DDT 24 - Modes of Disease Transmission

Question 1

pathogens

Answer 1

Disease-causing organisms

Question 2

examples of pathogens

Answer 2

Prions, 
Viruses, 
Bacteria, 
Fungi, 
Protozoa, and 
Metazoa

Question 3

what must a pathogen have to ensure survival

Answer 3

Pathogens must have a way to be transmitted from one host to another to ensure their species’ survival.

Question 4

infectious agent

Answer 4

are generally specialized for a particular method of transmission.

Question 5

how can a disease be transmitted from person to person

Answer 5

1.Air-borne transmission
2. Contact transmission
direct and indirect
3. Vehicle transmission (Water, milk, food, etc.)
4. Vector-transmission
5. Trans placental transmission

Question 6

methods of air-borne transmission

Answer 6

coughing sneezing and breathing

Question 7

how does coughing, sneezing and breathing transmit diseases

Answer 7

when one sprays out infected droplets by sneezing and coughing. The air carries these infected droplets to a healthy person.
when breathing we can inhale infected dust particles

Question 8

name diseases that are air-borne transmitted

Answer 8

(a) Cold and cough,
(b) Influenza (Flu),
(c) Measles, Small-pox, Chicken-pox.
(d) Whooping cough,
(e) Tuberculosis

Question 9

direct transmission

Answer 9

Personal contact i.e. coming in direct physical contact with an infected person.

Question 10

examples of direct transmission

Answer 10

Touching an infected person during a physical examination

Dirty hands

Question 11

indirect transmission

Answer 11

This is contact with a contaminated surface, transferring infection to hands then to another patient

Question 12

examples of diseases that are transmitted via contact transmission

Answer 12

(i) Ringworm,
(ii) Small pox,
(iii) Scabies,
(iv) Impetigo

Question 13

2 types of contact transmission

Answer 13

direct and indirect

Question 14

vehicle transmission

Answer 14

This describes transmission of the disease agent through contaminated water, ice, milk, food, serum, plasma or other biological products

Question 15

examples of diseases transmitted via vehicle transmission/water-borne transmission

Answer 15

Cholera,
Typhoid fever and
Viral hepatitis
E. coli

Question 16

what is vehicle transmission where the vehicle is water also called

Answer 16

Also known as ‘fecal-oral transmission’ or the ‘fecal-oral route

Question 17

vector transmission

Answer 17

Vectors are arthropods or other invertebrate hosts, which transmit infection by inoculation into the skin or mucosa by biting or by deposit of infective material on the skin or on food or other objects

Question 18

name 2 ways in which vectors transmit diseases

Answer 18

(a) Mechanical Transmission.

(b) Biological Transmission

Question 19

mechanical transmission

Answer 19

The disease agent is carried mechanically on the legs or body of the insect,

Question 20

name and describe an example of mechanical transmission

Answer 20

House Fly is the strongest carrier of the infection.
If it sits on a food, it spoils it.
First it sits on the sputum of a patient (the spittoon) and then it sits on the food.

Question 21

name disease caused by infected foods and drinks caused by mechanical transmission

Answer 21

b) Dysentery,
(c) Enteric fever,
(d) Diphtheria,
(e) Scarlet fever,
(g) Tuberculosis

Question 22

name 3 types of biological transmission

Answer 22

Propagative
Cyclo-propagative
Cycle-developmental

Question 23

propagative biological transmission

Answer 23

The disease agent multiplies and increases in the insect vector e.g; plague bacilli in rat fleas,

Question 24

cyclo-propagative biological transmission

Answer 24

The parasite undergoes a cycle of development in the body of insect host with multiplication e.g. malaria parasite in mosquito

Question 25

cycle-developmental biological transmission

Answer 25

The parasite undergoes a cycle of development without multiplication e.g. filarial parasite in culex mosquito and guinea worm embryo in Cyclops.

Question 26

trans-placental transmission

Answer 26

diseases can be carried trans placentally from infected mother to foetus in uterus

Question 27

name diseases that are transmitted via trans-placental transmission

Answer 27

Syphilis,
Rubella (German Measles),
Measles,
Toxoplasmosis

Question 28

communicable disease

Answer 28

An infectious disease that is readily transmitted from person to person

Question 29

when is a communicable disease considered endemic

Answer 29

a small number of cases are continually present in the population

Question 30

when is a communicable disease considered epidemic

Answer 30

proportions when relatively large numbers of the population are affected.

Question 31

pandemic

Answer 31

A pandemic is a disease epidemic that has spread across a large region, for instance multiple continents, or worldwide

Question 32

how does indirect transmission occur

Answer 32

via an intermediate mechanism such as by contaminated water or insects.

Question 33

what effective measures must be taken in order to eradicate a disease

Answer 33

Knowing the cause of the disease

Knowing its method of transmission

Question 34

what environmental measures must be taken to prevent diseases

Answer 34

Education - water quality and safety
Environmental engineering - Sanitation facilities and design
Food - hygiene and quality, could also link to malnutrition and disease
Climate - could link to global warming