Identification of helminth parasites. Virtual Lab

Scolex (head) of Taenia solium
Scolex (head) of Taenia solium
The helminths or parasitic worms correspond to three types: Trematoda, or staves, are a class of phyllo Platyhelminthes (flatworms); Cestoda, are another class of the same phyla, and Nematode, another phyllo, tubular worms. Usually the helminths have a macroscopic size, measuring from 1 mm to 1 m (0,03937 in to 3,28 ft) , and even more.

The identification of the parasite is fundamental for the correct diagnosis of the parasitosis. This requires training in microscopic techniques staining and identification.


Background

- Reading: Para-Site. Helminth Parasites


Procedure

The microscopic identification techniques of parasitic helminths are complex and require specialized training.

This experiment focuses on the identification of parasitic helminths by microscopic and macroscopic observation, not in the manipulation of samples, nor in the microscopic techniques of preparation and staining. For this, a series of parasitic helminths will be observed.

For the identification of cestodes:

- Reading: M. Arcari; A. Baxendine; C. E. Bennett. Guide to Parasitology. The Cestodes

For the identification of nematodes:

- Reading: M. Arcari; A. Baxendine; C. E. Bennett. Guide to Parasitology. The Nematodes

For the identification of trematodes:

- Reading: M. Arcari; A. Baxendine; C. E. Bennett. Guide to Parasitology. The Trematodes


Ways to perform the experiment

1. In Laboratory

The laboratory that performs parasitic helminthology experiments and tests, must have a supply of samples, adequate instruments and staff training. If this is not possible, the microscopic preparations can be purchased. The microscopic preparations of helminth parasites usually cost about 8-10 dollars each. If macroscopic samples of helminths are not available, a good and alternative option is to make visits to museums of Natural History.


2. In Home Lab

In principle, the experiment is not dangerous if carried out with commercial microscopic preparations. For the experiment it is necessary to have a microscope something better than a toy. There are possibilities for setting up a low cost home microscopy lab (in spanish).

If macroscopic samples of helminths are not available, a good alternative option is to make visits to museums of Natural History.


3. Virtually

For this purpose, microscopic images of parasitic helminths can be made in the same post in the next section.


Images of helminth parasites

Click on the image to enlarge.

Fasciola hepatica
Fasciola hepatica

Schistosoma mansoni
Schistosoma mansoni

Proglótidos de Diphyllobothrium latum
Proglottids of Diphyllobothrium latum

Taenia saginata
Taenia saginata

Trichinella spiralis en tejido muscular
Trichinella spiralis in muscle tissue

Huevos de Ancylostoma duodenale
Eggs of Ancylostoma duodenale

Huevo de Ascaris lumbricoides
Egg of Ascaris lumbricoides

Ascaris lumbricoides
Ascaris lumbricoides

Toxocara canis
Toxocara canis

Anisakis en arenques
Anisakis in herring
Huevo de Enterobius vermicularis
Egg of Enterobius vermicularis
Videos:



Removing by surgery of Ascaris lumbricoides




Removing a filarial worm in a eye

Questions and activities


1.- Draw the observed helminths.

2.- Make a table or diagram of identification of the observed helminths.

3.- Indicate the identifying characters of each helminth observed, a small description and their parasitological importance.

4.- Search the Internet for images of helminth parasites.

5.- Enter into the website Global Atlas of Helminth Infections, to Maps and observe in the maps the distribution of the parasitic diseases for helminths, for country or for type of parasite.


Resources for further learning

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