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Parasitic diseases may occasionally affect the cardiovascular system specifically the heart causing pericarditis, myocarditis or cardiomyopathies. In this article, we have covered important parasites affecting the heart muscle and its consequences.

Parasitic infections in humans can lead to an inflammation of heart tissue, pericarditis, which is an inflammation of the membrane around the heart; and cardiomyopathy, a disorder that hinders pumping and can lead to heart failure.

Parasites affecting the heart

Toxoplasma gondii

toxoplasma gondii image

Toxoplasmosis is a zoonotic disease that is capable of causing several clinical syndromes in immunocompetent and immunocompromised patients. Toxoplasma gondii is a parasite of members of the cat family, with humans and other warm-blooded animals serving as intermediate hosts

This microscopic organism, Toxoplasma gondii is responsible for the disease known as toxoplasmosis.

It can be transmitted to humans through contact with cats and may affect up to 2 billion people worldwide.

Toxoplasma gondii multiplies intracellularly at the site of invasion and may spread to distant organs by the invasion of lymphatics and blood. Tissue cyst formation occurs within the first week of infection and is responsible for latent infection.

T. gondii resides intracellularly in phagosomes within macrophages and myocardial cells. The parasite is propelled by an actin-myosin-dependent gliding-motility mechanism and establishes intracellular vacuoles . This remodeling prevents lysosome fusion, which leads to the intracellular survival of the parasite.

The immune competency of the individual is the determining factor in the recrudescence of latent infection.

Immunity in the immunocompetent individual persists for life.

T. gondii can persist in heart muscle, where it forms tissue cysts that can remain through the host's lifetime, and heart disease may be linked with chronic infection of T. gondii.

Transmission is by ingestion of oocysts and meat; congenital

Patients with toxoplasmosis present with; Fever, lymphadenopathy, retinochoroiditis, myocarditis, cardiac hypertrophy, and dilatation and pericarditis.

Entamoeba histolytica

Entamoeba histolytica

This parasite is the primary cause for amoebiasis, or amoebic dysentery, a colon infection marked by abdominal pain and diarrhea.

Amoebiasis is a protozoan infection of the intestinal mucous membrane usually of the colon caused by a protozoan known as Entamoeba histolytica.

The extraintestinal amebic disease involves the liver mainly. The involvement of the pericardium is very rare but is a serious complication of amebiasis .

In rare cases, this parasitic infection can lead to a serious heart complication known as amebic pericarditis, in which it causes abscesses in the pericardium which is the saclike membrane surrounding the heart.

Amebic pericarditis may present as either a pericardial rub with electrocardiographic changes associated with an abscess of the left lobe or purulent pericarditis from the perforation of the abscess into the pericardium. Amebic abscesses in the right lobe of the liver have also been reported to communicate with the pericardium.

The presenting clinical syndrome is usually one of two forms:

  • sudden onset as cardiac tamponade with chest pain, shortness of breath, and shock or
  • progressive effusion with a slower course to develop fever, dyspnea, and pain

Amebiasis is distributed worldwide but more frequent in the tropics and subtropics

The reservoir for amebiasis are humans

Its mode of transmission is by faeco-oral route

Trichinella spiralis

trichinela spiralis image

Trichinella spiralis is a parasitic roundworm that targets carnivorous and omnivorous mammals around the world.

It infects people who eat the undercooked meat of infected animals, entering the human hosts as larvae-filled cysts and causing trichinosis.

After a host swallows the cysts, stomach acid dissolves the sac and releases the Trichinella larvae which then cross the small intestine, where they travel through lymphatics and the bloodstream until finally encysting in striated muscle tissue. The striated muscle cell is induced to transform into a nurse cell, which supports the long-term viability of the encysted larvae.

Trichinella spiralis-associated myocarditis is not caused by the direct larval invasion of the myocardium with encystation but is likely induced by an eosinophil-enriched inflammatory response resulting in eosinophilic myocarditis similar to the pathogenic process associated with tropical endomyocardial fibrosis.

Severe complications from the parasite can include heart tissue inflammation and life-threatening arrhythmia, or irregular heartbeat.

Echinococcus granulosus

Echinococcus granulosus is the metacestode form of one of the four species of the tapeworm.tapeworms in the Echinococcus genus can infect people when their eggs are ingested after contact with feces from a dog or other canids.

Echinococcus granulosus causes cystic echinococcosis, the form most frequently encountered.

Humans become accidental intermediate hosts when they ingest eggs from the feces of infected dogs or other canids.

After the ingestion of the eggs by an intermediate host, the eggs hatch and release oncospheres, which cross the small intestine and spread to encyst in various visceral organs.

Cardiac cysts are rare, Clinical presentations of cardiac echinococcosis include arrhythmias, myocardial infarction, cardiac tamponade, pulmonary hypertension syncope, purulent pericarditis, and sudden cardiac death

The reservoir for this parasite is the dogs

Trypanosoma cruzi

Chaga’s disease also known as South American trypanosomiasis is a parasitic disease of the tropics caused by a protozoan known as Trypanosoma cruzi. It is spread by triatomine bugs, known as ‘kissing bugs

Triatoma bugs are insects that serve as a vector for protozoa called Trypanosoma cruzi. As a vector, that means triatoma insects, more commonly called "kissing bugs," are responsible for the spread of a damaging and devastating disease that occurs when the parasites burrow into their preferred home territory in the human body — the heart muscle.

The infection can be transmitted from mom to baby, blood transfusion or organ transplant, contaminated food, and laboratory accidents.

Chagas disease is caused not by the bite of the kissing bug, but from its feces. Called the "kissing bug" because it was believed to take its blood meal on, or around, the face, the bug defecates after feeding, leaving its poop on the victim. When the bite becomes itchy, a scratch of a hand from the victim deposits the parasite into the wound — and into the bloodstream.

Chaga’s disease develops in 2 phases.  The initial acute phase and later chronic phase. The initial phase lasts for about 2 months after infection.

  • Acute: Lasting approximately two months, the acute infection occurs just after infection and may seem like a common illness with fever, headache, loss of appetite, aches, and rash. Without treatment, these symptoms will usually subside as the infection becomes chronic.
  • Chronic: During the chronic stage, which can last a lifetime, a victim may have no symptoms ever or not until later in life.
    The parasite moves to the heart and inhabits the cardiac muscle, potentially causing abnormal heart rhythm or even sudden death. Gastrointestinal complications can occur as well. There is an approximate 30% chance of experiencing these serious impacts.

About 30% to 40% of people infected by T. cruzi develop heart complications associated with chronic Chagas diseasesuch as heart rhythm abnormalities, a dilated heart that doesn’t pump blood effectively, and congestive heart failure.


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