Parasitology Flashcards
What is a parasite?
An animal living in or on the body of another which gains an advantage of the host
What is an ECTOparasite? Give some examples?
Found on the outside (surface) of the host.
Need nutrients to stay attached. They have a divided body and a hard exoskeleton.
Lice (insect with 3 segments)
Mites (arachnids?)
What is an ENDOparasite? Give some examples?
Found with the body of the host.
Protozoa (malarial)
helminths (threadworm etc)
What are lice?
Ectoparasites that suck blood - their mouth is specialised for piercing skin and sucking
What are the 3 species of lice?
Pediculosis capitus (HEAD)
Pediculosis corporis (BODY)
Pediculosis pubis (PUBIC)
Where are body lice found?
Usually in the clothes then the go to the body to feed.
Common areas include soft creased areas like the armpit and waistline
How are body lice transmitted?
Clothing-clothing contact or skin contact
Where do body lice lay their eggs?
In the seams of clothing
What areas (not like body areas but like places) would body lice infections be common?
Areas of poor hygiene and crowding such as shelters, refugee camps and hostels
What is the only host for body lice?
Humans
If body lice fall of a person how soon will they die?
5-7 days
How do body lice move around?
CRAWL - do NOT jump, hop or fly
How big are body lice?
About the size of a sesame seed
What other diseases can body lice be a vector for?
Endemic typhus
Trench fever
Why do body lice cause intense itching?
Injection of their saliva into the skin
What symptoms may a person with body lice present with?
Intense itching
Eggs on body
Lice crawling in clothing seams (MAGNIFYING GLASS MAY BE NEEDED)
Rash
Red bumps
Thickening or discolouration of skin especially near waist or groin if untreated
Secondary bacterial infection
What treatment can be provided for body lice?
Insecticide and symptomatic relief (antihistamines)
What insecticides can be used in the treatment of body lice?
Permethrin 5%
Malathion 0.5% (Derbac M)
What hygiene measures are needed to help eradicate body lice?
Bathe/shower regularly
Wash clothing at 50 or higher
Store contaminated clothes in a closed container for over 2 weeks –> lice will die with no blood
Deep cleaning areas especially upholstery
Who else needs to be made aware if a person has body lice?
Close contacts and people they live with so they can keep an eye out for signs of infection
Why do we use the word ‘infection’ and not ‘infestation’?
Less daunting, embarrassing and shameful for the patient
What do adult pubic lice look like?
They are about 2mm long and yellow-grey or dusky red
Where do pubic lice attach their eggs (nits)?
To the base of coarse hairs in the pubic area but can be on other coarse hair such as eyebrows, eyelashes, beard and armpits
Do public lice transmit STIs?
No
What test is also reccomended if a person has pubic lice?
Sexual health check up
Do condoms protect against pubic lice?
No
What is another name for pubic lice
Crabs
How long do public lice live?
one to three months
How many eggs can a female public louse lay?
300
After the eggs hatch, what is the name for the immature pubic louse?
nymph
How long does it take to go from nymph to adult pubic louse?
2-3 weeks
When trying to identify if a person has a public lice infection what are we looking for?
Adult louse - may have to use a magnifying glass
How long can pubic lice live if not on the human body
24 to 48 hours
They depend on human blood to survive so rarely leave the body
How are pubic lice transmitted?
Close contact
Coitus
sometimes crawling through clothing and bedding
What are some signs and symptoms of pubic lice?
Itching in the affected area - may take a few weeks to present
Inflammation or irritation in the affected areas including thighs and lower abdomen
Black powder (Lice faeces) in the underwear or on skin
Blue spots of skin where lice are biting
Tiny blood spots in underwear or skin
Eggs (nits) near the hair follicles
What is a sign that there are pubic lice in the eyelashes?
Inflammation
When is itching caused by pubic lice worsened?
At night as this is when they feed
Why is important if a person has pubic lice but no symptoms?
They can still pass the lice on to other people
What HAS to used first line for treating public lice?
Insecticides
What are two insecticides that can be used to treat pubic lice?
Permethrin 5% (Lyclear cream)
Malathion 0.5% (Derbac-M)
How are insecticides applied in the treatment of pubic lice?
Apply to the whole body and leave overnight/for 12 hours then wash off
Repeat the application after a week
Who can permethrin 5% (Lyclear) not be provided to OTC?
People under 18 - would need to see a doctor
What is some non-drug management for pubic lice?
Wash clothing and bedding at at least 50
Vacuum the house
Treat al contacts at the same time
Avoid close contact until treated
What should you do if a patient’s eyelashes are affected by pubic lice?
REFER
What do headlice look like?
Grey-brown insects about 1-3mm long with 3 pairs of legs
How many eggs can a female head louse lay in its lifetime? Where are the eggs found?
300 - eggs are attached to the base of the hair shaft
How long does it take for headlice eggs to hatch and then mature?
7-10 days to hatch then 10 days to mature
How long do head lice live for?
1-2 months
What are nits
The empty white egg shell stuck very strongly to the hair
Is the presence of nits a sign of current headlice infestation?
No
Are nits removed by headlice treatment?
No
