Medically important Protozoa and fungi

Question 1

How are different Protozoa species transmitted?

Answer 1

Arthropod (insect) vectors (organisms that transmit disease) Faecal-oral route (water transmitted)

Question 2

How are different Fungi species transmitted?

Answer 2

Direct contact or inhalation transmission

Question 3

What kind of internal structure do Eukaryotic organisms have?

Answer 3

Complex internal structure

Question 4

How many Eukaryotic organisms infect humans?

Answer 4

Relatively few species

Question 5

Where do Eukaryotic organisms cause mortality mostly?

Answer 5

Significant cause of mortality in developing world

Question 6

How are Eukaryotic organisms transmitted?

Answer 6

Transmission through:

vectors –insects contaminated water

Question 7

Which is the most serious, Plasmodium vivax or Plasmodium falciparum?

Answer 7

Plasmodium falciparum

Question 8

What kind of environment is malaria found?

Answer 8

Tropical sub-tropical

swampy

Question 9

How is Malaria transmitted?

Answer 9

Female Anopheles biting a human

Question 10

What are the different stages of the Malaria life cycle?

Answer 10

Sporozottes are transmitted into the blood by a mosquito bight.

• > Live (Exoerythrocytic stage where Sporozoites are developed
• > Then go into the blood as Merozoites
• > Erythrocytic stage where it reproduced in the red blood cells
• > Gametocytes are developed
• > upon next bite the mosquito takes up the Gametocytes.

Question 11

What are the symptoms of malaria?

Answer 11

-During the stage of erythrocyte infection

a high temperature (fever) of 38°C (100.4F) or above sweats 
chills 
muscle pains 
headaches 
cough 
diarrhoea

Question 12

Define Asymptomatic

Answer 12

Organism becomes dormant and symptoms go away

Question 13

How can Malaria recur?

Answer 13

Malaria may recur for months or years

Sporozoites
survive in liver, re-infect blood stream

Question 14

How is Malaria diagnosed?

Answer 14

Plasmodium infected erythrocytes in blood smears

Question 15

What is Malaria treated?

Answer 15

Chloroquine
(cures infection within blood cells)

Primaquine
(cures infection outside blood cells)

Question 16

How is Malaria prevented?

Answer 16

( break life cycle )

Drain swampy areas

Eradicate mosquito with insecticides

Prevent insect bites

Question 17

What organism causes African sleeping sickness?

Answer 17

Trypanosomiasis

Trypanosoma brucei

Question 18

What the mechanism for African sleeping sickness?

Answer 18

disease transmitted by the tsetse fly minor swelling in region of bite local lymph node enlargement

months / years later recurrent fever
(as trypanosome multiplies surface antigens modify and hinder host defences central nervous system disorders (brain)

-listless, indifferent to food, coma, death

Question 19

What are the treatments for sleeping sickness?

Answer 19

Treatment essential to avoid death (mortality rate 80%)

prior to CNS involvement

• suramin -side-effect problems
• itching, vomiting

post CNS involvement

• arsenic based
• able to cross the blood
• brain barrier
• treatment kills 10%

Question 20

How is African sleeping sickness controlled?

Answer 20

Avoid insect bites -repellents / protective clothing

Organization of African Unity (OAU)

Trypanosomiasis Eradication Campaign

• insecticides
• breeding and release of sterilized male flies

Question 21

What is the most common protozoal parasite worldwide?

Answer 21

Giardiasis

Giardia lamblia

Question 22

What is Giardia lamblia Mechanism of disease?

Answer 22

cyst

survival form (drying / disinfection) -infective

1 week after ingestion (following passage to water course via faeces)

trophozoite

• lives in small intestine, sucking discs
• mechanical obstruction of absorptive surfaces of intestine (microvilli)
• multiplies, disrupt water uptake
• disrupts fats and vitamins absorption

Question 23

What symptoms do Giardia lamblia give?

Answer 23

explosive watery foul smelling diarrhoea, belching, flatulence, abdominal cramps -> severe weight loss

illness lasts 1 -2 weekschronic, months -years

Question 24

How are the symptoms of Giardia lamblia controlled?

Answer 24

Drinking water chlorination and filtration

Question 25

What are the mechanism of disease for Amoebiasis Entamoeba histolytica?

Answer 25

cysts
-infective

trophozoites
-grow on and in mucosal cells of the intestine

• prolific growth causes ulceration and watery diarrhoea
• severe invasion (dysentery) bloody diarrhoea
• possible spread to liver, lungs, brain
• 100,000 deaths annually

Question 26

What are the mechanism of disease for Cryptosporidiosis?

Answer 26

Cysts
-released into faeces, contaminate water courses cysts resistant to chlorination

Trophozoites
intracellular parasite of epithelial cells of intestine severe,cholera-like watery diarrhoea -lasts 2 –4 days

Question 27

What are two groups of pathogenic fungi?

Answer 27

Yeasts -unicellular

Question 28

How are Pathogenic fungi transmitted?

Answer 28

Transmission by direct contact or spore inhalation

Question 29

What are the mechanism of disease for Pathogenic fungi?

Answer 29

Allergy ( hypersensitivity )
Aspergillus-asthma

Mycotoxins
Aspergillusflavus-aflatoxins (aflatoxicosis)

aflatoxin B1 is usually predominant and is the most toxic (tumours -liver)
LD50 value

0.5 to 10 mg/kg body weight

Infection

mycosis ( mycoses )

innocuous -> severe

Question 30

How is Trichophyton spread?

Answer 30

spread via contact

Question 31

Explain Superficial mycoses

Answer 31

(dermatomycoses)
benign, self limiting
skin, hair, nails

Question 32

Explain Subcutaneous mycoses

Answer 32

deeper skin layers

farmers, miners -small wound infection

Sporothrix
schenckii-sporotrichosis

Question 33

explain Systemic mycoses

Answer 33

infection of internal organs

Primary -healthy individuals
Histoplasma capsulatum
-histoplasmosis
-lung infection

Secondary-impaired immunity

-immunosuppressive drugs or AIDS-

Candida albicans
candidiasis