Order Oxyurida and Spirurida

Question 1

What are the general features of Order Oxyurida?

Answer 1

Known as pinworm 
Direct lifecycle
Hosts - humans and horses 
Reduced pathogenicity 
Eggs are asymmetrical 
Oesophagus contain posterior bulb 
Females have pointed tail 
Males are smaller than females 
Males have single spicule 
transmission via ingestion of L3 egg

Question 2

What are the main features of the oxyuris equi species?

Answer 2

Infect horses
Adults located in large intestine
L4 feed on mucosal tissue and blood
Posterior end of females are pointed and males is pin shaped
Efggs are thick shelled, one cell with a mucousal plug and asymmetrical.
Eggs laid in perianal region of horses which contain morula or larvae

Question 3

What is the lifecycle of oxyuris equi?

Answer 3

Infection via embryonated eggs with food (pasture, hay, etc)
Females migrate to the anus and emerge into the enternal environment
The females lay many eggs embedded in a viscous substance which adheres the eggs to the perianal region
Will see yellow / grey crusts
Makes the horse itchy and will scratch against a pole and spread the eggs
Larvae development within the eggs

Question 4

What is another species from oxyuria?

Answer 4

Probstmayria vivipara

Question 5

what are the two superfamilies of Spirurida?

Answer 5

Superfamily Spiruroidea

Superfamily Filarioidea

Question 6

What are the main features of Spiruroidea?

Answer 6

Wide range of shapes
Posterior end of males are spirally coiled
Mainly Oviviparous (eggs contain L1)
Indirect lifecycle –> IH infection, ingestion of IH by DH

Question 7

What are the main features of Draschia megastoma?

Answer 7

Within horses
Adults in stomach, larvae within conjunctiva, skin and lungs –> form nodules
No teeth
Buccal vestibule (funnel shaped –> wider anterior and smaller cylindrical part)
2 lips
Eggs contain larvae that hatches quickly
IH = muscid flies

Question 8

What is the lifecycle of Draschia megastoma?

Answer 8

IH = flies
Females lay embryonated eggs, eggs/larvae passed in faeces
Worm larvae ingested by fly larcae
L1-L3 within fly
L3 reaches the mouthparts f the fly and when it feeds on the moist, warm surfaces of the horse, the larvae are stimulated and leave the fly

The larvae can be deposited around the mouth of the horse –> develop into adults in the stomach and cause gastric habronemosis

The larvae can also be deposited in wounds, perocular area, penis, prepuce, nostrils, etc –> cause severe pathology (no larval development) –> causes cutaneous / pulmonary habronemosis

Question 9

What are the main features of spirocerca lupi?

Answer 9

Hosts –> dogs
Adult parasites within the wall of the oesophagus and causes nodules
Immature stages can be within the stomach and dorsal aorta
IH = dung bettles
Eggs are ingested by IH, DH ingest infected IH. L3 released in stomach, reach aorta and migrate to oesophagus

Question 10

What are the main features of Gnathostoma spp.?

Answer 10

Within pigs, dogs / cats
PH = humans
thick worm
Anterior end has a cuticular swelling (doughnut) covered with rows of hooks
Body is covered in spines
Eggs have thickening at one or both poles of shell
Contain 2 IH = copepods and fish

Eggs passed in faeces, Develop in water and larvae hatch
Ingested by copepods, copepods ingested by fish, larvae molt to L3, DH ingests infected fish, mature in stomach and form nodules / ulcers

Humans can become infected by consuming raw freshwater fish containing L3 - VLM and OLM, do not mature

Question 11

What are the species of gnathostoma which infect the host?

Answer 11

Gnathostoma hispidum - stomach of pigs

Gnathostoma spingerum - stomach of dogs and cats, PH = humans

Question 12

What are the main features of Thelazia rhodesi?

Answer 12

Within ruminants and buffalo
Located in the conjunctival sac and lacrimal (tear duct) 
White worms 
Striations 
No lips 
Wide vestibule 
IH = flies 
Female worms lay larcae into lachrimal secretions, ingested by IH, L3 develops and migrates to mouth parts, transferred to DH when feeding around eyes

Question 13

What are the main features of Thelazia callipaeda?

Answer 13

Hosts - dogs, cats, foxes, humans
Located in conjunctival sac, underneath lids and membrane
IH = flies
Cause a lot of irritation due to striations

Question 14

What are the main features of Oxyspirura mansoni?

Answer 14

Hosts - birds (chickens, ducks)
Located in the corner of orbit, under membrane
Causes blindness
IH = cockroaches
Eggs deposited in eye, move to lachrymal ducts, mouth, swallowed, passed in faeces, ingestion by IH, reach infective stage, Ih consumed by DH, larvae within crop and mature into adults, move to the lachrymal ducts and matures.

Question 15

What are some features of Gongylonema pulchrum?

Answer 15

Hosts - ruminants, pigs, etc
Located in the submucosa of oesophagus and rumen 
Can infect humans 
IH = coprophagous beetles, cockroaches
Covered by plates / tubercles 
Infection via IH

Question 16

What are the general features of the superfamilt filarioidea?

Answer 16

Located in the blood / lymph, vessels, body cavity and CT
Indirect lifecycle –> arthropods as IH
Long and thin worms

Contain larvae or microfilariae –> no digestive tract

2 families
- Filariidae –> locate in skin / SC tissues. Cause lesions that attract IH

• Onchoceridae

Question 17

What are the main features of Parafilaria multipapillosa?

Answer 17

Horses
Adult females located in nodules in the subcutaneous and intermuscular CT
IH = haematobia fly

The skin nodules formed by the adults open and blood that contain larvae flow onto the skin of host. the IH ingest the L3 larvae on the body of the host. The IH then transfer the larvae when they feed again.

Mainly occurs in spring/summer, not in winter –> occurs annually for 3-4 years then resolves

Question 18

Stephanofilaria spp.

Answer 18

Found within the skin of cattle
Transmitted by Haematobia fly (Buffalo fly)
Common in cattle in QLD
Same lifecycle as Parafilaria

Question 19

What are the main features of Dirofilaria immitis?

Answer 19

Family Onchocercidae
Heartworm
Areas of tropical and subtropical regions
Causes severe cardiopulmonary pathology and death
Chemoresistance has developed - geographical range has increased in last 10 yrs
Can infect humans but do not mature

Adults - elongated, filiform worms, females longee than males. Viviparous. Males posterior end is curled. located in the pulmonary artery and R ventricles. R atrium and caudal vena cava are infected if heavy infestations occur. Depends on size of animal’s heart

Microfilaria - found within blood, no digestive tract, nonprogressive motility, have a tapering cephalic end and a straight caudal end

Question 20

What is the lifecycle of dirofilaria immitis?

Answer 20

Found within over 30 species - most common DH is dogs, cats can be infected but not suitable hosts
Can survive 5-7 years in dogs
IH = mosquitoes (females)
D. immitis habours intracellular bacteria called Wolbachia sp. which is an essential aspect for the survival and reproduction of heartworm. Used as a target of control (provide antibiotics) –> is involved in the pathogenesis of the disease.

Lifecycle is 6-9 months –> mosquitoes become infected with microfilariae when taking blood from infected host –> larvae mature to L3, migrate to mouthparts, when mosquito feeds next, the larvae leaves mouthpart into host via the puncture wound from IH. Travels through the skin, molts to L4, migrates to abdomen and then heart where they mature. Originally in smaller pulmonary arteries before migrating upstream to larger arteries into the heart (worms increase in size)

Question 21

What is the main features of Onchocerca cervicalis?

Answer 21

Hosts - horses
Located in the funicular portion of the nuchal ligament
Adult worms - females very long, striated
Microfilaria - most numerous in the skin over the linea alba, face and neck
IH = midges (Culicoides spp)
Causes hair loss and reaction to the microfilaria

Question 22

What species of Onchocercida are within cattle and their locations?

Answer 22

Oonchocerca gutturosa –> nuchal ligament

Onchocerca lienalis –> gastrosplenic ligament

Onchocerca gibsoni * –> coiled in nodues of the briskit, stifle and hip of cattle –> affects meat quality

Setaria labiatopapillosa –> located in peritoneal cavity

Question 23

What speces of Onchocercida are within horses and their locations?

Answer 23

Onchocerca cervicalis –> funicular portion of nuchal ligament

Setaria equina –> located in peritoneal and pleural cavities, etc.