Trypanosomiasis Lecture with Dr Balsam Mahdi Nasir MBBSYEAR
Trypanosomiasis Lecture with Dr. Balsam Mahdi Nasir MBBS/YEAR 1/SEM 2/2012
African trypanosomiasis (sleeping sickness) v Definition: It is a vector-borne disease. Ø Endemic to sub-Saharan Africa. Ø It is caused by the single cell flagellate protozoan Trypanosoma brucei. Ø v Geographic distribution: Trypanasoma brucei gambiense (West African sleeping sickness or Gambian trypanasomiasis). • Trypanasoma brucei rhodesiense (East African sleeping sickness or Rhodesian trypanosomiasis). • 2 Dr. Balsam 11/21/2020
Geographic distribution 3 Dr. Balsam 11/21/2020
Mode of transmission Via the bite of an infected tsetse fly. • 4 Dr. Balsam 11/21/2020
Morphology In the vertebrate it exists as a TRYPOMASTIGOTE. Elongated rather flattened. Spindle shaped organism. Blunted posterior end. Finely pointed anterior end. Central large oval nucleus. Kinetoplast is small and is situated at the posterior end. Undulating membrane. Flagellum. 5 Dr. Balsam 11/21/2020
Blood forms 1. Trypomastigote (long slender)→ dividing form. 2. Trypomastigotes (short broad stumpy form with or without attenuated flagellum)→ non dividing form → infective to tsetse fly. 3. Intermediate form. 6 Dr. Balsam 11/21/2020
Tsetse fly procyclic trypomastigote Epimastigote Metacyclic trypomastigote Infective stage to human Human Trypomastigotes Short stumpy form Intermediate form Long slender form Infective stage to tsetse fly 7 11/21/2020
Life cycle 8 Dr. Balsam 11/21/2020
Life cycle Definitive host • Man, game and domestic animals. Intermediate host • Tsetse fly (both male & female flies) • Reservoir of infection • Man (Trypanosoma brucei gambiense)→West African trypanosomiasis. • Animals (Trypanosoma brucei rhodesience)→ East African trypanosomiasis. Ø Infective stage to man • Metacyclic trypomastigotes 9 Dr. Balsam 11/21/2020
Pathogenesis and symptomatology Gambian disease Bite of infected • • Inoculation of trypomastigotes. Subcutaneous nodules→ 5 -15 days → painless chancre→ resolve in 2 -3 weeks. tsetse fly Incubation period Stage 1 Blood dissemination Stage 1 Lymphatics Stage 2 CNS invasion 10 • Asymptomatic • several weeks to months up to a year. • Intermittent fever pattern, chills, headache, myalgia, arthralgia. . etc • Lymphadenopathy, especially in the posterior cervical nodes (on the back of the neck) →Winterbottom’s sign. • • Occur at the end of 1 st year or the beginning of the 2 nd year Daytime sleeping, mental dullness, apathy, tremors, convulsions and coma followed by death from asthenia during the 2 nd or 3 rd year. Dr. Balsam 11/21/2020
Winterbottoms sign CDC DPDx Parasite Image Library 11 Dr. Balsam 11/21/2020
RHODESIAN SLEEPING SICKNESS clinical features It is more acute than the Gambian form Incubation period 2 -3 weeks 12 Fever, weakness, rapid loss of weight and myocarditis are the usual manifestation. Fatal within a year of onset before involvement of the CNS. Dr. Balsam Mania and delusion may occur but the typical sleeping sickness picture is seldom seen. 11/21/2020
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A woman caring for her comatose husband who is dying of African trypanosomiasis, Uganda, 1990 14 Dr. Balsam 11/21/2020
Diagnosis Clinical Patient from endemic area, irregular fever, palpable lymph nodes (post. cervical). Chronic disease with somnolence, personality changes and neurological symptoms. Laboratory Direct microscopy of a wet smear of unstained blood or Geimsastained thick smear→ trypmastigote. Chancre, lymph node, bone marrow and CSF aspirate→ wet preparation. Culture methods The standard serologic assay to diagnose West African trypanosomiasis is the card agglutination test for trypanosomiasis (CATT). Serological tests ELISA. 15 Dr. Balsam 11/21/2020
Trypanosoma brucei 16 Dr. Balsam 11/21/2020
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TREATMENT Haemo-lymphatic stage Suramine sodium→ Rhodesian disease. Suramine sodium or Pentamidine isethionate→ Gambian disease CNS involvement Melarsoprol → Rhodesian disease. Melarsoprol or DEMO (eflornithine) → Gambian disease. 18 Dr. Balsam 11/21/2020
PREVENTION AND CONTROL Elimination of the reservoir: Early Diagnosis and Treatment to reduce the reservoir of infection. Breaking the channel of transmission: Vector control. Protection of susceptible: Persons visiting endemic areas should wear protective clothing and apply repellents. 19 Dr. Balsam 11/21/2020
Chagas’ disease American trypanosomiasis v Definition It is a vector-borne disease Ø It is prevalent throughout South and Central America Ø It is caused by the flagellate protozoan Trypanosoma cruzi. Ø 20 Dr. Balsam 11/21/2020
Geographic distribution 21 Dr. Balsam 11/21/2020
• Mode of transmission Contamination of wound site, conjunctiva, or mucosa by infected feces of insect (reduviid bugs) 22 Dr. Balsam 11/21/2020
Morphology Trypomastigote The same as Trypanosoma brucei. 1. Long thin form 2. Short stumpy form 3. In blood film they appear C or U or S shape. Blood Amastigote form Oval bodies. Nucleus. Kinetoplast. Habitat: Striated muscle in heart, skeletal, neurological cells and cells of reticuloendothelial system. Tissue 23 Dr. Balsam 11/21/2020
Morphology 24 Dr. Balsam 11/21/2020
Trypomastigote Epimastigo te Metacyclic trypomastigote Reduviid bug Human Trypomastigot 25 e Amastigote Trypomastigot e Dr. Balsam 11/21/2020
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Life cycle Definitive host • Man, wild and domestic animals. Intermediate host • Triatomine bugs (reduviid bugs) Reservoir of infection Besides humans, the parasite infects a variety of wild and domestic animals. Ø Infective stage to man • Metacyclic trypomastigotes 27 Dr. Balsam 11/21/2020
Clinical features Acute • In less than 50% of people bitten by a triatomine bug, characteristic first visible signs can be a skin lesion (chagoma ) or a purplish swelling of the lids of one eye (Romana sign) • After 1 -2 weeks→ fever, headache, malaise, muscle pain, generalized lymphadenopathy and hepatosplenomegally. • Cardiac abnormalities followed by meningoencephalitis. 28 Chronic • The parasites are hidden mainly in the heart and digestive tract muscle. • Up to 30% of patients suffer from cardiac disorders. • Up to 10% suffer from digestive (megaesophagus or megacolon), neurological or mixed alterations. • In later years the infection can lead to sudden death or heart failure caused by progressive destruction of the heart muscle. 11/21/2020
Romana sign 29 Dr. Balsam 11/21/2020
Megacolon in patient with Chagas disease 30 Dr. Balsam 11/21/2020
Diagnosis Clinical may be suspected when general, cardiac or GIT symptoms are present in patients lived under low SES in endemic regions. Ø Laboratory Ø • Demonstration of the parasitic agent is the diagnostic procedure in acute Chagas'' disease. 1. Microscopic examination a) of fresh anticoagulated blood for detecting motile trypanosomes. b) 31 of thin and thick blood smears stained with Giemsa for identification of parasites. Dr. Balsam 11/21/2020
Trypanosoma cruzi amastigotes in heart tissue 32 Trypanosoma cruzi trypomastigote in a thin blood smear stained with Giemsa Dr. Balsam 11/21/2020
Laboratory diagnosis 2. If the parasites are scanty in blood Ø Ø Culture of the blood or suspected tissue specimen. Ø xenodiagnosis, where clean lab-reared reduviid bugs are fed on the patient's blood, and their gut contents examined for parasites 4 weeks later. Demonstration of antibodies to T. cruzi are required to diagnose chronic Chagas disease by serology – complement-fixation, direct agglutination and indirect haemagglutinatin and ELISA.
Treatment Nitrofurans and benzidazoles have been used in acute disease. Neither drug is expected to cure established chronic disease. It is unsatisfactory since the organisms are within cells in established infections. 34 Dr. Balsam 11/21/2020
Prevention and control Elimination of reservoirs: Control and elimination of domestic and peridomestic animals. Early diagnosis and treatment of infected cases. Vector control: Triatomine bugs are highly susceptible to chlorinated hydrocarbon insecticides which form the major weapon for their control. Protection of susceptible: Provision of better housing would prevent transmission because most human infections are transmitted by bugs living in cracks and crannies in the walls of ill kept tenement dwellings. 35 Dr. Balsam 11/21/2020
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