DISEASES OF THE NERVOUS SYSTEM

CHAPTER 24

Copyright © 2012 John Wiley & Sons, Inc. All rights reserved.

Bison both spread brucella to domestic cattle and are themselves sensitive to the organism (results in abortion)

A. TrueB. False

True

False

50%50%

Leading doctors warn that sepsis deaths will not be curbed without radical rethink of research strategy Leading doctors warn that medical and public recognition of sepsis - thought to contribute to between a third and a half of all hospital deaths - must improve if the number of deaths from this common and potentially life-threatening condition are to fall. Sepsis - sometimes misleadingly called "blood poisoning" - is a common condition whereby an infection triggers an extreme immune response, resulting in widespread inflammation, blood clotting, and swelling. Among the early (but not universal) symptoms of sepsis are high temperature and fast breathing; if left untreated, it frequently leads to organ failure and death. Although no specific cure for the condition exists, it can often be treated effectively with intensive medical care including antibiotics and intravenous fluid, if identified early enough. "Sepsis is both one of the best known yet most poorly understood medical disorders, and one of the most challenging medical conditions in routine clinical practice."* In the UK, sepsis is thought to kill 37000 people every year - more than three times the number killed by breast cancer or prostate cancer. "The number of people dying from sepsis every year - perhaps as many as six million worldwide - is shocking, yet research into new treatments for the condition seems to have stalled,"* says Professor Cohen. "Researchers, clinicians, and policymakers need to radically rethink the way we are researching and diagnosing this devastating condition."* Recommendations include prioritising research into biomarkers for sepsis, which would allow quicker diagnosis; better education of medical staff and improving public awareness to ensure earlier recognition; rethinking clinical trial design; recognising that sepsis affects different patients differently and using the power of modern genetics to develop targeted treatments ("personalised medicine"); and, after dozens of failed trials in recent decades, ensuring that universities and drug companies do not abandon research into new drug treatments.

Gut microbes important for serotonin production Serotonin is probably best known as a brain chemical that affects emotions and behavior, an imbalance of which is thought to contribute to depression. Less well-known is that scientists estimate 90% of serotonin is made in the gut, and imbalances in this peripheral serotonin have been linked to diseases ranging from irritable bowel syndrome and cardiovascular disease, to osteoporosis. Now, researchers from the California Institute of Technology (Caltech) in Pasadena report a study in the journal Cell that shows certain bacteria in the gut play an important role in the production of peripheral serotonin. "To start, we explored the idea that normal gut microbes could influence levels of neurotransmitters in their hosts."In the gut, there are three types of cell we know of that produce serotonin: immune cells, nerve cells or neurons, and enterochromaffin (EC) cells. The team found that in the germ-free mice, their EC cells produced around 60% less serotonin than the mice with normal gut bacteria. And when they restored bacteria colonies in the gut of the germ-free mice, their EC cells began producing normal levels of serotonin - showing the effect on the EC cells can be reversed. Further exploration in cell cultures revealed some of the molecular mechanisms underpinning the findings. The team found several metabolic byproducts of gut bacteria are controlled by the mix of spore-forming bacteria and act on EC cells to alter serotonin production. Other investigations have shown bacteria can make serotonin on their own. The researchers say their study suggests a lot of the serotonin in the body relies on the interaction between bacteria and host cells.

Diseases of the Brain and Meninges

Figure 24.1-The structure of the nervous system

Do not need to know the structure of the nervous system- the figure is for your reference

Central nervous system = brain and the spinal cord Peripheral nervous system = all nerves that branch off from the brain and spinal cord

The brain and spinal cord are covered and protected by three continuous membranes called meninges. An infection of the meninges is called meningitis. An infection of the brain is called encephalitis.

Bacterial Diseases of the Brain and Meninges - Meningitis

• Meninges

• Symptoms

• Meningococcal meningitis

• Heamophilus Meningitis

• Streptococcus pneumoniae meningitis

© 2012 John Wiley & Sons, Inc. All rights reserved.

Bacterial meningitis Three major types of bacterial meningitis caused by: 1. Neisseria meningitides 2. Streptococcus pneumoniae 3. Hemophilus influenzae

Listeriosis-Another kind of meningitis, listeriosis, is caused by Listeria monocytogenes, a small Gram positive bacillus that is widely distributed in nature.

Food borne transmission by improperly processed milk, cheese, meat, and vegetables is the most common source of infection. Cantaloup was responsible for about 30 deaths this year (2011)

In pregnant women the bacillus can cross the placenta, infect the fetus, and cause abortion, stillbirth or neonatal death. Listeriosis is responsible for many cases of fetal damage.

Viral disease of the brain and meningesViral meningitis-Unlike bacterial meningitis, which is

always fatal if untreated, viral meningitis usually self-limiting and nonfatal.

Enteroviruses account for approximately 40 percent of viral meningitis cases and mumps virus for 15 percent. The causative virus in 30 percent of cases remains unidentified.

Rabies. Disease is caused by a small RNA virus, rabies virus, which is typically transmitted by the bite of an animal whose saliva contains the virus. The virus belongs to the rhabdovirus family (negative stranded RNA-containing virus). Initially, the virus multiplies in skeletal muscle and connective tissue and remains localized for periods ranging from days to months. It is during this localized period that the rabies vaccine must be given. Following the localized period the virus travels along the peripheral nerves to the central nervous system, where it produces encephalitis. Neurological damage is often severe and the disease almost always results in death. Diagnosis is generally done using a fluorescent‑antibody test (IFAT) made on smears of cells.

The virus is propagated in human diploid cell culture and then chemically inactivated to produce the vaccine. Five intramuscular injections of the virus thus produced are recommended with a sixth dose often taken several months later. The best means of preventing rabies is to immunize pets, and such immunization is required in many countries.

Viral Diseases of the Brain and Meninges - Rabies

• Diagnosis

• Transmission

• Animal susceptibility

• Symptoms

• Prevention

© 2012 John Wiley & Sons, Inc. All rights reserved.

Encephalitis

• Togavirus

– Eastern Equine Encephalitis (EEE)

– Western Equine Encephalitis (WEE)

– Venezuelan Equine Encephalitis (EEE)

• Flavivirus

– St. Louis Encephalitis (EEE)

• Symptoms and prevention

© 2012 John Wiley & Sons, Inc. All rights reserved.

West Nile Fever

• U.S. transmission

• Diagnosis

• Preventions

© 2012 John Wiley & Sons, Inc. All rights reserved.

Other diseases of the Nervous System

Bacterial Nerve diseases – Hansen’s Disease

• Mycobacterium leprae

• Incidence and Distribution

– Tuberculoid

– Nodular

• Diagnosis

• Prevention

• Treatment and Elimination

© 2012 John Wiley & Sons, Inc. All rights reserved.

Other Diseases of the Nervous SystemHansen’s disease ( Leprosy). Caused by Mycobacterium leprae which is closely related to

the tuberculosis organisms (M. tuberculosis) and is an acid fast pleomorphic rod‑shaped organism. The organism is often referred to as Hansen's bacillus to avoid the stigma of using the term leprosy. The disease is vastly underreported, but an estimated 15 million cases exist worldwide today mainly in Asia, Africa and South America

Tetanus

• Clostridium tetani

• Disease

• Treatment

• Prevention

© 2012 John Wiley & Sons, Inc. All rights reserved.

Botulism

• Clostridium botulinum

• Disease

– Infant botulism

– Wound botulism

• Diagnosis

• Treatment

© 2012 John Wiley & Sons, Inc. All rights reserved.