Parasitic Flagellates

Parasitic Flagellates

Giardia intestinalis

Most common diagnosed flagellate in the human intestinal tract

Has both tropic and cystic stage The living trophozite is rounded

anteriorly and pointed posteriorly

Dorsally it is convex and ventrally it is provided with shallow, slightly notched concavity (sucking disc) which embraces practically the entire anterior of the organism


The pair of nuclei, one on each side of the midline about one fourth of the body length from the anterior end are ovoid and contain a central karyosome consisting of a single dense chromatin mass or a large number of relatively discrete nuclear membrane

A pair of crossed flagella arises from the midline Giardia intestinalis, was discovered in 1681 by Leeuwenhoek, common in the small intestine,

prevelance rates vary 1-30%. Parasite has a pair of adhesive suckers which gives it a characteristic appearance.

It attaches to the cells of the gut using the suckers and divides by binary fission, in this way huge numbers can build up in the intestine. They are spread by resistant cysts, each of which contains a pair of parasites, it is highly contagious. Causes diarrhoea, vomiting and loss of weight, the parasite does not break down host cells, but the dense layer of parasites over the surface of the intestine probably interferes with absorption and triggers the onset of disease. Giardia is a traveller's disease, widespread in Eastern Europe, also outbreaks in the USA, Aspen in Colorado, the ski resort.


The picture at right shows multiple views of a single Giardia lamblia (intestinalis) cyst as imaged at different instrument settings by confocal microscopy. (A) is the cyst imaged by transmission (differential interference contrast), only. (B) is the cyst wall selectively imaged through use of fluorescent-labelled (TRITC) antibody that is cyst wall specific. (C) is the cyst imaged through use of carboxy fluorescein diacetate, a viability stain. (D) is a composite image of (B) and (C). (E) is a composite image of (A), (B), and (C). Bar = 10 micrometres. Under a normal compound light microscope, Giardia often looks like a "clown face," with two nuclei outlined by adhesive discs above dark median bodies that form the "mouth." Cysts have four nuclei.


The pair of nuclei, one on each side of the midline about one fourth of the body length from the anterior end are ovoid and contain a central karyosome consisting of a single dense chromatin mass or a large number of relatively discrete nuclear membrane

A pair of crossed flagella arises from the midline

Trypanosome

Trypanosome

Gains access to man by blood, lymph, lymph gland, spleen, liver, and brain

Trypanosoma cruzi

T. cruzi, found in the southern U.S., Mexico, and Central and South America, causes symptoms similar to those of African sleeping sickness. Due to its location however, the disease is named Chaga's disease or South American trypanosomiasis.

The most important mechanism of transmission of T. cruzi to humans and other mammals is throughout the feces of infected triatomines. The vectors of Chagas disease are insects of the order Hemiptera, family Reduviidae and subfamily Triatominae.

Trypanosoma cruzi Chaga’s disease

T. cruzi inhabits the guts of the reduvid bug (panstrongylus megistus) The ineffective trypanosomes are passed with the feces of the bug, which are rubbed or scratched at the bite wound of the host

Tsetse fly

From genus Glossina

Trypanosomiasis

There are two types of African trypanosomiasis (also called sleeping sickness); each is named for the region of Africa in which they are found.

Trypanosoma brucei rhodesiense East African Trypanosomiasis

caused by a parasite named Trypanosoma brucei rhodesiense carried by the tsetse fly

Its primary vectors are Glossina mortisans and pallidipes

If a person fails to receive medical treatment for East African trypanosomiasis, death will occur within several weeks to months.

East African trypanosomiasis is found in parts of Eastern and Central Africa, including Uganda, Kenya, Tanzania, Malawi, Ethiopia, Zaire, Zimbabwe, and Botswana. Areas where infection is spread are largely determined by the location of the infected tsetse fly and wild animal population.

Trypanosoma brucei rhodesiense East African Trypanosomiasis

A bite by the tsetse fly is often painful and can develop into a red sore, also called a chancre. Fever, severe headaches, irritability, extreme fatigue, swollen lymph nodes, and aching muscles and joints are common symptoms of sleeping sickness. Some people develop a skin rash. Progressive confusion, personality changes, slurred speech, seizures, and difficulty in walking and talking occur when infection has invaded the central nervous system. If left untreated, infection becomes worse and death will occur within several weeks or months.

Symptoms begin within 1 to 4 weeks of getting an infected tsetse fly bite.

No one is immune from East African trypanosomiasis. Even if you had the disease once, you can get re-infected.

Trypanosoma brucei gambienseWest African trypanosomiasis

also called Gambian sleeping sickness, is caused by a parasite called Trypanosoma brucei gambiense carried by the tsetse fly.

A bite by the tsetse fly is often painful. Occasionally, within 1 to 2 weeks, the infective bite develops into a red sore, also called a chancre. Several weeks to months later, other symptoms of sleeping sickness occur. These include fever, rash, swelling around the eye and hands, severe headaches, extreme fatigue, aching muscles and joints. You may develop swollen lymph nodes on the back of your neck called

Winterbottom's sign. Weight loss occurs as the illness progresses. Progressive confusion, personality changes, slurred speech, irritability, loss of concentration, seizures, and difficulty in walking and talking occurs when infection has invaded the central nervous system. These symptoms become worse as the illness progresses. Sleeping for long periods of the day and having insomnia at night is a common symptom.

Characteristic swelling of cervical lymph nodes commonly called Winterbottom's sign.

stage wherein Trypanosomes multiply in the bloodstream and lymphatic system and there are few specific symptoms other than the characteristic swollen cervical lymph nodes

Trypanosoma brucei gambienseWest African trypanosomiasis

Chilomastix mesnili

The trophozoite is symmetrical with the spherical nucleus situated medially near the anterior end

The cystome is well define, rounded anteriorly and posteriorly with median costriction

The cytoplasm is granular containing numerous food vacuoles

The cysts are pear-shaped, rounded at one and bluntly conical at the other end

The cyst wall is a broad extension at one end forming a spade-like projection

Chilomastix mesnili

Chilomastix mesnili

C. mesnili is a normal inhabitant of the caecal region where trophozites live on enteric bacteria and multiply by binary fission

Cysts in water and food are direct transmitting agents in the life cycle of this parasite

Chilomastix mesnili

There is a single nucleus and a curved cytostomal fibril called the shepherd's crook. The image at right is a trichrome stain

Chilomastix mesnili

The trophozoites of C. mesnili are also pear-shaped and measure from 6 to 24 µm in length and 4 to 8 µm wide. The single nucleus usually has a prominent karyosome. The anterior flagella are difficult to see. The oral groove (cytostome) is sometimes seen near the nucleus. The image on the left is an iron hematoxylin stain (1000x).

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Parasitic Flagellates