Arthropodborne dz (third)

What are the 3 main routes of disease transmission?

1. Contact

2. Vehicle

3. Vector: involves an arthropod vector

What are arthropods, and what is their role in disease?

• Living, “insect-like” animals with segmented body parts and jointed appendages

• They deliver the pathogen to the host

Give the kingdom, phylum, and 2 classes of arthropods, with the vectors from each class.

• Kingdom Animalia, Phylum Arthropoda

• Class Insecta: lice, fleas, mosquitoes

• Class Arachnida: ticks

What 3 things interact in an arthropod borne disease?

1. Host/reservoir (human or animal)

2. Pathogen/parasite

3. Vector (arthropod)

What is the “big picture” chain of an arthropod borne disease?

Animal reservoir (with a pathogen)→ arthropod vector→ host (human)

Using plague as the example, name the reservoir, vector and host in the chain.

1. Infected rat = animal reservoir

2. Infected rat → infects rat flea = arthropod vector

3. Infected rat flea → infects human = host

What is the goal of arthropod vector adaptation?

Enhanced survival of the arthropod vector (vectors are extremely adaptable)

What 3 factors make arthropod vectors adaptable?

1. Multiple developmental stages / complex life cycle (egg and nymph in water → adult on land)

2. Diverse habitats, e.g. water and land

3. Several types of vertebrate hosts, e.g. mice/rodents and humans

What are the 3 types of arthropod vector adaptations (for arthropod survival)?

1. Physiological

2. Behavioral

3. Structural

Give the 2 examples of physiological adaptations.

• Kissing bug detects the host’s chemicals (CO₂) and bites around the mouth

• Mosquito bites with its needle and releases chemicals before and after a blood meal

What 3 things does the chemical the mosquito releases do?

1. Numbs the area

2. Dissolves clots

3. Forms a clot

Give the example of a behavioral adaptation.

Mosquito bites the host at the right times, usually at night when the person is still

Q: What are the 4 structural adaptations of arthropod vectors?

1. Wings

2. Compound eyes

3. Needle (proboscis)

4. Sensory bristles

What are wings and the needle (proboscis) used for?

• Wings: travel, to find a nutrient source and escape predators
  
  

• Needle: to take a blood meal and deliver pathogens to the host

What do compound eyes and sensory bristles do?

• Compound eyes: multiple lenses let it see 360° around and escape predators
  
  

• Sensory bristles: detect vibrations to find nutrients, escape predators and attract mates

Which 4 arthropodborne diseases are bacterial?

Plague, Lyme Disease, Epidemic Typhus, Rocky Mountain Spotted Fever (RMSF)

What is the 1 parasitic arthropodborne disease, and what kingdom is it in?

Malaria (Kingdom Protista)

What are the 7 arboviral diseases?

West Nile Virus Encephalitis, St. Louis Encephalitis, Eastern Equine Encephalitis, Zika, Yellow Fever, Dengue, Ebola

Which disease on the arboviral list is NOT transmitted by arthropods?

Ebola Virus Disease. It’s a viral disease, but no arthropod vector is involved

What is an arbovirus

An arthropodborne virus: a virus transmitted by an infected arthropod vector. Arboviruses belong to several viral families

Who is the usual arthropod vector for arboviruses?

Usually the mosquito. They’re caused by mosquito-borne viruses

Which arboviral diseases are considered EIDs?

Ebola Virus Disease and Zika Virus Disease

What is the range of arboviral symptoms, and what are the 2 types of severe symptoms?

They range from subclinical (mild) to severe:

• Neurological → Encephalitis

• Vascular (blood vessel) damage → Hemorrhagic fevers