NewLec30-09-62Cysticercosis

Cyclophyllidean group  Vitelline gland compact and unpaired, near the ovary  The genital pore is marginal  Each proglottid usually contains one or two sets of male and female reproductive organs



Cyclophyllidean group  Life cycle  Heteroxenous (Indirect), requiring one intermediate hosts  Vetebrate intermediate host  Invertebrate intermediate host

Life cycle of the Cyclophyllidean Tapeworms Vertebrate Intermediate host or Invertebrate Intermediate host

Life cycle of Cyclophyllidean  Egg ---> Onchosphere ---> Cysticercoid ---> Adult  Egg ---> Onchosphere ---> Cysticercus ---> Adult  Egg ---> Onchosphere ---> Coenurus ---> Adult  Egg ---> Onchosphere ---> Hydatid cyst ---> Adult



Life cycle of Cyclophyllidean  Cysticercoid  a small larva containing a scolex withdrawn into a fold of the body  Cysticercus  a bladder into which is invaginated a single scolex

Life cycle of Cyclophyllidean  Coenurus  similar to the cysticercus but with many scolices  Hydatid cyst  a large cyst containing free individual scolices, brood capsules from which these are generated, and daughter cysts.





ac 2 mm bd 0.5 mm

a b 0.5 mm 200 mm c 50 mm

ab c 1 mm

ab 2 mm 1 mm



Order Cyclophyllidea 14 families of the order have been recognised 6 families found in domestic animals and man are important

Order Cyclophyllidea 1. Family Mesocestoididae 2. Family Anoplocephalidae 3. Family Davaineidae 4. Family Dipylididae 5. Family Hyminolepididae 6. Family Taeniidae

Family Taeniidae  Normally the large tapeworms (except Echinococcus spp.)  The gravid segments are longer than they are wide

Family Taeniidae  The rostellum is usually armed with a double row of large and small hooks which have a characteristic shape

Family Taeniidae  The ginital pore is single and irregularly alternating

Family Taeniidae  There are, as a rule, a large number of testes  The ovary is situated in the posterior part of the proglottid

Family Taeniidae  The uterus has a median longitudinal stem and lateral branches  The eggs in gravid segments are typical of the family (radial striation)

Family Taeniidae  The egg is usually seen in the faeces without its outer shell (capsule)  Two envelopes separated by septa, so that the egg-envelope looks thick and radially striated

Family Taeniidae  Differentiation of genera and species is based on  Number and sizes of rostellar hooks  Morphology of mature segments  Number of uterus branches

Proglotid of T. solium



Family Taeniidae Adult tapeworms measure from ten to hundreds of centimeters in length, depending on the species

Family Taeniidae  The scolex has four suckers and a nonretractable rostellum armed with two rows of hooks (except for T. saginata)

Family Taeniidae The segments are more or less rectangular Unilateral genital pores alternating irregularly from one side to the other along the strobila



Family Taeniidae Gravid taeniid segments are shed and exit from the carnivorous definitive host by way of the anus

Family Taeniidae The segments crawl about on the surface of the fecal mass, emptying themselves of their eggs (oncospheres) in the process

Family Taeniidae  If ingested by a suitable vertebrate intermediate host, the egg hatches and hexacanth embryo enters the wall of the intestine and migrates to its organ of predilection

Family Taeniidae  Usually the liver and peritoneal membranes or the skeletal and cardiac muscles

Family Taeniidae  Here the hexacanth embryo grows, cavitates, and differentiates to form the second-stage larva, which is infective to the definitive host

Family Taeniidae  The fully developed second-stage larva of the family Taeniidae consists of a fluid- filled bladder with one or more scolices often called a bladderworm

Family Taeniidae  When a second-stage larva is ingested by a suitable definitive host, the bladder is digested away, the scolex embeds itself in the mucosa of the small intestine

Family Taeniidae Eggs of taeniid tapeworms first appear in the feces in six to nine weeks after ingestion of the larva

Family Taeniidae The larval stage found in intermediate host (vertebrate) is a cysticercus, a coenurus or an echinococcus (hydatid) cyst

Family Taeniidae  Taenia solium (Pork tapeworm)  T. saginata (Beef tapeworm)  T. taeniaeformis (Hydatigena taeniaformis) (Cat and Dog tapeworm)  T. hydatigena (Dog tapeworm)  T. pisiformis (Cat tapeworm)  T. multiceps (Multiceps serialis) (Dog tapeworm)  T. ovis (Dog tapeworm)  Echinococcus granulosus (Dog tapeworm)  E. multilocularis (Dog tapeworm)





Basic kinds of tapeworm’s cysts  There are five basic kinds of second-stage larvae (cysts).  Cysticercoid  Cysticercus  Strobilocercus  Coenurus  Hydatid

Basic kinds of tapeworm’s cysts  A cysticercoid is a form of larval tapeworm resembling cysticercus, but having the cyst small, almost devoid of fluid, and provided with a caudal appendage, as in Hyminolepis

Basic kinds of tapeworm’s cysts  A cysticercus is a larval form of tapeworm, consisting of a single scolex enclosed in a bladder-like cyst  A strobilocercus is a cysticercus that has already begun to elongate and segment while still in the intermediate host

Basic kinds of tapeworm’s cysts  A coenurus consists of a single bladder with many scolices, each with the potential of developing into a mature tapeworm

Basic kinds of tapeworm’s cysts  A hydatid cyst is a larval cyst stage of the tapeworms Echinococcus granulosus and E. multilocularis, which contains daughter cysts, each of which contains many scolices

Family Taeniidae  There are two kinds of hydatid cysts  Unilocular hydatid cysts  Alveolar hydatid cysts (Multilocular cysts)

Cysticercosis  Cysticercosis is an infection with cysticerci  In various animals it occurs as cysts found in striated muscles and causes no adverse symptoms (called also beef measles, pork measles, and sheep measles)

Cysticercosis  The cysticercus of the canine taeniid tapeworm Taenia hydatigena migrates through the liver tissue and encysts on the the peritoneal membranes of cattle, sheep, swine, and certain wild ungulates