Chagas Disease - Parasitology Lecture 1 PDF

LECTURE (1) Chagas disease  About 8 million people in Mexico, Central and South America have Chagas´ disease cause by Trypanosoma cruzi, causing 12,000 deaths yearly.  It can be found anywhere in the globe.  However, vector-borne transmission of the disease only occurs in Americas.  Migration...

LECTURE (1) Chagas disease  About 8 million people in Mexico, Central and South America have Chagas´ disease cause by Trypanosoma cruzi, causing 12,000 deaths yearly.  It can be found anywhere in the globe.  However, vector-borne transmission of the disease only occurs in Americas.  Migration from Latin America to other regions increased spread of Chagas´ disease, with 75 million at risk of infection. If untreated, the disease is life-threatening (silent killer).  Found in muscles, nerve cells & reticuloendothelial cells.  Oval bodies.  2-4 μm.  Having a nucleus and kinetoplast  No free flagellum.  Indistinguishable from Leishman- Donovan bodies.  Multiplication of the parasite in host occurs in this stage.  Found in peripheral blood of man & lymph & CSF other mammalian hosts, insect vector and in culture.  About 25 μ in length.  C or S shape.  Deeply stained central nucleus, large kinetoplast, long undulating membrane & free flagellum.  Non multiplying form.  Found in the insect vector and in culture.  Elongated body, about 20 μ in length.  It has a kinetoplast near to the nucleus, short undulating membrane & free flagellum.  Divides by binary fission in midgut of the vector   Man  Dogs, cats, domestic and wild animals  Reduviid or kissing bug (Silent Killer)  Metacyclic trypomastigotes in feces or urine of reduviid bugs  These bugs can live in cracks and holes indoors and in outdoor spaces.  Most are night biting, defecate while feeding.  A tiny kiss causing a mega syndrome. ① Contamination of the bite, skin or mucous membrane abrasion by bug's feces or urine. ② Blood transfusion. ③ Organ transplantation. ④ Accidental exposure in labs. ⑤ Vertical transmission. ⑥ Sexual transmission  Parasites uptake by host cell at site of bite & transform into amastigotes that multiply by binary fission.  After 5 days, cell ruptures liberating trypomastigotes, invade blood & lymph, and disseminate to tissues.  Inside cells, they are transformed into amastigotes that multiply, fill up cells, mainly cardiac muscle fibers.  Intracellular multiplication is repeated & cells rupture → damage to affected organs.  INCUBATION PERIOD: 1-2 weeks.  ’  May last for 1- 4 months.  Usually seen in children. CHAGOMA  Localized swelling with erythema & localized lymphadenopathy.  Inoculation of parasite in conjunctiva causes. ROMANA'S SIGN  Unilateral painless oedema of eyelids, with conjunctivitis.  Enlargement of lymph nodes (Classical sign of acute Chagas). IN SEVERE  Manifestations of meningoencephalitis, acute myocarditis & acute INFECTIONS congestive heart failure.  ↑↑ = Fever, generalized lymphadenopathy, hepatosplenomegaly ↑↑ OR ↓↓  ↓↓ = depression of bone marrow & anemia.  Death may occur OR DEATH OR RECOVERY  Recover (good immune response) OR OR CHRONICITY  Pass to a chronic stage. CHAGOMA ROMANA'S SIGN  60% -70% 30% - 40% Dormant form Deadly form  Enter the indeterminate form of chronic  Years to decades after initial infection. infection.  Remain in this subclinical state with no  They progress to the determinate form further consequences. of disease.  ’  It is found in adults.  Multiplication of T. cruzi in tissue cells causes inflammation, irreversible cellular destruction & fibrosis of muscles and nerves that control the tone of hollow organs, manifested by Mega syndrome:  Cardiomegaly. HEART DISEASE  Cardiac arrhythmias.  Congestive heart failure.  Due to destruction of intramural plexus. MEGAESOPHAGUS  Manifested by dysphagia & aspiration pneumonia.  Due to destruction of mesentric plexus. MEGACOLON  Manifested by intractable constipation & abdominal distention.  As small intestine OTHER MEGAVISCERA  Ureters. NERVE DISEASE  Peripheral nervous involvement as spastic paralysis.  Thyroiditis THYROID DISEASE  Thyroid insufficiency  CHAGAS´ DISEASE :  7-14 days incubation period.  Often in children: chagoma, Romaña sign, flu-like symptoms, ACUTE FORM lymphadenopathy, enlargement of liver and spleen, myocarditis, encephalitis. CHRONIC FORM  Asymptomatic (dormant). INTESTINAL DISEASE  Megaesophagus, Megacolon. HEART DISEASE  10-30% of cases, sudden death from aneurism.  Chronic chagas patients with HIV infection or low immunity are manifested by: ① Meningoencephalitis ② Space-occupying CNS lesions.  CONGENITAL INFECTION:  It is possible in both phases of the disease.  It causes myocardial and neurological damage. ① History of exposure to Reduviid bug bite. ② History of travelling or residence in endemic area. ③ Recent blood transfusion in an endemic area. ④ Chagoma is similar to injury caused by trauma, insect bite, bacterial or fungal infection. ACUTE CHAGAS CHRONIC CHAGAS Should be considered in patients in endemic areas with:  Febrile illness  Signs of cardiomegaly.  Lymphadenopathy.  Sever constipation or dysphagia.  Detection of T. cruzi in peripheral blood, aspirate or tissue biopsy of lymph node, muscle, liver, spleen and bone marrow by: ① Microscopy: a. Examination of peripheral blood (wet mount, thin and thick blood, or buffy coat smears) stained with Giemsa, show monomorphic trypanosomes (C or S shape). b. H & E stained tissue specimens show amastigotes ① DIRECT ② Culture:  Epimastigotes & trypomastigotes are found on NNN medium  1-6 weeks post incubation. ③ Animal inoculation:  Intra-peritoneal injection of specimen in experimental animal & blood examined after 10 days for trypomastigotes. ④ Xenodiagnosis:  Detect very low parasitaemia, mainly in chronic disease.  ① Immunological diagnosis: a. Serological tests:  Antigen detection: in urine and sera by ELISA.  Antibody detection: IHA, IFA, ELISA, CFT, and rapid immunochromatographic test. b. Cruzin intra-dermal test. ② Molecular technique:  For diagnosis of acute, chronic & congenital Chagas. ③ Endoscope: ② INDIRECT  Valuable for diagnosis of megaviscera. ④ Barium dye meal and barium dye enema:  For visualization of megaoesophagus & megacolon using x-ray. ⑤ X-ray chest and electrocardiography (ECG):  For diagnosis & prognosis of cardiomyopathy in chronic Chagas´ disease ① Nifurtimox. ② Benznidazole. Both are used for all ages, and for acute & early chronic cases. ③ Diuretics: for congestive heart failure (acute or chronic disease). ④ Treatment of megacolon: by surgery. ① Control of winged bugs by: Insecticides (Gammaxene, Lindane)  Elimination of cracks in wall by cement. ② Control of reservoir hosts. ③ Personal protection by using repellants and bed net. ④ Serological screening of blood & organ donors for T. cruzi. ⑤ Use of riboflavin & UV to reduce level of transfusion infection. ⑥ Detection and treatment of infected cases. ⑦ Early diagnosis & treatment of:  Infected women of child-bearing age.  Newborns with congenital Chagas  Chagas´ disease is a vector-borne disease caused by Trypanosoma cruzi.  The classical sign for acute Chagas´ is the Romana's sign.  Cases may remain asymptomatic for decade before chronic manifestations.  Chronic Chagas´ is characterized by mega viscera, mainly cardiomegaly.  Acute stage is diagnosed by microscopy or culture.  Chronic disease is diagnosed by at least two different antibody detection tests.  Treatment is by nifurtimox or benznidazole  A 16-year-old male with no significant past medical history presented to emergency department complaining of fever, headache, and left eye swelling 2 weeks after returning from a 3-week trip to Costa Rica. The patient visited a small village, where he slept on a wooden bed in a one-room cottage that lacked netted windows and doors.  These symptoms progressed rapidly over the next few days until the patient’s left eye was swollen shut. He was treated for blepharo- conjunctivitis with no initial response.  The patient was then evaluated for periorbital cellulitis.  On physical examination, there was periorbital edema and mild erythema of the left eye, and no visible discharge.  The right eye was normal. He had one small non-tender, freely mobile right posterior cervical lymph node, and otherwise, he had no significant lymphadenopathy.  Systems examinations were normal. Physical examination was otherwise unremarkable. Wet mount of peripheral blood showed flagellated S-shape like- organism, about 25μ in length.