1. Mallophaga
Three suborders:
Amblycera
Ischnocera
Rhynchophthirina
Haematomyzus elephantis :
African & Indian elephants
Haematomyzus hopkinsi on warthogs
2. Sub-order Anoplura
Superficially resemble chewing lice with their small, wingless, flattened bodies, but anopluran heads are narrower than the prothorax
Sucking mouthparts are retracted into the head when not feeding
Each leg has a single tarsal segment with a large claw (adaptation for clinging to host hair)
First legs are often smaller than other legs, and the third legs and their claws are usually largest
Mode of feeding
Solenophage – arthropods that introduce their mouthparts directly
into a blood vessel to withdraw blood
Telmophage – arthropods with mouthparts that cut through the skin
and vessels to produce and feed from a small pool of blood
Anoplurans are true solenophages
Pediculus humanus – body lice
Body lice – P. humanus humanus (a.k.a P. humanus corporis or P. humanus vestimenti)
Body lice descended from ancestral head lice after humans began wearing clothes.
Body lice more common in cooler parts of the world; in tropical areas people who wear few clothes usually have only head lice
Body lice spend most of their time in their host’s clothing, visiting the host’s only during feeding
Eggs (nits) of body lice are cemented to fibers in clothes and have a cap at one end to admit air and facilitate hatching
Pediculus humanus – head lice
Head lice – P. humanus capitis
Smaller than body lice
Their nits are cemented to hairs
Most prevalence on the back of the neck and behind the ears (do not infest eyebrows or eyelashes)
Easily transmitted by physical contact and stray hairs, even under good sanitary conditions!!
Heaviest infestations are associated with crowded condition and poor sanitation
Life Cycle – head louse
The louse feeds on blood several times daily and resides close to the scalp to maintain its body temperature.
They are hard to see and are often confused for dandruff or hair spray droplets.
Nits are laid by the adult female and are cemented at the base of the hair shaft nearest the scalp.
The nymph looks like an adult head louse, but is about the size of a pinhead.
Disease
Pediculosis (body/ head lice infestation) is not life threatening (unless it carry a disease organism)
Bites can cause red papule and may continue to exude lymph
Intense pruritis will induce scratching > dermatitis > 2obacterial infection
Years of infestation lead to a darkened, thickened skin (Vagabond’s disease)
If left untreated, the hair becomes matted together, a fungus grows,
and the mass develops a fetid (foul/ rotten) odor (plica polonica) – large
Lice as Vectors of Human Disease-(Louse-borne)
Transmitted by P. humanus humanus (body louse):
Typhus (epidemic)
Trench fever
Relapsing fever
Phthirus pubis
- Crab louse (or crabs)
- Grasping tarsi on the two larger pairs of their legs are reminiscent of crab’s pincers.
Life Cycle
Have three stages: egg, nymph and adult.
Eggs (nits) are laid on a pubic hair shaft
If adults are forced off the host, they will die within 24-48 hours without a blood feeding.
Pubic lice are transmitted from person to person most-commonly via sexual contact,
although fomites (bedding, clothing) may play a minor role in their transmission.
4 Steps to Lice Eradication
Prevention: Inspect frequently.
Treatment: May include use of lice shampoo.
Treatment of Belongings: Wash bedding and clothing in hot soapy water. Dry using “high heat” cycle. Bag other items.
Post-treatment Inspection: Inspect individuals up to 10 days following treatment.
Prevention of Head Lice
Head lice are spread by infested people.
Pets cannot get or spread an active case of head lice.
Only people get head lice.
Children should not share combs, hats and personal belongings.
Frequent inspections are a must.
Search entire head, especially back of head and neck.
Part hair section by section.
Remove lice with tweezers or lice comb.
Be careful not to spread lice to
others while inspecting.