Bugs & Flies

Question 1

Which two families of bugs are of medical importance?

Answer 1

Reduviidae= assassin bugs, kissing bugs. carries trypanosoma cruzi
Cimicidae= bed bugs

Question 2

What are the three species of human bed bugs?

Answer 2

Cimex lectularius: common bed bug. cosmopolitan
Cimex hemipterus: Indian bed bug. restricted to tropical and subtropical regions
Cimex boueti: tropical regions of Africa and South America

Question 3

Can humans be infected by other bed bug species?

Answer 3

very rare, but can be accidental hosts of Cimex bat and bird species

Question 4

Where are bed bugs found?

Answer 4

in human habitats, remain hidden in cracks and furniture

Question 5

How do you know that you have been bitten by a bed bug?

Answer 5

characteristic to have several bite marks because bed bugs take a few blood meals and change position after each one

Question 6

What does the salivary fluid of bed bugs contain?

Answer 6

anti-coagulants and anesthetics so that the host does not feel the bite

Question 7

Where do female bed bugs lay their eggs?

Answer 7

they lay about 5 eggs a day in a sheltered area (hidden, not on host)

Question 8

How many nymphal stages do bed bugs have?

Answer 8

5 nymphal stages that each require a blood meal to molt

Question 9

How long are the bed big feeding times and how long can they go without a blood meal?

Answer 9

3-10 minutes to feed and can go 6-12 months without a blood meal

Question 10

What is traumatic insemination?

Answer 10

the unique way bed bugs mate where the male pierces the female’s abdominal cavity with his external genitalia to inseminate her

Question 11

What do bed bugs do to humans?

Answer 11

do not cause disease, but they can cause inflammatory reaction (allergic reaction to saliva)

Question 12

How can bed bugs be treated?

Answer 12

can use antiseptic creams or lotions to prevent infection after a bite
strong pesticides can be used

Question 13

What is the order that flies belong to and what are some parasitic species?

Answer 13

order Dipteria

• biting midges (filariid nematodes)
• sandflies (leishmaniasis)
• blackflies (onchocerciasis)
• mosquitoes (malaria)
• horse and deerflies (filarial eye worm)
• tsetse flies (sleeping sickness)

Question 14

Which stage of the flies causes disease?

Answer 14

can either transmit other diseases or the larvae can be pathogenic (obligate parasites)

Question 15

Define myiasis

Answer 15

burial of larvae in tissues.

can be an obligatory step or an incidental step, depending on the species

Question 16

Where does myiasis occur?

Answer 16

may be cutaneous, arterial, intestinal, or urinary, in necrotic or healthy tissue

Question 17

Which flies cause myiasis in humans?

Answer 17

bot fly, screw worm fly, tumbu fly

Question 18

Describe the bot fly life cycle

Answer 18

• female fly lays eggs on a blood-sucking arthropod.
• larvae develop in the egg and remain on the vector until it takes a blood meal from a host, at which point the larvae will penetrate the host
• mature larvae drop from the host and pupate
• one month later they molt into adults

some species lay their eggs directly on the host at the site of a wound

Question 19

What do the flies have on their anterior end and on their on their posterior end?

Answer 19

mandibles on the anterior end

spiracles on the posterior end

Question 20

How does the new world screw worm infect its host?

Answer 20

female lays eggs directly around the wound

Question 21

How does the old world screw worm infect its host?

Answer 21

larvae penetrate mucous membranes or necrotic tissue around the eyes, mouth, and nose

Question 22

Describe the tumbu fly life cycle

Answer 22

cause accidental myiasis
flies lay eggs on soil contaminated with urine and feces
emerging larvae attach to host and penetrate skin

Question 23

What are the clinical features of bot fly worm infections?

Answer 23

cutaneous swellings on body or scalp that may produce discharges and be painful

Question 24

How can screw worm fly be more dangerous than other fly infections?

Answer 24

larvae can migrate in the body, may not remain subdermal

Question 25

How can fly infections be treated?

Answer 25

• physical removal of worms
• screw worm fly larvae may need to be surgically removed, depending where they have migrated
• antibiotics can be given to treat secondary infections