Transmission of Diseases

Question 1

What must a pathogen be able to do?

Answer 1

• A pathogen must be able to travel from one host to another, get into the host’s tissues, reproduce, and cause damage to the host.

Question 2

What are the most common forms of transmission?

Answer 2

Through a vector, physical contact, droplet infection.

Question 3

What causes malaria?

Answer 3

• Eukaryotic Plasmodium falciparum, P. vivax, P. malariae cause malaria.

Question 4

What is the cycle in which parasites are transmitted?

Answer 4

 Infected host – mosquito sucks parasites into its stomach.
 Gametes fuse, and zygote develops in stomach.
 Infective stages formed, passing to the salivary gland.
 Mosquito bites another person; injecting saliva as anti-coagulant, which contains infective parasite.
 In human infective stages enter the liver, multiply, before passing into the blood.
 Enter RBC where gametes are produced.
 Malaria can be spread by the human immunodeficiency virus. Enters body and remains inactive (HIV-positive) – becomes active, destroying T-h cells –resulting in an inability to fight infections effectively. Contract opportunistic infections. AIDS = Acquired immune deficiency syndrome.

Question 5

How can HIV be contracted?

Answer 5

body fluid exchanged, unprotected sex, unscreened blood transfusions, unsterilized surgical equipment, hypodermic needle sharing, needle-stick, across placenta, breast feeding.

Question 6

What is TB caused by?

Answer 6

• TB caused by Mycobacterium tuberculosis and M. bovis. Usually found in the lungs. Contracted by droplet infection. Bacteria contained in tiny droplets of liquid.

Question 7

When is TB more likely to be spread?

Answer 7

TB is more likely to spread when: overcrowding, poor ventilation, poor health, poor diet, homelessness. TB can be contracted from milk/meat of cattle.