Parasitology Flashcards
What are protozoa?
Microscopic single celled organisms (can be free-living or parasitic)
- can multiply and cause serious infection
How are protozoa transmitted from humans?
Protozoa living in human intestine transmitted by fecal-oral route
Protozoa living in blood or tissues transmitted by arthropod vector
What is a parasitic protozoa and how it it transmitted?
Organisms that lives on/in host and get its food at expense of host and is transmitted by vector
What is a free-living protozoa and how are you infected?
Lives in environment e.g. pond, infected by exposure
How are types of protozoa classified?
Mode of movement
What are the classificiation of protozoa?
Amoeba - use pseudopodiums (projections)
Flagellates
Ciliates
Sporozoa - not motile in adult stage
Name medically important protozoa infections?
- copy paste from slide
What are helminths?
Large multicellular organisms (worms)
What are the three main groups of helminths?
Nematodes (roundworm)
Trematodes (flukes)
Cestapodes (tapeworms)
What does number of worms in infection rely on?
Number of eggs inside human, cannot multiply as in adult form in humans
What are the categories of medically important nematodes? and examples of each
Soil transmitted helmiths - ascaris lumbricoides
Filarial parasites - loa loa
Name a few medically important trematodes?
Schistosoma mansoni
Fasciola hepatica
Name a few medically important cestodes?
Taenia saginata
Taenia solium
What are ectoparasites?
Blood sucking arthropods that attack/burrow into skin and remain there for long periods of time
name a few ectoparasites
ticks, fleas, lice and mites
What are the 2 types of ticks?
hard and soft
What are the types of hosts for parasites?
Intermediate - host in which larval/asexual stages develop
Definitive - host in which adult and sexual stage occurs
What are the types of vectors parasites can have?
Mechanical when no development of parasite in vector
Biological - some stages of parasite life cycle happens in vector
What determines parasite infection spread and distribution?
Depends on mode of tranmission
Faeco-oral - access to clean water, household sanitisation
Food - government controls
Complex life cycle of parasite - host is intermidiate or definitive
Education
Urban / rural
Why is a parasite life cycle complex?
have diff types of hosts(definitive and intermediate) and vectors (biological and mechanical)
What is chagas disease?
Protozoa disease caused by trypansoma cruzi protozoa
What is the life cycle of trypansoma cruzi?
Triatomine bug takes blood meal allowing tyrpansoma cruzi to enter through bite wound
It penetrates cells and transforms into AMASTIGOTES
Amastigotes multiply by binary fission in infected cells
Intracellular amastigotes transform into trypomastigoes and bust out cell and enter blood stream and either cycle starts here and enters another cell
Triatomine bug takes blood mean and carries of the parasite for cycle to start again in new person
What are the phases of chagas disease?
Acute, chronic intermediate, deteminate chronic disease
What happens in the acute phase of chagas disease? + symptoms
Tryposomes in blood Mild to no symptoms - Local swelling - fever - anorexia
What happens in the chronic “intermediate” stage of chagas disease?
Lifelong infection - parasite present at low levels - may not be detected from serum , can useing ECG and X rays
What happens in the determinate chronic disease phase of chagas disease?
Seropositive, can detect in blood and effects organs including heart+ digestive system
How does Chagas effect the heart?
Parasite infests hearts purkinje fibres in conduction systems causing inflammation and fibrosis damaging to conduction system leading to:
- arrythmia
- cardiomyopathy
- aneurysm at apex
- enlarged heart with thin walls - causes heart failure
How does Chagas affects the digestive system + symptoms?
Esophagus, rectum, and SIGMOID colon most affected
MEGACOLON - constipation, faecaloma, obstruction, sigmoid volvulus, ulceration
What is the pathogenesis of chagas in the diff phases of disease? ie the cytokines and cells involved
Acute - tissue damaged by inflammatory response and antibodies kill parasite activated by innate immune response and Th1 pro-inflammatory cytokines
Chronic intermediate - regulatory immune response by IL10 and IL17
Chronic determinate - chronic inflammatory response due to perisistent paraites in muscles and nerve cells - predominantly Th1 cytokines and CD8+ cells
What is leishmania?
Parasite disease
What is the vector for leishmania?
SAND FLY
What is the life cycle of leishmania?
Sand fly has blood meal and transmits promastigote
Promastigotes enter macrophages + form amastigotes via asecula reproduction
Cell bursts and amastigotes released to further infect via another sand fly or to other cells
What are the types of leishmania disease?
Visceral leishmaniasis
Cutaneous leishmaniasis
How can leishmania disease be viewed?
Under microscopes inside cells as amastigotes
What is the vector for leishmania?
sand fly
What are the reservoirs for leishmania?
Dogs (domestic), rodents
What are the clinical forms of leishmania disease?
Ulcers, lesions from continuous reactivation
What is diffuse leishmania?
Nodules packed with leishmania parasites
What is mucocutaneous leishmania?
decomposes + damage of tissue = loss of septum
What is the stages + pathogenesis of cutaneous leishmanias?
Acute lesions
Latency
Relapse
How do you know currently have latent cutaenous leishmania?
Balance between Th1 and pro-inflammatoy reponse
