Central Nervous System Infections

Encephalitis is a condition characterized by inflammation of the brain. The correct answer is "Blood-brain barrier" because encephalitis occurs when pathogens or immune cells infiltrate the brain tissue through the blood-brain barrier. The blood-brain barrier is a protective barrier that separates the blood vessels in the brain from the surrounding neural tissue. It regulates the entry of substances into the brain, allowing only certain molecules to pass through while blocking others. When the blood-brain barrier is compromised, pathogens and immune cells can cross over into the brain, leading to inflammation and the development of encephalitis.

HSV-1 is primarily transmitted through oral contact, such as kissing or sharing utensils, while HSV-2 is typically transmitted through sexual contact, including oral, vaginal, and anal sex. Therefore, the correct answer is "oral, genital."

Tuberculous meningitis is caused by the bacteria Mycobacterium tuberculosis, which primarily infects the lungs. The bacteria can spread from the lungs to other parts of the body, including the brain, through the bloodstream or by direct extension. In the case of tuberculous meningitis, the bacteria reach the brain through the bloodstream, causing inflammation and infection in the meninges, the protective membranes surrounding the brain and spinal cord. Therefore, the lungs are the primary site of infection for tuberculous meningitis.

Encephalitis is the correct answer because it refers to the irritation and swelling (inflammation) of the brain. This condition can be caused by viral infections, such as herpes simplex or West Nile virus, and it can lead to symptoms such as fever, headache, confusion, and seizures. Prompt diagnosis and treatment are crucial to prevent complications and minimize long-term effects.

In meningococcal meningitis, a hemorrhagic skin rash with petechiae is indicative of septicemia. Septicemia, also known as blood poisoning, occurs when bacteria from an infection enters the bloodstream. In meningococcal meningitis, the bacteria Neisseria meningitidis infects the meninges, the protective membranes surrounding the brain and spinal cord. The bacteria can then enter the bloodstream, causing septicemia. The presence of a hemorrhagic skin rash with petechiae is a characteristic symptom of septicemia in meningococcal meningitis, indicating that the infection has spread to the bloodstream and is causing widespread damage to blood vessels, leading to bleeding under the skin.

The rabies virus is shed in the salivary glands. This means that the virus can be present in the saliva of an infected animal, making it highly contagious and easily transmitted through bites or scratches. It is important to be cautious around animals that may be infected with rabies to prevent the spread of the virus to humans or other animals.

Polio and rabies viruses invade neurons because these viruses have the ability to specifically target and infect nerve cells. Neurons are the primary cells of the nervous system responsible for transmitting electrical signals, and they provide an ideal environment for the replication and spread of these viruses. By invading neurons, these viruses can disrupt the normal functioning of the nervous system and cause the characteristic symptoms associated with polio and rabies infections.

HSV-1 is responsible for 95% of HSE cases. HSE, or herpes simplex encephalitis, is a rare but severe viral infection that affects the brain. HSV-1 is the herpes simplex virus type 1, which is primarily associated with oral herpes, causing cold sores or fever blisters. However, in rare cases, HSV-1 can also cause HSE when it spreads to the brain. HSV-2, on the other hand, is primarily associated with genital herpes. Therefore, HSV-1 is the most common type of HSV responsible for causing HSE.

Bacterial meningitis is most commonly caused by Neisseria meningitidis. This bacteria is a leading cause of meningitis worldwide, especially in children and young adults. It can cause severe illness and can be life-threatening if not treated promptly. Other common causes of bacterial meningitis include Streptococcus pneumoniae and Haemophilus influenzae. Viral meningitis is actually more common than bacterial meningitis and typically presents as a milder infection. An increase in CD8+ T cells in the cerebrospinal fluid (CSF) is not typically seen in bacterial meningitis.

HSV-2 is the correct answer because it is the second leading cause of aseptic meningitis. Aseptic meningitis is a condition characterized by inflammation of the meninges, the protective membranes surrounding the brain and spinal cord. While HSV-1 is primarily associated with oral herpes, HSV-2 is primarily associated with genital herpes. However, HSV-2 can also cause meningitis, although it is less common than HSV-1.

HSV (Herpes Simplex Virus) and VZV (Varicella-Zoster Virus) are favorable for infection of the Central Nervous System (CNS) because they establish latency in the dorsal root ganglion. The dorsal root ganglion is a cluster of nerve cell bodies located along the spinal cord, specifically in the dorsal root. These viruses have the ability to enter sensory neurons and establish a dormant or latent infection within the dorsal root ganglion. This latency allows the viruses to evade the immune system and reactivate later, leading to diseases such as herpes simplex encephalitis or shingles.

Waterhouse-Friedrichsen syndrome presents with bleeding into the brain and adrenal glands as a result of acute Addisonian crisis seen in severe cases of meningococcal meningitis. This syndrome is characterized by adrenal gland failure, leading to low levels of cortisol and aldosterone, and can result in life-threatening complications such as shock and organ failure. It is important to recognize and treat this condition promptly to prevent further complications. Cushing's Disease is a condition characterized by excessive production of cortisol, Wilson's Disease is a genetic disorder that leads to copper accumulation in the body, and Wirsung syndrome is a condition involving obstruction of the pancreatic duct.

HSV neonatal disease is associated with HSV-2 infection during delivery. This is because the transmission of the virus to the newborn typically occurs during the birth process, when the baby comes into contact with the infected genital tract secretions of the mother. HSV-2 infection during pregnancy can also pose a risk to the baby, but the highest risk of transmission and subsequent neonatal disease occurs during delivery. Therefore, it is crucial to identify and manage HSV infections in pregnant women to prevent the transmission of the virus to the newborn.

PCR analysis is the key diagnostic test for HSV because it allows for the detection and amplification of viral DNA or RNA in a patient's sample. This technique is highly sensitive and specific, making it a reliable method for identifying the presence of HSV in a patient. ELISA is an immunoassay technique used to detect antibodies, but it may not be as accurate in diagnosing an active HSV infection. Urine dipstick tests are typically used for detecting urinary tract infections, not HSV. Cytochrome cell culture is not a commonly used diagnostic test for HSV.

The likely causative agent in this case is Streptococcus pneumoniae. This gram-positive bacteria is a common cause of bacterial meningitis, especially in adults. It is known to cause symptoms such as headache, fever, and a stiff neck, which are consistent with the patient's presentation. Additionally, the positive CSF culture confirms the presence of the bacteria in the cerebrospinal fluid. Neisseria meningitidis and Haemophilus influenzae are also common causes of bacterial meningitis, but Streptococcus pneumoniae is the most likely causative agent based on the information provided. Staphylococcus aureus is not typically associated with bacterial meningitis.

Aseptic meningitis is the type of meningitis that is associated with negative bacterial cultures of cerebrospinal fluid (CSF). This means that when a sample of CSF is taken and tested for bacteria, no bacteria are found. Aseptic meningitis is usually caused by viral infections, such as enteroviruses, herpes viruses, or HIV. It can also be caused by other non-bacterial agents, such as fungi or parasites. The absence of bacteria in the CSF culture helps differentiate aseptic meningitis from acute bacterial meningitis, which would show positive bacterial cultures.

Complement (C5-C9) is an important mediator of protection against bacterial invasion. Deficiencies in complement have been shown to increase susceptibility to bacteremia, including meningococcal meningitis. Complement proteins play a crucial role in the immune response by promoting inflammation, opsonization (enhancing phagocytosis), and the formation of membrane attack complexes that can directly kill bacteria. Therefore, a deficiency in complement can impair these protective mechanisms, making individuals more vulnerable to bacterial infections.

more likely to be due to microbial sequelae because neonatal immune system is poorly developed.

Elsberg syndrome is a neurological disorder characterized by inflammation of the nerve roots in the lumbosacral region. It is often caused by viral infections, including herpes simplex virus (HSV). Lumbosacral radiculitis, as mentioned in the question, refers to the inflammation of the nerve roots in the lumbosacral region, which aligns with the symptoms of Elsberg syndrome. Therefore, Elsberg syndrome is the correct classification for the neurological manifestation of HSV infection resulting in infected nerves and nerve roots.

NOTE: ALL but HHV-8 are classified as neurogenic