Parasitic infections Flashcards
define infection?
define disease ?
what is the difference?
infection : invasion by and growth of pathogenic microorganisms within the body
disease : a disordered or incorrectly functioning organ, part structure or system of the body resulting from the effect of genetic or developmental errors, infection poisons nutritional deficiency or imbalance toxicity or unfavourable environmental factors, illness, sickness or ailments
define a parasite?
organism living in or on a host and dependent on it for nutrition - normally causing damage
what are the two different types of parasite?
Endoparasites- exist inside the host
Ectoparasites - exist ON the host
what are the types of endoparasites?
Protozoa eg. • Amoeba • Coccidia • Ciliates • Flagellates
Metazoa eg.
•Roundworms
•Flatworms
• Flukes
what is a protozoa?
- These are SINGLE celled organisms
- They are eukaryotes
(they have their genome within a membrane bound
nucleus and there are complex organelles in the cytoplasm) - NO eosinophilia
what is a Metazoa?
- MULTICELLULAR organisms
- They are worms
- Free living, intermediate hosts and vectors
- some inhabit the gut (geohelminths) others invade the tissue
- There is eosinophilia if they invade the blood
what parasitic class is amoebae? what are examples?
how does it cause infection?
Amoeba eg. Entamoeba histolytica
- infection occurs by ingestion of mature cysts in food or hands contaminated by faeces
how common is infection by Entamoeba histolytica ?
- very common 10% of world infected
- It is the third most common cause of death of parasitic infections
- especially common in warm climate
what are the symptoms of infection with Entamoeba histolytica?
- 90% of infections are asymptomatic
- remaining 10% causes symptoms like intense diarrhoea
- Incubation period may be as long as 7 days
how do the cysts infect humans?
- the cysts enter the s. intestine and release active amoebic parasites
- these invade the epithelial cells of the large intestine causing flask shaped ulcers
- the infection can then spread to other organs
how to diagnose Entamoeba histolytica ?
- wet mount
- look for cysts
what is the treatment for Entamoeba histolytica ?
NITROIMIDAZOLE derivatives = act on the trophozoite but not on the cysts
- PARMOMYCINE or DILOXANIDE FUROATE
what is the difference in structure of mature cyst and immature cyst?
mature cyst: 4 nuclei
immature cyst : 1-3 nuclei
what are Coccidial infections in humans?
zoonoses
from animals
what are examples of Coccidial organisms?
Plasmodium species = malaria
Toxoplasma = toxoplasmosis (dangerous for foetus)
Cryptosporidium = diarrhoea
what are the different types of plasmodium in Malaria
Malariae Falciparum Ovale Vivax Knowlesi
what are the two types of host in malaria?
Humans
Female anopheles mosquito
what are the two stages of malaria infection in humans?
Liver
Blood
symptoms of malaria?
when do symptoms occur?
symptoms can occur as early as 7 days or as late as a year
main symptoms : • Fever • Headache • Chills • Vomiting • Muscle pain • paroxysmal (happens every 4-8 hours)
what are complications of malaria?
- Severe anaemia
- Cerebral malaria
- Liver failure
- Shock
- Pulmonary oedema
- Abnormally low blood sugar
- Kidney failure
- Swelling and rupturing of the spleen
what are treatments for malaria?
mild
severe
MILD
•Chloroquine (main one)
•Atovaquone-proguanil
•Artemether-lumefantrine •Quine sulfate
plus one of the following: Doxycycline • Tetracycline • Clindamycine quinine sulfate • Mefloquine
SEVERE
Artemisinin based combination therapy (ACT)
Toxoplasma gondii route of infection to humans
- eating undercooked meat of animals with tissue cysts
- food or water with cat faeces
- Blood transfusion
- organ transfusion
- Contaminated environmental samples
immunocompromised patients infected with Toxoplasma gondii
might develop CNS disease, brain lesions, pneumonitis or retinochoroiditis
Cryptosporidium symtoms diagnosis treatment vulnerable people
- Causes diarrhoea in humans
- stool examination
- fluid rehydration
- common in HIV
example of Ciliates?
Balantidium coli causes balantidiasis
what are the Reservoir hosts of Balantidium coli?
Pigs
Rodents
Primates
symptoms of balantidiasis ?
- most patients are asymptomatic
- immunocompromised patients may experience the following symptoms:
Persistent diarrhoea
Dysentery
abdominal pain
weight loss
vomiting
if untreated might cause perforation of the colon can occur
how to diagnose balantidiasis?
stool examination
example of Flagellates?
Giardia lamblia
which causes GIARDIASIS
how do Flagellates infect?
- Flagellated trophozoites attach by their suckers to the surface of duodenal or jejunal mucosa
- they can survive standard chlorination procedure