(M) Nematoda: Secernentea: Strongylida (lecture-based) Flashcards
Necator americanus, A. duodenale, A. caninum, A. braziliense, A. cantonensis
Phylum
nemathelminths (round worms)
Class
Nematoda
Subclass
Secernentea
Order
Strongylida
Superfamily
Superfamily: Ancylostomatoidea
Superfamily: Metastrongyloidea
Superfamily: Ancylostomatoidea
Necator americanus
Ancylostoma duodenale
Ancylostoma caninum
Ancylostoma braziliense
Superfamily: Metastrongyloidea
Angiostrongylus cantonensis
Human hookworms
- Necator americanus
- Ancylostoma duodenale
Non-human hookworms
- A. caninum
- A. braziliense
- A. ceylanicum
Intestinal hookworm
Diganostic
Eggs in feces
Intestinal hookworm
Common pattern of development
- Eggs in feces
- Rhabditiform larva hatches
- Filariform larva in environment
- Filariform larva penetrates skin
- Adults in small intestine
Intestinal hookworm
Infective stage
Filariform larva
Intestinal hookworm
The Eggs are passed in the stool, they will hatch in how many days?
1-2 days
Intestinal hookworm
The Eggs are passed in the stool, they will hatch in 1 to 2 days to become the
rhabditiform larva
Intestinal hookworm
After 5-10 days, it will develop into
Filariform larva
Intestinal hookworm
Filariform Larva can survive for how many weeks?
3-4 weeks
Intestinal hookworm
What stage penetrates the skin?
Filariform larva
Intestinal hookworm
Reside there and mature into an adult
Small intestine
but before that, it went blood-lung phase
Intestinal hookworm
Some of this larva can become dormant in the intestine or the muscle.
A. duodenale
MOT
Manner of Transmission
* Penetration of Skin or Mucosa by the Filariform Larva.
* Ingestion of the filariform larvae in Water, Soil-contaminated Foods, or from the Fingers contaminated with Soil that contains the Filariform Larvae.
* Autoinfection is possible since the Egg may hatch inside the Intestine and thereby develop into Filariform Larval Stage.
* Through the Mammary Glands via the Milk.
Differentiation of human hookworms
Common name
New world hookworm (N. americanus)
Old world hookworm (A. duodenale)
Differentiation of human hookworms
Uncinariasis
N. americanus
Differentiation of human hookworms
Worldwide
both
Differentiation of human hookworms
Predominant in tropical countries
N. americanus
Differentiation of human hookworms
Predominant in temperate regions
A. duodenale
Differentiation of human hookworms
Jejunum
Both
Differentiation of human hookworms
Duodenum
N. americanus
Differentiation of human hookworms
Proximal Ileum
A. duodenale
Differentiation of human hookworms
Lifespan 15 years
N. americanus
Differentiation of human hookworms
Usually 3-5 years
N. americanus
Differentiation of human hookworms
1-6 years
A. duodenale
Differentiation of human hookworms
Route of infection: percutaneous and oral
both
Differentiation of human hookworms
Egg produced: 6k to 10k
N. americanus
Differentiation of human hookworms
Egg produced: 25k to 30k
A. duodenale
Differentiation of human hookworms
Bloodloss .03mL/day
N. americanus
Differentiation of human hookworms
Bloodloss .15mL/day
A. duodenale
Differentiation of human hookworms
Cephalic part bent ventrally assuming a
C-shape
A. duodenale
Differentiation of human hookworms
Cephalic part bent dorsally assuming an
S-shape
N. americanus
Clinical Manifestations
- “Ground-itch Lesion”
- Pain and itching at the site of Larval entry.
- The larvae that enter the skin cause dermatitis, which is often referred as the ground-itch lesion.
- There is pain and itching of the skin
- The usual site of entry is between its toe webs or the its feet and lower legs.
- Skin lesions are transient, which may not be noticed at all, but may have secondary bacterial
Cutaneous phase
Clinical Manifestations
- Leaving Ulcers that ooze out Blood and some Proteins.
Causes: - Hyperperistalsis
- Nausea
- Vomiting
- Diarrhea
- Bloody-mucoid Stool
- Anemia
Intestinal phase
Clinical Manifestations
create temporary leukocytosis, particularly eosinophils, and may result in pneumonitis.
Symptoms of Pneumonitis
* Fever
* Cough
* Dyspnea
* Chest Pain
Lung phase
Larva
Laboratory Diagnosis
- Stool exam
- Sputum
- Harada mori
Larva
Treatment
- Anthelmintic drugs such as albendazole and mebendazole, are the drugs of choice.
- It is usually given for 1-3 days.
- Commonly Infect Cats.
- Larva migrate from skin to subcutaneous tissue; do not mature but “creep” in subcutaneous tissue.
Ancylostoma braziliense
Ancylostoma braziliense AKA
cat hookworm
Ancylostoma braziliense
MOT
Skin penetration
Ancylostoma braziliense
Treatment
Thiabendazole
Life cycle: Ancylostoma braziliense
Diagnostic stage
Coming from the Animal’s eggs in the feces
Life cycle: Ancylostoma braziliense
Infective stage
Skin penetration of filariform larva
Life cycle: Ancylostoma braziliense
Definitive host
Animal
Life cycle: Ancylostoma braziliense
The Rhabditiform larva develops into what in the Environment?
filariform larva
- Commonly Infects Dogs
- Wide Buccal Capsule, with 3 Pairs of Large Equal-Sized Teeth.
- Eosinophilic enteritis (adult worm), itchy rash “cutaneous larva migrans”.
Ancylostoma caninum
Ancylostoma caninum
AKA
dog hookworm
Life cycle: Ancylostoma braziliense
MOT
Skin Penetration of Filariform Larvae
Ancylostoma caninum
Treatment
Thiabendazole
- The only Zoonotic Hookworm Species.
- Able to produce Symptomatic Infections in humans, with the Majority of Cases being in Southeast Asia.
- 2nd most common hookworm species infecting humans.
- Comprising between 6% and 23% of Total Patent Hookworm infections based on Recent Molecular based surveys in Asia.
Ancylostoma ceylanium
- A form of Dermatitis characterized by Serpiginous, Intracutaneous Lesions due to Migration of Nematode Larva.
- Usually it does not Infect Human.
Cutaneous larva migrans
Cutaneous larva migrans
Clinical manifestation
Papular, Erythematous, Pruritic Rash at entry point.
Cutaneous larva migrans
When does this occur? Narrowed Lesions, Linear, Slightly Elevated, Serpingenous with Intracutaneous tunnels.
After 2 - 3 Days
Superfamily of Angiostrongylus cantonensis
Metastrongyloidea
Angiostrongylus cantonensis
AKA
Rodent lung worm
- First described by Chen (1935) in Cantonese Rats.
- Identified in the Cerebrospinal Fluid of a patient with Eosinophilic Meningitis. (by Nomura & Lim in Tawain in 1944)
- In 1955, Mackerass and Sanders identified the Life Cycle of the Worm.
- Found in China, Tahiti, Hawaii, Philippines, Sumatra, Cuba, and India.
Angiostrongylus cantonensis
Angiostrongylos cantonensis
Infective stage
Accidental ingestion of gastropod or larvae
Angiostrongylos cantonensis
DF
Larvae migrate to brain
Angiostrongylos cantonensis
Where does the adult worm will live?
Pulmonary arteries
Intermediate host of Angiostrongylus cantonensis
Snail or slug
Angiostrongylus cantonensis
The female adult worm (pulmonary arteries) will lay eggs that hatch and yield the?
1st stage larva
Angiostrongylus cantonensis
Example of the snail or slug
A. canaliculatus
Angiostrongylus cantonensis
the Golden Apple Snail, is an important vector for A. cantonensis in China.
A. canaliculatus,
Angiostrongylus cantonensis
Infective stage to humans
L3 larva
taken from the snail
Angiostrongylus cantonensis
Incidental host
Humans
Angiostrongylus cantonensis
Clinical Manifestation
Eosinophilic meningitis
Angiostrongylus cantonensis
- Patients will just present High Level of Eosinophilia. By history taking, there might be a possible history of ingestions of snails or slugs.
- From the brain it can also go to the vitreous cavity in the vitreous canal infecting the eye.
Eosinophilic meningitis
Angiostrongylus cantonensis
Laboratory diagnosis
- Demonstration and identification of the larvae and young adults in the CSF.
- Eosinophilia in CSF.
- ELISA, CT Scan
Angiostrongylus cantonensis
Prevention & Control
Proper and Adequate Cooking of Snails. Eradication and Control of Rodents. Public Education.