Hazards: Disease Outbreaks and Biological Events

Threats: Disease Outbreaks and Biological Events

St. Louis City regularly monitors and responds to disease outbreaks  and biological events.  The City's Department of Health has a state-of-the-art Electronic Surveillance System for Early Notification of Community-Based Epidemics (ESSENCE),  24/7 system for monitoring disease patterns.  The "syndromic surveillance" system involves routinely tracking emergency room visits, ambulance runs, medical examiner, special events and pharmacy sales to provide an early warning signal of a possible outbreak.

The City of St. Louis Department of Health maintains multiple surveillance systems designed to monitor the health of the population, the detection of disease outbreaks and the occurrence of unusual diseases.  The systems are monitored by the Epidemiologists for any unusual event such as the following:

  • Reporting of an actual or suspected case of any particular agent of bio-terrorism.
  • An unusual disease agent.
  • An elevation of any particular disease.
  • A common pattern among cases of any disease.
  • A report of  a suspected outbreak.
  • An elevation of any particular disease syndrome.

This type of surveillance can be done by Passive or Active surveillance.  The High Alert Surveillance System (HASS) is a form of surveillance.  It is a system for early detection of a bioterrorist event and for generally monitoring the health of the community.  This system collects indicator data from a variety of sources.  The indicators were chosen with the following criteria in mind.

  • The usefulness of the indicator to detect quickly a change in health care usage of increase in syndromes.
  • To reduce the burden of reporting by using computerized systems within the facilities wherever available.

In addition to naturally occurring disease outbreaks, certain biological agents may be used by terrorists to cause illness or death.  These agents include microbes, such as bacteria or viruses, or toxins derived from plants or animals.

In the event of a health emergency, the City may open Points of Dispensing (POD's), which are special clinics to distribute antibiotics or vaccines.  If POD's are activated, you may locate the one closest to you by listening to local media, calling 211, or accessing stlouis.missouri.org/citygov/health.dhss.mo.gov.

IN THE EVENT OF A HEALTH EMERGENCY

  • Cover Coughs and sneezes.
  • Stay home if experiencing cough or fever.
  • Frequently wash hands with soap or an alcohol-based cleaner.
  • Tune in to local TV and radio for health officials' announcements.

Potential Public Health Threats to the City of St. Louis

DISEASE OUTBREAKS

Pandemic flu - The Health Department tracks signs and symptoms that could indicate a flu pandemic.  Flu outbreaks are prevented by the promotion of good, regular hygiene and flu shots for people whose immune systems are compromised.  For more information, visit www.pandemicflu.gov.

Avian flu - Avian (bird) influenza (flu) is a strain of the flu virus that primarily infects birds.  H5N1, the strain of bird flu detected in Asia and Europe, has been transmitted from infected birds to people in Asia.  Currently, the disease does not readily spread from person to person.  However, there is concern that H5N1 may eventually mutate and spread among people.  As a result, health and government agencies around the world are carefully monitoring avian flu activity.

Severe Acute Respiratory Syndrome (SARS) - Caused by a virus, SARS is characterized by high fever, headache, cough and breathing difficulties, which in some patients can be severe or even fatal.  Transmission of the disease occurs when persons come into contact with infected droplets, expelled by coughing, or with contaminated materials or surfaces.  The Department of Health (DOH) has been watching for cases since the outbreak began in early 2003.  There have been no laboratory positive cases, nor has there been any evidence of spread to health care workers or household members, nor evidence of community spread of SARS in St. Louis City.  DOH works closely with hospitals and medical providers to increase their knowledge about SARS and to help them identify any cases.

West Nile Virus - A mosquito-borne virus that can cause serious health conditions including encephalitis and meningitis, West Nile is most prevalent during peak mosquito season.  The City closely monitors suspected cases of the disease in humans, and has a vigorous prevention and monitoring program.

BIOTERRORISM AGENTS

Anthrax - Caused by the bacterium Bacillus anthracis, Anthrax is a disease commonly found in livestock, but has been manufactured for use as a bioterror weapon. There are three primary forms of the Anthrax infection. Cutaneous Anthrax is an infection of the skin caused by external exposure to Anthrax spores. It is treatable with antibiotics and does not typically lead to death. Inhalation Anthrax is a much more severe form of the disease, caused by breathing the spores into the lungs resulting in flu-like symptoms and eventually worsening and often fatal unless treatment is received. The third form of anthrax occurs upon ingestion, and is extremely rare.

Smallpox - A virus similar to Chickenpox, Smallpox causes high fever and rash and has a high fatality rate of around one in three. The disease is contagious, but is no longer a naturally-occurring threat thanks to the production of vaccines that have eliminated its spread. Because the United States stopped widespread Smallpox vaccinations in the 1970s, most people no longer carry immunity against the disease, making it an attractive tool to terrorists desiring to cause widespread illness and panic in a population.

Botulism -

Botulism is a muscle-paralyzing disease caused by a toxin made by a bacterium called Clostridium botulinum.

Three main forms of Botulism:

  • Foodborne botulism occurs when a person ingests pre-formed toxin that leads to illness within a few hours to days. Foodborne botulism is a public health emergency because the contaminated food may still be available to other persons besides the patient.

  • Infant botulism occurs in a small number of susceptible infants each year who harbor C. botulinum in their intestinal tract.

  • Wound botulism occurs when wounds are infected with C. botulinum that secretes the toxin.

With foodborne botulism, symptoms begin within 6 hours to 10 days (most commonly between 12 and 36 hours) after eating food that contains the toxin. Symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness that moves down the body, usually affecting the shoulders first, then the upper arms, lower arms, thighs, calves, etc. Paralysis of breathing muscles can cause a person to stop breathing and die, unless assistance with breathing (mechanical ventilation) is provided.

Botulism is not spread from one person to another. Foodborne botulism can occur in all age groups.

Tularemia -

Tularemia is a potentially serious illness that occurs naturally in the United States. It is caused by the bacterium Francisella tularensis found in animals (especially rodents, rabbits, and hares).

What are the Symptoms of Tularemia?

Symptoms of tularemia could include:

  • sudden fever
  • chills
  • headaches
  • diarrhea
  • muscle aches
  • joint pain
  • dry cough
  • progressive weakness

People can also catch pneumonia and develop chest pain, bloody sputum and can have trouble breathing and even sometimes stop breathing.

Other symptoms of tularemia depend on how a person was exposed to the tularemia bacteria. These symptoms can include ulcers on the skin or mouth, swollen and painful lymph glands, swollen and painful eyes, and a sore throat.

How Does Tularemia Spread?

People can get tularemia many different ways:

  • being bitten by an infected tick, deerfly or other insect
  • handling infected animal carcasses
  • eating or drinking contaminated food or water
  • breathing in the bacteria, F. tularensis

Tularemia is not known to be spread from person to person. People who have tularemia do not need to be isolated. People who have been exposed to the tularemia bacteria should be treated as soon as possible. The disease can be fatal if it is not treated with the right antibiotics.

Plague - Plague is an infectious disease that affects animals and humans. It is caused by the bacterium Yersinia pestis. This bacterium is found in rodents and their fleas and occurs in many areas of the world, including the United States.

Y. pestis is easily destroyed by sunlight and drying. Even so, when released into air, the bacterium will survive for up to one hour, although this could vary depending on conditions.

Pneumonic plague is one of several forms of plague. Depending on circumstances, these forms may occur separately or in combination:

  • Pneumonic plague occurs when Y. pestis infects the lungs. This type of plague can spread from person to person through the air. Transmission can take place if someone breathes in aerosolized bacteria, which could happen in a bioterrorist attack. Pneumonic plague is also spread by breathing in Y. pestis suspended in respiratory droplets from a person (or animal) with pneumonic plague. Becoming infected in this way usually requires direct and close contact with the ill person or animal. Pneumonic plague may also occur if a person with bubonic or septicemic plague is untreated and the bacteria spread to the lungs.
  • Bubonic plague is the most common form of plague. This occurs when an infected flea bites a person or when materials contaminated with Y. pestis enter through a break in a person's skin. Patients develop swollen, tender lymph glands (called buboes) and fever, headache, chills, and weakness. Bubonic plague does not spread from person to person.
  • Septicemic plague occurs when plague bacteria multiply in the blood. It can be a complication of pneumonic or bubonic plague or it can occur by itself. When it occurs alone, it is caused in the same ways as bubonic plague; however, buboes do not develop. Patients have fever, chills, prostration, abdominal pain, shock, and bleeding into skin and other organs. Septicemic plague does not spread from person to person.

With pneumonic plague, the first signs of illness are fever, headache, weakness, and rapidly developing pneumonia with shortness of breath, chest pain, cough, and sometimes bloody or watery sputum. The pneumonia progresses for 2 to 4 days and may cause respiratory failure and shock. Without early treatment, patients may die.

Early treatment of pneumonic plague is essential. To reduce the chance of death, antibiotics must be given within 24 hours of first symptoms. Streptomycin, gentamicin, the tetracyclines, and chloramphenicol are all effective against pneumonic plague.

Antibiotic treatment for 7 days will protect people who have had direct, close contact with infected patients. Wearing a close-fitting surgical mask also protects against infection.

A plague vaccine is not currently available for use in the United States.

Viral Hemorrhagic Fevers - Viral hemorrhagic fevers (VHFs) refer to a group of illnesses that are caused by several distinct families of viruses. In general, the term "viral hemorrhagic fever" is used to describe a severe multisystem syndrome (multisystem in that multiple organ systems in the body are affected).  Characteristically, the overall vascular system is damaged, and the body's ability to regulate itself is impaired.  These symptoms are often accompanied by hemorrhage (bleeding); however, the bleeding is itself rarely life-threatening. While some types of hemorrhagic fever viruses can cause relatively mild illnesses, many of these viruses cause severe, life-threatening disease. 

Viruses associated with most VHFs are zoonotic. This means that these viruses naturally reside in an animal reservoir host or arthropod vector. They are totally dependent on their hosts for replication and overall survival. For the most part, rodents and arthropods are the main reservoirs for viruses causing VHFs. The multimmamate rat, cotton rat, deer mouse, house mouse, and other field rodents are examples of reservoir hosts. Arthropod ticks and mosquitoes serve as vectors for some of the illnesses. However, the hosts of some viruses remain unknown - Ebola and Marburg viruses are well-known examples.

Viruses causing hemorrhagic fever are initially transmitted to humans when the activities of infected reservoir hosts or vectors and humans overlap. The viruses carried in rodent reservoirs are transmitted when humans have contact with urine, fecal matter, saliva, or other body excretions from infected rodents. The viruses associated with arthropod vectors are spread most often when the vector mosquito or tick bites a human, or when a human crushes a tick. However, some of these vectors may spread virus to animals, livestock, for example. Humans then become infected when they care for or slaughter the animals.

Some viruses that cause hemorrhagic fever can spread from one person to another, once an initial person has become infected. Ebola, Marburg, or Lassa and Crimean-Congo hemorrhagic fever viruses are examples. This type of secondary transmission of the virus can occur directly, through close contact with infected people or their body fluids. It can also occur indirectly, through contact with objects contaminated with infected body fluids. For example, contaminated syringes and needles have played an important role in spreading infection in outbreaks of Ebola hemorrhagic fever and Lassa fever.

Specific signs and symptoms vary by the type of VHF, but initial signs and symptoms often include marked fever, fatigue, dizziness, muscle aches, loss of strength, and exhaustion. Patients with severe cases of VHF often show signs of bleeding under the skin, in internal organs, or from body orifices like the mouth, eyes, or ears. However, although they may bleed from many sites around the body, patients rarely die because of blood loss. Severely ill patient cases may also show shock, nervous system malfunction, coma, delirium, and seizures. Some types of VHF are associated with renal (kidney) failure.

Patients receive supportive therapy, but generally speaking, there is no other treatment or established cure for VHFs. Ribavirin, an anti-viral drug, has been effective in treating some individuals with Lassa fever or HFRS. Treatment with convalescent-phase plasma has been used with success in some patients with Argentine hemorrhagic fever.

Scientists and researchers are challenged with developing containment, treatment, and vaccine strategies for these diseases. Another goal is to develop immunologic and molecular tools for more rapid disease diagnosis, and to study how the viruses are transmitted and exactly how the disease affects the body (pathogenesis). A third goal is to understand the ecology of these viruses and their hosts in order to offer preventive public health advice for avoiding infection.

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