L36 - protozoal & helminth infections Flashcards
outlines
- what protozoa and helminths are
- main diseases that these organisms cause
- life cycle of some key species
- potential problems with resistance (malaria)
what are protozoa?
- single celled
- animal like eukaryotes
- 2-100 micrometres
- most free living
- some pathogens
- found in subtropical regions
- can infect tissues/organs
- transmission by vector/ contaminated water/soil/food
how do protozoa infect tissues/organs?
- intracellular parasites in cells
- extracellular parasites in blood, intestine, urogenital system
how do amoeba move?
pseudopodia
how do flagellates move?
flagella
ciliates
have cilia (most not pathogenic)
apicomplexa (sporozoa)
- have apical complex
- all are parasitic
- e.g. Plasmodium
malaria life cycle
- parasites injected with saliva of blood feeding female mosquitos
- multiply in liver (2 weeks)
- released from liver - infect RBC’s repeatedly (days)
- mosquitoes ingest parasites with blood meal
- parasites go through reproductive phase inside mosquito
most common causative agent that causes the most severe malaria
plasmodium falciparum
uncomplicated malaria symptoms
- classic malaria attack: 6-10 hours
- cold stage: shivering
- hot stage: fever
- sweating stage
- headaches, bodyaches, nausea, weakness, enlarged spleen
severe malaria symptoms
- cerebral malaria: abnormal behaviour, seizures, coma
- shock: sudden drop in blood flow
- severe anaemia due to heamolysis
- pulmonary oedema: breathing issues
- liver failure, jaundice
- swelling, rupturing of spleen
chemoprophylaxis - malaria - areas without drug resistance
- chloroquine
- proguanil
chemoprophylaxis - malaria - areas with limited drug resistance
proguanil + chloroquine
chemoprophylaxis - malaria - areas of chloroquine resistance
- mefloquine
- doxycycline
- atovaquoe-proguanil
what is malaria caused by?
Plasmodium falciparum
helminths
- multicellular
- differentiated organs
- no circulatory tract
- 1mm to 10m
- an anterior end some have suckers, hooks, plates for attachment
helminths features
- most worms do not have full life cycle in humans
- replicate freely in another host or only part of life cycle in humans
- infection proportional to infecting organisms
- tough cuticle so hard to immune system to eradicate
- some camouflaged by coating with host molecules
- parasitic helminths feed on bodily fluids or intestinal contents
3 main classes of helminths
- nematodes (roundworms)
- cestodes (tapeworms)
- trematodes (flukes)
nematodes (roundworms)
- cylindrical body, alimentary canal
- intestinal nematodes
cestodes (tapeworms)
flat, ribbon shaped; no digestive tract – nutrients absorbed through cuticle
trematodes (flukes)
leaf shaped, blind branched alimentary tract
ascariasis
- adult worms
- 10-30cm
- migration of larvae to the lungs = most damage
- heavy infection: abdominal pain, malnutrition
- severe infection: blockage of intestines
- can migrate to other organs
