Ascarids Flashcards
Ascarid lifecycle
Ascarid of pigs and humans
Ascaris suum
Ascaris lumbricoides
Ascarid of horse and donkey
Parascaris equorum
WHO significance of Ascaris lumbricoides
infects 1 billion people globally
Economic impact of ascarids?
Production loss
-lumina feeders, malnutrition, reduced weight gain, stunting of growth
Clinical Disease
- diarrhoea (yellow and pasty), colic, vomiting (may vomit worms)
- intestinal ileus, blockage, rupture -> peritonitis
- bile duct occlusion (cholestasis)
- gall stones (in humans)
Significane of hepatopulmonary migration?
Can cause mechanical and inflammatory damage to organs
Milk spots in pigs -> condemned at slaughter
Eosinophilic pneumonia - calves, piglets, pups, kittens, foals
- predisposes to viral and bacterial pneumonias
- damaged lungs do not regenerate, FOALS!
Zoonotic ascarids in humans
- A.suum + lumbricoides infect humans
- Larvae of Toxocara canis and T. cati cause ocular and visceral larva migrans
- Larvae of anisakids cause eosinophilic/gastritis
Features of Toxocara Canis
- Direct and paratenic LC
- Transmammory and transplacental transmission
- L3 in egg -> HPM
PPP
- TP; 2 weeks (larva in lungs)
- TM+PH; 2-3 weeks
- eggs; 5 weeks
- zoonotic
Features of Toxocara cati
- Direct and paratenic LC
- Transmammory transmission
- L3 in egg -> HPM
PPP
- TM+PH; 3 weeks
- eggs; 8 weeks
- zoonotic
Features of Toxocaris leonina
- Direct and paratenic LC
- No HPM
PPP
-eggs; 7-10 weeks
Somatic migration of Toxocara
Some larvae in circulation end up in muscle instead of the lungs -> cause granulomatous lesions -> in 3rd trimester of pregnancy they move into the puppy TP or TM when suckling
Stage passed in faeces?
Unembryonated egg
What stage is infective?
Embryonated egg (L2 in paratenic, L3 in direct)
Duration taken to reach infectivity in the soil
2 weeks
Time that infective stage survives in soil?
5-10 years
What happens with somatic migration?
No eggs does not mean no infection! esp in breeding females
Diagnosis of ascarids
Faecal float
Identify in the correct order
Ascaris, Toxocara, Toxocaris, Parascaris
Identify this worm
Toxocara
Identify this worm
Toxocaris
Identify these worms in order
T. cati, T. canis, Toxocaris leonina
Pulic Health significance of Toxocara
- young humans
- larvae may be encapsulated in tissue for years
- > Uticaria or fever, hepatomegaly, eosinophilia, cough
- usually self limiting, but potentially serious - eosinophilic encephalitis, myocarditis etc
- ocular larval migration, treatment is unsuccessful
Ascarids of birds
Ascaridia spp (SI)
Heterakis spp (caeca)
Features of bird ascarids
- Direct LC
- PPP ~4-6 weeks
- eggs take 2 weeks to embryonate, viable for a year.
- Earthworms are transport host.
Ascaridia in chicken?
Ascardia galli
Effects of Ascaridia galli
- Larvae develop into adults in duodenal and SI wall -> synchronous eruption of larvae -> enteritis +/- haemorrhagic
- Adult worms -> intestinal occlusion
- Nutritional deficiency -> increased susceptibility to disease, poor growth etc
Lesions in affected turkey caused by?
Heterakis gallinarum
Features of Heterakis gallinarum?
- may cause caecak thickening in chickens
- tranmission of Histomonas meleagridis through egg
- protozoa highly pathogenic in turkeys “black disease”
- > necrotising typhlitis and focal necrosis of liver
Size of Heterakis?
1.5cm
Size of Ascaridia
12cm
How to manage ascardids in extensive system?
Challenging!
-Rotate pastures, especially young animals
How to manage ascarids in intensive system?
Hygiene - removal of faeces
Decontamination of premises (bleach, flame gun)
Rodent and pest control (cockroaches)
Don’t feed raw meat
Treat and quarantine new animals
Deworm at regular intervals
What animals to treat?
- clinically affected (watch out for obstruction by removing all worms at once)
- young animals to prevent likelyhood of disease (just prior to PPP)
- Prophylactic prevention of placental and lactogenic infections in pups and kittens
Outdoor system treatment regime (pigs)
- Treat growers at 8 weeks
- Treat sows and boars every 3 months to reduce pasture contamination
- treat sows 7-14 days prior to farrowing
- use levamisole, ivermectin, morantel, piperazine (narrow spectrum)
- test herd every 6 months
How to treat foals?
Deworm foals every 2 months (rotating MLs, BZs, pyrantel)
- start at 2 months old until they are 1 year old
- FEC prior to deworming in spring
- rotate pastures
How to treat puppies?
- treat at 2 weeks old and then every 2 weeks until 10 weeks old -> monthly until 6mo
- treat bitch at the same time
Treat adult dogs?
Treatment of the pregnant bitch
- can’t kill arested larvae but kill them when the emerge into the bloodstream.
- Fenbendazol 50mg/kg daily pour on from day 40 of pregnancy to 14+ days post whelping
- Selamectin topically 40d and 55d of pregnancy
- labeled use of monthly moxidectin topically
Kitten Treatment
- De-worm kittens at 3 weeks of age and then every 2 weeks until 8 weeks old, then monthly until 6 months old.
- de worm queen at the same time
How to de worm adult cat?
Faecal exam and deworm according to risk
-prevent lactogenic transmission to kittens by applying selamectin, moxidectin or emodepside topically to queen at the end of gestation
Lifecycle of fish born Anisakidae
Anisakidiasis
Aquired through injesting L3 in raw, insufficiently cooked or smoked fish.
Invasive (1hour - 2 days)
- penetrate gut mucosa
- Eosinophilic gastritis, eneritis
- acute vomiting and diarrgoea
- allergic response to antigens
**Cook well or freeze for more than 7 days
