Ectoparasites 2 (Dr Smith) IFL

Question 1

What is the latin name for human flea?

Answer 1

Pulex irritans

Question 2

What is the general profile of a flea?

Answer 2

Blood sucking, can fly, often host specific re infestation (a cat flea may bite you but cannot infect you).
Actively seek host (CO2 or hormone taxis)
Can survive prolonged starvation.

Question 3

Are there nymph forms of fleas?

Answer 3

No

Question 4

What is the life cycle of a flea like?

Answer 4

Eggs shed by females into environment
Eggs hatch into larvae
Larvae form pupae
Adults hatch from pupae and then can infect host i.e. cat, human etc

Question 5

What are the signs and symptoms of a flea infestation?

Answer 5

Bites grouped in clusters and are itchy

Question 6

How can flea bites be treated (symptomatically)?

Answer 6

Cold compress, deter scratching, antihistamine to reduce swelling and itching

Question 7

What does ‘Fleas as vectors of disease’ mean?

Answer 7

Fleas can carry and transmit diseases such as the Plague and Murine Typhus

Question 8

What is the name and profile of a sand flea?

Answer 8

Tunga Penetrans
‘Chigoe flea, jigger flea, sand flea’
Does not transmit disease, small size compressed, females burrow into skin
Wear shoes in infected areas.

Question 9

What is the life cycle of Tungiasis?

Answer 9

Eggs shed by female into the environment
Eggs hatch into larvae that develop into pupae
Adults hatch from pupae
Adult females burrow into the stratum granulosum
Gravid females reside in subcutaneous lesion

No treatment; self limiting or suffocation

Question 10

What is the latin name for lice?

Answer 10

Pediculus humanus

Infestation is known as pediculosis

Question 11

What is the general profile of lice?

Answer 11

Cling to hair shafts, do not fly or jump but crawl
Can travel up to 25cm per minute
Highly contagious
Persistent for over a year if untreated

Question 12

What are the three types of lice?

Answer 12

Head lice (pediculus humanus capitis)
Body lice (pediculus humanus humanus)
Public lice / Crabs (phthirus pubis)

Question 13

What is the life cycle of lice?

Answer 13

Eggs -> 3 nymphs -> Adults

Hop on, lay eggs, life cycle on host, repeat.

Question 14

What are the signs and symptoms of head lice?

Answer 14

Itching, difficulty sleeping, scratching, (secondary infection), often raised bumps on neck.

Diagnosis upon visual inspection (scalp and comb).

Question 15

What are the pharmaceutical treatments for head lice?

Answer 15

8-12 hours contact time
Dimeticone lotion 4% (Conotrane) - does not kill live eggs
Benzyl alcohol emulsion 25% - does not kill live eggs
Malathion Lotion 0.5% (Derbac-M) - kills live lice and partially ovicidal
Lindane Shampoo 1% - antiquated, can cause neurological damage / death (banned in UK and from the EU in 2008).

Question 16

How does Dimeticone work?

Answer 16

Silicone based, forms water impervious coat of silicone on the lice and suffocates them

Question 17

How does Malathion work?

Answer 17

Organophosphorous anticholinesterase; promotes cholinergic neurotransmission and is a neurotoxic insecticide.
No more than 4 consecutive applications
Can be irritating to skin/scalp

Question 18

How does Lindane work?

Answer 18

Gamma-hexachlorocyclohexane
An ion channel agonist
Neurological toxin that binds to an inhibits GABAa chloride channel complex

But GABAa found in animals so cab interfere with mammalian central neurotransmission
GABAa is antiepileptic, dampens /inhibits neuronal activity
Lindane can cause seizures and convulsions

Question 19

How can you prevent/remove head lice?

Answer 19

Wet comb
Pyrethoids used in children better than shampoo and comb
Malathion and lindane - neurotoxin

Question 20

What is the difference in the lice infesting head vs pubic hair?

Answer 20

Body louse claws are adapted for round hair common on head

Pubic louse claws are adapted for oval shaped hair common with pubic hair and eye lashes

Question 21

What are the signs and symptoms of pubic lice?

Answer 21

Itching in affected area, inflammation caused by scratching
Black powder in underwear
Blue-coloured spots on skin
Tiny blood spots on skin or underwear
Pubic hair but also body hair (armpits, chest, leg, facial hair, beards/eyebrows)
Diagnosis via visual detection of lice

Question 22

How are crabs spread?

Answer 22

Mainly through sexual contact; most contagious STD
Condoms do not protect
Non sexual spread by contact with clothing, linen and towels less common but possible

Question 23

How are pubic lice treated?

Answer 23

Insecticides applies initially once to whole body:
Permethrin (Lyclear)
Malathion (Derbac-M)
Applied for 12 hours
Repeat after 7 days to kill newly hatched lice
Treat household members and sexual partners
(Not dimeticone)

Question 24

What are the signs and symptoms of body lice?

Answer 24

Pruritus 
Skin discolouration/thickening
Secondary bacterial infection
Red rash 
Diagnosis - visual detection of lice

Question 25

What is the treatment for body lice?

Answer 25

Laundering to prevent reinfestation
Insecticides applied initially once;
Permethrin
Malathion
Applied for 12 hours
Reapply after 7 days to kill newly hatched lice
Treat household members or sexual partners

Question 26

Body lice can transmit bacterial diseases; where is this particularly likely?

Answer 26

Refugee camps, overcrowded prisons and in cramped living conditions

Question 27

What is Borrelia recurrentis?

Answer 27

Louse-Borne Relapsing Fever
Recurring episodes of fever 5-15 days after louse infestation; headache, muscle and joint aches and nausea
Sweating sickness

Question 28

What is Bartonella quintana?

Answer 28

Trench Fever
Less serious LBF with bone pain
Characteristic 5 day relapsing fever that is rarely fatal and can be treated with antibiotics.

Question 29

What are the three bacterial diseases that can be transmitted by body lice?

Answer 29

Louse-borne relapsing fever
Trench fever
Epidemic typhus

Question 30

What is Rickettsia prowazekii?

Answer 30

Epidemic typhus 
Jail fever / Camp fever / Famine fever
Severe symptoms; headache, cough, fever, muscle pains, chills, hypotension, stupor, photosensitivity, delirium.
Fumigation needed
Vaccine?