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Phthiraptera

Johari Jalinas

Medical and Urban Entomology

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Phthiraptera

The name Phthiraptera is derived from the

Greek "phthir" meaning lice and "aptera"

meaning wingless. The literal translation,

wingless lice, is appropriate for all members of

the order

Parasitic Lice / Biting Lice / Sucking Lice

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Characteristics

Wingless (apterous) ectoparasites Three nymphal instars

Hemimetabolous (having a simple metamorphosis, i.e. nopupa)

Mouthparts - mandibles for chewing lice, stylets for suckinglice

Tarsi 1 or 2 segmented (1 in Anoplurans)

Dorsoventally flattened head

Development of operculum in egg

Reduced labial palps Reduced compound eyes and no ocelli

Antennae are 3 to 5 segmented and capitate

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Major Families:

Philopteridae (Bird Lice) -- a large family (500 species) containingseveral species that are pests of poultry.

Trichodectidae (Mammal Chewing Lice) -- ectoparasites ofmammals, including pests of domestic cattle and sheep (e.g.,Bovicola bovis).

Menoponidae (Poultry Lice) -- includes several important pests ofpoultry (e.g., Menopon gallinae and Menacanthus stramineus).

Haematopinidae (Ungulate Lice) -- ectoparasites of cattle, deer,pigs, horses, and zebras (e.g., the hog louse, Haematopinus suis).

Pediculidae (Body Lice) -- includes the human body louse (Pediculus

humanus humanus) and the human head louse (P. humanuscapitis).

Pthiridae (Pubic Lice) -- includes Pthirus pubis, the human pubic (orcrab) louse.

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Suborder Mallophaga (chewing lice)

The chewing lice are sometimes consisted to be twosuborders, the Amblycera and Ischnocera.

They are small, flat, wingless, parasitic insects with mouthparts formed for chewing. Legs and antennae are short.

Immature stages resemble the adults except for size. These insects feed upon feathers of birds or on hair and

skin scales of other animals. They are important pests ofdomestic fowl and animals, but they do not live on man.About 1/6 to 3/16 inch long when mature. The chicken

head louse,C

uclo

to

gaster hetero

graphus (Nitzsh)(Phthiraptera; Ischnocera: Philopteridae) is an example.

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Suborder Anoplura (sucking lice)

Anoplura are small, flat, wingless, parasitic insects withmouthparts formed for piercing and sucking. Legs andantennae are short. Immature stages resemble the adults.

These insects are found commonly on domestic animals,

but not on birds. The human louse belongs to this suborder.They feed by sucking blood and are important pests ofdomestic animals and man.

The human body louse has been responsible for millions ofhuman deaths through the centuries. They spread the

organism causing epidemic typhus from one person toanother. The hog louse, Haematopinus suis (Linnaeus)(Phthiraptera; Anoplura: Haematopinidae) is an example.

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Distribution

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Life Cycle

Lice have relatively short lives of 2-8 weeks

depending on the species. The female lays up

to 9 eggs per day on the hair or feathers of the

host. The nymphs resemble adults and

develop through 3 instars before they reach

sexual maturity.

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Life Cycle- Head lice

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Diseases elapsing fever (synonym: typhinia)is an infection caused by certain

bacteria in the genus Borrelia. It is a vector-borne disease that istransmitted through louse or soft-bodied tick bites.

Borrelia recurrentis is the only agent oflouse-borne disease.Pediculus humanus, is the specific vector. Louse-borne relapsingfever is more severe than the tick-borne variety.

Mortality rate is 1% with treatment; 30-70% without treatment.

Poor prognostic signs include severejaundice, severe change inmental status, severe bleeding, and prolonged QT interval on ECG.

Lice that feed on infected humans acquire the Borrelia organismsthat then multiply in the gut of the louse.When an infected lousefeeds on an uninfected human, the organism gains access when thevictim crushes the louse or scratches the area where the louse is

feeding. B. recurrentis infects the person via mucous membranesand then invades the bloodstream. No animal reservoir exists.

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elapsing fever

The human body louse is responsible for the spread ofrelapsing fever (Borellia recurrentis), epidemic typhus

(Rickettsia prowazeki), and trench fever (Rickettsia

quintana). epidemics amid poor living conditions, famine

and war in the developing world;[4] it is currently prevalent in

Ethiopia and Sudan.

Lice associated with domestic animals have also been

implicated in the transmission of disease (e.g., hog lice

spread pox virus and cattle lice spread rickettsialanaplasmosis).

Biting lice do not usually spread disease pathogens, but

heavy infestations in poultry can cause severe skin

irritation, weight loss, and reduced egg production.

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Trench fever

Trench fever (also known as "Five day fever," "Quintanfever," "Urban trench feveris a moderately seriousdisease transmitted by body lice] . The disease persistsamong the homeless. Outbreaks have been

documented, for example, in Seattle and Baltimore inthe United States among injection drug users and inMarseille, France, and Burundi.

The disease is caused by the bacterium Bartonellaquintana (older names: Rochalimea quintana,

Rickettsia quintana), found in the stomach walls of thebody louse.[3] Bartonella quintana is closely related toBartonella henselae, the agent ofcat scratch fever.

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Symptoms

It is usually characterized by skin irritation,

allergic reactions, and a general feeling ofmalaise

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Control and Treatments

Picture of a lice comb in use. The small dark

spots in the foam are lice.