Parasitic infections Flashcards
What are the eukaryotic pathogens?
Helminths, protozoa and arthropods.
What are arthropods?
Multicellular invertebrae animals which cause disease such as fleas, mites and and insects.
What are the multicellular eukaryotic pathogens?
Helminths and arthopods
What are the unicellular eukaryotic pathogens?
Protozoa which feed on organic matter. Divided into amoebas, flagellates, ciliates and sporozoas.
What are neglected tropical diseases?
Conditions caused by a range of pathogens in tropical and sub-tropical regions that primarily affect people in poverty conditions in close contact with animals and vectors.
What are the considerations for parasitic infections?
Parasitic diversity, the parasite life cycle (such as tissue specificity and sequestration) concomitant immunity to reinfection, intensity of infection and host-pathogen interactions
What are the important considerations for treatment?
It is a eukaryotic pathogen and shares similar cellular processes to our own, therapeutic window may be very narrow and most anti-bacterials are ineffective
What is an ideal anti-parasite drug?
Selective toxicity to parasites, effective at different life stages of the parasite, unlikely to develop resistance, easy to administer and cost effective.
Where do most deaths from malaria occur?
Subharan Africa in children below 5 years
Where does sexual reproduction of plasmodium occur?
In the stomach, midgut and salivary glands of Anopheles
What does a blood film of a patient with malaria show?
Erythrocytes with rings and infected trophozoites.
How is malaria diagnosed?
RDT/ rapid diagnostic test, blood films or PCR diagnosis
Which malaria strain is the only one to show rings on a blood film?
Plasmodium falciparum- this species can infect RBC of any age and has the highest virulence. The ring is crescent shaped.
Which malaria strain targets senescent RBC?
Plasmodium malariae- infected RBC will tend to be smaller than surrounding cells and have a band marker with a rosette dots shape
Which malaria strain targets reticulocytes?
Plasmodium ovale which causes an oval shape and plasmodium vivax with two characeristic dots
What is quartern malaria?
Fever onset occurs every 3 days caused by rupture of mature schizonts in erythrocytes in p.malariae and p.falciparum
What is tertian malaria?
Fever onset occurs every 2 days caused by rupture of mature schizonts in erythrocytes in p.ovale and p.vivax
Which malaria strains are tertian?
Plasmodium vivax and plasmodium ovale
Which malaria strains are quartern?
Plasmodium malariae and falciparum
What are the clinical features of p. falciparum?
Fevers, chills, sweating, vomiting. Complications include anaemia, cerebral malaria and acidosis respiratory distress.
What is cerebral malaria?
Severe complication of malaria charactersied by seziure and coma shortly after. This occurs due to rupturing of the blood-brain barrier that leads to haemhorrhage unrelated to hypoglycaemia or coma.
Which malaria species causes cerebral malaria?
Plasmodium falciparum-
What are the classes of anti-malarial durgs?
Quinoline drugs: Chloroquinine and quinine
Artemisinin compounds: artemether
Anti-folate: pyromethamine
How do quinoline drugs work?
Prevents parasite detoxification of haem by inhibiting lysis
How do artemisin compounds work?
Interacts with ahem in infected cells to generate free oxygen radicals to alkylate and oxidise proteins and lipids
What is African trypanosomiasis?
Disease caused by either two strains of the parasite rhodeisiensi or gambienesi carried by the tsetse fly found in rural Africa. It destroys ganglion cells of the myenteric plexus and affects the oseophagus.
What is the pathophysiology of African trypanosomiasis?
It is injected as metacyclic tryptomastigotes which enter the circulatory system and become bloodstream tryptomastigotes that multiply via binary fission in areas of the body. When another tsetse fly bites an infected person, bloodstream tryptomastigoes -> procyclic tryptomastigotes which attach to fly midgut and multiply. They leave the midgut and transform into epimastigotes. Epimastigotes enter salivary glands and become metacyclic tryptomastigoes
What is the cause of African trypanosomiasis?
What are the stages of African trypanosomiasis?
Stagr 1: found in peripheral circulation with unspecific symtpoms
Stage 2: parasite is found in CNS by crossing blood-brain barrier and causes neurological disturbances which lead to coma
How can African African trypanosomiasis be prevented?
No prophylactic treatment so can only minimise contact with tsetse flies
How can the rhodeisiensi strain be identified?
Blood test- it is a more acute strain found in East and Southern Africa
How can the gambiensi strain be identified?
Lymph node fluid and card agglutination tests for antibodies. It is a more chronic strain found in Central and West Africa
How can late stage African trypanosomiasis be identified?
CSF
What is Chaga’s disease?
Parasitic disease caused by the faeces deposition of the trypanosoma cruzi arthopod
What are the stages of Chaga’s disease?
Acute stage which lasts weeks -> months with mild symptoms and if left untreated progresses to chronic stage
Chronic stage where parasites are sequested in cardiac muscles and digestive system, causing alterations
What is Leishmaniasis?
Parasite flagellate infection transmitted by infected phelbotomine sandlies. It is injected as leishmanias promastigotes which infect macrophages to become amastigotes and lack a flagella, causing cutaneous ulcers. The reservoir for this infection is rodents and dogs.
What is the treatment for Leishmaniasis?
There is no prophylaxis treatment. treated with amphosterin
What are the features of disease by Leishmania?
3 types:
Cutaneous characterised by large sores nad swollen glands
Visceral with fever, weight loss and splenomegaly and hepatomegaly. This takes days -> years
Mucosal: destruction of mucosal membranes such as those in the nose
What is toxoplasmosis?
Caused by parasite toxoplasmosis gondi present in cat faeces where it reproduces sexually or contaminated conditions. It causes mild lymphadenopathy in adults but in those with immunocomproised, causes formation of cysts in the brains and create neurological disturbances. During pregnancy, can lead to
What is the treatment for toxoplasmosis?
Anti-folates
Pyramethine
Sulfadiazine
What are the non-pathogenic gut protozoans?
Entamoeba, such as entamoeba coli/hartmanni/poleckinana
Lodamoeba buetschelli
These reside in the large intestine
What is amaeboasis?
Caused by foeco-oral transmission of pathogenic entamoeba histolytica cyst which has pseudocytoplasmic projections. It enters the small intestine as it hatches into a trophozoite and in the large intestine destroys mucosa causing diarrhoea and illness.
What are the clinical manifestations of ameoboasis?
May be:
Asymptomatic: luminal ameoboasis
Intestinal invasive: casues colitis, dysentery(IGI disease) due to pore formation and disrupting junctions
Extraintestinal invasive: lesions such as liver abscess and lesions in the genitals
What is giardasis?
Parasitic infection by the flagellates which is transmitted via foeca-oral route, causing diarrhoeal illness from contaminated food or water. Within the intestines, it forms trophozoites that hatch to become cysts.
What is trichomoniasis?
Parasitic flagellate infection of trichomoniasis vaginalis transmitted via sexual contact that leads to genital infection
Which strains of malaria infect RBCs of all ages?
Plasmodium falciparum and ovals.
Which strains of malaria affect older RBCs?
Plasmodium malariae. It has weeks of incubation time.
