Parasitology
Lab-16 (D.latum + H.nana)
1- Diphyllobothrium latum (fish tapeworm):
1- It is the largest human tapeworm 3-10 meters in length
2- definitive host : man , dog , cat
3- intermediate host : 1) first : freshwater crustacean (copepod)
2) Second : fresh water fish
4- habitat : small intestine ( jejunum – ilium )
5- infective stage to man : plerocercoid larvae
6- diagnostic stage to man : egg and gravid ( stool examination )
7- route of infection : eating raw or uncooked infected intermediate host fish
8- life cycle
غير هام
(( The adults of D. latum attach to the mucosa of small intestine by
scolex immature eggs are passed in feces, after maturation the oncospheres
develop into a coracidia larvae After ingestion of these larvae by a suitable
freshwater crustacean (the copepod first intermediate host) After ingestion of the
copepod by a suitable second intermediate host(fresh water fish) the procercoid
larvae are released from the crustacean and they develop into a plerocercoid larvae
(sparganum) which is the infective stage to humans Humans can acquire the
disease by eating raw or uncooked infected intermediate host fish the plerocercoid
develop into mature adult tapeworms in the small intestine. Maturation of the
parasites occurs within 20 days and the adult worm can release the eggs in the small
intestine and pass with feces as a diagnostic stage ))
9- morphology :
1- Scolex :
almond-shape - spoon-shape - deep
longitudinal grooves(dorsal and
ventral) - no hooks - 1-2mm
2- mature segments : broader than long - contain both male and female
organs
3- it has 3000 segment
4- egg : oval in shape with operculum at one end
10- Clinical Features: abdominal discomfort – diarrhea – vomiting - weight loss -
Vitamin B12 deficiency -intestinal obstruction.
2- Hymenolepis nana (dwarf tapeworm):
1- It is the smallest human tapeworm 15 to 40 mm in length
2- definitive host : man , mice , cat
3- intermediate host : none
4- habitat : small intestine ( ilium )
5- infective stage to man : cysticercoids larva - egg
6- diagnostic stage to man : egg and gravid ( stool examination )
7- route of infection : oral route - arthropod bite - autoinfection
8- life cycle
غير هام
(( The adult present in small intestine of human The eggs pass
as a diagnostic stage and are immediately infective when passed with the stool of
patient If the eggs are ingested by an arthropod intermediate host, they develop
into cysticercoids larva(Infective stage), which can infect humans or rodents (Difinitive
hosts ) by ingestion and develop into adults in the small intestine If the eggs are
ingested with contaminated hands,food or water from infected feces the oncospheres
(hexacanth emberyo ) inside the eggs are released and penetrate the intestinal villus
and develop into cysticercoid larva,which rupture the villus, then return to the intestinal
lumen, and develp into adult worm which attached to the intestinal mucosa and
develop into adults and start producing gravid proglottids ))
9- morphology :
1- Scolex :
1-2 mm - 4 suckers – one row of hooks – rectictile rostellum
2- mature segments : broader than long - contain both male and female
reproductive organs
3- neck
4- it has 200 segment
5- gravid segment : uterus with eggs
10- Clinical Features: weakness – headaches – anorexia - abdominal pain – diarrhea
Treatment : 1- Praziquantel is the drug of choice for Hymenolepis nana
2- Niclosamide is the drug of choice for Diphyllobothrium latum