Umm Al-Qura University بسم الله الرحمن الرحيم Umm Al-Qura University Health Sciences College at Al-Leith Department of Public Health Lecture (14)

Siphonaptera Fleas البراغـــــــــــــيث

Objectives 1/ Define of Fleas species. 2/ Define Fleas classification, Geographical Distribution, External morphology, Life cycle, Adult behavior and Medical important. 3/ Understand the role of Fleas in Transmission of parasitic diseases. 4/ Understand the Mechanisms of Fleas diseases Transmission to human. 5/ Define Treatment of Fleas diseases and Prevention. 6/ Apply of Fleas control methods.

Phylum: Arthropoda Class: Insecta Subclass: Pterygota Classification: Phylum: Arthropoda Class: Insecta Subclass: Pterygota Order: Siphonaptera

Families: 1- Pulicidae

Distribution A world wide distribution External morphology

Adults are relatively small (1-8.5 mm) More or less oval insects Compressed laterally and varying in colour from light to dark brown. Wings are absent

There are three pairs of powerful and well developed legs There are three pairs of powerful and well developed legs. The hind pair of which are specialised for jumping. The legs and also much of the body are covered with bristles and small spines.

The head is triangular in shape bears a pair of conspicuous black eyes and short three segmented antennae. The mouthparts point downward.

Each thoracic segments has a conspicuous dorsal plate.

المشط الصدري pronotal comb genal combالمشط الخدي

Life cycle

A female flea that is ready to oviposit may leave the host to deposit her eggs in debris accumulates in the hosts dwelling place.such as rodent burrows or nests.

With species that occur on man or his domestic pets, such as cats and dogs females often lay their eggs in or near cracks and crevices on the floor amongst dust, dirt and debris.

Sometimes however eggs are laid while the flea is still on the host and these usually, but not always fall to the ground. Eggs are very small, oval or roundish in shape white or yellowish.

They are thinly coated with a sticky substance which usually results in them becoming covered with dirt and debris.

Adult fleas may live for up to 6-12 months, or possibly two years or more and during this time a female may lay 300-1000 eggs mostly in small batches of about 15-30 aday.

Eggs hatch within about 2-14 days depending on species of flea, temperature and also humidity. Larva has a small blackish head with a very small pair of antennae, followed by 13 segments. The last segment ends in a pair of finger-like ventral processes termed the anal struts.

The presence of these struts on the body distinguish larval flea from all other types of insects of medical importance.

دورة الحياة: Life cycle

Larvae are very active. They avoid light and shelter in cracks or amongst debris on floors of houses or at the bottom of nests and animal burrows.

Sometimes larvae found on people who have unclean habits and dirt clothes and occasionally in beds.

Larvae feed on almost any organic debris including the hosts faeces and partly digested blood envacuated from the alimentary canal of adult fleas.

Larvae are scavengers and feed on small dead adult fleas of their own kind. There are usually three larval instars, but in some species there are only two instars.

The larval period may last as little as 10-21 days and may be prolonged more than 200 days by unfavourable condition.

Mature larvae are about 5mm long. About two to three days after having spun a cocoon around itself the larva pupates within the cocoon.

Adult emerge from the pupa after about 7-14 days. The lifecycle from egg to adult emergence may be as short as two to three weeks for certain species under optimum conditions.

Behaviour:- Fleas avoid light and there fore usually found sheltering amongst the hair of animals on man under his clothing or his bed. Fleas feed several times during the day or night on their hosts.

While feeding fleas eject faeces composed at first of semi-digested blood of the previous meal and then excess blood taken during the act of feeding.

Although most species of fleas have one or two favourite specie of hosts. Fleas co jump about 18 cm vertically and 35cm horizontally.

Medical importance Flea nuisance Caused by their bites, which may result in discomfort and irritation.

People that become hypersensitive to flea bites can suffer from dermatitis and inhalation of flea faeces can cause allergies.

Plague: Bubonic plague caused by Yersinia pestis is a zoonosis being primarily a disease of wild animals, especially rodents.

Flea-borne endemic typhus or murine typhus caused by Rickettsia mooseri

Thanks Radia 47