med vet exam 1

How do arthropods impact humans and animals?

Allergies to proteins or venom
Annoyance
Fear and mental stress
Parasitism
Transmission of disease pathogens

Delusory parasitosis

A psychological state where p a person mistakenly believes that they are being bitten or are infested by a parasite

Myiasis

invasion of host tissue by fly larvae

Epidemiology

The study of factors determining the occurrence of disease in population

Biocenosis

Term widely adopted in disease relationships to refer to the interacting organisms involved in a disease

Biogeocenosis

Includes environmental factors as well as the interacting organisms involved in a disease

Epidemic

Usually large number of cases of a human disease

Epizootic

Epidemic associated with an animal disease outbreak

Incidence

Number of new cases in a defined population during a time interval

Incidence rate

Number of new cases per unit of time

Prevalence

Number of cases in a population at a given time

Endemic

Disease is stable, new cases balanced with increases in disease-free hosts

Enzootic

Animal version of endemic

Arthroponoses

Disease only occurs in humans

Primary or definitive host

Sexual reproduction of the pathogen, required for maintenance of transmission

Secondary or intermediate host

No sexual reproduction, not essential, but may enhance amplification

Immunity

All properties of the host that confer resistance to infection

Natural immunity

Immunity with no prior exposure to disease

Acquired immunity

Immunity due to previous exposure, either transient or lifelong

Amplification

General increase in the number of parasites in a given area

Amplification host

Often short-term, may develop disease

Reservoir Host

supports parasite development, infected for long periods of time, disease usually not acute

Dead-end host

Either do not support infection level sufficient for transmission or become ill and die before parasite completes development

Bovine Piroplasmosis

Cattle fever

What are the six principal arthropod orders?

Diptera
Siphonaptera
Phthiraptera
Hemiptera
Blatteria
Metastigmata

Obligate parasite

Parasitism is the only means of existence, they have to parasitize to live

Facultative parasites

A free-living form that infests a host, they do not have to parasitize to live

Extrinsic incubation period

Time required after infection of arthropod vector until the pathogen can be transmitted

Intrinsic incubation period

Time for pathogen to develop and cause clinical signs of disease symptoms in vertebrate host

Venereal

Abovirus' also are transovarially transmitted
Infected male infects during mating

Horizontal transmission

Vector to non-arthropod

Anterior-station

Parasites leave vector through mouthparts or salivary glands

Posterior-station

Parasites transmitted via feces

Salivarian transmission

Salivary secretions injected during feeding

Stercorarian transmission

Parasites passed in feces
host causes entrance by scratching

Regurgitation transmission

Parasites mass and prevent successful blood feeding
Leishmannia and Yersinia

Assisted escape/passive transfer

Host macerates annoying arthropod vector

Active escape transmission

Filariae break out of the vector's mouthparts

Ingestion of vector

Grooming

Vector Competence

Susceptibility of an arthropod to infection with a parasite and ability to transmit the parasite

What factors make a competent vector?

Maintaining or increasing the pathogen
size of the vector population
limited or extensive groups of hosts
vector longevity
feeding frequency and probing behavior
vector mobility
physiological and behavioral plasticity

Anautogenous

Eggs matured w/aid of blood meal

Autogenous

Eggs produced without a blood meal

What are some mosquito-transmitted viruses?

Yellow fever
Dengue
Zika
Rift Valley Fever
Chikungunya
Encephalitis

What are some biting midge transmitted viruses?

Bluetongue
Vesicular stomatitus

What is a tick-transmitted virus?

African Swine fever

What are the three grate plague pandemics?

Justinian's plague
Black Death
1855-1950 Asia

Justinian's plague

AD541- Africa/40 mil deaths

Black Death

1347- from Asia trade routes
25 mil deaths in Europe, lasted 200 years

1855-1950 Asia

Over 12 mil deaths in India alone
Plague was introduced into US from this outbreak

The golden age for med/vet entomology started when?

1877 (was a 50 year period)

What happened in 1848?

Josiah Nott published belief mosquitoes produced malaria and yellow fever

What happened in 1850?

Livingstone published the bite of poisonous tsetse fly caused death of animals

What did Partick Manson observe in 1877?

development of Muchereria bancroft in the body of a mosquito

What is Koch's Postulate?

– Micro-organism always present in diseased host
– Micro-organism isolated from diseased host and grown
– Micro-organism obtained from pure culture injected into new host to produce disease
– Micro-organisms isolated from the experimentally infected host.

What is the first mosquito-borne virus?

Yellow Fever

What happened in 1902?

Discovered dengue is transmitted by mosquitoes

What happened in 1903?

The first transmission of spirochetes by soft tick

What year did the USDA cattle fever tick eradication program start?

1906

Why did Sanibel island eradication fail?

Because they were too close to the mainland, screwworm flies kept coming back (1954)

What happened in 1908?

Chagas discovered trypanosomes transmitted by bugs

What was the first virus transmitted by ticks?

Nairobi sheep disease

What was eradicated in 1943

cattle tick fever

Physical control

The use of various types of energy to control, attract or repel insects

Mechanical control

The removal or destruction of insects by hand or by devices that are mechanical in nature

Environmental control

One or more components of the environment are modified to the pests detriment

Why were the entomologists drop from the program?

Less than 1000 cases of screwworm so they didn't need them

1935

Baumhover - 1.2 million known cases of screwworm in the southern US

1936

Laake found separation in primary and secondary screwworm flies

1938

Knipling proposed sterile male control program for screwworms

1961

Eradication program in Florida completed
400 males to 1 female per square mile released per week

When were screwworms eradicated in Florida?

1959

When were screwworms totally out of the US?

1966

What are 4 of the 6 internationally quarantinable diseases?

yellow fever
louse-borne typhus
plague
louse-borne relapsing fever

What happened in 1889?

Babesia bigemina was discovered in cattle blood by Theobald Smith, the first zoonotic agent found