L20: Ticks and Lice

Question 1

What are ticks

Answer 1

*small, hematophagus that undergo incomplete metamorphosis
*wingless, no jump just crawl

*survive 1+ year without feeding
*transmit to viruses, bacteria, fungi and protozoa
*the bite is painless but causes allergic responses, paralysis and secondary infections

Question 2

What are the two morphologically and ecologically distinct ticts

Answer 2

Hard tick -> ixodidae
*hard dorsal scutum
*unfed they are flat and found in busy grassy areas
*feed for long time 24-58hrs
*single blood feel per feeding life stage
*mates on host while eggs laid off host
*after feeding, adult female falls off host, lays eggs then dies
*1 nymphal instar
*1, 2 or 3 hosts host life cycles

Soft tick -> agarsidae
*when unfed raisin shaped and hides in cracks/burrows in daytime
*feed in less than hour and several blood meal per life stage
*mating and eggs laid off hosts
*females are gonotrophic they can alternate between feeding and egg laying
*mutli host life cycle

Question 3

life cyle slide 5 +6

Answer 3

life cyle slide 5 +6

Question 4

Describe tick mouthparts, describe secretions and their effect

Answer 4

three visible components

1. palps: two outside jointed parts that move laterally while feeding, not in host skin
2. Chelicerae: cutting mandibgles in between palps that are flexible and used to probe and cut skin
3. hypostome: rod shaped tube with beak projections pointing backwards to secure tick place on host, attachment organ that is protected by Chelicerae

the tick secret cement that also further anchors and anticoagulant to prevent blood coagulation

Question 5

Associate ticks with disease and distrubution

Answer 5

lyme disease -> B.burgforegi -> not africa

rocky mountain fever ->Rickettisa => North America

Baberosis -> babesia -> Worldwide => North america ….

Question 6

What is lice

Answer 6

small parasitic insects with no free-living stages, incomplete metamorphosis with 3 nympha stages

wingless only crawl

doroventrally flattened with reduced/no eyes

mostly host specific and dependant on it to complete life cycle, cling to host using tarsal claws and eggs are glued to hair

skin, hair, feathers

Question 7

What are the three types of lice

Answer 7

Biting lice:
*mammals/birds
*blunted head that is wider than thorax
*ventral biting mandibles
*feed on epidermal debris and are active, move through hair

Sucking lice
*infect mammals with pointy head that is narrower than thorax
*piercing mouth parts and feed on blood
*less active/move slow often found embedded in skin

Question 8

Discuss human lice, disease, role or pets

Answer 8

have predilection sites
human are the only host for 3 sucking lice
head lice p.humanus.captis
body lice … humaous, humaous
pubic lice pubis

head and body cause pediculosis
pubic causes pthiraiss

pets play no roll

Question 9

Describe head lice and life cycle

Answer 9

called pediculus humanus captis
*very common and worlside
*school, more girls than boys
*does not transmit disease but can cause secondary infections from scratching
*not related to hygiene just spreads

life cycle: egg => nymp => adult

Question 10

Life Stages of Pediculus humanus capitis

Answer 10

Nits:
*hard to see and look like dandruff
*oval, yellow white
*6mm within scalp

Nymphs
*look like adult but smaller, pinehead size

adult
*sesmee head, 6 legs with claws
*tan, feamels are bigger
*30 days, feed several times a day
*without blood meal dies in 2 days

Question 11

Clinical Presentation, diagnosis, treatment of P. h. capitis

Answer 11

causes Pediculosis
* asymptomatic
*tickly, itchy feeling
*seconday bright infects
*small red paules under hairline

diagnosis
*finding live nymphs/adult or nits 6mm within scalp

Treatment
*pediculicides like lice/nit killing shampoos
*not combs

Question 12

Body lice, morphology, habits, transmission and disease

Answer 12

Pediculus humanus humanus

*morphologically similar to head lice but with a different life cycle
*in clothing, bedding and go to human body to feed, can be found in hair

*worlwide but less common than lice, related to hygiene so poor, war, homeless

*transmission by contact with fomites

*only body louse spread diseases like typus, trench fever and louse borne relapsing fever spread by poop

Question 13

Clinical Presentation of P. h. humanus Pediculosis

Answer 13

*red spots and bumps on back, neck and wasite, irritation from allergic reaction to bite
*small crust on skin and blood from bites
*seconday infection

heavy infection and prolonged infection have thickendded discoloured skin on bitten areas and secondary iron defincy anemia

Question 14

Diagnosis and treatment of P. h. humanus Pediculosis

Answer 14

*find eggs and crawling lice on clothes or mature lice feeding on skin

*better hygiene, clean/changes clothes, hot water
*pediculicide but not needed if ur clean

Question 15

Pubic Lice tranmission, symptoms, morphology

Answer 15

Pthirus pubis

• causes pthiriasis found in pubic hair
  *broader and crab like
  *life cycle like head lice, world wide and asymptomatic

*when present symptoms life head lice, tickly, itching

*transmission by sexual contact and formites play minor role in transmission

Question 16

Public lice diagnosis and treatment

Answer 16

diagnosis
*find live nymphs or adult in hair of person
*can also be found on coarse hair like armput or moustache, beard, lashes

treatment
*lice killing lotions, fine tooth combed