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CESTODES
Diphyllobothrium latum (Fish tapeworm)
Infective Stage DH: Plerocercoid larva IH: Procercoid larva
Diagnostic Stage Unembyonated eggs
Definitive Host Man
Intermediate Host/s 1st: Freshwater copepod 2nd: Freshwater fish
Treatment
Clinical Features B12 deficiency (Megaloblastic Anemia)
Unique Features Raw fish consumption Rosette uterus
Spirometra mansoni (Sparganosis)
Infective Stage DH: Plerocercoid larva (spargana) IH: Procercoid larva *Man can be infected by both
Diagnostic Stage Unembryonated eggs
Definitive Host Dogs and cats
Intermediate Host/s 1st: Freshwater copepod 2nd: Snakes, frogs, fishes, man
Treatment
Clinical Features Edema and migrating tumor or nodules
Unique Features Drinking water with infected copepod Eating infected second IH Spiral uterus
Taenia saginata (Beef tapeworm)
Infective Stage DH: Cysticercus bovis (larva) IH: Eggs
Diagnostic Stage Eggs or gravid proglottids
Definitive Host Man (upper jejunum)
Intermediate Host/s Cattle
Treatment
Clinical Features Intestinal taeniasis (via adult worm)
Unique Features Absent hooks and rostellum 4 suckers Gravid segment: 15-20 lateral branches Mature segment: 2 lobes of ovary Eggs infect only cattle
Taenia solium (Pork tapeworm)
Infective Stage DH: Cysticercus cellulosae and egg* IH: Eggs
Diagnostic Stage Eggs or gravid proglottids
Definitive Host Man (upper jejunum)
Intermediate Host/s Pigs, man
Treatment Praziquantel, corticosteroids
Clinical Features Intestinal taeniasis (via adult worm) Cysticercosis (via larval stage) Neurocysticercosis (brain)
Unique Features 4 suckers with 2 rows of hooklets Gravid segment: 7-13 lateral branches Matura segment: 3 lobes of ovary Eggs infect pigs and humans
Hymenolepsis nana (Dwarf tapeworm)
Infective Stage Embryonated eggs (autoinfection) Cysticercoid (to fleas)
Diagnostic Stage Embryonated eggs
Definitive Host Man (proximal ileum)
Intermediate Host/s Optional: fleas or rats
Treatment Praziquantel
Clinical Features Hymenolepiasis (enteritis)
Unique Features 4 suckers and retractile rostellum Mature proglottids: 3 testis, 1 ovary Egg: Bipolar filaments
Hymenolepsis diminuta (Rat tapeworm)
Infective Stage DH: Cysticercoid in insects (man) IH: Embryonated eggs (to fleas)
Diagnostic Stage Eggs
Definitive Host Man, rodents
Intermediate Host/s Arthropod adults or larvae
Treatment Praziquantel
Clinical Features Minimal and non-specific
Unique Features 4 suckers and unarmed rostellumi Mature proglottids: sack like uterus Egg: lacks bipolar filaments
INTESTINAL NEMATODES
Enterobius vermicularis (Human pinworm)
Infective Stage Embryonated egg (ingestion or self inoculation or retroinfection)
Diagnostic Stage Eggs on perianal fold
Definitive Host Man (large intestine)
Reservoir Soil; may persist in linen, clothes, bed
Treatment Mebendazole
Clinical Features Enterobiasis - Nocturnal pruritus ani Migration causes appendicitis, vulvovaginitis, and infection
Unique Features Ova: D-shaped Males: with spicules
Trichuris trichiura (Whipworm)
Infective Stage Embryonated egg
Diagnostic Stage Unembronated egg in feces
Definitive Host Man (colon or cecum)
Reservoir Soil
Treatment Mebendazole / Albendazole
Clinical Features Rectal prolapse
Unique Features Egg: Bipolar plugs at each end Male: Coiled posterior end
Female
Male
Strongyloides stercoralis (Threadworm)
Infective Stage L3 Filariform larva (skin penetration)
Diagnostic Stage L1 Rhabditiform larva
Definitive Host Man and dogs (small intestine)
Reservoir Soil
Treatment Ivermectin / Albedazole
Clinical Features Dry cough, tracheal irritation, GI symptoms, larva currens
Unique Features Has parasitic and free living forms Parthenogenesis
Rhabditiform Larva (L1)
Filariform Larva (L3)
Adult male
Adult female
Ancylostoma duodenale Necator americanus (Hookworms)
Infective Stage L3 Filariform larva (skin penetration)
Diagnostic Stage Egg
Definitive Host Man and dogs (small intestine)
Reservoir Soil
Treatment Mebendazole/Albendazole
Clinical Features Itching at site of infection, anemia, growth and mental retardation
Unique Features Egg: thin shelled and colorless N. americanus: S shaped anterior end with semilunar cutting plates A. duodenale: C shaped curvature with two pairs of teeth
Rhabditiform larva (L1)
Filariform larva (L3)
Adult
TISSUE NEMATODES
Wuchereria bancrofti
Infective Stage Man: L3 larva Mosquito: Microfilaria
Diagnostic Stage Microfilaria in blood or lymph
Definitive Host Man
Intermediate host Anopheles minimus flavirostris, Aedes poecilus, Culex
Periodicity Subperiodic, Nocturnal
Clinical Features Acute adenolymphangitis, filarial fever, elephantiasis (chronic)
Unique Features 1:1 Cephalic space, non confluent body nuclei, graceful appearance
Brugia malayi Brugia timori
Infective Stage Man: L3 larva Mosquito: Microfilaria
Diagnostic Stage Microfilaria in blood or lymph
Definitive Host Man
Intemediate host Anopheles barbirostris, Mansonia bonnae, Mansonia uniformis, Anopheles, Culex
Periodicity Nocturnal only
Clinical Features Elephantiasis (only in the lower part of the limbs, not including scrotum)
Unique Features Sheathed with a 2:1 cephalic space Body nuclei: Indistinct & confluent, angular curvature
Onchocerca volvulus
Infective Stage Man: L3 larva Mosquito: Microfilaria
Diagnostic Stage Microfilaria
Definitive Host Man
Intermediate host Black fly (Simulium damnosum)
Periodicity Diurnal, 1 to 2 hours after dawn & 1 hour before sunset
Clinical Features River/Onchocercal blindness, Sclerosing keratitis in anterior chamber of the eye, Onchocercoma, Dermatitis, Leopard skin, Hanging groin
Unique Features Adult: annulations in its body; tail is hooked or sharply bent Microfilariae: Unsheathed; Nuclei do not extend to the tip of the tail
Trichinella spiralis
Infective Stage Encysted larvae (ingestion)
Diagnostic Stage Encysted larvae in the skeletal muscle
Definitive Host Man, pig, and bear
Intermediate host Man, pig, and bear
Treatment Albendazole/Mebendazole
Clinical Features Trichinellosis
Unique Features Spear-like, burrowing anterior tip
Toxocara canis (Dog ascarid) Toxocara cati (Cat ascarid)
Infective Stage Embryonated eggs with L3 larvae
Diagnostic Stage L3 larvae in tissues
Definitive Host Dogs and cats
Accidental Host Man
Treatment Albendazole or Mebendazole
Clinical Features Visceral larva migrans, Ocular larva migrans, Covert toxocariasis, Neurologic toxocariasis
Unique Features T. canis: narrow cephalic alae, 3 lips T. cati: broad cephalic alae, 3 lips Ova: golden in color, spherical to slightly pear shaped
Adult
T. cati
T. canis
Ancylostoma braziliense Ancylostoma caninum
Infective Stage Filariform Larva/L3 Larva (Skin penetration)
Diagnostic Stage Filariform Larva Tracks on Skin
Definitive Host Dogs and cats
Accidental Host Man
Clinical Features Cutaneous Larva Migrans/Creeping Eruption
Unique Features 2 pairs of teeth for A. braziliense 3 pairs of teeth for A. caninum
Buccal Capsule: A. caninum
A. braziliense
Adult
