Arthropods amd Disease Weekend Work

Lice Taxonomy: Two Suborders:

Anoplura (Sucking lice)

Amblycera, Ischnocera, and Rhynchopthirina (chewing lice)

Anoplura:

• Sucking Lice

• 550 Species

• All are obligate (require host), hematophagous ectoparasites of placental mammals

• The ones humans get

Amblycera, Ischnocera, and Rhynchopthirina

• Chewing Lice

• 850 Species

• Obligate parasites of birds, marsupials, or placental mammals

• Ingest some blood, but mostly feed on feathers, fur skin, and skin products

Lice Morphology

• Small, 0.4-10mm in the adult stage

• Wingless

• Dorso-ventrally flattened

  • Except for human body louse all lice cement eggs (nits) onto the hair or feathers

  • Male genitalia are large and occupy almost half the length of the abdomen

• Females have genitalia that have two pairs of finger-like gonopods

Lice Life History:

• Hemimetabolous (no pupal stage from larval to adult)

• Egg stage lasts 4-15 days

• Nymphal instar for 3-8 days

• Adults live up to 35 days

• Can complete 10-12 generations a year

• Female lice can lay 0.2-10 eggs per day

Transfer between hosts

Direct Contact is the primary mechanism

• Can transfer during mating or fighting

• Infested mother can pass to children during feeding or nest sharing in birds

Sheep foot louse can survive several days off host and crawl to new host

Phoresy - seen in non-human chewing lice

• Attach temporarily to other arthropods and are carried to a new host

Human Body Louse:

Pediculus humanus humanus

• Large problem among the homeless and in Africa, Asia, Central + South America

• Only louse of humans known to naturally transmit pathogens

• 2.3-3.6mm long

• Infest clothing + crawl to body to feed

• Oviposit on clothing

• Biting can cause intense irritation (saliva)

• Can Cause Vagabond’s or Hobo’s disease

Human Head Louse:

Pediculus humanus capitis

• Almost impossible to distinguish from body louse

• Transmission by person to person contact and shared objects

• 8% of children age 3-12 in the US are infested

Who gets head lice?

• Almost anyone! They do not discriminate

• Head lice are not a health hazard or sign of poor hygiene

• Children attending preschool or elementary school, and those who live with them, are the most commonly affected

How do head lice spread?

• Most often spread by direct head-to-head contact.

• Head lice cannot jump or fly

• They cannot live off the head for long, so it is uncommon to spread head lice by contact with clothing or other personal items

• Dogs, cats, and other pets DO NOT play a role in spreading head lice

Is it head lice?

Some are asymptomatic but most experience:

• Tickling feeling on the scalp or in the hair

• Itching (caused by the bites of the louse)

• Irritability and difficulty sleeping (lice are more active in the dark)

• Sores on the head (caused by scratching)

Finding a live louse is the best indication of an infestation

Lice Nits (eggs)

• Teardrop shaped

• Attached to the hair shaft

• Yellowish or white

• Can be confused with dandruff, but cannot be brushed off

Lice Nymph

Baby louse

• Grows to adult size in one to two weeks

• Found on the scalp or in the hair

Adult Louse

• Size of a sesame seed

• Tan to grayish-white

• Commonly behind the ears and near the neckline

• Get their reproductive organs

Treating head lice

Key Treatments:

• Resistance to some over-the-counter head lice treatments has been reported, but the prevalence is not known (use name brand doctor stuff)

• There is not scientific evidence that home remedies are effective

• There are prescription treatment options available, contact your healthcare provider to determine what is appropriate for you.

Household members and close contacts should:

• Anyone with evidence of lice infestation should be treated

• They should be treated at the same time

Do you need to clean after finding lice?

• Adult head lice survive less than 1-2 days, and nits generally die within a week after falling off a person and cannot feed.

• Vacuum floor and furniture where the infested person sat or lay

• Fumigants or fogs are NOT necessary and may be dangerous if inhaled or absorbed through the skin

• Family bed linens and recently used clothes, hats, and towels, as well as personal articles like combs, brushes, and hair clips, should be washed in very hot water or sealed in a plastic bag for two weeks.

Human Crab Louse

Pthirus pubis

• Tibio tarsal claws for coarse hair

• Can infest other regions

• Transfers during sexual contact

• Can only survive for a few hours off of host

• Intense itching + purplish lesions at bite sites.

Lice of Cattle

• Dair and beef cattle are affected

• Chronically infested cattle will be pulled from the herd

  • Don’t infest other cattle

Lice of Livestock

Economic Losses

• Cost of Treatment

• Reduced productivity

• Diminished health

• Damage to leather

  • Scratches in hide

  • light spots (lesions from erosion of enamel of hide)

Lice of hogs

• Hair is lost and skin becomes scaly

• Eat less

• Can become anemic with high infestations

• Can vector swinepox

  • Serious and potentially fatal disease

  • Large pock mark lesions on belly

Lice of Sheep and Goats

• Significant losses to sheep occur

• Can lead to anemia and death in goats

Lice of Poultry and Other Birds

Nine species of lice infest poultry

• Chicken body louse is the most common and destructive

• Found on skin instead of feathers

• Lay 1-2 eggs per day

• New generation in about 2 weeks

Epidemic Typhus - The Organism

• Rickettsia prowazekii

  • Obligate intracellular bacteria

  • Pleiomorphic rods

  • Susceptible to moist heat

History

• 1489: Arrival in Europe

  • Soldiers returning from Cyprus

• 1557-59: Outbreak in England

  • Killed 10% of the population

  • Poor sanitation

• 1880

  • Typhoid bacillus identified

• 17th - 19th century

  • Epidemics in Europe as a result of war, disaster, or in prisoners

• 1909: Transmission by lice

• 1917-1925: Russia

  • Estimated 25 million cases

• End of WWII

  • DDT used for control

  • Vaccine developed

Epidemiology of Typhus

• United States

  • 30 cases since 1975

• Africa

  • 1997 Burundi

    • 20,000 cases from January to March

• Most common in people living under unhygienic conditions

  • Refugee Camps

Transmission of Typhus

Human body louse

• Pediculus humanus corporis

• Infective for 2-3 days

• Infection acquired by feeding on infected person

• Excrete R. prowazeki in feces at time of feeding

• Lice dies within two weeks of getting the infection

Transmission of Typhus 1

• Louse feces rubbed into bite or superficial abrasions

• Inhalation of feces

• Sylvatic typhus - animal typhus?

  • Flying squirrel

  • 30 human cases in eastern and central US

Transmission of Typhus 2

• Humans or flying squirrel required for life cycle

  • Organism dies with louse

  • Not transferred transovarially

    • Adult female louse won’t give Typhus to their child

  • Host responsible for maintaining infection

• No person-to-person transmission of Typhus only from louse

Clinical Symptoms of Typhus

Incubation: 7-14 days

• High fever, chills, headache, cough, severe, myalgia (muscle soreness)

  • May lead to coma

• Macular eruption (dark spots on skin)

  • 5-6 days after onset

  • Initially on upper trunk, spreads to entire body

    • Except face, palms and soles of feet

Diagnosis of Typhus

• Initial diagnosis

  • Clinical signs and history

  • Laboratory tests not diagnostic

• Confirmatory diagnosis

  • Culture

  • Serology

  • Biopsy

  • PCR

Brill-Zinsser Disease

• Occurs years after primary attack

  • Person previously affected or lived in endemic area

  • Viable retained organism reactivated

  • milder systems

    • Febrile 7-10 days

  • Rash often absent

  • Low mortality rate

Treatment of Typhus

• Chloramphenicol

• Tetracycline

  • Doxycycline 200mg

• Response within 48 hours (usually)

• Vaccine

  • Developed after WWII

  • Not commercially available

Prognosis of Typhus

• Case fatality rate

  • 1-20% with antibiotic treatment

  • up to 100% without treatment

  • Increases with age

• Once attack usually confers long lasting immunity

Prevention and Control

• Treat clothing and bedding

  • 160 degrees water for one hour

• Chemical control

  • Permethrin (0.5%) temephos (2%), popoxur (1%) and carbaryl (5%)

• Biosafety level 3

  • Handling infectious materials, lice, carcasses

• Proper hygiene

Typhus as Biological Weapon

• Readily available

• Stable in lice feces for weeks

• Aerosolized

• World Health Organization

  • 50kg of aerosolized typhus

  • City of 5 million would result in:

    • 300,000 people exposed in 30 minutes

    • 125,000 people sick

    • 8,000 deaths

Louse-Borne Relapsing Fever

• Transmitted by human body louse

• The organism:

  • Borrelia recurrentis

History of Louse-Borne Relapsing Fever

• 1727 -1729: Outbreak in England killed all inhabitants of many villages

• 1919 -1923: 13 million cases and 5 million deaths in an epidemic from Europe to RUssia

• After WWII more than one million cases in Europe

Transmission of Louse-Borne Relapsing Fever

• The lice become infected by feeding on humans that are infected by the spirochetes

• When the lice are transferred to another human, the infection spreads by the contact of the hemolymph (fluid found in the circulatory system of arthropods) with abraded skin

• This contact can occur by scratching, which then opens the skin and crushes the body of the lice, exposing the hemolymph

Clinical Symptoms of Louse-Borne Relapsing Fever

• Fever, headache, muscle ache, anorexia, dizziness, nausea, coughing and vomiting

• As disease progresses the liver and spleen enlarge (Jaundice)

• Case fatality for untreated outbreaks

  • 5-40%

• Can be treated with antibiotics

Current Epidemic of Louse-Borne Relapsing Fever

Ethiopia

• 1,000 to 5,000 cases per year

• Accounts for 95% of cases in the world annually

Trench Fever

• Caused by bacterium Bartonella quintana

• Transmitted by human body louse

Symptoms of Trench Fever

• Headaches, muscle aches, fever, and nausea

• Can be cyclic (Sick, Okay, Sick, Okay, Sick…)

  • Can cause relapses years later

• Can be treated with antibiotics

History of Trench Fever

• Was isolated in 4,000-year-old tooth

• First recognized as a clinical problem in soldiers during WWI

• 200,000 cases were recorded in British troops

• Re-emerged in WWII

Transmission of Trench Fever

• Transmitted via posterior station

• Can remain infective in dried feces for several months

• Aerosol transmission rare, but possible (not good bioterrorist weapon)

Trench Fever Today

• Considered to be a rare disease until recently

• Homeless or immunocompromised people have presented with the disease

  • Manifested as vascular tissue lesions

Prevention and Control of Lice 1

• Pediculicides

  • Chemicals used to kill Lice

• Clothes should be washed in VERY hot, soapy water

• Try to avoid overcrowded and unsanitary conditions should be avoided

• Crab lice can be avoided by not having multiple sexual partners

Prevention and Control of Lice 2

• Permethrins, Pyrethrins, and Avemectrins are effective chemical control

• DDT used in developing countries

• Can be used in powders, fogs, or sprays for furniture

Prevention and Control of Lice 3

• Well-groomed animals less likely to get lice

• Small animals can be treated topically

• Many products for livestock

  • Need to be careful about milk production

Hemiptera: Reduviidae (Kissing bugs)

• True Bugs

• Named because of nocturnal feeding and bites around the lips

• 23 subfamilies

  • Triatome most important for public health

  • Occur from south of the great lakes to southern argentina

  • All triatomines have potential to transmit Trypanosoma cruzi

Triatomine Biology

• Found mostly in the New world

• 3 habitat Groups

  • Sylvatic

  • Domestic

  • Peridomestic

    • Non-exclusive, they can switch between groups

Sylvatic

Inhabit nests and burrows

Peridomestic

• Utilize domestic animals as hots

• Live in chicken coops, bird enclosures, stables, and other outdoor animal housing.

Domestic

• Colonized human habitations where they depend on human or domestic animal blood

Triatome biology

• Hide in cracks and crevices

• Nocturnal

• Nymphs and adults of both sexes are blood feeders

• Can survive months without a blood meal

Chagas Disease

• Pathogen is Trypanosoma cruzi

• Protozoan parasite only found in the America’s causes Chagas disease

• Vector-borne zoonosis, humans not necessary to cycle

• Infection of host and vector is LIFE-LONG

• Enormous domestic and sylvatic reservoirs

• Infects > 100 domestic and wild mammals

  • Typical hosts: opossums, wood rats, raccoons, dogs, and cats

Chagas Disease Overview

• Also called American trypanosomiasis and the Kiss of Death

• A tropical parasitic disease caused by the flagellate protozoan Trypanosoma cruzi

  • flagellate so can move throughout the body

• Spread to humans through the bite of an insect vector

Acute stage of Chagas Disease

• Nonspecific symptoms, i.e., fever, diarrhea, and vomiting

• Swelling and inflammation

• Romana’s sign

  • The swelling of the left eye to the point where you cannot open it

  • Sometimes swelling on both lower and upper eye lid

Chronic Stage of Chagas Disease

• About 30% develop medical problems

• Cardiac Damage

• Digestive system damage

• Neurological disorder

Potentially fatal if untreated

Chagas Disease (broad overlook)

• Most serious parasitic disease in the Americas

• 12-15 million people in Central and South America

• 200,000 new cases/year

• high morbidity

Transmission of Chagas Disease

• A triatomine becomes infected

• Hides during day, Emerges at night

• Bites, feeds, and then defecates

Transmission of Chagas Disease 2

• Scratching Feces into skin

• Blood transfusions, organ transplants, or breast milk (rare)

• Congenital transmission

  • 13% of stillborn deaths in parts of brazil

Cultural Practice Transmission

• Eating of Triatoma for aphrodisiac properties

  • Mexico

• Rubbing of feces to cure warts on children

  • Mexico

History of bugs and T. cruzi in the US

• 1855- Vector bugs identified in Georgia

• 1860/70 - Vector bugs identified in six more states

• 1909 - Discovery of parasite and disease

• 1916 - Parasite first observed in CA

• 1930 - Reservoir host infections studied in US

• 1955 - First autochthonous cases of Chagas disease reported (got it in the US)

Diagnosis of Chagas Disease

• Detailed patient history including having seen the bug and having stayed within mud walls or thatched roofs, in a country with known Chagas risk

• Serum samples may be sent to CDC through your state health department

• Can be diagnosed with a blood smear

Xenodiagnoses

• Using insects to determine if they have the infection

  • Put non infected insect on a person to feed

  • Test to see if the insect has Chagas disease

  • Cheaper and faster than other methods

Treatment of Chagas Disease

• Two drugs:

  • Nifurtimox: Birth to younger than 18yo, weighing at least 2.5kg

  • Benznidazole: 2-12yo

• Some drugs you take up to 60 days

Prevention and Control of Chagas Disease

• Treat homes with residual insecticides

• Improve homes

• Screening of blood donations

• Wear protective clothing, repellents

• No vaccine available

Bed Bugs

• Climex lecularius

  • Family Cimicidae

• Small flat insects, reddish-brown

• Typically about 1/4 inch long as an adult

• Crawl, don’t fly or jump

• Prefer dark, generally hide out of site

• Feed on human blood

Bed Bugs 2

• Aggregate in cracks and crevices all day

• Feed between midnight and 5:00 am

• Stimulated by increase of CO₂ in the room

• Will travel many yards to find a host

Traumatic Insemination

• The male injects sperm into the female’s paragenital sinus

• Females can retain permanent scars

• Females can produce viable eggs up to 7 weeks after mating and feeding

  • A male can piece another male, and it can go from A’s sperm into B, and then when B mates/stabs a female, it will be A’s sperm

Brief History of Bed bugs

• Have long history as a pest to humans

• Mentioned in ancient Egyptian hieroglyphics

• First called a pest in the 17th Century

• Believed they came to America with the first European explorers and colonists

• With each wave of settlers came a new wave of bedbugs

• Bedbugs were a fact of life for many years

• Early efforts at extermination were troublesome

Early Bed Bug Remedies

• Rabbits foot at end of bed

• Corrosive sublimate with the white of an egg, applied with a turkey feather

  • “corrosive sublimate” = MERCURY

  • From “Good Housekeeping” 1988

• Arsenic

• Turpentine

• Gasoline

• 1922, the Department of Agriculture recommended cyanide fumigation

• Return of DDT again

DDT

• dichloro diphenyl-trichloroethane

• Developed in the early period of WWII to stop infectious diseases:

  • Malaria

    • Typhus

• Used against mosquitoes, lice, and other pests after they found it effective

• After WWII, DDT was made available to the general public.

DDT 2

• Nearly brought the extinction of bed bugs in North America

• During the mid-20th century, finding bedbugs for research was difficult

• DDT was banned in 1972 after research showed links to cancer and caused harm to wildlife like birds.

Bed Bugs re-emerged in the mid 19-?

• mid 1990’s

• Increased internation travel to location with active bedbug populations

• Increased immigration

• Many newer strains of bedbugs have increased resistance to multiple resticides

• Less pesticide use

Life as a Bed Bug

• Thrive in conditions of 70 to 80 degrees

• One female can Lay 200-500 eggs in her life span

• Can complete development within one month

• Can produce three or more generations in one year

• Nymphs need a blood meal for each life stage

• Life span can be many months when active, up to a year in an inactive state without a food source

Bed bugs are known to spread disease: True or False

• False

The Blood Meal

• The bite takes from 3 to 10 minutes

• During the bite, an anticoagulant is released

  • Stops the blood clotting

  • Numbs the bite area

• The host seldom knows they are being bitten

The Blood Meal 2

• Many people are allergic to the anticoagulant, which can affect their reaction and symptoms

• Symptoms of bites vary with each individual

  • Many symptoms develop within a day

  • Some people have little or no reaction

  • Some people have a delayed reaction (3-5 days)

What do Bed Bugs Do to Humans?

• Bed bugs feed on humans to obtain the blood they need to survive

  • Bed bugs are not known to transmit disease

  • Generally bite at night

  • Feed on exposed skin

• Bite characteristics

  • A small, hard, swollen white or red welt may develop at the site of the bite

  • Rash may occur

  • May cause itching that lasts several days

Where are bed bugs found?

• Places where people often move/relocate

  • Hotels/motels, Commercial offices

  • Dormitories, Movie theaters/ libraries

  • Shelters, Laundry facilities

  • Homes, Prisons

  • Schools, Nursing homes

  • Apartments, Hospitals

Where are Bed Bugs Found?

• The bedroom is a favorite location, but not the only room.

• Furniture is convenient

• Clutter makes it easier for them to hide and more difficult to treat

Signs of an Infestation

• Typically, they infest mattresses, box springs, bed frames, and couches

  • These areas will have dark spots and stains from dried excrement

  • May be red or rusty spots of blood on bed sheets

  • Heavy infestations may also have a musty smell (not a good indicator)

• Bed bugs can survive without feeding for a year

  • Even vacant units can contain bed bugs

How are bed bugs spread?

• Very efficient hitchhikers

  • Often, infestations can be traced to travel

  • Attach to luggage, backpacks, clothing from beds, furniture

    • Bed bugs move when and where the infested object is moved

• Often spread through the re-use of secondhand furniture

  • Use beds, couche,s and other itemsthat can be infested with eggs and nymphs that can be hard to see

  • DO NOT pick up items from the curb

Major Events

• The 2000 Olympics in Australia

• 95% of the hotel rooms in Sydney are said to have had bed bug infestations

• Anywhere large groups of people from various regions meet and stay

How can Bed Bugs be Prevented?

• Do not use secondhand beds, mattresses, box springs, couches, or furniture, especially if you are unsure of their history

• Watch for signs of bed bugs when you travel by examining bed sheets, the mattress/box spring seams, and headboordheadboard

• Keep your suitcase off the floor and away from the bed when traveling.

Travel tips

• Look at the room for hiding spots

  • carpet edges, headboards, mattress seams, pillow cases, linings, wall trim or other tiny cracks

  • Look for signs of bed bug activity: feces, eggs, bloodstains, or even bed bugs themselves

  • Use hangers or hooks capable of keeping all clothing distant from the floor.

  • Zip your suitcase or travel bag closed

  • Elevate luggage off the floor to tables or chairs - could be hiding there but less likely. ,

  • Keep any bed bugs you find to show the hotel owner/manager

  • Trust your instinct

If you come in contact with bed bugs

• Clothing and bedding should be washed in hot soapy water and dried in a dryer hot cycle

• Suitcases, backpacks, and personal bags

• Inspect thoroughy

Taxonomy

• ~ 4,000 Species worldwide

• 70 species in the US, 24 have been introduced

Cockroach Morphology

• Cerci with 8 or more segments

• Biting-Chewing Mouthparts

• Head concealed by large pronotum

• Hind femora not enlarged

• Dorsoventrally flattened

Life History of Cockroaches

• Multiple eggs in each egg case, called ootheca

• Many eggs mean many nymphs

• Nymphs look like small versions of the adults

German Cockroach #1

• Most important domestic pest throughout the developed world

• Adults about 16mm, bronze, w/ two dark stripes on the pronotum

• Found everywhere, but likely warmth, moisture, and darkness

• Found in kitchens, pantries, bathrooms, and is nocturnal

German Cockroach #2

• Does not move between buildings readily

• Produce an ootheca with 30-50 embryos 4-8 times

• Mother carries eggs to term even if she is dead

• Eats almost anything

Brown-banded Cockroach

• Small: 13-14.5 mm w/ side to side stripes

• Found in warm and dry spots, often high up

• Confided to indoor environments of heated structures

• Development from egg to adult in about 6 months

• Females affix their ootheca to furniture

American Cockroach #1

• Large: 34 to 53cm and reddish-brown color

• Undergoes 10-13 molts over 1.5 to 2 years

• Female produces 9-10 egg cases w/ 12-16 embryos

• Lives in buildings, sewer system, tree holes, ships, and mines

American Cockroach #2

• Can move through crawl spaces of hospitals via pipe chases into other areas

• Most cosmopolitan species

• Likes it hot

Oriental Cockroach

• 25-33cm, black in color

• Development about one year

• Lives in sewers, basements, and mulch, sump pumps, and floor drains

• Likes it cool and wet

• Mobility fairly restricted, rarely seen during the daytime