3.5 - HUMAN HOOKWORMS AND STRONGYLOIDES Flashcards
- blood sucking nematodes causing anemia
- attaches to the intestinal mucosa
- soil-transmitted helminthes
human hookworms
Ancylostoma duodenale
old world hookworm
Necator americanus
new world hookworm
host
man
habitat
small intestine
MOT
skin penetration
infective stage
L3-Filariform
diagnostic stage
egg
- 56-60 um in length by 36-40 um wide
- Bluntly round ends
- Single thin transparent hyaline shell
- 2-8 cell stage of division
eggs
Hookworm eggs are most commonly described as
thin shelled eggs
young larva
Rhabditiform
- larger than the threadworm (strongyloides)
- more attenuated posteriorly
- longer buccal cavity
- genital primordium is smaller
rhabditiform larvae
Eggs of strongyloides and hookworms are very much similar, and the way for differentatiting them is by looking at their
rhabditiform and filariform
infective larval stage
filariform
- conspicuous - very visible, obvious
- inconspicuous - not visible, not obvious
filariform larvae (L3)
buccal spears are conspicuous and parallel throughout their lengths
Necator americanus
buccal spears are inconspicuous and traverse striations on the sheath in the tail region
Ancylostoma duodenale
- male - broad caudal bursa, rib like rays
- mouths have semilunar cutting plates
- Small cylindrical fusiform grayish-white nematodes
- Head is curved opposite to the curvature of the body
- They look like s-shaped worms
- Spicules are fused
- Female: darkly stained (bigger)
Necator americanus
- 5-9mm by 0.3 mm
- broad membranous caudal bursa with rib-like rays
male N. americanus
9 to 11mm by 0.35 mm
female N. americanus
- Slightly larger
- Head continues in the same direction as the curvature of the body
- Mouths: 2 pairs of teeth
- Spicules are split (separated)
Ancylostoma duodenale
smaller sized hookworm
N. americanus
larger sized hookworm
A. duodenale
s-shaped
N. americanus
c-shaped
A. duodenale
semilunar cutting plate
N. americanus
2 pairs of teeth
A. duodenale
bipartite (2 digits)
N. americanus
Tripartite (3 digits)
A. duodenale
long, fused and barbed spicule
N. americanus
simple and barbed spicule
A. duodenale
life span of N. americanus
14 years
life span of A. duodenale
1 year
more prevalent in the PH
N. americanus
blood loss from N. americanus
0.03 mL/day
blood loss from A. duodenale
0.15-0.25mL/day
MOT of N. americanus
percutaneous
MOT of A. duodenale
Percutaneous and oral route
life cycle
- eggs will shed in the soil
- rhabditiform larva
- filariform larva
- skin penetration
- lungs
- trachea
- cough
- swallow
- small intestine - final habitat
- copulate
- stool formation
- contact with soil
A. duodenale is also capable of infection causing ?, besides skin penetration
ingestion of larvae or larval ingestion
Ancylostoma spp. larvae can become developmentally arrested and dormant in tissues. Re-activated larvae may ?.
enter the small intestine
egg hatches after
1-2 days
development of rhabditiform to filariform
7-10 days
- skin at the entry of the site
- lungs
- small intestine
- iron-deficient type anemia / microcytic hypochromic anemia
- hypoalbuminemia
pathogenesis and clinical manifestations
Skin at the site of entry (Cutaneous)
o Ground Itch (Dew itch)
o Miner’s Disease
Lungs (Pulmonary)
o Bronchitis or pneumonitis (Wakana disease)
o Löffler’s syndrome - may also be observed
Small Intestine (Intestinal)
o Abdominal pain
o Steatorrhea - stool samples with too much fat
stool samples with too much fat
Steatorrhea
- DFS
- kato thick/katz
- concentration test
- harada mori
diagnosis
disadvantage of kato thick/katz
rapid clearance of hookworm eggs after 30-60 minutes
Recommended for species identification
Harada Mori
harada mori: sediments
hookworm larva
harada mori: upper end of the filter paper
S. stercoralis
Philippine setting
Necator > Ancylostoma
factors for transmission
- defecation in soil
- not wearing of shoes
- environmental factors
paratenic hosts
rabbit, lambs, calves, pigs
additional MOTs for Ancylostoma
ingestion, transmammary, transplacental
treatment
- albendazole
- iron supplement (ferrous sulfate)
o CN: Cat Hookworm
o Buccal cavity: 2 pairs of teeth
Ancylostoma braziliense
o CN: Dog Hookworm
o Buccal cavity: 3 pairs of teeth
Anyclostoma caninum
o If we get infected by Ancylostoma braziliense and Anyclostoma caninum
o The worms will be trapped under your skin or stuck in the subcutaneous tissues
Creeping Eruption (CLM)
Cutaneous Larva Migrans
Animal hookworms will not be able to complete their life cycle if they infect ? instead of cats and dogs
humans
associated eosinophilic enteritis
A. caninum
- mistaken as A. braziliense
- observed from civet cat
- hookworms of cats and dogs in Asia
- second most common hookworm infecting humans
Ancylostoma ceylanicum