.g. malathion, carbamates
• Pyrethroids
– E.g. permethrin
• Boric Acid Powder (borax)
– Contact insecticide and stomach poison.
• Organophosphates and Carbamate Insecticides
– 1-2% added to baits of food
• Insect Growth Regulators (IGRs)
– E.g fenoxycarb, hydrophen, methoprene.
• Pheromones and sticky traps

11. TRUE BUGS
Bed bugs and Triatomine bugs

12. Basics
• Order: Hemiptera
• 80,000 known species most in tropics.
• Worldwide distribution
• The most sucessful of the Hemimetabolic insects.
• Divided into two groups the Heteroptera and the
Homoptera.

13. Family Cimicidae
(Bed bugs, poultry bugs, bat bugs)
• 20 different genera
• Name given for host they
feed on.
• Nocturnal.
• Host specific, but will
cross over it no natural
host is available.
• Three main species:
– Oeciacus spp. (swallow
bugs)
– Cimex hemipterus (Tropical
Bed Bug)
– Cimex lectularius (Bed
Bug)

14. Life Cycle
• Egg  Nymph (5 instars)  Adult
• Both sexes take blood meals.
• Can live up to one year without meal.
• Visit host only for bloodmeal then leave.
• Females lay 2-3 eggs a day (150-200 in lifetime).
• Adults can live up to 4 years.

15. Medical Importance
• Hep. B Virus and
other pathogens.
• No evidence can
transmit to humans.
• Not considered
vectors!
• Reaction to bites
can be severe.
• Annoyance may
cause sleepless
nights.
• Anemia in infants.

16. Diagnosis
• Can detect by presence
of live bugs, nymphal
skins, hatched and
unhatched eggs.
• Small dark brown or black
marks may be visible on
bed sheets or mattress.
• No wings, do not spread
far.
• Usually, introduced with
furniture and bedding.

17. Control
• Insect repellents
• Pyrethroid-impregnated bed-nets.
• Spray floors, walls, furniture with 5% DDT emulsion
(Tropical countries)
• Malathion, diazinon, carbaryl, pyrethrins.
• Mattresses and wooden slates across beds can be
sprayed or dusted with insecticides.
• Fumigate.

18. Family Reduviidae
(Assassin bugs, Kissing bugs)
• Sub-family: Triatominae
• More than 130 species in
16 genera.
• Evolved into a blood
feeder that feeds on a
wide variety of hosts.
• Why called kissing bug?

19. Chagus Disease
• Host: Variety of vertebrates.
• Vector: Triatoma spp.
– Triatoma infestans
– Triatoma dimidiata
– Triatoma brasiliensis
– Rhodnius prolixus
– Panstrongylus megistus
• Etiologic Agent: Trypanosoma cruzi (protozoan)
• Reservoir: Wild animals (opossums, armadillos,
rodents, monkeys, etc).
• Chagus disease is a zoonosis, a parasite of wild
animals.

20. Distribution
• Most Triatoma occur in
the Americas.
• From the Great Lakes
of the U.S. to Southern
Argentina.
• 13 species are found in
the Old World tropics.
• All medically important
species are confined to
the Southern U.S.,
Central and South
America.

21. Life Cycle of the Vector
• Hemimetabolous
• Egg  Nymph  Adult (6-10 months
• Eggs
– Deposited in or near the habitation of host.
• Nymph
– Hatch after 10-15 days
– Stay hidden for 2-3 days
– 5 instars (each requires 1 blood-meal)
– Can ingest 6-12 times their weight in blood.
– wingless
• Adult
– 1-2 eggs laid each day; 200-300 over lifetime
– Ingest 300-400 mg of blood every 4-9 days!
– Nocturnal, feeding lasts 10-25 minutes.

22. Life Cycle

23. Transmission
• People can become infected with Chagas by
• unknowingly touching their eyes, mouth, or open cuts
after having come into contact with infective triatome bug
feces
• bugs directly depositing infected feces in their eyes
• eating uncooked food contaminated with triatome bug
feces
• receiving infection from mother during pregnancy or at
birth
• receiving an infected blood transfusion or organ
transplant
• Animals can become infected in the same way, or they
might eat an infected bug.

24. Medical Importance
• Affects an estimated 16-18 million people throughout
South and Central America and Mexico.
• 50,000 die each year!
• In the United States only 5 cases have been reported in
humans.
• Domestic transmission cycle, Southern Texas USA.

25. Case Study: San Benito, Texas
• Three pet dogs died from
Chagas cardiomyopathy.
• Blood drawn from dogs
and owners.
• A follow-up serologic
survey was conducted.
• Inspection of the
residence.
• Triatoma gerstaeckeri
• Domestic transmission
cycle.

26. Signs and Symptoms
• There are three stages of
infection in Chagas disease.
• (1) Acute Stage – 1% of cases
– Romaña's sign – a person's
eye on one side of the face
swells, usually at the bite
wound or where feces were
deposited or accidentally
rubbed into the eye.
– fatigue, fever, enlarged liver
or spleen, swollen lymph
glands

27. Signs and Symptoms
• (2) Indeterminate Stage
– 8-10 weeks after infection
– Once it begins it may last many years
– people do not have symptoms.
• (3) Chronic Stage
– 10-40 years after infection 20-30% of infected people may
develop the most serious symptoms of Chagas disease.
– Cardiac problems, including an enlarged heart; altered
heart rate or rhythm; heart failure; or cardiac arrest.
– enlargement of the esophagus or large bowel, which
results in problems with swallowing or severe constipation.

28. Diagnosis/Treatment
• Xenodiagnosis
• Medication for Chagas disease
is usually effective when given
during the early acute stage of
infection. Once the disease
has progressed to later stages,
medication may be less
effective.
• In the late chronic stages of
infection, treatment focuses on
managing the symptoms
associated with the disease.

29. Prevention and Control
• Avoid sleeping in thatch,
mud, or adobe houses.
• Use insecticides
• In some countries, the
blood supply may not
always be screened for
Chagas disease.
• Bed Net with insecticides.
• Camp under cover.

30. Prevention and Control
• Control is based on spraying residual insecticides inside
houses on walls, floors and roofs.
• Insecticidal Smoke Bombs
• Make the houses unattractive resting sites for bugs.
– Plaster walls to cover up cracks.
– Cost is high for rehousing.