Introduction

Adenoviruses are DNA viruses, and humans of all ages are affected by adenoviruses. As far as their variants are concerned, they number over a hundred.¹

One of the most important aspects of adenoviruses to know is that, like any infection, it gets treated by itself via the body’s own immune system. However, what would happen to those with weaker immunities? As expected, perhaps, adenoviruses show their maximum effect on patients whose immunity is compromised.^3,11

Adenoviruses can affect many parts of the human body, for instance, the gastrointestinal tract, kidney and respiratory system as well as various other organs as well. Heart diseases of different kinds have been found to occur due to adenoviruses.^4,5

It is a proven fact that the most common viral cause of an inflammation condition of the inner lining of the heart, and another condition in which all of the heart chambers get thinner than normal, are adenoviruses.⁶

Adenoviruses

Viruses can be categorised into two types depending on their type of genetic material, i.e. DNA viruses and RNA viruses. Adenovirus is of the former category. It is found commonly in humans and animals, and all age groups can be affected by it. Adenovirus is found in over 100 variants and there are around 50 that can affect humans.¹

Research has even shown that adenovirus can cause cancer in rats.

One important feature of adenoviruses is they are typically self-limited, as it is easily controlled by a person with adequate immunity. It has a typical form (latent adenovirus) of existence in which it stays calm and inactive (mainly in the specific type of cells related to the kidneys’ functionality) for years, and becomes active in people who suffer from weak immunity.¹¹

Direct relationship of adenoviruses with heart diseases

One of the most common causes of death in children and adults is problems related to the heart, and these could be caused by viral infections of the heart. These cause the inflammation of the inner lining of the heart (which is called acute myocarditis), and it decreases the thickness of the heart walls significantly (called dilated cardiomyopathy or DCM), thereby affecting its functionality.

In a study, samples of the inner lining of the hearts from patients suffering from the viral infection of the heart and a medical condition in which walls of the heart chamber gets thin, were taken. A few other samples were also taken, including blood, secretions from the nose and throat, urine, and stool samples.

On evaluation, the death rate was found to be 51% for the patients with acute myocarditis, which is of course way too high for any medical condition. For the DCM cases, more than 40% of patients needed heart transplants and one of those patients died after around 2 months of the transplant. For the rest of the patients, the heart functionality recovered in an extremely poor manner.^5,9,11

Adenoviruses were found to be present in almost all the cases. There are also a few cases mentioned in which children suffering from adenoviral pneumonia died, who also had associated myocarditis.¹⁰

In another conducted study, it was found that heart muscles are replaced in the form of a specific substrate generated by the adenovirus, which causes complications related to heartbeat and then, sudden heart failure occurs.⁶

One of the most surprising findings uncovered by research is that adenovirus can cause myocarditis in almost all age ranges. There are receptors, named Coxsackievirus and adenovirus receptor (CAR), found in the mammalian body, which allows adenovirus to bind and act, causing myocarditis and DCM.^13,14

CARs have been found at various sites around the body, such as the heart, lungs, testes and brain. This research also makes researchers and physicians think that adenoviruses may be responsible for a genetic heart disorder, i.e. inflammation of the heart muscle because the reason that parents suffered from this condition and then passed it onto the next generation.^{7, 8}

Another study showed the presence of a special type of cell associated with the presence of adenovirus found in those suffering from atrial fibrillation, a condition in which there is an irregular and very fast heartbeat. In this condition, there is the risk of blood clots forming within the heart, leading to an increased risk of heart failure and stroke.¹²

Symptoms

Most adenovirus infections cause only mild symptoms. However, in patients with weak immunity or any preexisting respiratory or heart issues, it may present more severely. These symptoms include:³

• Common cold symptoms
• Sore throat
• Inflammation of the sites where inhaled air by the human body is purified in the lungs
• Lung infection and lungs may get filled with pus
• Inflammation in the intestine and stomach, causes pain in the stomach, diarrhoea, and vomiting

When, where and how adenoviruses attack

They most commonly attack in winter or early spring, but can occur in any season. Adenoviruses can attack patients of almost all ages, however, it most often affects infants (of the age 6 months to 2 years), and can occur in the 5 years to 9 years age group as well.³

It may enter the body from outside, an already existing virus might get reactivated, or from coming into contact with someone who already has adenovirus. It also spreads in the form of droplets suspended in the environment which can affect the eyes directly, and when breathed in, can cause the infection of the respiratory system. However, the most common route of adenoviruses transmission has been proven to be the oral faecal route.²

When adenovirus enters the body, an inflammatory response can often be observed at the site of entrance. Interestingly, it can settle and remain dormant for many years within the immune organs of the body.³

Most adenovirus cases are transmitted in crowded places, viz., daycare centres, military and police barracks, and public swimming pools. New joiners of the military are among the most affected adults.¹⁰

Treatment

In most cases of adenovirus infection, supportive treatment is preferred. It is recommended to drink plenty of water, and non-steroidal painkillers may be given.^2,7

Patients who possess a strong immunity will usually not require antiviral medicines, however, patients with a weaker immunity might need to take them as well.

Vaccination can prevent the further spread of the adenovirus, and this technique is widely used in the military.^2,3

Measures to prevent the spread of adenovirus include: 

• Chlorination of swimming pools
• Masks and/or safety goggles to avoid droplet infection
• Gloves to avoid contact

Summary

Adenoviruses are DNA viruses that are present as more than 100 species, nearly half of them able to infect humans. They can affect a broad range of organs within mammals and may be especially dangerous in those with weakened immune systems. They mostly attack infants and children, but can affect people of almost all age ranges, mostly being transmitted in crowded places.

Adenoviruses have been found to be causative agents for many heart problems. These include inflammation of the inner lining of the heart, or making the heart walls thinner than normal. They have also been associated with sudden heart failure, which can lead to death.