Subphylum Mastigophora PDF

Phyllum Sarcomastigophora. Subphyllum Mastigophora (flagellates) Genus Trypanosoma Genus Giardia Genus Trichomonas Genus Leishmania Phylum Sarcomastigophora  Includes two subphyla: ➢ subphylum Sarcodina ➢ subphylum Mastigophora (flagellates): the main feature of the representatives of this...

Phyllum Sarcomastigophora. Subphyllum Mastigophora (flagellates) Genus Trypanosoma Genus Giardia Genus Trichomonas Genus Leishmania Phylum Sarcomastigophora  Includes two subphyla: ➢ subphylum Sarcodina ➢ subphylum Mastigophora (flagellates): the main feature of the representatives of this subphylum is the presence of one or more flagella (flagellum) by means of which they move Genus Trypanosoma All members of the genus Trypanosoma exist at sometime in their life cycle, as trypomastigote stage with an elongated spindle-shaped body, central nucleus, a posterior kinetoplast and long undulating membrane. Reserve food granules are found in cytoplasm too. Trypanosoma pass their life cycle in two hosts: 1. vertebrate hosts 2. insect vectors . reproduction – longitudinal binary fission Classification of Trypanosomes • Trypanosomes infecting man 1. Trypanosoma brucei complex includes: subspecies 1.1 Trypanosoma brucei gambiense 1.2 Trypanosoma brucei rhodesiense Cause African trypanosomiasis (sleeping sickness) • Trypanosomes infecting animals ➢Trypanosoma equiperdum – causes ,,stallion's disease’’ (dourine) in horses and mules Trypanosoma gambiense and Trypanosoma rhodesiense Trypanosoma brucei gambiense is widespread in Central and West Africa. Trypanosoma brucei rhodesiense is widespread in Еаst Africa. Habitat • Trypanosomes live in man and other vertebrate host (game animals, domestic animals). They are essentially a parasite of connective tissue, where they multiply rapidly and then invade regional lymph nodes, blood and finally may involve central nervous system (cerebrospinal fluid). А) Cytological slide prepared from cerebrospinal fluid from a child with congenital trypanosomiasis B) Blood smear from the child Vector of Trypanosoma brucei rhodesiense and Trypanosoma brucei gambiense Tsetse fly – Glossina species (Glossina morsitans, Glossina palpalis) Forms of T. brucei rhodesiense and Т. brucei gambiense  Trypomastigote form 1. In vertebrates 2. The nucleus is oval and centrally located 3. Narrow, spindle-shaped body elongated and pointed at the end 4. Basal body (blepharoplast) and a flagellum starting from it at the back end 5. The blepharoplast is posterior to the nucleus 6. Undulating membranе (supports cell movements) 7. Kinetoplast (an organelle of mitochondrial origin) Forms of T. brucei rhodesiense and Т. brucei gambiense  Procyclic form – in the midgut of tsetse fly  Epimastigote form 1. Leaving the midgut, procyclic forms transform into epimastigotes (in proventriculus) 2. The blepharoplast passes in front of the nucleus and the undulating membrane shortens 3. The epimastigotes reach the fly’s salivary glands Forms of T. brucei rhodesiense and Т. brucei gambiense  Metacyclic form 1. In the salivary glands of tsetse fly 2. Strongly shortened flagellum 3. Undulating membrane is absent 4. This is the invasive form of parasite for humans Life cycle of T. brucei rhodesiense and Т. brucei gambiense Antigenic variation • Way of trypanosomes to evade our immune system: ✓ African trypanosomes infect our blood, organs and tissues but, unlike viruses, they do not invade our cells. Therefore, they are continuously exposed to the antibodies that we generate against them, and which also circulate in our bloodstream ✓ In fact, most of the circulating trypanosomes are successfully destroyed by these antibodies. The problem is that there are always survivors: trypanosomes that change their surface antigens, so they are not recognized by the current antibodies. These are unaffected by antibodies that are already generated, so the immune system has to start over again (this process continues essentially indefinitely, until the death of the host) ✓ One consequence of this is that our immune system becomes quite exhausted and our blood levels of antibody increase, without useful effect. VSG – Variant surface glycoproteins (the frequent switching of the VSG on the surface accounts for antigenic variation) IMPORTANT!!!! SLEEPING SICKNESS • TRYPANOSOMA BRUCEI RHODESIENSE CAUSES ACUTE FORM OF SLEEPING SICKNESS (EAST AFRICAN TRYPANOSOMIASIS) AND IS TRANSMITTED BY GLOSSINA MORSITANS. • TRYPANOSOMA BRUCEI GAMBIENSE CAUSES CHRONIC FORM OF SLEEPING SICKNESS (WEST AFRICAN TRYPANOSOMIASIS) AND IS TRANSMITTED BY GLOSSINA PALPALIS. Sleeping sickness – clinical features:  A painless chancre (trypanosomal chancre) appears on skin at the site of bite by tsetse fly.  With the entry of trypanosomes into the bloodstream begins and the appearance of fever, rashes, enlargement of lymph nodes.  CNS involvement is demonstrated by headache, stiffness and limited neck mobility, sleep disturbances, progressive mental retardation, seizures. In the extreme phases of the disease, patients fall into coma and die. It is not necessary to study the symptoms of sleeping sickness trypanosomal chancre Trypanosomes can pass through placenta & infect baby enlarged lymph node How can we diagnose trypanosomiasis?  Detection of trypanosomes in: Wet mount preparation of: => lymph node aspirate => blood smear => stained smear of cerebrospinal fluid  Serology methods  Molecular diagnosis (PCR) Blood smear PROPHYLAXIS OF AFRICAN TRYPANOSOMIASIS  Control of tsetse fly population (most important preventive measure) by wide spraying of insecticides, traps and baits impregnated with insecticides. Dourine  Parasitic venereal disease of equines (horses and mules)  It’s caused by Trypanosoma equiperdum – It is transmitted by sexual contact, without the need for an insect vector  Trypanosoma equiperdum is also found in Bulgaria Trypanosoma equiperdum Genus Leishmania The genus Leishmania is named after Sir William Leishman, who discovered the flagellate protozoa causing kala-azar, the Indian visceral leishmaniasis (VL). All members of the genus Leishmania are obligate intracellular parasites that pass their life cycle in two hosts: 1. the mammalian host 2. the insect vector, female sandfly (insect from genus Phlebotomus) Leishmania donovani forms Genus Leishmania ln humans and other mammalian hosts, they multiply within macrophages, in which they occur exclusively in the amastigote form. In the sand fly, they occur in the promastigote form. Amastigote form o Оval form o Contains nucleus, kinetoplast, basal body Phlebotomine sandfly (The picture shows Phlebotomus papatasii) Promastigote form o Spindle-shaped body o Contains nucleus, kinetoplast, basal body and single flagellum, arising from anterior end Three different diseases are caused by various species of genus Leishmania:    Visceral leishmaniasis (kala-azar) is caused by Leishmania donovani complex Cutaneous leishmaniasis is caused mainly by Leishmania tropica complex, L. mexicana complex Mucocutaneous leishmaniasis is caused by Leishmania braziliensis complex Leishmania donovani promastigote form amastigote form (in macrophages) • Causes kala-azar disease (visceral leishmaniasis) • Reservoir of L. donovani are dogs, jackals, foxes. In addition to humans, it also parasitizes other vertebrates. • Amastigote form is known also like Leishman-Donovan body (LD) • L. donovani reproduces mainly in phagocytes of the spleen, liver, bone marrow, lymph nodes and blood macrophages. It is also found in our country (mainly in southern Bulgaria) Life cycle of Leishmania donovani Amastigote and promastigote forms dividing is by binary fission. Visceral leishmaniasis Visceral leishmaniasis or kala-azar is a major public health problem in many parts of world. Humans acquire by bite of an infected female sandfly. It can also be transmitted vertically from mother to fetus, by blood transfusion and accidental inoculation in the laboratory. Visceral leishmaniasis Symptoms: • High temperature, splenomegaly, hepatomegaly, limphadenomegaly • Skin becomes dry, rough and darkly pigmented (hence, the name kala-azar) • Loss of weight is seen It is not necessary to study the symptoms of visceral leishmaniasis How is visceral leishmaniasis diagnosed? ❑ DEMONSTRATION OF AMASTIGOTES IN SMEARS OF TISSUE ASPIRATES (SPLENIC ASPIRATE, BONE MARROW PUNCTATE, LYMPH NODE ASPIRATE, PERIPHERAL BLOOD) IS THE GOLD STANDARD FOR DIAGNOSIS OF VISCERAL LEISHMANIASIS. Amastigote parasite can be seen within the macrophages, often in large numbers. ❑ Serodiagnosis is also useful (detection of specific antigens and antibodies). ❑ Molecular diagnosis (PCR) Prophylaxis of kala-azar • Integrated intescidial spraying to reduce sandfly population • destruction of animal reservoir host in cases of zoonotic kala-azar • use of anti-bite repellents LEISHMANIA TROPICA COMPLEX Remember Leishmania tropica only for your exam. lt includes three species: 1. Leishmania tropica 2. Leislzmania major 3. Leishmania aethiopica All these species cause old world cutaneous leishmaniasis (typical for Africa, Asia). The amastigote forms occur in the reticuloendothelial cells of the skin (macrophages), endothelial cells of skin vessels, whereas promastigote forms are seen in sandfly vector. LEISHMANIA TROPICA COMPLEX Morphology of L. tropica complex is indistinguishable from that of L. donovani. The vectors of L. tropica complex are Phlebotomus sandflies: 1. L. tropica – Phlebotomus sergenti 2. L. major – Phlebotomus papatasii 3. L. aethiopica – Phlebotomus longipes It is not necessary to remember the species in the Leishmania tropica complex and their respective phlebotomus species. The most common mode of infection is through bite of sandflies. Phlebotomus sergenti CUTANEOUS LEISHMANIASIS: SUBTYPES Antroponotic urban type (dry cutaneous leishmaniasis): 1. It begins as a raised papule, which grows into a nodule that ulcerates over some weeks 2. Lesions may be single or multiple 3. Usually localized on the face 4. The dry ulcers usually heal spontaneously in about an year CUTANEOUS LEISHMANIASIS: SUBTYPES Zoonotic rural type (wet cutaneous leishmaniasis): 1. Moist, secreting ulcers which are inflamed, often multiple, mainly on the extremities 2. Rats and other rodents are the reservoirs. DIAGNOSIS OF CUTANEOUS LEISHMANIASIS Smear is made from the material obtained from the indurated edge of nodule or sore. Amastigotes are found in large numbers inside the macrophages. Mucocutaneous leishmaniasis L. braziliensis complex causes mucocutaneous leishmaniasis (espundia). L. braziliensis causes the most severe and destructive form of cutaneous lesion. It involves the nose, mouth and larynx. The patient experiences a nodule at the site of sandfly bite with symptoms consistent with oriental sore. Subsequent mucocutaneous involvement leads to nodules inside the nose, perforation of the nasal septum and enlargement of the nose and lips (espundia). Ulcerated lesions may lead to scarring and tissue destruction that can be disfiguring. If the larynx is involved, the voice changes as well. The disease occurs predominantly in Bolivia, Brazil and Peru. Diagnosis of mucocutaneous leishmaniasis Amastigotes are demonstrated in smears taken from lesions of skin and mucous membrane. Serology: ELISA is also a sensitive method to detect antibody; being positive in 85% of cases. Prophylaxis of cutaneous and mucocutaneous leishmaniasis • Due to sylvatic and rural nature of the disease, control is often difficult. • Use of insect repellants, spraying of insecticides and screening are advisable. • Forest workers should use protective clothing and other protective measures Giardia lamblia (Lamblia duodenalis or Lamblia intestinalis) •It is found in all countries of the world •Lives in the duodenum •Two morphological forms: vegetative (trophozoite) and cyst Cyst: Small and oval, quadrinucleate Trophozoite: pear-shaped, 2 nuclei, 4 pairs of flagella, one pair of axostyles, two sausage-shaped parabasal (median) bodies. Dorsally, it is convex and ventrally, it has a concave sucking disk, which helps in its attachmemt to the intestinal mucosa. Trophozoite and cyst of Giardia lamblia adhesive disks THE TROPHOZOITE IS MOTILE, WITH A SLOW OSCILLATION ABOUT ITS LONG AXIS, OFTEN RESEMBLING FALLING LEAF. Life cycle of Lamblia duodenalis Giardia passes its life cycle in one host. Invasive form – cyst Man acquires infection by ingestion of cysts in contaminated water and food. Children are commonly affected. Within half an hour of ingestion, the cysts hatches out into trophozoites. Trophozoites multiply successively by longitudinal binary fission and colonize in the duodenum (and upper part of jejunum). During unfavorable conditions, encystation occurs usually in colon. Cysts are passed in stool and remain viable in soil and water for several weeks. In addition to humans, the host of the Giardia are domestic dogs. G. lamblia is typically seen within the crypts of duodenal and jejunal mucosa. It does not invade the tissue, but remains tightly adhered to intestinal epithelium by means of the sucking disk. Giardia lamblia damages the resorptive surface of the intestine mechanically or by release of toxins. Variant-specific surface proteins (VSSPs) of Giardia play an important role in virulence and infectivity of the parasite. Antigenic variation helps the parasite in evasion of host immune system. Giardia lamblia in duodenal mucosa Individuals with low serum IgA levels are less resistant to disease! CLINICAL FEATURE The name of disease, caused by Giardia lamblia, is called giardiasis (lambliasis). The most common clinical sign in giardiasis is prolonged diarrhea, accompanied by a disturbance in absorption especially of fats, disaccharides and vitamin A. The stool contains excess mucus and fat but no blood. Patients lose weight, complain of listlessness, easy fatigability, lassitude, abdominal discomfort. Occasionally, Giardia may colonize the gallbladder, causing biliary colic and jaundice. How can we diagnose giardiasis? 1. Microscopy: • stool examination for cysts of Lamblia duodenalis • detection of trophozoite in duodenal contents 2. Serology: • detection of Giardia antigens in feces • detection of antibodies against Giardia 3. Molecular diagnosis (PCR) – detect parasitic DNA in stool specimen Diagnostic preparations of trophozoite and cystic form. Measures for prophylaxis of giardiasis  prevention of food and water cyst contamination  good personal hygiene (handwashing before eating)  washing fruit and vegetables Genus Trichomonas Trichomonas differs from other flagellates, as they exist only in trophozoite stage. Cystic stage is not seen. Genus Trichomonas has three species, which occur in humans: 1. Trichomonas vaginalis 2. Trichomonas tenax 3. Trichomonas hominis TRICHOMONAS VAGINALIS • Pear-shaped or ovoid • Short undulating membrane reaching up to the middle of the body • It has four anterior flagella, 1 posterior, the posterior flagellum is running along the outer margin of the undulating membrane • A prominent axostyle runs throughout the length of the body and projects posteriorly like a tail • Тhe cytoplasm shows prominent siderophilic granules around axostyle • Cytostome • It is motile with a rapid jerky or twitching type movement. TRICHOMONAS VAGINALIS Habitat: • In females: lives in vagina, cervix (may also be found in Bartholin’s glands and urethra) • In males: occurs mainly in the anterior urethra, rarely in the prostate and preputial sac Life cycle of T. vaginalis ➢ Sexual transmission is the usual mode of infection ➢ Trichomoniasis often coexists with other sexually transmitted diseases like candidiasis, gonorrhea, syphilis, or human immunodeficiency virus (HIV). ➢ Trophozoites divide by binary fission. ➢ Many favorable for its reproduction is the acidic environment of vagina with pH 5.8 to 6.5 and temperature 3537oC. Clinical features  Disease: trichomoniasis  In males: infection is often asymptomatic (some may develop urethritis, epididymitis and prostatitis)  In females: colpitis (vaginitis) with yellowish green frothy discharge, cervical erosions, infrequent complications are endometritis and pyosalpingitis  T. vaginalis has been isolated from the respiratory tracts of children born to mothers with urogenital trichomoniasis. How can we diagnose trichomoniasis? 1. Microscopic examination:  In females: detection of T. vaginalis in vaginal or urethral discharge  In males: detection of T. vaginalis in a discharge from the prostate or urethra 2. Culture - ,,gold standard’’ 3. Serology tests T. vaginalis (arrow) in saline wet mount preparation. 400x Prophylaxis of trichomoniasis  The use of a condom in the period of invasion is a safe method of prophylaxis. ТRICHOMONAS TENAX T. tenax, also known as T. buccalis, is a harmless commensal which Inhabits the oral cavity mainly of people with carious teeth or periodontal disease. It is transmitted by kissing, through salivary droplets. There are sporadic reports of its involvement in respiratory infections and thoracic abscesses. Trichomonas tenax Тrichomonas hominis It is a very harmless commensal of the large intestine. Carries five anterior flagella and an undulating membrane that extends the full length of the body. Transmission occurs in trophic form by fecal-oral route. Created by: Assist. Prof. Dr. Stoyan Stoyanov