parasitic infections Flashcards
parasitic infections: explain the classification of parasites and compare differences between them, recall examples of each and explain the main symptoms they cause
define infection
invasion by and growth of pathogenic microorganisms within the body
define disease
disordered or incorrectly functioning organ, part, structure, or system of
the body resulting from effect of genetic or developmental errors, infection, poisons, nutritional deficiency or imbalance, toxicity, or unfavourable environmental factors; illness; sickness; ailment
define parasite
organism living in/on host and dependent on it for nutrition, causing damage
2 types of parasite
endoparasite, ectoparasite
2 types of endoparasite
protozoa, metazoa
4 types of protozoa
amoeba, coccidiae, ciliate, flagellates
3 types of metazoa
roundworms, flatworms, flukes
features of protozoa
single celled organisms, eukaryotes, varied pathogenesis, some have insect vectors, no eosinophilia
features of metazoa
multicellular organisms, free living, intermediate hosts and vectors, some just inhabit gut while others invade tissues, eosinophilia if invade blood
2 examples of amoeba
E. histolyica (invasive), E. dispar (normal GI commensal)
how does infection by amoeba occur
ingestion of mature cysts in food or water, or on hands contaminated by faeces
describe time frame of amoeba infection
incubation period as short as 7 days, tissue invasion after first 4 months
describe spectrum of amoeba disease
asymptomatic -> dysentry -> amoebic liver abscess (3rs most common cause of death of parasitic infections)
describe how humans, E. histolyica’s only reservoir, are infected
cysts enter small intestine -> release active amoebic parasites (trophozoites) -> invade epithelial cells of large intestines -> cause flask-shaped ulcers -> spread ot other organs via venous system
describe laboratory diagnosis of amebiasis
wet mount of stools to look for mature cysts
treatment of amebiasis
nitroimidazole derivatives (act on trophozoite, not cyst)
in humans, what type of parasite are coccidial infections mostly
zoonoses, so via animals
3 types of coccidia infection
Plasmodium species (5 species), Toxoplasma, Crytosporidium
what disease is Plasmodium species responsible for
malaria
describe life cycle of malaria: types of host and stages in human
different types of plasmodium, 2 types of host (human and female Anopheles mosquito), 2 stages in human (liver and blood)
when do malaria symptoms appear
as early as 7 days, but can be as long as one year
symptoms of malaria
fever, headache, chills, vomiting, muscle pain, paroxysm, severe anaemia, cerebral malaria, liver and kidney failure, shock, pulmonary oedema, hypoglycaemia, rupture of spleen
treatments of uncomplicated malaria
chloroquine, tetracycline
treatments of severe malaria
ACT
diagnosis of malaria
blood film, Giema stained (rapid antigen detection tests are more expensive and less sensitive)
symptoms of toxoplasmosis in immunocompetent individuals (serious danger to foetus)
fever, swollen lymph nodes, headaches, sore throat
infection routes by Toxoplasma gondii
undercooked meat with tissue cysts, food/water contaminated by cat faeces, contaminated environmental samples, blood transfusion, organ transplantation, transplacentally
diagnosis of toxoplasmosis
serological test
what can toxoplasmosis in immunocompromised patients cause
CNS disease, brain lesions, pneumonitis, retinochoroiditis
disease caused by cryptosporidium, and major symptoms
cryptosporidiosis, causing diarrhoea (more severe in immunocompromised)
transmission of cryptosporidium
faecal-oral
diagnosis of cryptosporidiosis
stool examination
treatment of cryptosporidiosis
fluid rehydration
disease caused by ciliate protozoa Balantidum coli
balantidiasis
reservoir hosts of Balantidum coli
pigs, rodents, primates
symptoms of Balantidum coli
persistent diarrhea, dysentery, abdominal pain, weight loss, nausea, and vomiting (left untreated, perforation of colon)
diagnosis of Balantidum coli
stool examination
problem of asymptomatic carriers
don’t get treated as no symptoms, but still spread disease
disease caused by flagellate Giardia lamblia
giardiasis
2 stages of giardiasis
trophozoites, cysts