Medical arachnoentomology. Arthropods as pathogenic organisms and carriers of agents of infections and invasions Lecturer: ass. Nedoshytko Khrystyna

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Medical arachnoentomology. Arthropods as
pathogenic organisms and carriers of agents of
infections and invasions
Lecturer ass. Nedoshytko Khrystyna
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Plan of lecture

• Phylum Arthropoda general characteristic,
  classification, medical importance.
• Crustaceans as intermediate hosts of helminthes.
• Class Arachnida general characteristic,
  classification, medical importance.
• General characteristics, classification of class
  Insecta.
• Order Anoplura (lice). Morphology, medical
  importance, methods of control.
• Order Siphonaptera (fleas). Morphology, medical
  importance, methods of control.
• General characteristics, classification, medical
  importance of order Diptera.
• Anopheles, Aedes, and Culex mosquitoes and their
  role in transmission of infections.

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• Three-fourth of all animal species belong to the
  Phylum Arthropoda. The name arthropod comes
  from two Greek words, arthros, jointed, and
  podes, feet.
• All members of the Phylum Arthropoda share the
  following characteristics
• 1. Arthropods have jointed appendages.
• 2. The arthropod body is segmented.
• 3. Arthropods have an exoskeleton.
• 4. Arthropods have a ventral nervous system, an
  open circulatory system, a digestive system, and
  specialized sensory receptors.

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• Phylum Arthropoda includes
• 3 classes of medical importance
• 1.Class Crustacea cyclops, crabs.
• 2. Class Arachnida (Octapoda) scorpions,
  spiders, ticks and mites.
• 3.Class Insecta (Hexapoda) mosquitoes, flies,
  bugs, lice, fleas.

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Class Crustacea

• Most crustaceans have two pairs of antennae,
  three pairs of chewing appendages, various
  numbers of pairs of legs.
• Crustaceans differ from the insects in that they
  have legs on their abdomen as well as on their
  thorax.
• Medical importance 1)Cyclopes are intermediate
  hosts of the fish tapeworm (Diphyllobothrium
  latum) and Dracunculus medinensis.
• 2) crabs or crayfish are Intermediate hosts of
  the
• Human lung fluke
• (Paragonimus westermani).

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Class Arachnida.

• The Class Arachnida is a group of more than
  100,000 species, including spiders, scorpions,
  ticks, and mites.
• Most arachnids are adapted to kill prey with
  poison glands, stingers, or fangs.
• Arachnids have a body that is divided into a
  cephalothorax and an abdomen.
• Attached to the cephalothorax are 4 pairs of
  legs, a pair of chelicerae, and a pair of
  appendages called pedipalps.
• The pedipalps aid in chewing in some species
  pedipalps are specialized to perform other
  functions.
• Arachnids undergo incomplete metamorphosis.

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Class Arachnida includes 3 orders of medical
importance
Order Scorpiones.
Order Araneae (spiders)
Order Acari (ticks and mites).
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Class ArachnidaOrder Scorpiones Scorpions
E. Tenczar
E. Tenczar
Flat Rock Scorpion,Hadogenes troglodytes,female,
native toSouth Africa
Lined Devil Scorpion,Vaejovis spinigerus,female
from Arizona with young
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Interesting Facts about Scorpions

• Scorpions live everywhere except the Arctic and
  Antarctic
• Male and female scorpions find each other by
  vibration, scent, or touch. Then they dance
  together for half an hour or more.
• Females often eat the males when they are done
  with the dance.
• 25 types can harm/kill man
• Alive before the dinosaurs
• Scorpions have 8 legs and 2 claws.
• The bigger the claws are, the less
• venom it has.

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Scorpions differ from spiders in two ways

• Scorpions have greatly enlarged pedipalps, which
  they hold in a forward position.
• They also have a large stinger on the last
  segment of the abdomen.
• Scorpion Sting SymptomsA scorpion sting is
  never fun. The following are common symptoms of a
  scorpion sting
• Intense pain at the sting site
• Mild swelling around sting site
• Numbness in area of sting
• Sensitivity to touch
• Nausea or vomiting
• Excessive salivation
• .

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Stepwise first aid

• If a scorpion stings you, follow this scorpion
  sting first aid plan for minimization of pain
• Wash the affected area If possible, get the site
  of the sting under cold water immediately.
• Medicate topically Apply a layer of ointment
  containing an antihistamine, a corticosteroid,
  and an analgesic.
• Apply ice Hold a bag of ice over the ointment on
  the area. The ice will reduce the pain and
  inflammation.
• Medicate orally Take one dose of Benadryl
  (antihistamine) and one dose of a pain killer
  (acetaminophen).
• Go to the hospital Because some scorpion stings
  can be fatal, you will need to go to the
  emergency room to get evaluated for scorpion
  anti-venom. If possible, get someone else to
  drive you.
• Ice as needed Keep applying ice until pain is
  tolerable.  You may experience pain for any
  length of time between a few hours to a couple
  days.

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Spiders are not a bug

• Spiders are not insects they are part of a group
  called Arachnid
• There are more than 35,000 different species of
  spiders

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Arachnophobia

• Arachnophobia is the fear of spiders
• This is the number one fear of Americans today
• Although most spiders are harmless and helpful to
  our lives

This spider has a venomous bite that causes
serious wounds
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Spider Eyes

• Most spiders have either six or eight eyes
• Even so they cannot see far away
• They use the hair on their bodies as sensors to
  feel their way around and to tell when other
  animals are near

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How dangerous are black widow spider bites?

• If a black widow spider bites a person, do not
  panic!
• Very often the black widow will not inject any
  venom into the bite and no serious symptoms
  develop. Wash the wound well with soap and water
  to help prevent infection.

If muscle cramps develop, take the patient to the
nearest hospital. Some victims, especially
young children, may be admitted overnight for
observation and treatment. There is treatment
for a black widow spider bite that can take care
of the symptoms. Various medications are used to
treat the muscle cramps, spasms and pain of a
bite. Black widow spider antivenin is seldom
necessary.
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Order Acari

• Most mites are small, less than 1 mm long,
• the adult length from 100 nm to 2 cm.
• the cephalothorax and abdomen are fused into an
  unsegmented ovoid body.
• Respiration occurs either by means of tracheae
  or directly through the exoskeleton.
• They are found in virtually every terrestrial,
  freshwater, and shallow marine habitat known and
  feed on fungi, plants, and animals they act as
  predators and as internal and external parasites
  of both invertebrates and vertebrates.

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SarcoptidaeScabies Mites

• Sarcoptes scabiei
• Also called the itch mite of humans
• Not Vectors of any disease.
• Morphology male (0,2 mm) is smaller than female
  (0,4 mm).
• Body is oval, convex dorsally and flat ventrally.
  

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Sarcoptes scabiei (itch mite)

• Mouthparts
• rudimentary hypostome without teeth.
• chelicerae end in pincer-like structures.
• pedipalps are short and 3-segmented.
• The whole cycle takes about 2 weeks.

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small male large female
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Distribution

• Worldwide
• All races and socioeconomic classes
• All climates
• 300 million cases annually!

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Behavior

• Burrowing initially occurs in thinner skin of the
  body.
• Bend of knee and elbow.
• Webbing between fingers and folds of the wrist.
• Genitalia and buttocks.
• Breasts.

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Scabies Rash
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Life cycle
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Transmission

• Spread by ovigerous female mites through
• Personal (prolonged close) contact
• Occasionally by infested sheets (rare).
• Touching or shaking hands (unlikely).
• Sexual activity.
• Among children (outbreaks).
• Mites can survive up to 24 hours off host.

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Diagnosis

• Diagnosis is made by
• itching of affected surfaces at night
• specific lesions
• finding of the parasite in the tunnels by a
  needle.
• Control is provided by
• - proper treatment of infected persons
• - sterilization of clothes and bedding
• - personal cleanliness.

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Ticks
Ticks are divided into hard-bodied ticks (family
Ixodidae) and soft-bodied ticks (family
Argasidae)
Ticks are blood-feeding ectoparasites (parasites
that occur on the surface of their host).
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TICK LIFE CYCLE
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Life cycle

• female ticks lay eggs.
• Larvae hatch, feed on blood and then drop to the
  ground.
• Larvae molt into nymphs.
• Nymphs feed on blood and molt into adults.
• Adult male and female feed on blood.
• Life cycle takes several months (1-2 years in
  some species).

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Anatomy of IXODES ticks
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Size
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Female Deer Tick

• Male Deer Tick Crawling

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Female Deer Tick Larvae
All stages of I. ricinus will feed on humans, and
their bite can be painful. This tick can also
transmit several diseases that affect humans,
including CrimeanCongo hemorrhagic fever and
Lyme disease.
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Ticks

• Medical importance.
• - Mechanical injury by the bite.
• - Tick paralysis progressive flaccidity due to a
  failure of acetylcholine liberation in the
  neuromuscular junction. Ticks toxin produces a
  block in the motor nerve fibers. The toxin is
  elaborated by the ticks ovaries and is secreted
  by salivary glands.
• Vectors of diseases
• -hard-bodied ticks (Ixodidae) are carriers of
  rickettsial, spirochaetal, viral, bacterial, and
  protozoan diseases.
• soft-bodied ticks (Ornithodorus) are vectors of
  endemic relapsing fever (caused by Borrelia
  duttoni) and Q-fever.
• Control of ticks
• Repair of cracks.
• Insecticide spraying on floors and cracks.
• Infested animals are dusted by insecticide
  agents or dipped in special solution.
• In endemic areas wear light-colored, tightly
  woven slacks and a long sleeved shirt spray
  clothing with an insect repellant containing
  N,N-diethyltoluamide

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Insects

• Insects have three body sections
• the head, thorax, and abdomen
• three pairs of legs, all attached to the thorax
• one pair of antennae.
• they may have one or two pairs of wings.
• The mouthparts of insects are elaborate.
• There are two principal kinds of metamorphosis in
  insects simple and complete.

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Insects

• Class Insecta is divided into 4 orders of medical
  importance
• 1. Order Anoplura (lice).
• 2. Order Siphonaptera (fleas).
• 3. Order Hemiptera (bugs).
• 4. Order Diptera (mosquitoes and flies).

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Order Anoplura (lice)

• Order Anoplura (lice). Body is flattened
  dorso-ventrally.
• Lice are wingless insects with short legs.
• Order Anoplura displays incomplete
  metamorphosis.
  
  
  
• Head louse
• Morphology (Pediculus humanus)
• Adult louse is 2-5 mm in size, male is smaller
  than female.
• Body is divided into head, thorax and abdomen.

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• The head louse found on humans is specific to
  people. It cant be contracted from the family
  dog, cat or any other animal. Mammals and birds
  can have lice but they are species specific.

• These are insects that CANNOT jump or fly.
• Their method of movement relies on 6 legs, each
  of which ends in a claw which can grasp human
  hair.

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Lice

• Life cycle.
• - Female louse lays about 10 eggs daily.
• Eggs are cemented to hairs or to fibers of
  clothes.
• Eggs hatch in about one week.
• Nymphs feed on blood and pass through 4 instars.
• Adult louse emerges in about two weeks.

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Transmission of Head Lice

• Host-to-host (direct contact from someone who is
  infested)
• By wearing infested clothing (hats, scarves,
  coats, hair ribbons etc.)
• By using infested combs, or brushes
• By lying on a bed, couch or carpet that has
  recently been in contact with an infested person.
  

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• Head Lice are NOT known to transmit pathogens
  (germs). They are a nuisance but NOT a health
  hazard.
• Lice dont mount expeditions, striking off to
  find new heads. They are obligate human
  parasites, their goal is to stay on the head
  where they presently live!!!!!

Disease transmission (body louse). Epidemic
typhus caused by Rickettsia provaceki, Trench
fever. Epidemic relapsing fever
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Order Siphonaptera (fleas)

• About 2500 species, most parasites of mammals
• only approx. 100 species on birds
• Temporary obligate parasites, blood-feeding
  exclusively
• as adults
• Most fleas of medical and veterinary importance
  are not
• host species-specific
• increases the potential for acquisition and
  transmission of pathogens

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Flea eggs
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Adult fleas
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Important Flea Species
Xenopsylla cheopis (Oriental rat flea) - primary
urban plague vector Pulex irritans (human flea)
- occasional epidemic plague vector Ctenocephalid
es felis, C. canis, - cat and dog flea - primary
pest species Tunga penetrans sand flea (chigoe)
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Parasitic Flies Order
Diptera
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Flies - Diptera

• The key distinguishing adult structure two
  wings.
• All Flies are Holometabolous (having a complex
  metamorphosis
• i.e. egg, larvae pupa, and adult)

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One of Great Adaptations of of Flies - The
Habitat of larval stage

• The habitat of the larval stage is basically
  aquatic or semi-aquatic, and they have adapted
  to live in very, very challenging environments.

Allows them to invade Dead and Living tissues
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Diptera Flies as parasites

• Ectoparasites
• Adults are free living but blood feeding with the
  larvae stages aquatic or in moist semi-aquatic
  habitats. (Nematocera and Brachycera)

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Diptera Flies as parasites

1. Adults ectoparasites (or blood feeding) but
   larvae develop within female and essentially
   pupate after emerging from mother (Glossina,
   Hippoboscidae)

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Diptera Flies as parasites

• Endoparasites
• Adults free living but larvae are internal or
  partially internal (flesh feeding) parasites of
  vertebrates (Oestrus, Gasterophilus, Cochliomyia
  hominovorax)

Gasterophilus intestinalis
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Myiasis Defined

• The invasion of organs and tissues of humans or
  other vertebrate animals with dipterous larvae,
  which for at least a period feed upon the living
  or dead tissue or, in the case of intestinal
  myiasis, on the hosts ingested food.

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Metallic Flies

• Cochliomyia hominivorax

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Lucilia spp.
Calliphora spp.
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Musca domestica.

• Housefly is a medium-sized fly, 6- 10 mm in
  length the female is generally slightly larger
  than the male.
• Distribution cosmopolitan.
• Morphology. Adult fly has a gray color. Body is
  divided into head, thorax, and abdomen.
• Life cycle. 1. Eggs are laid into masses of
  decaying organic substances, garbage, refuse or
  manure.
• 2. Larvae hatch in 6-24 hours and feed on organic
  matter.
• 3. They molt 2 times giving 3 larval stages.
• 4. The third larva pupates inside the larval
  skin.
• 5. The adult emerges after a few days .The whole
  cycle takes about one week.

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House fly
4th vein angled
4 dark stripes
Red eyes

• Breeding media
• Garbage
• Decaying fruit or vegetables
• Decaying meat
• Human or animal feces
• Grass clippings

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• Medical importance
• 1. Indirect mechanical transmission of
  microorganisms (as typhoid, poliomyelitis and
  bacillary dysentery), eggs of helminthes and
  cysts of protozoa.
• 2. Accidental myasis.
• Control
• Sanitary disposal of refuses, garbage and manure
  (breeding media) by dumping, burning or
  application of insecticides.
• Control of adult flies by screening or space
  spraying of insecticides.

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Mosquitoes

• Bloodfeeding - only females take blood
• Males feed on plant sugars
• Gonotrophic cycle - feed, egg development,
  oviposition (half-gravid, gravid)

Disease transmission Some species of Anopheles
transmit 1. Human malaria     2.  Wuchereri
bancrofti Some species of Culex transmit 1.
Wuchereria bancrofti 2. Encephalitis      3.
Rift valley fever
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Differences between Anopheles and Culex.
Eggs 3 strategies

• Singly on water surface
• Anopheles
• Singly in a pile, on moist substrates
• Aedes/Ochlerotatus
• Form of a raft, on water surface
• Culex
• Culiseta

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Larval Stage Growth Stage

• Larval instars (4)
• Aquatic, Filter feeders
• Respiration

Anopheles
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Pupa Lighter than water

• Non-feeding
• Respiration

Pupal Stage Comparison
Anopheline
Culicine
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Mosquito Pupa and Larvae
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Mosquito Emerging from Pupal Exuvia
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Adults
Emergence Mating Feeding
Adult Stage Comparison
Culicine
Anopheline
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Culex
Anopheles
Aedes aegypti
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Thank you for attention !