The diagnosis of parasitic infection is done by

Clinical symptoms

Laboratory diagnosis

Purposes of performing laboratory diagnosis is 

Confirmation of clinical diagnosis

Identification of clinically undiagnosed infection

Specimen collected for laboratory diagnosis specimen is collected depending on the type of parasitic infection suspected 

Stool 

Blood

Serum and plasma

Tissue and aspirate 

Other specimen like sputum, urine,anal swab, duodenal aspirate, urogenital specimen

Stool examination

Sample collection 

The stool sample is collected in a clean and dry container

It should not be mixed with urine or disinfectant

Specimen can be obtained by enema or laxative

Sometimes use of preservatives may be indicated

Examination of the stool sample

Gross examination

Consistency should be noted.The stool may be liquid, formed or semiformed.sometimes the gross examination may reveal the type of parasitic infection e,g mucoid blood stained some parasite can be detected macroscopically in the stool sample e.g ascaris 

Microscope examination 

Saline mount, iodine mount,the Saline and iodine wet mount help in the identification of protozoa,cyst, eggs and larva of helminth and crystal

Permanent stained smears

Iron haematoxylin

Wheatleys trichrome stain 

Modified ziehl neelsan stain 

Concentration method are done in case where the parasite are scanty in the specimen 

Floatation techniques are solution which have High specific gravity eggs and cyst will float and the other debris will sink 

The important agent used are

Saturated sodium chloride

Zinc sulphate centrifuge floatation

Sedimentation techniques are solution which have low specific gravity

The most commonly used is formol ether

Antigen detection

Fresh or preserved stool sample are used for antigen detection

There are several commercial ELISA kita for diagnosis of amoebiasis 

Direct immunofluorescence assay is done for giardia cyst 

Molecular diagnosis

The polymerased chain reaction is used for identification of parasites in the stool sample the amplified fragments can be further analysed by using restrictions fragments length polymorphism or by dna sequence 

Blood examination

The blood samples that are collected are 

Fresh capillary blood of finger 

Venous blood collected in edta 

Blood samples will be used for

Microscopic examination thin smear thick smear wet mount for microfilaria 

Thick smear

Used to screen a large amount of blood

Another advantage is that it can be stained later

Thin smear

It is used to examine malarial parasite in the RBC thin smear help in th identification of plasmodium species 

Molecular diagnosis1 to 5 ml blood samples is collected in tube with edta dna is extracted usin5dna extraction kits 

Used to identify the plasmodium species