Dengue cases have been on rise worldwide and the severity of the disease too has witnessed an uptick in recent times. Along with the many complications dengue puts us at risk of, the virus’s impact on brain has come in focus. Cases of dengue encephalopathy is on rise in young children and adolescents. The rare complication that happens due to inflammation of brain caused by dengue virus, shows up in the form of symptoms like drowsiness, sleepiness and even seizures. As per a recent study published in bioRxiv, ‘SARS-CoV-2 antibodies cross-react and enhance dengue infection. This could be another reason why dengue is become deadlier and severe, threatening to affect crucial body functions.
Dengue’s effect on brain has been in focus since WHO released new dengue guidelines in 2009 that included CNS (Central Nervous System) involvement in the definition of severe disease. This means that a person can experience brain complications like encephalitis, meningitis, stroke with severe disease leading to worrying symptoms that can also prove deadly.
WHY PEOPLE GET SEVERE DISEASE WITH DENGUE?
“Dengue fever is an infection caused by 1 of the 4 viruses, called the ‘dengue viruses’ – DENV 1, DENV 2, DENV 3, DENV 4. They are related to each other, but they are not exactly the same. Getting sick from the dengue virus does not protect you from getting the others. A person can get dengue fever more than once. Dengue fever is spread by mosquitoes that carry dengue viruses,” says Dr Jyoti Bala Sharma -Director, Neurology, Fortis Hospital, Noida.
DENGUE AND ITS EFFECT ON BRAIN
So, what are these neurological complications that can come with dengue. We asked experts.
“Previously it was thought that dengue virus does not directly invade brain. Recent research has shown direct invasion of brain. Neurological complications have increased in recent years and their incidence varies from 0.5 to 20%. Neurological complications involve individual from 3 months to 60 years. The possible reason for rise in neurological complication is better diagnostic services and preexisting comorbidities. Risk factors for neurological complications increase in the presence of high fever, dehydration, low platelet count, skin rash, and liver dysfunction. Neurological complications are mostly related to DENV-2 and DENV3 type of dengue virus,” says Dr Bala.
Dr Rahul Chirag, Consultant – Internal Medicine, CARE Hospitals Hitec City, Hyderabad, agrees that dengue can affect the brain in severe cases, leading to a condition known as Dengue Encephalitis or Dengue-Associated Neurological Complications (DANC).
Dr Chirag says that although the virus primarily targets the immune system and blood vessels, but it can also enter the central nervous system. This can result in various neurological issues and complications.
Dr Bala says dengue neurological complications are classified into three categories:
1. Dengue encephalopathy
2. Dengue encephalitis or Viral invasion including meningitis, myositis, and myelitis;
3. Autoimmune reactions
Dengue encephalopathy: In the condition brain is affected by toxins which accumulate because of liver and kidney dysfunction in dengue and deranged electrolyte and other parameters. There may be swelling and haemorrhages in brain.
Dengue encephalitis: There is direct invasion of virus into brain, covering of brain (meninges), spinal cord or muscles. This is considered severe form of infection
Autoimmune reaction: Autoimmune reactions include acute disseminated encephalomyelitis, neuromyelitis optica, optic neuritis, myelitis, encephalopathy, and Guillain-Barré syndrome. This results from altered immune response. The immune systems gets confused between virus and brain and the attack which is supposed to be against virus is directed towards brain which results in damage to brain tissues.
TOP NEUROLOGICAL COMPLICATIONS DENGUE CAN CAUSE
“The exact reasons why neuro issues are becoming more common in dengue patients are not fully understood, but it may be due to a combination of factors, including variations in the dengue virus strains, the individual’s immune response, and genetic predisposition. Early diagnosis and appropriate medical care are crucial in managing these complications and reducing their severity. If you suspect dengue infection and experience neurological symptoms, seek medical attention immediately,” says Dr Chirag.
Dengue virus can directly infect the brain, causing inflammation and swelling, which can lead to encephalitis. This can result in symptoms like confusion, altered consciousness, seizures, and even coma.
In some cases, dengue infection can lead to viral meningitis, which is the inflammation of the protective membranes covering the brain and spinal cord. This can cause symptoms like severe headaches, neck stiffness, and fever.
Dengue can increase the risk of stroke by causing abnormalities in blood clotting or affecting blood vessels in the brain. Stroke can lead to various neurological deficits.
4. Guillain-Barré Syndrome (GBS)
GBS is a rare but severe neurological complication associated with dengue. It’s an autoimmune disorder that affects the peripheral nervous system, leading to muscle weakness and paralysis.
“There is no direct antiviral therapy available against the DENVs. Management is supportive, which largely consists of maintaining adequate intravascular volume. Dengue virus transmission occurs when person, dengue virus and mosquitoes capable of transmission are co-located in space and time. Preventive measures are mosquito control and personal proactive measures,” adds Dr Bala.