Assis.Prof.Dr. Suhad Faisal Hatem Hemoflagellates-2 Assis.Prof.Dr. Suhad Faisal Hatem

Flagellate of blood and tissue are haemoflagellates that live in the blood and tissues of human hosts include three spp. T. gambiense : -cause West African sleeping sickness T. rhodesiense:- cause: East African sleeping sickness T. cruzi: - cause: American trypanosomiasis or Chagas' disease. T. Gambiense It inhabits connective tissues space of many organs like lymph node,spleen, cerebralspinal fluid and blood .Transmission by: The bite of an infected tsetse fly- -Blood transfusion -Organ transplant -Congenital transmission (from pregnant mother to fetus).

Morphologically 1-Trypmastigote: - exists in blood of vertebrate host called (Polymorphic or Metacyclic form ). Spindle shaped – Central nucleus – free flagellum – undulating membrane .The kinetoplast and basal body are posterior of nucleus. The flagellum arises from the posterior end of the body. it has 3 forms long slender form (30µ): active motile with free flagellum Intermediate form (20µ): with a short free flagellum. Short stumpy form (15µ): sluggish without free flagellum 2-Epimastigote: - which is found in tsetse fly, It has kinetoplast and basal body lie anterior to the nucleus, with a long flagellum attached along the cell body. The flagellum starts from the centre of the body.

Life cycle

Pathogenicity 1-Both male and female of testse fly suck blood during day morning or evening and transmit infection. Metacyclic form enters directly into the blood stream causing chancre (3-4cm) its hard painful nodule with discharge contains dividing Trypmastigotes resolve spontaneously within 1-2 weeks. 2-Trypmastigotes reach to the blood and lymph nodes causing lymphadenopathy. 3-If untreated cases, nervous system is involved and the Trypmastigotes will enter subarachnoid space then to brain substance with infiltration of plasma and lymphocytes cells and proliferation of endothelial and neuroglia cells. In this stage patient has severe headache, malaise, weakness, anorexia, and night sweats develop to sleeping sickness and die (West African sleeping sickness).

Lab. Diagnosis 1-Stained films for Trypmastigotes in blood or in lymph node, bone marrow, cerebrospinal fluid aspirates. 2-Acridine orange buffy coat technique may more efficient than thick blood film 3-Cultivation: T. gambiense can grown in Weinman ,s medium. 4-Serologic technique by using ELISA, IFA, IHT these tests detect antibody in the serum and CSF of patients and use antigen from blood Trypanosomaes .High level of IgM has been considered in diagnosis of this parasites. Treatment 1-Suramin is used to treat patients with primary stage do not involve the CNS because it does not cross blood-brain barrier. 2-Melarsoprol can cross the blood-brain barrier, it is used to treat the late secondary CNS stages of Trypanosomiasis.

T. Rhodesiense The habitat , antigenic variations, morphology, transmission by fly, Lab diagnosis, treatment are identical to T. gambiense, cause (East African sleeping sickness). The major difference between them that T. rhodesiense is more acute and rarely lasting 9 month before death occurs, whereas T. gambiense is chronic lasting up to 4 years with other differences (table 1).

T. cruzi It occurs in Central & South America causing Chagas' disease .It lives as Trypomastigote form in blood and as Amastigote form in reticuloendothelial cells and other tissue cells of human host. In addition to Epimastigote in triatomine bug vector. Life cycle Intermediate Host (triatomine bug) A triatomine bug (kissing bug) serves as the vector. While taking a blood meal, it ingests T. cruzi. In the triatomine bug (Triatoma infestans) the parasite goes into the epimastigote stage, making it possible to reproduce. After reproducing through binary fission, the epimastigotes move onto the rectal cell wall, where they become infectious, infectious T. cruzi are called metacyclic trypomastigotes . When the triatomine bug subsequently takes a blood meal from a human, it defecates. The trypomastigotes are in the feces of bug and are capable of swimming into the host's cells using flagella.   Definitive Host (man) The trypomastigotes enter the human host through the bite wound or by scratch.The host cells contain macromolecules such as laminin and fibronectin that cover their surface. These macromolecules are essential for adhesion between parasite and host and for the process of host invasion by the parasite. The metacyclic trypomastigotes will transform to amastigotes inside the cells tissue and it will divide by binary fission to be trypomastigotes again.  

 

Pathogensity Acute Form At the site of entry a sub-cutaneous inflammatory nodule develops called chagoma  trypomastigotes enter through the wound, or through intact mucous membranes, such as the conjunctiva cause Conjunctivitis . Then enter via lymph node and blood to many organs and tissue causing Fever, enlarged lymph nodes, skin rash, enlarged liver & spleen.Acute stage more common and sever in children. This stage cause fever hepatosplenomegaly, edema, rash, diarrhea and acute myocarditis may lead to meningoencephalitis in infants and adults. Acute stage more common and sever in children. Chronic form 1-Parasite produces antigens similar to patient’s self antigens ,The body produces auto-antibodies that cause damage to Heart muscle fibers (heart failure) and esophageal muscle fibers. 2-Chronic infection causing change in cardiac arrhythmias palpitation, chest pain, edema, dizziness…..etc

Lab. Daignosis 1-During the acute infection, the blood films (thin &thick) searching about (trypomastigotes) by using Gimsa stain also the Buffy coat test help to detect the trypomastigote in centrifuged serum. 2- Culture in NNN medium for 1-2 weeks and examined microscopically. 3-PCR used to detects Trypomastigote in blood of patients with chronic chaga ,s disease because its lack sensitivity to the serological test. 4-Xenodiagnosis: method of animal inoculation using laboratory- bred bugs &animals in the diagnosis of some parasitic infections when the infectingorganism  cannot be demonstrated in blood films; used in Chagas' disease .Depend on feed the bugs on patient’s blood, after 2 weeks it will be examined for presence of the parasite. (examination of the feces  of clean bugs fed on the patient's blood) . 5-Intradermal test: after inoculation of parasite culture extract, a delayed hypersensitivity reaction is obtained. 6- Biopsy from lymph node or muscles help to detect amastigote form. 7-Serology test: antibody detected in patient serum by complement fixation,IFT,ELISA,IHT but the sensitivity is low because there is cross reactions with other microorganisms. Treatment : Nufurtimox & Benznidazole

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