Parasitic Infections Flashcards
what is a PARASITE
An organism that lives in (or on) (infects) the host and is dependent on it for nutrition, often causing damage or disease
What are protozoa
are single-celled eukaryotic organisms whose pathogenesis is varied and many are carried by insect vectors
- They do not produce eosinophilia in the host
What are metazoa
- Helminths/worms are complex multicellular organisms known as metazoa which can be free living or transmitted by vectors and their lifecycle involves an intermediate host – humans are the definitive host
- Adult worms lay eggs or produce microfilariae but cannot themselves multiply in man, so they’re a cause of morbidity rather than mortality
- Forms which invade the blood often cause eosinophilia
Do protozoa evoke eosinophilia
No
Do metazoa evoke eosinophilia
Yes
What are ectoparasites
Parasites that live externally
What are endoparasites
Parasites that live internally
4 types of protozoa?
Amoeba, coccidiae, ciliae, flagellates
3 examples of metazoa?
roundworms, flatworms, flukes
Difference between protozoa and metazoan?
Protozoa: single celled, no eosinophilia, can cause mortality
Metazoa: multicellular, eosinophilia, cause morbidity rather than mortality
2 examples of ectoparasites?
Scabies, live
Example of an amoeba?
Entamoeba histolyca
What does Entamoeba histolyca cause?
bloody diarrhea (dysentery) when it infects the colon and can also lead to abscess formation in the liver – these amoebae can ingest red cells
Example of an coccidiae? (3)
- Plasmodium species e.g. P. falciparum, ovale, vivax, knowlesi and malariae cause malaria – the lifecycle involves the invertebrate (Anopheles mosquito) and the vertebrate (man)
- Toxoplasma gondaa
- Cryptosporidium
What type of parasite is Entamoeba histolyca
Amoeba
What type of parasites are plasmodium
Coccidiae
Pathophysiology of malaria? (5)
febrile illness, paroxysm, cerebral malaria, respiratory distress and severe anaemia
What type of parasite is Toxoplasma gondaa
coccidia
What type of parasite is Cryptosporidium
coccidia which can infect the small bowel and produces severe diarrhea – infection is commonly waterborne/faeco-oral
What does cryptosporidium cause
coccidia which can infect the small bowel and produces severe diarrhea – infection is commonly waterborne/faeco-oral
How do you diagnose malaria? (2)
Blood films are used to diagnose, rapid test is also available via antigen detection test
Example of Flagellate? (4)
- Giardia
- Trichomonas
Lieshmania
Trypanosoma (Tsetse flies)
Giardia is example of what type of protozoa?
Flagellate
Trichomonas is example of what type of protozoa?
Flagellate
Lieshmania is example of what type of protozoa?
Flagellate
Trypanosoma is example of what type of protozoa?
Flagellate
What does giardia infect
the upper small bowel (jejunum)
What does giardia cause
giardiasis (prolonged diarrhea, sometimes causing malabsorption
What does trypanosoma cause
febrile illness with lymphadenopathy
What does trichonomonas cause (3)
vaginitis
Causes an offensive odour, can cause abdominal pain
Example of a ciliate and what it causes?
- Balantidium is an unusual pathogen in man causing balantidiasis, which involves diarrhea in immunocompromised patients
What is a vector
A vector is an organism that acts as an intermediary host for a parasite.
4 examples of roundworms?
- Ascaris
- Filaria
- Hookworm
- Strongyloides
What does ascaris cause? What does this lead to?
ascariasis in the bowel, they live in the intestines – worms can cause obstruction of the bile duct or the bowel, and have no intermediate host, abdominal pains, or malnourishment
What does hookworm cause?
Iron deficiency
How does hookworm enter the body
via the skin
examples of a metazoa with no intermediate host?
Ascaris
What do filaria cause?
Aedes mosquitoes, blackflies and mango flies and can cause lymphatic filariasis (elephantiasis), cutaneous filariasis (onchoceriasis) and loaiasis (Loa Loa) (eyeworm)
What does the aedes mosquito act as a vector for and cause?
filaria and can cause lymphatic filariasis (elephantiasis)
What do blackflies act as a vector for and cause?
filaria and cutaneous filariasis (onchoceriasis)
What do mango flies act as a vector for and cause?
filaria and loaiasis (Loa Loa) (eyeworm)
What does Strongyloides worm cause
severe illness especially when the host is immunocompromised – cause of diarrheal illness in the tropics
Example of a flatworm?
- Taenia (tapeworm) - pork (taenia solium) or beef (taenia saginata)
what does taenia infectation cause and what does it lead to the acquisition of?
can invade host tissues especially the brain leading to cysticercosis with fits and neurological signs
- Commonest cause of acquired epilepsy
Example of a fluke?
- Schistosoma
what do schistosoma do to the human?
Adult worms live in the urinary bladder or bowel where they lay eggs which may spread to the liver and cause inflammation leading to fibrosis and obstruction of the HPV – this results in esophageal varices and hemoptysis
Example of a lice?
Pediculus humanus capitis, pediculus humanus corporis and pthirus pubis
What can lice serve as a vector for (3)
Rickettsia prowazekii (epidemic typhus), Bartonella Quintana (trench fever) and Borrelia recurrentis (louse-borne relapsing fever)
What is the vector for leishmania
sandflies
Difference between leismania in the human vs in the sandfly host?
No longer has flagella in the human
3 forms of leishmaniasis and what are the defining features?
Visceral: most severe, irregular fever, weight loss, swelling of liver and spleen, anaemia
Cutaneous: skin lesions on exposed body parts, can create serious disability and scars
Diffuse cutaneous: disseminated lesions, resembles leprosy, no spontaneous healing, frequent relapses
mucocutaneous: disfiguring, destroys mucous membranes
what are the defining features of visceral lieshmaniasis? (4)
irregular fever, weight loss, swelling of liver and spleen, anaemia
what are the defining features of cutaneous lieshmaniasis? (3)
skin lesions on exposed body parts, can create serious disability and scars
what are the defining features of diffuse cutaneous lieshmaniasis? (4)
disseminated lesions, resembles leprosy, no spontaneous healing, frequent relapses
what are the defining features of mucocutaneous lieshmaniasis? (2)
disfiguring, destroys mucous membranes
