Multicellular Parasites Flashcards
Platyhelminthes
flatworms dorsoventrally flattened bilateral acoelomates monoecious mostly (some diocious)
Turbellaria
free living flatworms
Monogenea
ectoparasites of cold water vertebrates
very little harm at normal levels
problem if in fish farms
monoxenous
Haptar
hold fast structures
Monogenea life cycle
- adults
- eggs
- oncomiracidium (ciliated stage, swims to find host)
ASpidobothria
bridge between parasitic and free-living flatworms
infect marine and fresh water invertebrates
faculatative in turtles, fishes
monoxenous
ASpidobrothria life cycle
- adults
- eggs
- cotylocidium
Trematoda subclasses
Aspidobothria Digenea (flukes)
Protandrous
male sex organs develop first
Digenean eggs released through:
sputum
feces
urine
miracidian
ciliated larvae infects first IH
sporocyst
asexual stage in 1st IH
Redia
feeds on host tissues, produces daughters
Cercariae
penetrates 2nd IH or is infective to DH
metacercariae
inside 2nd IH or infective to DH
Steps inside snail (1st IH)
mother/daughter redia
mother/daughter sporocyst
Fasciola hepatica
DH: humans
RH: sheep cattle rabbits
1st IH: snail
Fasciola hepatica life cycle
- adult flukes in biliary system
- eggs passed in feces
- in water, eggs hatch
- miracidium penetrates snail
- cercariae in water
- encysts as metacercariae in aquatic vegetation
- human eats metacercariae
- juvenille chews through liver
Diagnosis F. hepatica
fecal smear for eggs
false positive positive if a person eats non-infective eggs
Treatment F. hepatica
Triclabendazole
Control F. hepatica
don’t eat fresh watercress
fence off vegetation in low-lying watering holes
Fascioloides magma
“Liver Butterflies”
DH: wild ungulates–deer, sheep cattle
Only problematic in sheep
life cycle like F. hepatica
Dicrocoelium dentriticum
DH: sheep, cattle
no chewing through tissue
1st IH: terrestrial snail
2nd IH: brown ants (Formica)
D. dentriticum life cycle: interesting part
when inside brown ants, get into brain and change behavior: make them hang on the ends of grass so sheep eat them
Clonorrhis sinesis
" Chinese Liver Flukes" DH: humans 1st IH: snail 2nd IH: fish RH: dogs and cats
C. sinesis transmission to humans
eating undercooked fish
night soil fertilizer
C. sinesis pathology, diagnosis, treatment
carcinogenic so can lead to liver cancer
fecal smear for eggs
Proziquantel
Liver Flukes
F. hepatica
F. magna
D. dendriticum
C. sinesis
Fasciolopsir buski
DH: humans
1st IH: snail
RH: pigs
F. buski pathology/diagnosis
diarrhea, mucusy stool
fecal smear for eggs
night soil fertilizer perpetuates infection*
F. buski life cycle
- adult fluke in intestine
- eggs passed in feces
- get to water
- snail eats eggs
- cercariae
- metacercariae on aquatic vegetation
- human consumes MC on waterchestnuts, bamboo, lotus
Paramphistomum cervi
DH: domestic cervids (cows)
Problems caused by migration of juveniles from penetrating out of gut to stomach to rumen
Control: keep cattle away from low lying vegetation
Nanophyetus salmincola
“salmon poising fluke”
DH: dogs
1st IH: snails
2nd IH: Salmonids (salmon and trout)
RH: Muskellids (skunk and racoon–>do not experience salmon poisoning)
hyperparasitism b/c parasite also in fluke
Echinostoma spp.
DH: humans
1st IH: snail
2nd IH: snails, mussels
Allaria americane
DH: canids
1st IH: snail
2nd IH: tadpole
PH: snakes
Intestinal flukes
F. buski P. cervi N. salmincola Echinostoma spp. A. americane
Paragonimus westermani
DH: humans 1st IH: snail 2nd IH: fresh water crabs RH: feral cats cosmopolitan in tropics/asia
P. westermani and P. kellicotti pathology/diagnosis/treatment
chronic cough, more if wandering worms
fecal or sputum smear
Proziquantel
Paragonimus kellicotti
DH: animals only unless you’re drunk and have been dared
1st IH: snail
2nd IH: crayfish
Control strategies for all flukes
snail control: molluskocides kill indiscriminately
vaccine/drug development
increased sanitation: indoor plumbing/latrines
keep animals from water vegetation
change human behavior
Cestoda
tapeworms
all heteroxenous except 2
parasitic to all classes of vertebrates
Tegument
lining around outside of cestode body
increases surface area and nutrient uptake
Proglottids
segments of cestode
can mate with themselves or other worms
Gravids
oldest teguments
filled with eggs
break off from body, released through feces
Strobila
all proglottid segments of cestode
Pseudophyllidean vs cyclophyllidean
Pseudo: no oral suckers. Bothria instead & eggs released through birth pore into feces
Cyclo: 4 oral suckers. gravids released through feces
metacestode
juvenile stage. infective to DH
Stages pseudophyllidean life cycle
coracidium: infective to IH
procercoid: develops inside 1st IH
pleraceroid: develops inside 2nd IH
stages cyclephyllidean life cycle
cysticerroid cysticercus strobilocerus coencerus hydratid *all inside IH, infective to DH*
Caryophyllidean
third class of cestoda Archgetes spp.
Archigetes spp.
unsegmented worms
DH: bottom feeding fishes
IH: aquatic oligochaetes
have single set of reproductive organs
Neotany
sexual maturation of juvenile. happens in Achigetes spp.
can produce own eggs and infect more IHs.
Pseudophyllideans
Diphyllobothrium latum
D. latum
Broad Fish tapeworm DH: humans 1st IH: copepod 2nd IH: fish RH: lots DH infective stage: plerocercoid
D. latum pathology/diagnosis/treatment/transmission
verminous intoxication=nausea, diarrhea + vit b12 deficiency
fecal smear for eggs
Praziquantel
eating undercooked fish (Jewish grandmothers)
Sparganosis
result of infection by spargamun=pleraceroid of unknown origin
Contraction of sparganosis
- drinking water with infected copepods
- eating reptiles, amphibians, pigs, cats
- traditional medical practices
Treatment/diagnosis of sparganosis
surgery and praziquantel
physical identification of sparganum
Taenia saginata
"Human Beef Tapeworm" DH; Humans IH: cattle cosmopolitan anywhere beef is eaten infective stage to humans: cysticercus
Species Schistosoma
S. haematobium S. mansoni S. japonicum S. mekongi S. intercalatum
location/disease of S. haematobium
pelvic veins
urinary schistosomiasis
location/disease other 4 forms Schistosoma
mesenteric veins
intestinal schistosomiasis
Important Life cycle part Schistosoma
Egg: contains miracidium (infective to snail IH)
Cercariae: released in water, infective to humans
Rhlotaxis
cercariae are motionless in water until they feel vibrations of possible host to save limited energy
Pathology Schistosoma
liver fibrosis
impaired circulation
portal hypertension
hepatosplenomegaly
Treatment/Control Schistosoma
Praziquantel (Merck to give free drugs for indefinite future)
vaccine (unlikely in near future)
increased sanitation
snail control–indiscriminate killer
Pathology/Diagnosis/Treatment/control T. saginata
asymptomatic
fecal smear for gravids, look for 15-20 lateral branches
Praziquantel
Don’t defecate in cow pastures, freeze meat for a week
Taenia solium
Human Pork Tapeworm
DH: humans
IH: pigs, human
Pathology/diagnosis treatment adult T. solium
asymptomatic
fecal smear for gravids look for 7-13 lateral branches
praziquantel
Pathology/diagnosis/treatment cysticercosis
swiss cheese brain, other problems because of inflammation
imaging (ultra sound, MRI)
surgery
Taenia pisiformis
DH: dogs
IH: rabbits
infective stage: cysticerus
identified by square gravids in feces
Taenia taeniaformis
DH: cats
IH: rats
Infective stage: strobilocerus
Taenia multiceps
DH. canines
IH; sheep
infective stage: coenerus (softball sized)
If human ingests eggs, dead end intermediate host
Dipilidium caninum
Double Poored tapeworm cosmopolitan DH: dogs (humans if they eat fleas) IH: fleas Gravids identified by lots of visible eggs
Hymenolepis dimunata
DH: rats, humans IH: grain beetles (Tenebrionadae) asymptomatic fecal smear for gravids model parasite for tapeworms
Hymenolepis nana
Dwarf tapeworm DH: humans IH: beetles OPTIONAL infective stage: cysticercoid if human consumes eggs, cysticercoid can develop in villi, mature, and travel to gut.
Blood flukes
S. mansoni
S. japonicum
S. heamatobium
Lung flukes
Paragonimus westermani
P. kellicoti
cyclophylidea
T. saginata T. solium D. caninum T. pisiformis T. taeniaformis T. multiceps H. dimunata H. nana Echinococcus granulosus E. multiocularis
Echinococcus granulosus
causes Echinococcosis 3 segmented worm (very small) DH. carnivores IH: herbivores **humans only act as accidental IH, never get adult worms** cosmopolitan sylvatic cycles: 1. wolf-moose 2. wolf-reindeer 3. lion-warthog Domestic cycles: 1. dog-sheep (most important) Infective stage: hydatid
Transmission E. granulosus
- Kenyan tribe eats dog intestine
- Turkana tribe does not bury dead; leaves them for animals
- dogs fed hydatid and dogs lick children
- tanners in Lebanon use dog feces in tanning
- sheep herding
E. granulosus pathology/diagnosis/treatment
dependent on location of hydatid. If reptures, anafalactic shock, death
MRI or ultrasound imaging
usually surgery if accessible or Abendazole
E. multilocularis
DH; dog, fox
IH: rodents
Infective stage: multilocular hydatid (spreads through body like cancer)
Pathology/diagnosis/treatment E. multiolularis
depends on location
imaging but often mistaken for malignant tumor
very difficult. Abendazole ok. Praziquantel stimulates growth
Two worms that are/can be monoxenous
Archigetes spp.
H. nana
Worms whose eggs cause pathology in humans
P. kellicotti sparganosis T. solium (swiss cheese brain) H. nana E. granulosis E. multilocularis
