L32 - Intro To Helminths And Protozoa Flashcards
What are protozoa?
- diverse group if sinlge celled “animal like” eukaryotes
- part of protists
What are protozoa like?
- most free livinv, some are pathogens
- prevalent in (sub)tropical regions
What do protozoa do?
- infect tissues/organs
- intracellular parasites in cells
- extracellular in blood, intestine, urogenital system
How are protozoa transmited?
- vectors // malaria
- contaminated water/soil/food //amoeba
What do protozoal cells have (organelles, structures)?
- mitochondria
- ER
- golgi apparatus
- food vacuole
- contractile vacuole
- pseudopodia
What is the classification of protozoa?
- amoeba - move by pseudopodia
- flagellates - have flagella
- ciliate - have cilia
- apicomplexa (sporozoa) - have apical complex, all parasitic // plasmodium
What are facts about malaria?
- bad air, also called marsh fever
- > 100 countries, tropical areas (africa, asia and south america)
- 40% world at risk, 90% of deaths in africa
- deaths dec over last 5-10 yrs (due to prevention strategies, new drugs)
What are malaria - causative agents from less common and moderate disease to more common and severe disease?
- plasmodium malariae
- plasmodium ovale
- plasmodium vivax
- plasmodium falciparum
What is the life cycle for malaria?
- parasite injected with saliva of blood-feeding female mosquitoes
- multiply in liver (~2 weeks)
- released - infect RBCs repeatedly (days)
- go through reproductive phase inside mosquito
What are uncomplicatedsymptoms of malaria?
- 6-10 hours
- cold stage - shivering
- hot stage - fever
- sweating stage
- headache, body ache, nausea, vomiting, weakness, enlarged spleen
What are severe (complicated) symptoms of malaria?
- cerebral malaria - abnormal behaviour, seizures, coma
- shock (drop in blood flow)
- severe anaemia (haemolysis)
- pulmonary oedema (breathing problems)
- liver failure, jaundice
- swelling, rupturing of spleen
What is chemoprophylaxis like in areas without drug resistance?
- chloroquine
- proguanil
What is chemoprophylaxis like in areas with limited drug resistance?
Proguanil plus chloroquine
What is chemoprophylaxis like in areas of chloroquine resistance?
- mefloquine
- doxycycline
- atovaquone-proguanil
What are general feautres of helminths (structure)?
- multicellular, differentiated organs (no circulatory tract)
- <1 mm to >10 m
- anterior end, have suckers, hooks, plates (used for attachment)
- touch cuticle - difficult for immune system to eradicate
What are general features of helminths (facts)?
- most worms dont have full life cycle (replicate free, weight of infection prop. To num of infecting organisms)
- some camouflage by coating with host molecules
- feed on body fluids or intestinal contents
What are the 3 main classes of helminths?
- nematodes (roundowmrs, cylindrical, alimentary canal)
- cestodes (tapeworms, flat, ribbon, no digestive tract - nutrients through cuticle)
- trematodes (flukes, leaf-shaped, blind-branched alimentary tract)
What are the types of nematodes?
- large roundworm
- threadworm
- hookworm
- whipworm
What is the transmission and symptoms of large roundworm?
- fecal-oral
- heavy infection - slows development, shortness of breathm coughing, malnutrition, blockage intestines
What is the transmission and symptoms of threadworms?
- fecal-oral
- mild anal itching
What is the transmission and symptoms of hookworms?
- larvae in soil penetrate skin
- slows growth and development, anaemia
What is the transmission and symptoms of whipworms?
- fecal-oral
- usually asymptomatic, heavy infection, bloody diarrhoea
What are adult worms of ascariasis like?
10-30 cm
What are infections like with ascariasis?
- max intensity infection in children at 5-10 yr
- migration of larvae to the lungs causes most of the damage
- heavy infection - abdominal pain, malnutrtition, escape from anus, mouth, nose or ears
- severe infection - blockage of intestines
- adults parasites migrate
What is the cycle of tissue nematodes in blood?
- adults in tissue/lymphatic system
- microfiliariae circulate in blood
- ingested with blood meal by arthropod
- dev into infectious stage (L3)
- enter skin when arthopod feeds
- migrate and develop in tissue
What is lymphatic filariasis (elephantiasis)?
Damage to lymphatic system and fluid build up = results in enlargement of parts of body
What is onchocerciasis (river bilndness)?
Micrifiariae enter internal tissue of eye
= inflammation, bleeding = blindness
What is loiasis?
Adult loa loa worm travels through subcutaneous tissues
= inflammation in the skin and eye
What are facts about cestodes?
- > 10m, live dor decades
- humans as primary host - ingestion of cyst from undercooked meat/fish - worm in lumen
- secondary host - ingestion of egg, develop into larva that invades tissue
What are facts about trematodes (flukes)?
- live for decades in tissue or blood vessels
- progressive damage to vital organs
- snail as intermediate host = secondary host
What are the different types of flukes?
- lung fluke - eating infected crab and crayfish
- liver fluke - freshwater fish
What are schistosomiasis?
- worms 0.6-2.6cm
- contamination through infected water
- // bilharzia, snail fever
What are symptoms of schistosomiasis?
- days - develop rash/itchy skin (swimmers itch)
- 1-2 months - fever, vhills, cough, muscle aches
- main damage - eggs stuck in tissues
- organ damage from inflammation and scarring // liver, intestines, lungs, bladder = bladder cancer
What is the diagnosis for helminths?
- intestinal nematodes/cestodes - eggs/larvae in faceal sample/ incidental diagnosis
- schistosomas - eggs/larvae in faecal sample or urine
- tissue nematdodes - adults in tisssue, microfilaria in blood
How could helminths be used as therapeutics?
- not declared bc they are able to modulate immune system
- nematode infection protects against allergic disease
- // Gi nematode lead to reduced skin reactivity to dust mite allergen
- // inverse correlation between incidence of asthma and hookworm infection
