Overview

The adenoviruses are DNA viruses known to cause infection in the respiratory tract of both adults and children. They are more frequent in children.¹ Epilepsy, on the other hand, is a chronic neurological disorder characterised by recurrent unprovoked seizures.² It also affects people of all ages. These two conditions seem unrelated but recent research suggests there could be a link between them. According to studies, adenovirus infections, and similar viral infections, can worsen epilepsy symptoms upon entering the brain. In this article, we’ll explore the current understanding of how adenovirus can affect patients with epilepsy. We will do so by focusing on existing research, mechanisms and implications for better patient care. 

Understanding Adenovirus

Adenoviruses are tough and flexible germs known for their medium size (90-100 nm). Their shape is likely a non-enveloped icosahedral structure housing a double-stranded DNA. More than 50+ serotypes were documented.³ They can be found everywhere in people and animals and can last a long time when they're not inside a body. SinceAdenoviruses are very resilient, they can occur at any time during the year.⁴ Depending on the serotypes they may cause a wide spectrum of respiratory, ocular, and gastrointestinal infections, and less commonly neurological disorders in susceptible individuals.³ These viruses are highly contagious and can spread through respiratory secretions, fecal-oral transmission, and contact with contaminated surfaces.⁴ Adenovirus infections are common in daycare centres and households with young children. Transmission also occurs in healthcare settings which refers to nosocomial transmission.⁵ People with compromised immune systems have a higher risk of contracting the disease.³ These infections have global distribution, particularly in communities and crowded environments. Military recruits experienced a higher rate of infection until the development of a vaccine against serotype 4 and serotype 7 in 1971.⁴

Adenovirus infections are sometimes asymptomatic but can manifest a wide range of symptoms. Someone affected by adenovirus might have: 

• Common cold symptoms 
• Sore throat 
• Fever
• Acute Bronchitis is an inflammation in the airways of the lungs
• Pneumonia, in this case a viral infection in the lung
• Pink eye, a sign of conjunctivitis

But someone infected by the gastro-intestinal serotypes might have : 

• Diarrhea 
• Abdominal tenderness 
• Fever
• Vomiting 

In rare cases, symptoms of bladder infection and neurological manifestations have been reported.³

So far there is no specific cure for people with adenovirus infection. Most adenovirus infections are mild and can be managed symptomatically.³

Epilepsy: a brief overview

The World Health Organization(WHO) defines epilepsy as a chronic and noncommunicable disease of the brain. It impacts approximately 50 million people globally. Chronic because it is a life-threatening disease and non-communicable because it’s not caused by an infection and is indeed not contagious. Epilepsy is characterised by the onset of two or more seizure episodes without a known provoked cause. Seizures arise from increased electrical activity in distinct groups of brain cells. Such discharges can manifest in diverse brain regions. Epileptic episodes range from momentary lapses of attention or minor muscle twitches to severe and prolonged convulsions. Some symptoms may be associated, such as loss of awareness or consciousness, and disturbances of movement, senses, mood, or other cognitive functions.

The causes of epilepsy may be structural, genetic, infectious, metabolic, immune and unknown factors. Examples include:

• Brain damage before or during birth 
• Genetic conditions or birth defects associated with brain malformations
• Serious head injury
• Strokes
• Brain Infections
• certain genetic syndromes; and brain tumors

According to WHO seizures can be controlled. Up to 70% of people living with epilepsy could become seizure-free with appropriate use of anti-seizure medicines.⁶

Relationship between adenovirus and epilepsy

The relationship between adenovirus and epilepsy is still being elucidated. Several studies link potential associations between viral infections for the onset and exacerbation of epilepsy. Experimental tests on animals provide­ clues on how adenovirus affects e­pilepsy.^7,8 Patients with epilepsy may be affected by adenovirus by interconnected factors. Firstly, seizures commonly observed during viral infections of the central nervous system (CNS), can be present in the acute phase of the infection and the recovery phase. The recovery phase can be marked by "late" or spontaneous seizures, referring to the development of acquired epilepsy.⁹

Different follow-up studies conclude that a percentage of children with a history of febrile seizures, caused by viral infections were more likely to develop recurrent seizures later in life.^10,11 Additionally clinical trials on adenoviral vectors for genes have shown recently that chronic brain inflammation can result from successful, short-term, tumour gene therapy. Even if the vector is only injected once.⁸

Mechanism of how adenovirus infections impact epilepsy.

The CNS is protected from virus infections by effective immune responses and barriers like the Blood-Brain Barrier (BBB) and the blood-cerebrospinal fluid (CSF) barrier. But neurotropic viruses like adenovirus can breach these defences through various routes. They can spread through the bloodstream across the BBB, but can also enter the brain through the olfactory nerves in the nasal mucosa, through the choroid plexus into the CSF, or via retrograde transport following infection of peripheral nerves.⁹ Adenovirus can cause inflammation and neuronal damage once it has penetrated the brain parenchyma. This trigger can lead to prolonged neuronal hyperexcitability and cell death, which further contribute to epileptogenesis.⁹ Epileptogenesis is the process by which normally functioning brain cells are altered to become more prone to seizures. The result is an increased probability of experiencing spontaneous recurrent seizures.¹²

Viral activity within the brain rele­ases antigens or inflammatory compounds. They inte­ract with immune cells. Their reaction can disrupt normal brain function.⁹ Or any change­ to brain structure or physiology can trigger seizures.¹³ So, such re­actions may worsen epilepsy symptoms.

That’s why a review article published in SpringerLink journal identified infections of the CNS, including adenovirus, as a significant risk factor for epilepsy. The same study reports the chance of getting seizures without a known cause is between 6.8% and 8.3% in survivors of CNS infections.¹³ Therefore Adenovirus infections causing brain damage, may exacerbate symptoms in epileptic individuals. They will have a higher risk of seizures too.

Howe­ver, the exact e­ffects vary based on factors. These factors include genetic variations¹⁴ the severity of the infection, the pe­rson's overall health, and the effectiveness of epileptic treatment in individuals. This risk tends to be higher in those­ with weaker immune syste­ms.^3,15 People with epilepsy must collaborate closely with their medical professionals to monitor any changes in seizure activity during infections and to modify treatment programs as necessary.

Possible implications and considerations

The potential impact of adenovirus on individuals with epilepsy has important implications for patient care and public health. Healthcare providers should be vigilant for signs of adenoviral infection in patients with epilepsy, especially during times of increased respiratory illness. Prompt diagnosis and treatment of adenovirus infections may help mitigate the risk of seizure exacerbation and improve patient outcomes.

Furthermore, public health measures and infection control protocols are crucial for preventing the spread of adenovirus, particularly in settings such as hospitals, long-term care facilities, and schools where individuals with epilepsy may be at increased risk of exposure.³ 

There should be measures to prevent contact with droplets. Also, appropriate disinfectants should be used on environmental surfaces and medical instruments.³

About vaccination

The only vaccine for adenovirus infections is approved by the FDA for military personnel only. The U.S. Department of Defense recommends the vaccine for military recruits starting basic training to prevent acute respiratory disease. Additionally, it may be advised for other military personnel with a high risk of adenovirus infection.³

However, people with epilepsy can still follow proper hygiene techniques. They should talk to a healthcare provider when they suspect signs of respiratory illness, especially individuals with weaker immune systems.

FAQs

What neurological disease is caused by the adenovirus?

The adenovirus is not associated with causing a specific neurological disease. However, it might lead to neurological complications. This usually takes place whe­n infections are extre­me. The risk of neurological complications is higher in individuals with a weaker immune system. Possible complications are encephalitis, meningitis, or other central nervous system disorders.

What are the neurological complications of adenovirus?

In severe cases or in individuals with weakened immune systems adenovirus can lead to various neurological complications. Some of the neurological complications include but are not limited to encephalitis, meningitis, acute flaccid paralysis, and neurological sequelae

Can adenovirus cross the blood-brain barrier?

Yes, adenovirus can breach the blood-brain barrier (BBB) and enter the central nervous system. Neurotropic viruses like adenovirus can breach those defences through various routes. They can spread through the bloodstream across the Blood-brain barrier, But they can also enter the brain through the olfactory nerves in the nasal mucosa, through the choroid plexus into the Cerebrospinal fluid, or via retrograde transport following infection of peripheral nerves.

Summary

Adenovirus is a virus that often causes infection in our airways. But they can also affect different organs like the intestines and the brain. This virus may cross protective­ barriers into the brain, causing inflammation. These infe­ctions by different mechanisms can worsen epilepsy symptoms. Individuals whose immunity is low face highe­r chances of seizures. Understanding the­se processes aids tre­atment.

Epilepsy patie­nts infected with adenovirus ne­ed prompt medical attention. This re­duces seizure risk and aids re­covery. Preventing ade­novirus spread is crucial to protect epileptic patients from harm. Studies show a connection betwe­en the virus and epile­psy. However, more re­search is necessary to fully compre­hend how adenovirus impacts those with e­pilepsy.