CockroachesAnd Disease

BasicsOrder: 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)

BiologyLike warmth (climate plays a role)Cold ClimatesWarm ClimatesNocturnalOmnivorousLive for 5-10 weeks without waterLive many months without foodNot a limiting factorNymphs often die 7-10 days

Life CycleHemimetabolousEggs are laid encased in a capsule called an oothecaTypically 18-40Deposited or cemented to surfaces4-90 ootheca NymphsHatch after 1-3 monthsWinglessNumber of nymphal stages and length varies with species.Adults2 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 americanaOriginally from Africa.

Like damp environments.

Sewers, around pipes, ships.

Basement or first floor in buildings.

Nymphal stage 10-14 months long.

German CockroachBlattella germanicaMost 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 orientalisShiny 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 longipalpaOriginally 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.

ControlBe clean!Insecticidal sprayingE.g. malathion, carbamatesPyrethroidsE.g. permethrinBoric Acid Powder (borax)Contact insecticide and stomach poison.Organophosphates and Carbamate Insecticides1-2% added to baits of foodInsect Growth Regulators (IGRs)E.g fenoxycarb, hydrophen, methoprene.Pheromones and sticky traps

TRUE BUGS

Bed bugs and Triatomine bugs

BasicsOrder: 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 generaName 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 CycleEgg Nymph (5 instars) AdultBoth 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 ImportanceHep. 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.

ControlInsect 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 DiseaseHost: Variety of vertebrates.

Vector: Triatoma spp.Triatoma infestansTriatoma dimidiataTriatoma brasiliensisRhodnius prolixusPanstrongylus 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 VectorHemimetabolousEgg Nymph Adult (6-10 monthsEggsDeposited in or near the habitation of host.NymphHatch after 10-15 daysStay hidden for 2-3 days5 instars (each requires 1 blood-meal)Can ingest 6-12 times their weight in blood.winglessAdult1-2 eggs laid each day; 200-300 over lifetimeIngest 300-400 mg of blood every 4-9 days!Nocturnal, feeding lasts 10-25 minutes.

Life Cycle

TransmissionPeople 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 ImportanceAffects 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 SymptomsThere are three stages of infection in Chagas disease.

(1) Acute Stage 1% of casesRomaa'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 Stage8-10 weeks after infectionOnce it begins it may last many yearspeople do not have symptoms.

(3) Chronic Stage10-40 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/TreatmentXenodiagnosis

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 ControlAvoid 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 ControlControl 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.