Parasitic infection Flashcards
Define infection
Invasion by growth of pathogenic microorganisms within the body.
Define disease
A disordered or incorrectly functioning organ/part/structure or system of the body resulting from the effects of genetic or developmental errors, infection, poison, nutritional deficiency or imbalance, toxicity or unfavourable environmental factors
Define a parasite
Organism living in or the host and dependent on it for nutrition - causing damage
What are the two types of parasites?
Endoparasites
Ectoparasites
What are the two different types of endoparasites?
Protozoa
Metazoa
Give 4 examples of Protozoa
Amoeba, coccidiae, ciliae, flagellates
Give 3 examples of Metazoa
Roundworms, flatworms, flukes
What are Protozoa?
Singles celled organisms
All of genome within a nucleus and organelles within cytoplasm
What is the difference between ectoparasites and endoparasites?
Ectoparasites live on the surface of the host whereas, endoparasites live inside the body of the host
What can be used to differentiate protozoa from metazoa infection?
Protozoa infections are not associated with eosinophilia
What are metazoa?
Multi cellular organisms, free living, intermediate hosts and vectors
Some just inhabit the gut others may invade tissue
Eosinophilia if invasion of blood.
Give 2 amoebae species
Entamoeba histolytica - diseases/pathogenic
Entamoeba dispar - normal commensal(non-harmful) of GIT
How does amoeba infection occur?
Ingestion of mature cysts in food or water or on hands contaminated by faeces.
Give 1 epidemiology fact about Amoeba
10% of world infected with E.histolytica
Diarrhoea is main sign
3rd most common death from parasitic infections.
What is the issue with the asymptomatic presentation of amoeba?
Pass cysts in the faeces and the asymptomatic carriage state can persist indefinitely, cysts can remain viable for up to 2 months, issue for lesser developed countries where you can’t poo in a toilet.
The cycle is continued for a while.
What can invasive amoebiasis cause?
Main symptom is diarrhoea
Amoebic liver abscess
May affect the lung, heart, brain, urinary tract and skin.
How do you diagnose E.histolytica?
Microscopy, dispar and histolytica look the same but cysts.
Wet mount and look for the cysts or trophozoite.
Mature cyst will contain 4 nuclei.
Does E.histolytica have an intermediate host?
NO
and the human is the final host
Give 3 examples of coccida
Coccidal infection in humans are mostly zoonoses(spread from non human animals)
Plasmodium species - malaria
Toxoplasma
Cryptospordium
How is malaria vector born?
Transmitted by the bite of a mosquito
What are the 5 different types of plasmodium?
P.falciparum (most severe) P.ovale P.malariae P.vivax Pknowlesi
How can these different types be differentiated?
Different shapes in a blood smear/film
What are the two stages of malaria?
Liver stage
Blood stage - actually starts to cause symptoms when parasites are causing symptoms.
Give some symptoms of malaria?
Symptoms vary as a result of which parasite has infected the host. P.falciparum is the shortest in onset of presentation.
Cycle of fever, headache, chills, vomiting, muscle pain
Complications - anaemia (destruction of red cells), cerebral malaria(swelling, seizure, coma)
Describe treatment of malaria
Differs for uncomplicated and severe malaria.
Severe involves a triple therapy to which some resistance is developing.
How can malaria be diagnonsed?
Blood film with Giemsa stain
Rapid test - antigen detection test which is less sensitive, blood film requires more training to make diagnosis and this test is quicker.
What does toxoplasma cause?
Mild disease in immunosuppressed individuals: fever, swollen lymph nodes, headache, sore throat
In pregnancy it’s dangerous for the foetus.
What is the intermediate host of toxoplasma gondii?
Mice and Cats
Contaminated food with cat faeces.
Test gondii?
Serological test
What is cryptosporidium?
Diarrhoea
Immunocomprimised HIV patients are the real vulnerable lads.
Faecal oral transmission.
Diagnosed by stool examination .
Give an example of a ciliate
Balantidium coli
Faecal oral transmission
Asymptomatic individuals
What symptoms will Balantidium coli cause if you are immunocomprimised?
Persistent diarrhoea, abdo pain, weight loss, nausea, vomit
Untreated can cause perforation of the intestine.
Asymptomatic carriers that don’t suffer will continue to transmit these parasites.
Give an example of a flagellate
Giardia lamblia
Common, beautiful swimming parasites at trophozoites stage
Main symptom is diarrhoea
Faecal oral transmission.
What are some symptoms of Giardiasis?
most people will experience nothing
Acute: Diarrhoea, greasy stools that tend to float, stomach or abdominal cramps, upset stomach or nausea/vomiting and dehydration.
Stool examination
Symptoms dependent on dose of Giardiasis
What is another flagellate?
Trichomonas
Sexually transmitted
What are symptoms of trichomoniasis?
Females: 10-50% are asymptomatic, vaginal discharge, vulval itching, dysuria, offensive odour.
Male: same percentage asymptomatic, discharge and/or dysuria.
May enhance HIV risk
How is trichomoniasis diagnosed?
Microscopy - swimming
Rapid test via antigen
Give one more example of flagellate
Leishmania – sand fly vector, 4 main types of Leishmania
What are metazoa also called?
Helminths
Worms
What are metaezoa?
Complex multicellular parasites
Cycles may involve insect vectors and intermediate hosts
For most humans are definitive hosts, few are zoonoses.
Adult worm cannot multiply in man
Lay eggs, microfilaria, larvae
Give examples of roundworms
Ascaris, hookworm, filaria, strongyloides
How long are adult worms?
Male = 15-30cm Female = 25-35cm
Where do adult worms live?
Lumen of the small intestine
Describe the life cycle of the ascariasis
Live in the small intestine and eggs are passed with faeces.
After infective eggs are swallowed, larvae hatch and invade the intestinal mucosa. They are carried via the portal and then systemic circulation to the lungs.
The larvae mature in the lungs, penetrates the alveolar walls, ascends and is then swallowed.
When they reach the small intestine, they develop into adults (live for 1-2 years).
What are symptoms and treatment for ascariasis
o Symptoms – often asymptomatic but can cause abdominal pain or intestinal obstruction.
Adults feed on SI contents can compound problems in malnourishment in heavy infection.
Penetration of lungs can cause Loeffler’s pneumonia – pools of blood clog the lungs.
o Diagnosis – stool examination.
o Treatment – albendazole or mebendazole.
What can hookworms(nematode) cause?
Iron deficiency anaemia Adult hookworms about 1cm long and curved. They are attached by their buccal capsules to the villi of the small intestine
What is life-cycle of Hookworm?
Larvae are carried through the circulatory system to the heart and then lungs.
Penetrate the alveoli and ascend to be swallowed and reach the SI to mature.
In the SI, they attach to the lumen and cause localised bleeding.
You have larvae that go through the skin
What is trichuris trichiura?
Also known as whipworm
Faecal oral transmission
Eggs hatch in SI and release larvae to mature in colon.
Adults live in the caecum and ascending colon and are fixed in this location.
The worms leave open wounds that causes inflammation of the intestinal wall.
What are the symptoms and diagnosis technique of whipworm?
Only small amounts cause symptoms
o Symptoms – bloody diarrhoea, anaemia (severe vitamin and mineral loss).
Inflammation due to open wounds in intestine, few cases can have rectal prolapse.
o Diagnosis – stool examination.
o Treatment – albendazole or mebendazole.
What are the two types of lymphatic filariasis/filaria?
Brugia malayi, Wucheria bancrofti.
What are symptoms?
o Symptoms – Cause elephantiasis when they block the lymphatic systems.
o Microfilariae are found in peripheral blood.
During the day, they are present in deep veins and at night they migrate to the peripheral circulation.
o Diagnosis – blood smear or antigen detection with an immunochromatic test (CARD) or ELISA.
What is easiest way to diagnose?
In the night because the microfilariae are in the peripheral in the night
What is type of roundworm can get in your eye?
Loaiasis Loa Loa
Mainly confined to Africa
Give an example of a flatworm
Taenia spp.
Give an example of a flatworm/cestode
Taenia spp.
What is the definitive host for tenia?
Humans
What are the symptoms and transmission?
Uncooked meat larvae from muscle of the meat.
Eggs can survive for days to months.
most people are asymptomatic.
T. saginata (up to 10m) often experience more symptoms – abdominal pain, loss of appetite, weight loss, upset stomach, passes white segment.
T. solium(up to 3m)causes cysticercosis – most common cause of acquired epilepsy worldwide.
Give an example of Flukes/Trematodes
Schistosomiasis
What are the 3 types of schistosomiasis?
Schistosoma mansoni. Eggs to SI.
Schistosoma haematobium. Eggs to bladder and ureter.
Schistosoma japonicum. Eggs to SI.
Explain the life cycle of schistosomiasis
Eggs eliminated in water via faeces or urine. These hatch and release miricidia, which penetrates the snail. The snails release cercariae that penetrate the skin.
They then migrate to different tissues and transform into adults and females which reside in venules. Eggs move progressively towards the lumen of the SI (mansoni and japnicum) or the bladder and ureters (haematobium).
What is the vector is schistosomiasis?
Snails
What is the vector in schistosomiasis?
Snails
If snails killed no transmission
What are the symptoms of schistosomiasis?
Days – rash/itchy skin – most people are asymptomatic early on.
Months – fever, chills, cough, myalgia.
Repeated infection in children can cause anaemia, malnutrition and learning difficulties.
o Diagnosis – stool or urine examination.
Treatment – praziquantel.
Give an example of an ectoparasite
Live on skin
Sarcoptes Scabiei
What does sarcoptes scabiei cause?
Burrow in the skin and rash, transmission from human to human
Give another example of ectoparasites except sarcoptes scabiei
Pediculus humanis corporis – body louse.
Pediculus humanis capitis – head louse.
Pthirus pubis – crab louse of pubic area.
What are the 3 stages of lice?
eggs, nymphs and adult
Transmission by direct contact
How is diagnosis of lice made?
Finding a live nymph or adult louse on scalp or hair of a person
