Introduction:
In recent eras, new infectious diseases have emerged in the human population. These infectious diseases mostly occur due to RNA viruses. And also, half of these newly identified infections cause neurologic disease. As there is an expansion of viruses to new geographic regions that are spread from animal reservoirs, air, food, and mosquitoes, there is the emergence of new viral diseases of the CNS. The most common and deadly neurological manifestations of infectious disease are encephalitis, meningoencephalitis, acute dissemination, meningitis, Guillain–Barré syndrome, ophthalmic abnormalities, etc. This article explains the neurological symptoms that emerge after infections.
How Do Infections Cause Neurological Disorders?
Viral infections can be associated with various neurological disorders. Measles, meningitis, chickenpox, subacute sclerosing panencephalitis, and polio are common infections causing neuro-related diseases. Immunizations are key to the prevention of many viral infections. However, it is difficult to eradicate all infections as the environment is surrounded by many viruses that even scientists are unaware of. Also, it is necessary to note that besides vaccines, which help reduce the infection-acquiring risk, no specific measure exists to prevent a neurological disorder progression. The correlation between viral infections and neurological conditions is unclear and still under intense research. Also, there is no clear data about why some people develop neurological issues after contracting a virus, while others do not.
When a person is affected by a viral infection, several mechanisms take place in their body that may be associated with the neurological disorder's progression. During viruses and microorganisms' invasion of the body, they may infect various organs and lead to mild to severe illnesses. In some cases, these viruses or microorganisms can directly attack the nervous system and cause severe problems like meningitis or encephalitis. The direct attack on the nervous system can generate an inflammatory response throughout the body, causing further severe damage.
Another mechanism is called molecular mimicry, which indirectly affects predisposed people. After viral infection, molecules similar to those found in the body and nervous system are left behind, which may confuse the immune system and mistakenly attack similar molecules in the healthy nervous system.
What Are the Neurological Manifestations in Rare Infectious Diseases?
1. Nipah Virus:
Nipah virus is a rare and deadly disease that is transmitted from animals (such as bats or pigs) to humans, or can also be transmitted directly from infected human-to-human. It was first identified in 1998 in Malaysia during an outbreak in pigs. Fruit bats are considered the natural reservoir hosts. Transmission of the Nipah virus in humans occurs through direct contact with infected animals or their body fluids, such as pigs or bats, or through consuming food contaminated by an infected animal's body fluids, close contact with a Nipah-infected person or their body fluids. The fatality rate of the Nipah virus has been reported to be as high as 70 %.
The signs and symptoms of the Nipah virus appear between 4 and 14 days following exposure to the virus. Initially, the symptoms will be mild respiratory issues such as cough, sore throat, and difficulty breathing, which may be followed by severe and deadly neurological manifestations such as encephalitis.
The symptoms include:
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Fever.
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Headache.
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Vomiting.
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Sore throat.
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Cough.
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Difficulty breathing.
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Encephalitis (brain inflammation) can lead to severe headaches, disorientation, confusion, and altered consciousness.
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Seizures (abnormal electrical activities in the brain leading to convulsions or loss of consciousness).
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Coma (in severe cases, affected individuals become unconscious and unable to respond to stimuli).
2. West Nile Virus:
West Nile virus (WNV) is a mosquito-borne disease that is spread through the bite of infected mosquitoes. This disease spreads during the starts in the summer and continues through fall. WNV is seen in various parts of the world, including Africa, the Middle East, Europe, and North America. Fortunately, the majority of WNV infections are asymptomatic. Only about 20 percent of infected people develop mild symptoms. But in some rare cases, infected individuals develop severe symptoms, which can turn fatal.
The signs and symptoms of WNV include:
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Fever.
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Fatigue and body aches.
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Swollen lymph glands.
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Nausea and vomiting.
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Skin rash, especially on the trunk of the body.
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Confusion.
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Neck stiffness.
In severe cases, individuals may experience seizures, encephalitis, acute flaccid paralysis (sudden onset weakness or paralysis of limbs), and coma. Serious neurological complications are reported in older adults and individuals with compromised immune systems.
Diagnosis is typically confirmed through serological tests, which detect specific antibodies against WNV in the blood or cerebrospinal fluid. There is no specific antiviral treatment for the west nile virus, and supportive care is the mainstay treatment for patients with severe neurological involvement.
There is no specific treatment or vaccination for West Nile Virus. Rest, fluids, and over-the-counter painkillers may be provided to relieve some symptoms. In severe cases, supportive treatment in the hospital is provided to reduce and treat complications. As no specific treatment is available, following all preventive measures, such as using mosquito repellents, eliminating mosquito breeding sites, wearing protective clothing, etc., can help reduce the risk of infection.
3. Hantavirus Infections:
Hantaviruses is a viral infection transmitted to humans from rodents. There are several species of hantaviruses, and depending on the infected species, the virus affects various organs like the liver (cardiopulmonary syndrome) or kidney (renal syndrome).
The symptoms of hantavirus begin after exposure to rodent droppings or urine; initial symptoms include sudden fever, headache, fatigue, muscle ache, abdominal pain, diarrhea, and vomiting. In later stages, when the severity of the infection increases, it can cause coughing and shortness of breath in cardiopulmonary syndrome and shock and kidney failure in people with renal syndrome. Neurological manifestations are rarely noted in some individuals, including confusion and seizures.
4. Japanese Encephalitis:
Japanese encephalitis (JE) is a rare mosquito-borne viral infection that spreads by the bite of infected Culex mosquitoes. Infection is caused by the Japanese encephalitis virus (JEV). It is seen in several parts of the world, including India, Japan, China, South Korea, and Indonesia.
Most people affected by JE show no symptoms or develop mild symptoms like fever, headache, abdominal pain, and vomiting. Neurologic symptoms might develop over the next few days like weakness, mental changes, movement disorders, and seizures, especially in children. Treatment includes rest, adequate water, and over-the-counter pain medications that may relieve some symptoms. In severe cases, supportive therapy relieves symptoms and stabilizes the patient. Vaccination is recommended for high-risk people.
Conclusion:
Emergent neurological disorders in rare infectious diseases present unique challenges for healthcare providers. Because of the rare occurrence of the infection, the diagnosis may be delayed or missed, which can add further complexity to managing the diseases. So a clear history and investigations are crucial in timely diagnosis and appropriate management.
