Medically important Protozoa and fungi Flashcards
How are different Protozoa species transmitted?
Arthropod (insect) vectors (organisms that transmit disease) Faecal-oral route (water transmitted)
How are different Fungi species transmitted?
Direct contact or inhalation transmission
What kind of internal structure do Eukaryotic organisms have?
Complex internal structure
How many Eukaryotic organisms infect humans?
Relatively few species
Where do Eukaryotic organisms cause mortality mostly?
Significant cause of mortality in developing world
How are Eukaryotic organisms transmitted?
Transmission through:
vectors –insects contaminated water
Which is the most serious, Plasmodium vivax or Plasmodium falciparum?
Plasmodium falciparum
What kind of environment is malaria found?
Tropical sub-tropical
swampy
How is Malaria transmitted?
Female Anopheles biting a human
What are the different stages of the Malaria life cycle?
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.
What are the symptoms of malaria?
-During the stage of erythrocyte infection
a high temperature (fever) of 38°C (100.4F) or above sweats chills muscle pains headaches cough diarrhoea
Define Asymptomatic
Organism becomes dormant and symptoms go away
How can Malaria recur?
Malaria may recur for months or years
Sporozoites
survive in liver, re-infect blood stream
How is Malaria diagnosed?
Plasmodium infected erythrocytes in blood smears
What is Malaria treated?
Chloroquine
(cures infection within blood cells)
Primaquine
(cures infection outside blood cells)
How is Malaria prevented?
( break life cycle )
Drain swampy areas
Eradicate mosquito with insecticides
Prevent insect bites
What organism causes African sleeping sickness?
Trypanosomiasis
Trypanosoma brucei
What the mechanism for African sleeping sickness?
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
What are the treatments for sleeping sickness?
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%
How is African sleeping sickness controlled?
Avoid insect bites -repellents / protective clothing
Organization of African Unity (OAU)
Trypanosomiasis Eradication Campaign
- insecticides
- breeding and release of sterilized male flies
What is the most common protozoal parasite worldwide?
Giardiasis
Giardia lamblia
What is Giardia lamblia Mechanism of disease?
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
What symptoms do Giardia lamblia give?
explosive watery foul smelling diarrhoea, belching, flatulence, abdominal cramps -> severe weight loss
illness lasts 1 -2 weekschronic, months -years
How are the symptoms of Giardia lamblia controlled?
Drinking water chlorination and filtration
What are the mechanism of disease for Amoebiasis Entamoeba histolytica?
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
What are the mechanism of disease for Cryptosporidiosis?
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
What are two groups of pathogenic fungi?
Yeasts -unicellular
How are Pathogenic fungi transmitted?
Transmission by direct contact or spore inhalation
What are the mechanism of disease for Pathogenic fungi?
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
How is Trichophyton spread?
spread via contact
Explain Superficial mycoses
(dermatomycoses)
benign, self limiting
skin, hair, nails
Explain Subcutaneous mycoses
deeper skin layers
farmers, miners -small wound infection
Sporothrix
schenckii-sporotrichosis
explain Systemic mycoses
infection of internal organs
Primary -healthy individuals
Histoplasma capsulatum
-histoplasmosis
-lung infection
Secondary-impaired immunity
-immunosuppressive drugs or AIDS-
Candida albicans
candidiasis
