Parasitaemia

Bacteraemia/Septacaemia vs Parasitaemia/Fungi/Viraemia

People are more aware of bacteraemia / septicaemia but do not forget parasitaemia/fungi/viraemia can also occur. These occur when parasites, fungi, viruses get into the blood stream. Our focus for this lecture is parasitaemia.

Blood culture vs Blood examination

A blood culture is when you take a sample of blood into a bottle (aerobic / anaerobic environment) and watch for any growth of organisms in a selective growth medium. A blood examination is when you take a sample of blood, put a drop of blood onto a slide and smear it ≫ prepare a slide.

When do take the blood specimens?

For parasites it does matter when the blood specimen is taken. Parasites are only present in blood when patients are febrile. Some parasites only appear at certain times of the day ≫periodicity of organism.

Sending specimens?

When you send the specimen and a blood examination is done, they prepare a thin + thick blood flim.

Examination of the blood film?

A series of options are available:

• Blood film stain – giemsa, aendine

• Concentration techniques

• Inoculate animals – and see the result of this (i.e.: what clinical features animals show, work backwards from this)

• Have specific antibodies to specific antigen in dipstick – and see if complex is formed (i.e.: this means antigen you are testing for is +ve)

• Serology – look for IgM/IgG discrepancy between acute & convalescent period

• Eosinophilia – detects filiariasis

Some times bacteria are diagnosed with blood examination. An example of this is relapsing fever – caused by spirochaetes (i.e.: you get relapsing pyrexic attacks), Borrelia recurrentis. Treatment of relapsing fever: tetracycline.

Category: Microbiology Notes