Parasitology Test 1

Parasite

An animal or plant that lives on or in another organism and draws nutrients directly from it

Causes harm to the host

Parasite

Exhibits some degree of structural modification

Parasite

Endoparasite

Lives inside of the host

Infection _ disease

does not equal

Infection

establishment and possibly multiplication of organisms in body tissues

Microparasites

multiply within their definitive hosts, increases number of parasites within host

Macroparasites

does not multiply within hosts, reproduction leads to eggs or larva which need to leave the host, host does not end up w more parasites

Intracellular parasites

Live inside of cells

Extracellular parasites

Live outside of cells

Ectoparasite

live on or outside of host

Infestation

presence of macroparasite on outside of host

Obligate parasite

must be a parasite

accidental or opportunistic parasite

usually free living, does not NEED to be a parasite

Infectious

cause by or capable of being communicated by infection

Infective

form or stage of parasite capable of producing infection, depends on life cycle stage

Life cycle

parasite life history including all stages and hosts

Direct life cycle

one host cycle

Indirect Life cycle

2 or more hosts, more complex

Host

animal or plant that harbors and provides sustenance for a parasite

Definitive/Final Host

required for parasite, final point and where replication occurs

Intermediate host

necessary part of life cycle, parasite cannot sexually reproduce in host, asexual reproduction may or may not occur

Transport host or paratenic host

not required to complete life cycle, no development occurs

Abnormal or aberrant host

Animal not normally used as a host, often associated with disease

Pre patent period

time required after infection occurs of the definitive host for the parasite to reach sexual maturity, infection -> reproduction period. most organisms cannot be diagnosed until parasite becomes patent

Patent Infection

Mature infection in definitive host, reproduction can occur. from sexual reproduction -> death

Zoonosis

disease transmitted from animals to humans

Reservoir host

animal carrying an infection that can be transmitted to humans

Vector

agent transmitting disease (usually arthropod)

Mechanical vecotr

assists in the transfer of parasitic forms between hosts but not essential for the life cycle of the parasite

Biological vector

crucial part of life cycle, organisms in which the parasite undergoes essential development, multiplication, or both before being transmitted to the next host

Age Immunity

as hosts get older they become more immune to parasites

Number pathogenicity

fewer parasites in host means less disease/ better symptoms

Immunity prevents

disease but not infection/infestation

complex organisms have

complex immune responses

parasites require to recognize potential host

specific cellular receptors, pH levels, bile

Aggregation/overdispersion

number of parasites indicates level of disease

Negative binomial distribution

aggregation or overdispersion

aggregated parasite populations

hosts vary in susceptibility

susceptibility factors include

age, current diseases, nutrition, genetic differences

70/30 Rule

bottom 70% of animals have 30% of parasites, top 30% of animals have 70% of parasites

Parasites that develop and survive in the environment are at the mercy of

the weather; temperature and moisture

to kill a parasite in the environment

dry it out

three main categories of parasite control

interventions to reduce transmission of parasites, use of anti-parasitic drugs, and vaccines

one health approach

Integrates human, animal, and environmental health

Arthropods

bilaterally symmetrical, segmented, chitinous (cannot grow normally), grow by molting, possess complex body systems

Arthropods complex body systems

neurologic system, digestive tract, open circulatory system

Phylum Arthropoda

arachnids, insects, and crustaceans

arachnids

4 pairs of legs

insects

3 pairs of legs

Ticks

phylum: arthropoda, order: acari

ixodidae

hard ticks, can see mouth parts

hard shiny appearance

ixodidae

Scutum

females - cover .5-.25% of dorsal surface, males - covers entire dorsal surface

argasidae

soft ticks, look soft and squashy, mouth parts not visible

capitulum or gnathosoma

from body and above

basis capitulum

small part of head attached to mouth parts

idiosoma

body and below

scutum

round covering of body

tick paralysis

typically caused by toxin produced by female tick that attaches close to the central nervous system. tick can be attached for days before producing toxin, removing tick results in rapid recovery

tick borne illnesses are becoming more

prominent

Haller's organ

organ on first pair of legs that ticks wave around until they find CO2 - called questing

How ticks find hosts

by questing, detecting body odor and CO2, they can also sense heat, moisture, and vibrations

Life stages of ixodid ticks

egg, larva, nymph, adult

3 host tick life cycle

have one blood meal and molt in between stages

ticks - eggs

female lays eggs in environment

ticks - larva

small, have 6 legs, find a host for blood - feed for a few days and fall off

ticks - nymph

have 8 legs, lack genital opening, takes a blood meal, and feeds and drops into environment

ticks - adults

have 8 legs and genital opening, sex difference shown in scutum, mate on host, females drop off, lay eggs in environment and die

Tick attachment

ticks do not feed directly after attachment, wonder on host for several hours/days before attachment

hypostome

mouth parts that insert into skin to form attachment

initial feeding period

lasts for several days, slow feeding

Rapid feeding period

12-36 hours before tick detaches, faster feeding

American dog tick

dermacentor variabilis

Black-legged or Deer tick

ixodes scapularis

Lone star tick

amblyomma americanum

brown dog tick

rhipicephalus sanguineus

Asian longhorned tick

Haemaphysalis longicornis

Insects

class insecta

Orders of insecta

siphonaptera (fleas) phthiraptera (lice) diptera (flies) hemiptera (kissing bugs, bedbugs)

Insecta characteristics

3 pairs of legs, 3 body segments: head, thorax, abdoment

wing and leg attachment

thorax

complex or complete metamorphosis

larva have no resemblance to the adult

simple or incomplete metamorphosis

larva look like a smaller adult

Siphonaptera (fleas)

macroscopic, usually brown, no wings, complex metamorphosis

Cat flea

ctenocephalides felis

cat flea characteristics

most common flea in US, feeds on cats dogs ferrets, occ other animals, animals get fleas from environment, immature stages prefer warm temps and high humidity

Cat flea life cycle

eggs, larva, and pupae live in environment and adults emerge on hosts. adults are only stage that live on hosts, life cycle lasts 12-14 days

cat flea larvae require ___ for blood they need to live

cat flea feces

cat flea eggs

2 days

cat flea larva

6 days

cat flea pupa

6 days

cat flea adults

2 days

flea control on animal

adulticides, some can kill larvae and eggs

common otc flea drugs

methoprene and pyriproxygen

flea control in envrionment

vacuuming, washing pet bedding, sprays and foggers

rodent fleas

vectors of the plague in southwest US

Phthiraptera (lice)

small, wingless, flattened, white/gray/brown, incomplete metamorphosis

entire life cycle occurs on host

lice

transmitted by direct contact

lice