FLEA (Siphonaptera)

General Characterstics:

·           These are wingless insect with laterally compressed body about 1.5-4 mm long.

·           The chitinous covering is thick, glossy surface and dark brown in color.

·           Compound eyes are absent but some species have large or simple eyes.

·           The abdomen has ten segments, the ninth abdominal segment have (both in male and female) dorsal plate called sensilium or pygidiumm which is covered with sensory setae.

·           The tergum of 9^th abdominal segment of the male is modified to form “claspers”.

·           The antennae are short and club like which recessed into the head.

·           The legs are long, strong and adopted for leaping, the 3^rd pairs of legs are much longer than others, an adaptation for leaping on and off their hosts.

·           In some species there are a number of large spines on the head and thorax known as “Combs or Ctenidia”.

·           The spine which present on head is called “genal comb” and which are present at the posterior border of the 1^st thoracic segment is called “pronotal comb”.

·           Flea with ponotal and genal comb-      Ctenocephalides spp.

·           Flea with ponotal comb but no genal comb-    Ceratophyllus spp.

·           Flea without any type of comb-   Echidnophaga spp.    Pulex spp.   Xenopsylla cheopis

Life cycle:

·           Both sexes are blood sucker.

·           Egg – larvae- cocoon (pupa)- adult (complete life cycle).

·           They lay eggs on ground or on the host body which immediately drop off on the ground. The larvae are maggot-like and have a coat of bristle which have chewing mouth parts and feed on debris. Larvae moult twice then become a cocoon, a form of wooly puparium, from which the adult emerges.

·           In warm temperature, whole life cycle may require about 3 weeks; in low temperature it may extend up to 2 years.

·           Most of the flea’s life cycle is spent away from the host.

Flea of mammals:

·        Ctenocephalides canis

·        Ctenocephalides felis

Both are found in dog and cat and also in man but C. canis are more dominant in dog. Both are wide distributed. Both act as intermediate host for Dipylidium caninum (tape worm of dog)

·        Pulex irritans -  man, dog, cat

Cosmopolitan in nature.It act as intermediate host for Dipylidium caninum and also causes “flea-bite” dermatitis.

·        Xenopsylla cheopis – Rodents; Africa, Asia, South America and parts of Asia.

It is called “oriental or black rat flea”.It acts as a main vector of “Plague” (Yersinia pestis) in man.

·        Spilopsyllus cuniculi – mainly rabbits but also found in ear of dog, cats.It acts as a main vector of Myxomatosis virus.

Flea of birds:

·        Ceratophyllus gallinae – domestic poultry

·        Ceratophyllus collumbae- domestic pigeon

Both are worldwide distributed.They are responsible for irritation, restlessness and even anemia.

·        Echidnophaga gallinacean – Mainly chicken but dog, cat, and man may also affect.They are called “stick-tight” flea is one of the burrowing fleas. They cause nodules formation in comb and wattles.

·        Tunga penetrans – Man, common name is “Jigger” flea. It is burrowing flea.

Morphological difference between Ctenocephalides canis and Ctenocephalides felis

Ctenocephalides canis	Ctenocephalides felis
The head is strongly rounded and slopes markedly.	The head is elongated and slopes gradually.
The first spine of genal comb is half as long as the second.	The first spine is near about same in length in compare to the second spine.

 

            

Pathogenesis and Pathology:

·           Due to biting of flea an allergic reaction is developed which is called “flea bite allergy” and as a result profound clinical signs are developed.

·           Flea bite allergy is a hypersensitive reaction to the flea saliva (contains hapten) released into the skin during feeding.

·           In dogs and cats the biting site of the fleas are the back, the ventral abdomen and inner thighs.

·           Some flea causes nodules and ulceration in comb and wattles of birds.

·           In addition to their direct effects, flea are also important in transmission of different pathogenic agents, like- Plague, tularemia, myxomatosis, salmonellosis, rickettsia, helminthes etc.

Treatment and control:

·        In flea bite allergy, if there is much discomfort corticosteroid may be used tropically.

·        Insecticides may be used, in the form of dust, spray or shampoo, should be applied to the animal at weekly intervals.

·        For dusting organophosphorous is used.

·        Melathione,methoprine, carbamide are used as dusting powder  for – cleaning of dog and cay house with insecticide.

·        Flea collar containing different insecticide is used.

·        Cleaning of animal environments, like bedding materials, carpets, habitats etc are important for controlling flea.

·        Recently an insect growth regulator or inhibitor, methoprone has been marked as an aerosol for direct application to bedding, carpets and other habitats of flea larvae. When chemical ingested by the larvae it prevents the emergence of adult flea from larvae.