Module 8 Flashcards
etiological agents
Organisms that directly cause diseases in other organisms
Direct impact
Disease vectors
Organisms that transmit other disease causing bacteria from one host to another
How can an insect cause irritation to an animal like a horse
By flying too close to the eyes mouth or nose
Presence of bugs and mosquitos can cause
Irritation and harm to animals such as a lack of eating and self injury
Bed bugs
Bite humans at night when sleeping
Extermination of bed bugs is
Very difficult because it is difficult to reach them with insecticides and they have great numbers
How can insects contaminate food
Leaving behind body fragments
Transfer of pathogen onto food
Example of insect that transfers pathogens onto food
Cockroaches
Arthropods that inject venom as a defence mechanism
Many Hymenoptera
Some Hemiptera
Spiders
Scorpions
Caterpillar setae can cause
Irritation and harm to humans
Exsanguination
Blood loss
Ticks infest
Moose and cause exsanguination
Tick infestations of moose can lead to how much blood loss
20L for one moose
Average moose has 32L of blood
Maggots cause harm by
Invading host tissue
Maggots either infest
Subcutaneous tissue or organs
Two types of human psychological disorders associate with insects
Phobias
Delusional parasitosis
Entomophobia and Arachnophobia
Fear of insects and spiders
People with Entomophobia and Arachnophobia may apply
Insecticides which leads to health issues
Delusional parasitosis
Individuals are convinced they are inhabited by parasites. The emotional distress significantly decreases quality of life
Transmission cycle
Process of diseases being transmitted to a host by a vector
Transmission cycle or an arthropod to a host consists of 3 cycles
A vertebrate host is infected
An arthropod vector picks up the infection from the vertebrate
The arthropod passes it on to another vertebrate host
Disease causing organism only reproduces in
The definitive host
Intermediate host
A host where the parasite may produce asexually rather than sexually
Humans are considered
Definitive hosts for parasitic worms
Mosquitos are considered
Intermediate hosts for parasitic worms
Disease vectors find suitable hosts by cues such as
Body heat
CO2
Color
Shape
Odour
Vectors have well developed
Sensory organs to respond to host cues
Two basic mechanisms of disease transmission
Mechanical transmission
Biological transmission
Mechanical transmission
Occurs through direct contact between the vector and the disease causing host
The disease does not undergo development during this
Common avenues of mechanical transmission
Infected mouthparts or regurgitation during feeding
Because during mechanical transmission no development occurs, this means
The number of infectious units declines over time
House flies vector diseases through
Mechanical transmission
Infects hosts food
Biological transmission
Diseases causing organisms go through development on the vector
Biological transmission leads to an increase in
Infection rate with time due to development
Malaria is an example of
Biological transmission
Biological transmission vectors often have
Adapted mouthparts to access blood of hosts
Chagas disease is transmitted through
Excretion
Feces contaminated with feeding kissing bugs are accidentally scratched into an open wound
Biological transmission can be categorized into either
Horizontal transmission or vertical transmission
Horizontal transmission
Disease causing organisms moving between vectors and organisms or just between vectors
Vertical transmission
Occurs when disease causing organisms are passed between generations
Passed form adult female to her offspring
Transmitted through infected ovarian tissues into the embryo
Disease is maintained through development
Vector competence
Vectors ability to maintain and transmit disease
Barriers to vector competence
Maintenance of the disease causing organism will be compromised if it is attacked by the vector’s immune system
Global trade and travel has led to the movement
of insects and disease vectors
Vectors in new ranges can become
Invasive by the diseases they carry
asian longhorned tick
Moved from Asia to Australia and has expanded and vectors several human and animal diseases
Has recently been found in East USA
Diseases are greatly carried by
Ticks
Human activities like deforestation can cause
Significant change in disease transmission dynamics
Human factors that affect vector born disease spread
Human nature involvement
Human movement and package movement
Climate change
Morbidity
being sick
Mortality
Death
WHO says that vector born diseases make up
17 percent of all diseases
Medical entomology
Field of study that focuses on arthropods and insects that affect human health
Epidemiology
The branch of science that deals with the incidence, distribution and control of diseases and other factors that affect populations
Medical entomologists study
Study biological and environmental variables that affect insect vectors and spread of disease
Until world war 2 more soldiers died from what than actual war
Disease
Human Body Louse causes
Prediculus humanus
Epidemic Typhus
Human Body Louse is a
An intracellular parasite that destroys the cells that line blood vessels
Epidemic Typhus patients suffer from
Rashes and muscle aches. If left untreated, patients have low blood pressure and slip into a coma and die
Epidemic Typhus greatly affected which historical events
Napoleon’s army was greatly affected and led to his loss
Russian Civil War
World War 1
The bacteria that causes epidemic typhus is classified as a
Bioterrorism agent
The plague is caused by the bactera
Yersinia pestis
Yersinim pestis is bacteria that comes from
Fleas
Most common flea culprit of the plague
Oriental Rat Flea
Human Fleas
Symptoms once infected by Yersinia pestis
The lymph nodes swell and if they break open, the bacteria spreads into the bloodstream and lungs
Epidemics occur
When a disease spreads across a large region
1st Plague Outbreak is known as the
Justinian Plague
Justinian Plague occurred in the
6th century and killed 15-40% of human populations in the Middle East and Europe
2nd Plague outbreak is known as
The Black Death
Black death occurred in
Europe and killed 10-40percent of population in area
3rd plague outbreak occurred in
China and India in the late 19th and 20th century
Most human plagues modern day occur in
Africa
Arthropod born diseases are most common in
Developing tropical regions of the world where conditions are best for insect vectors
Lymphatic Filarial or Elephantiasis
Round worms are transmitted by mosquitoes and cause tissue swelling and thickened skin
Lymphatic Filarial or Elephantiasis leads to
High morbidity and disfiguration
Lymphatic Filarial or Elephantiasis occurs mostly in
Tropical regions
Lymphatic Filarial or Elephantiasis treatment methods
Preventative chemo and deworming drugs
Malaria is transmitted by
Mosquitoes
Malaria causes
Sever anemia and multiple organ failure and death
Who is most at risk of malaria
children followed by pregnant women and hiv patients
Malaria happens mostly in
Tropical and sub-tropical regions
Mostly in Africa and south-east Asia
Primary method of preventing malaria
Bed nets as well as insecticide
Zika virus had a n outbreak in
Brazil in 2015
Zika virus was most likely transmitted by
Travelers
Zika has an association with
Microcephaly (deforms infants)
Zika is transmitted by
Aedes mosquitos
Zika is found in
Tropical environments
Zika symptoms
Fever, headache, muscle and joint soreness and rashes
Symptoms are mild
Zika complications happen when
It is passed on through pregnancy, can lead to brain abnormalities in the fetus
Concerns that zika can be transmitted
Sexually
Zika used to not be a problem until
Human movement has led to the vector being more spread and common
Lyme disease comes from
Ticks
Lyme disease happens mostly
in the northern hemisphere
Lyme disease symptoms
Vary among individuals
Lyme disease can lead to
Chronic neurological and heart issues
Veterinary entomology
How insects affect domestic animals
Feeding by mites can cause
Inflammation of the skin and itching and irritation which can further lead to crusting and hair loss
Mange
Caused by mites and spreads by contact
Livestock affected by mange must be
Quarantined
Mange can be passed to
Humans depending on the species of mite
Some biting arthropods can transfer
Disease causing organisms
Dog heartworm
Transmitted by infected mosquitoes
Worm feeds on dog and grows larger inside dog
Dog heart worm can cause
Blockage of circulatory system
Exhaustion
Abnormal lungs
Death
Recurring infection of dog heart worm is
possible
Dog heart worms can not cause issues to
Humans
Bluetongue is caused by
RNA viruses which come from biting midges
Bluetongue affects
Cattle deer buffalo goats etc.
Most severely affects sheep
Bluetongue causes
Lesions
Internal hemorraging
Fluid buildup in lungs
Death
Disrupted wool growth
Underweight/deformed young
Stillbirths and miscarriages
Weight loss
Nagana virus is passed on by
Tsetse flies
Nagana infects
Red blood cells and causes fever weakness and lethargy
Nagana leads to
Weight loss
Nagana has led to the lack of agriculture in
Africa
What arthropod types cause disease to plants
Aphids
Planthoppers
Leafhoppers
Bark beetles
Types of transmission for plant viruses
Non-persistent
Semi-persistant
Persistent
Non persistent transmission
Virus only remains on mouthparts and is passed on while feeding
Unique to aphids
Does not require incubation to become viral so can be passed on immediately after taking the virus
Semi-persistent transmission
Virus moves into foregut of vector and does not move into tissue
Can be transmitted in a short timespan
Persistent transmission
Require a persistent feeding period and the disease must be incubated and remain in the vector for a long time
Disease circulates in the tissues
Some can be passed from mothers to offspring
Happens in leafhoppers
Potato leafroll virus vector
Green peach aphid
Potato leafroll virus
Can cause curling of the lead
Can stunt growth and cause necrosis if it reaches roots
Fireblight affects
Pear and apple tissues
Fireblight causes
A scorched appearance of dead leaves and infected fruit
Infected fruit wither and darken
Insects as vectors for fireblights
Can be caused be feeding, wood boaring and pollination
Dutch elm disease caused by
Elm bark beetles
Dutch elm disease causes
Blocking of nutrient uptake of tree
Disfiguration and loss of leaves of the tree then occur
Dutch elm tree development may take
Years but death of the tree can happen after months
Dutch elm disease is moving
westward
Alberta has the highest population of
Dutch elm disease free elm trees
Preventative measures of dutch elm disease
Burning of trees and use of fungicide
