cockroaches and disease
TRANSCRIPT
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CockroachesCockroaches
And Disease
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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)
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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
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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
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“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
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American CockroachPeriplaneta americana
• Originally from Africa.
• Like damp environments.
• Sewers, around pipes, ships.
• Basement or first floor in buildings.
• Nymphal stage 10-14 months long.
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German CockroachBlattella 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.
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Oriental CockroachBlatta 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.
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Brown-Banded CockroachSupella 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.
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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
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TRUE BUGS
Bed bugs and Triatomine bugs
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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.
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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)
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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.
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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.
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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.
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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.
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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?
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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.
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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.
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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.
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Life Cycle
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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.
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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.
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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.
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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
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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.
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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.
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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.
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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.