CockroachesCockroaches

And Disease

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)

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

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

“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

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.

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.

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.

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.

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

TRUE BUGS

Bed bugs and Triatomine bugs

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.

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)

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.

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.

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.

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.

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?

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.

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.

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.

Life Cycle

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.

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.

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.

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

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.

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.

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.

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.