Microbiology Laboratory

Introduction to PARASITOLOGY Lab

Written by MicroDok

Parasitology is simply defined as the study of parasites. But for the purpose of this work, only medically important parasites (i.e. parasites that cause disease in humans) shall be considered here. Parasites are organisms that depend entirely on another organism known as the host, for all or part of its life cycle and metabolic requirements. Specimens encountered in the clinical Parasitology laboratory includes: feaces, urine, liver aspirates, blood, bile, sputum, corneal scrapings, duodenal aspirates and tissues. Though majority of the analysis or investigations carried out with these specimens are normally undertaken microscopically, specialist Parasitology laboratories (and reference laboratories) also incorporate serology (e.g. ELISA) and polymerase chain reaction (PCR) techniques in their parasitological investigations.

A parasite is an organism that is able to live in or on the body of another organism called a host and cause disease. The relationship that exists between a host and a parasite (in which only the parasite benefit) is called parasitism. There are two types of parasite: ectoparasites and endoparasites. Ectoparasites are parasites that live on the body of their host. Example of ectoparasites include: lice and tick. Endoparasites are parasites that live inside the body of their host. Example of endoparasites include: worms, Plasmodium and Trypanosome. Parasites (endoparasites and ectoparasites) are implicated in a variety of tropical diseases including malaria and diarrhea and, they present a major public health issue in most parts of the world especially in the developing countries where sanitation, water supply and environmental sustainability is still being improved upon.

The parasitological unit of the microbiology laboratory is mainly responsible for the macroscopic and microscopic investigation of parasites, their cysts, and ova’s in the specimen of patient’s. The specimens encountered in the parasitological unit of the microbiology laboratory are: urine, stool (feaces), blood, and skin snip. An essential procedure in the diagnosis of all parasitic infections is the microscopic recognition or identification of ova or larvae of the infecting parasites in feaces, blood, urine, or tissues of patients as they report to the hospital with one helminthic infection or the other. 

PARASITES OF MEDICAL IMPORTANCE ENCOUNTERED IN THE PARASITOLOGY LABORATORY

PARASITE COMMON NAMES DISEASE CAUSED/ORGAN ATTACKED 
Wuchereria bancrofti Microfilaria Bancroftian filariasis
Ancylostoma duodenale Hookworm Parasitosis
Fasciola hepatica Liver fluke Liver
Loa loa Microfilaria Loiasis
Ascaris lumbricoides Roundworm Parasitosis
Onchocerca volvulus Microfilaria River blindness
Necator americanus Hookworm Parasitosis
Paragonimus westermani Lung fluke Paragonimiasis
Trypanosome cruzi Blood parasite Chagas disease
Giardia lamblia Intestinal protozoa Giardiasis
Balantidium coli Intestinal parasite Balantidial dysentery
Entamoeba histolytica Intestinal parasite Amoebic dysentery
Isospora belli Intestinal coccidia Diarrhea in AIDS patients
Cyclospora cayetanensis Intestinal coccidia Diarrhea in AIDS patients
Cryptosporidium parvum Intestinal coccidian Diarrhea in AIDS patients
Trichuris trichiura Whipworm Trichuriasis
Strongyloides stercoralis Dwarf threadworm Strongyloidiasis
Schistosoma species Intestinal parasites Schistosomiasis
Fasciolopsis buski Intestinal fluke Fasciolopsiasis
Taenia sanigata Beef tapeworm Taeniasis
Taenia solium Pork tapeworm Taeniasis
Diphyllobothrium latum Fish tapeworm Diphyllobothriasis
Trypanosoma brucei gambiense Blood parasite Sleeping sickness (West African trypanosomiasis)
Trypanosoma brucei rhodesiense Blood parasite Sleeping sickness (East African trypanosomiasis)
Hymenolepsis nana Dwarf tapeworm Diarrhea
Leishmania species Kala-azar Leishmaniasis
Dracunculus medinensis Guinea worm Dracunculiasis
Toxoplasma gondii Toxoplasma Toxoplasmosis
Plasmodium species Blood parasite Malaria

SOME OF THE MAJOR PROCEEDINGS UNDERTAKEN IN THE PARASITOLOGICAL UNIT OF THE MICROBIOLOGY LABORATORY INCLUDE:

  • Stool analysis
  • Urine analysis
  • Occult blood test (OBT)
  • Skin snip
  • Wet mounting
  • Concentration/floatation technique
  • Urine chemistry

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MicroDok

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