12. Lab diagnosis of parasitic infections

what are the three main classes of parasites?

protozoa

helminths

ectoparasites

what are protozoa?

single celled microscopic organism

intestinal or urogenital type

blood or tissue type

what are helminths?

parasitic worms that can live in the intestines, blood, or tissue of a host. They are typically multicellular and can be categorized into flatworms and roundworms.

what are ectoparasites?

organisms that live on the surface of a host, such as fleas, ticks, and lice, and can cause irritation or disease.

what are the samples most likely to be taken in case of parasitic infections?

Stool, blood, urine, or tissue samples.

parasite identification from stool - what can you see?

cysts or trophozoites in case of protozoa

egg, larvae, parasites or parts of parasites in case of helminths

what are the concentration methods of eggs?

sedimentation method

• using specific gravity solutions

flotation method

• using centrifugation or floatation techniques to separate eggs from fecal material.

how can you isolate/identify eggs from urine sample?

in case of shictosoma haematobium → snail fever

24 hrs collection of urine

1. sample put in plastic tube

2. leave to sediment for 2-3 hrs

3. decant supernatant fluid

4. centrifuge tubes for 10 mins at 2000 rpm

5. sediment can be examined with microscope

methods for detection of parasitic agents in the stool?

direct fluorescent antibody

enzyme immunoassay

rapid immunochromatographic test

thick blood smear?

used to confirm plasmodium species

not good for malaria though (thin smear should be used)