cardiovascular system infection - myocarditis

8/13/2019 Cardiovascular System Infection - Myocarditis

1/17

Cardiovascular System Infection - Myocarditis


2/17

Definition

Myocarditis is inflammation of the heart muscle(myocardium)

It resembles a heart attack but coronary arteries are notblocked

Myocarditis is most often due to the infection by

1- Common viruses, such as Parvovirus B19 2- Non-viral pathogens (less commonly)

Borrelia burgdorferi (Lyme disease)

Trypanosoma cruzi (Chagas disease)


3/17

Myocarditis could be caused by hypersensitivityresponse to drugs

The definition of myocarditis varies, but the central

feature is an infection of the heart, with aninflammatory infiltrate, and damage to the heartmuscle, without the blockage of coronary arteries thatdefine a heart attack (myocardial infarction) or other

common non-infectious causes.


4/17

Myocarditis may or may not include death (necrosis)of heart tissue

It may include Dilated cardiomyopathy

Dilated cardiomyopathy or DCM is a condition in whichthe heart becomes weakened and enlarged, and cannotpump blood efficiently

The decreased heart function can affect the lungs, liver,and other body systems


5/17

Dilated cardiomyopathy or DCM Gross pathology of idiopathic cardiomyopathy

Opened left ventricle of heart shows a thickened, dilated left ventricle withsubendocardial fibrosis manifested as increased whiteness of endocardiumautopsy


6/17

Cellular infiltration and cardiac necrosis

Histopathological image of myocarditis at autopsy in a patient withacute onset of congestive heart failure due to viral infection.


7/17

Myocarditis is associated with an autoimmune reaction

Streptococcal M protein and Coxsackie B virus have regions(epitopes) that are similar to cardiac protein myosin

M protein is a virulence factor that can be produced bycertain species of Streptococcus

M protein is strongly anti-phagocytic protein and is amajor virulence factor

Cross-reactivity of anti-M protein antibodies with heartmuscle is the basis for Rheumatic fever

After the virus is gone, the immune system may attack

cardiac myosin


8/17

Causes of Myocarditis In Europe and North America, viruses are common cause

of myocarditis

Worldwide, however, the most common cause is Chagasdisease, an illness endemic to Central and South Americathat is due to infection by the protozoan Trypanosomacruzi

Transmission of trypanosomiasis occurs when the Wingedbug of the genus Triatoma deposits feces on the skinsurface and subsequently bites; the human host thencontaminating the bite area, with infected feces


9/17

Photomicrograph of Giemsa-stainedTrypanosoma cruzi (CDC)

Triatoma infestans

Trypansoma cruziparasite in a thin blood

smear (CDC Photo)


10/17

Rhodnius prolixus nymphs and adult

Rhodnius prolixus

Triatoma infestans Panstrongylus geniculatus


11/17

Pathogenesis of Trypanosoma cruzi

Human American trypanosomiasis, or Chagas disease, is a fataldisease of humans

The disease has two forms, a trypomastigote found in humanblood, and an amastigote found in tissues

The acute form usually goes unnoticed and may present as alocalized swelling at the site of entry

In the chronic stage, 10 to 20 years after infection, the parasiteinvades the myofibrils of the heart causing myocarditis

The gradual autoimmune destruction of heart myocardium leadto cardiac enlargement and arrhythmias, and heart failure


12/17


13/17

Signs and symptoms

The acute phase lasts for the first few weeks or months ofinfection. Mild symptoms can include fever, fatigue , headache,rash, loss of appetite, diarrhea, and vomiting

The signs on physical examination can include mild enlargementof the liver or spleen, swollen glands, and local swelling (achagoma) where the parasite entered the body

The symptomatic chronic stage affects the nervous

system, digestive system, and heart

About two thirds of people with chronic symptoms have cardiacdamage, including dilated cardiomyopathy, which causes heartrhythm abnormalities and may result in sudden death


14/17

Cardiac muscle pathology; Chagas disease

Heart radiology Chagas diseaseHeart pathology Chagas disease

Romaa's sign, the swelling of thechild's eyelid, is a marker of acuteChagas disease. The swelling is dueto bug feces being accidentally

rubbed into the eye, or because thebite wound was on the same side ofthe child's face as the swelling.Photo courtesy of WHO/TDR.


15/17

Toxoplasma gondii infection Toxoplasma gondiiis a species of parasitic protozoa in

the genus Toxoplasma

The definitive host of T. gondiiis the cat, but the parasitecan be carried by many warm-blooded animals (birdsor mammals, including humans)

Toxoplasmosis, the disease of which T. gondiiis thecausative agent, is usually minor and self-limiting but canhave serious or fatal effects on a fetus whose mother firstcontracts the disease during pregnancy or onan immunocompromised human


16/17

ToxoplasmagondiiLife cycle


17/17

Life cycle of T.gondii

cardiovascular system infection - myocarditis

Documents