The Parasite's Way of Life

What is the definition of PROTZOA

single cell eukaryotic parasites mostly microscopic

Do protozoa multiply and how ?

• Multiply within hosts

• A tiny dose can become an overwhelming infection

What are examples of Protozoa

• Giardia

• Cryptosporidium

• Toxoplasma

• Trypanosoma

Protozoa causes what ?

Cause disease through cell invasion/replication and inflammation; some have vector-borne transmission.

What is the definition of helminths

Multicellular worms; adults easily visible to the naked eye

How and do helminths multiply?

Do not multiply inside the animal; produce eggs and larvae. Burden reflects exposure

What are examples of Helminths

Roundworms, tapeworms, flukes

What are the causes of Helminths what do they do

Cause disease through migration, tissue damage, obstruction, blood loss, nutrient competition

What is the defintion of arthropods

Multicellular, segmented body, jointed legs; visible

Do arthropods multiply ?

Many are temporary visitors that feed and leave; some (lice, mange mites) live and reproduce entirely on the host.

What are examples of arthropods

Insects – Flea, mosquito

Arachnids – Ticks and Mites

What can some arthropods cause

Can damage skin/hide, hypersensitivity, disease transmission

What is the definition spurious parasite

is a real parasite of another animal, eaten and passed straight through — the dog that eats sheep feces and passes sheep parasite eggs in its faeces.

what is the definition of pseudoparasite

was never an organism at all: pollen, plant hairs, air bubbles.

The role is DEFINITIVE host: What happens there?

• Where the parasite reaches sexual maturity, or where sexual reproduction occurs.

e.g. cats for Toxoplasma gondii

The role is INTERMEDIATE host: What happens there?

• A required host in which larval or asexual development occurs.

• Some cycles use two, in sequence.

• e.g. snails and slugs for lungworms

The role is PARATENIC (transport) host: What happens there?

• The parasite survives but does not develop.

• Not required — it bridges a gap in the food chain

The role is RESRVOIR host: What happens there?

• A host population that maintains the parasite in nature and acts as a source for others.

• Usually shows little or no disease

The role is ACCIDENTAL host: What happens there?

Infected outside the usual cycle. The cycle normally stops there — hence "dead-end"

The role is VECTOR host: What happens there?

Transfers the parasite between hosts. A biological vector supports development or multiplication and may also be the intermediate host; a mechanical vector simply carries it → L05

The route is via faecal-oral how does that occur

• Swallowed from a contaminated environment

• (pens, yards, litter trays, pasture, water).

How do we prevent faecal-oral from entering into the system

Pick up faeces quickly; manage stocking density; protect food and water from contamination.

The route is via Eaten (predation/offal): how does it enter

The next host eats the last one (raw meat, offal, rodents, scavenging).

How do we prevent Eaten (predation/offal) from entering into the system

Cook meat; no raw offal; stop scavenging

The route is skin pentration: how does that occur

Infective larvae actively penetrate skin from soil, bedding or wet ground.

How do we prevent Skin penetration (percutaneous) from entering into the system

Keep animals off heavily contaminated ground; improve drainage and bedding hygiene; use protective footwear/gloves for handlers.

THe route is vector-borne: how does that occur

A biting arthropod injects it (mosquito, tick, fly, flea).

How do we prevent vector borne from entering into the system

Kill or repel the vector with preventives; reduce vector

habitat; use year-round prophylaxis in at-risk animals.

The route is direct contact: how does that occur

Animal-to-animal spread with little or no environmental stage (close contact, grooming, shared housing).

How do we prevent direct contact from entering into the system

Isolate cases; treat all in-contact animals; improve hygiene of shared equipment and housing.

The route is sexual: how does that occur

Transmitted at mating (natural service or AI).

How do we prevent sexual contact from entering into the system

Use AI where possible; test and certify breeding animals; apply biosecurity protocols for semen and embryos.

The route is vertical: how does that occur

Dam to offspring via placenta, milk or peripartum exposure.

How do we prevent vertical contact from entering into the system

Time treatments around late gestation and early lactation;manage colostrum and nursing; design herd protocols, not one-off treatments.

The route is latrogenic: how does that occur

We move it with needles, instruments, transfusions or equipment.

How do we prevent iatrogenic contact from entering into the system

Use single-use needles; follow strict aseptic technique; screen donors and sterilise equipment correctly.