Biological Agents -- Viruses
Viruses are the simplest type of microorganism and are much smaller than bacteria. Viruses lack a system for their own metabolism and are therefore dependent on host cells to provide the necessary machinery for them to survive.

Examples of viruses that could be utilized by bioterrorists include:

• Arboviral encephalitis (Venezuelan equine encephalitis)
  
• Ebola virus hemorrhagic fever
  
• Lassa fever
  
• Marburg hemorrhagic fever
  
• Smallpox
  

Arboviral encephalitis
Description
Q: What is arboviral encephalitis?
A: Arboviral encephalitis is a group of viral illnesses that cause inflammation (swelling) of the brain and are transmitted to humans by biting insects. Types of arboviruses include West Nile and eastern equine encephalitis.

Q: What is encephalitis?
A: Encephalitis means inflammation of the brain. It can be caused by infections spread by viruses, bacteria, and other microorganisms.

Q: Can terrorists spread the disease in a way other than through contaminated insects?
A: Yes, some arboviruses have been developed for aerosol release by several countries, including the U.S.

Q: Are arboviruses fatal?
A: This depends on the particular virus. There is great variability depending on the type of virus and an individual's susceptibility. West Nile virus is rarely fatal and most people infected recover. Eastern equine encephalitis is fatal in most cases.

Transmission
Q: What insects transmit arboviral encephalitis?
A: In the U.S., arboviruses are contracted primarily from mosquitoes. Ticks and biting flies also spread Arboviral encephalitis.

Q: Do all mosquitoes carry the virus that causes arboviral encephalitis?
A: No, most do not. But, if a mosquito bites an infected animal, it can then transmit the disease by biting a person or another animal. Some arboviruses are passed from one generation of mosquito to another without requiring an infected animal as a reservoir.

Q: Which animals carry the encephalitis virus in the first place?
A: Birds are the reservoir for Eastern equine encephalitis and West Nile virus. Rodents, bats, reptiles, amphibians, mosquitoes or ticks may also maintain other arboviruses in nature. Some reservoirs are still unknown.

Symptoms
Q: What are the symptoms of arboviral encephalitis?
A: Depending on the particular arbovirus there can be a wide range of symptoms:

• Some infections produce no symptoms.
  
• Other viruses produce mild, flu-like illnesses exhibiting fever, headache, muscle aches and tiredness.
  
• Sometimes, symptoms can be severe with high fever, stiff neck, disorientation, coma, tremors, convulsions and paralysis leading to death. Encephalitis may develop in advanced stages.
  

Q: Is there a vaccine for arboviral viruses?
A: There are no available vaccines in the U.S. for use in humans.

Q: What should I do if I think I have contracted an arboviral infection?
A: If a mosquito bites you, you don't necessarily need to see a doctor. Most people suffer a mild illness due to West Nile virus and no treatment is necessary for recovery. Cases that exhibit more extreme symptoms will need to be diagnosed by a doctor. Supportive treatment may be needed. Diagnosis involves a blood or spinal fluid test that takes time to confirm.

Q: I know there are no vaccines for people, but is there a vaccine available to give to my animals?
A: Some vaccines exist to prevent certain arboviral infections in horses. Check with your veterinarian for information on how the viruses affect animals.
Preventative measures

Q: Is there anything I can do to protect myself from insects that may carry the disease?
A: There are some simple preventive measures to reduce your chances of exposure to biting insects:

• Reduce time outdoors when mosquitoes or other insects are biting.
  
• Wear long, loose and light-colored clothing.
  
• Apply mosquito repellants to exposed skin or over clothing.
  
• You can also eliminate common mosquito breeding areas around the home:
  
  • Turn over or remove containers in your yard where rainwater collects, such as old tires, potted plant trays, boats, buckets and toys.
    
  • Do not leave garbage can lids upside down or allow water to collect in your garbage can. Eliminate standing water on tarps and flat roofs.
    
  • Clean out birdbaths and wading pools once a week.
    
  • Clean roof gutters and downspout screens regularly.
    

Bioterrorist Threat
Q: Why are arboviruses potential terrorist weapons?
A: These viruses have been developed for aerosol release. It is also possible to deliberately spread arboviruses via vectors such as mosquitoes, ticks and fleas. These vectors can be produced in large numbers and can be contaminated by allowing them to feed on infected animals or infected blood reservoirs.

Q: If terrorists use arboviruses in weapons, how potent could the weapons be?
A: U.S. Army medical research believes mortality would be high following a biological weapon release. An aerosol-released arbovirus is most likely to infect the olfactory nerve and spread directly to the central nervous system causing an increase in encephalitis cases.

Ebola virus hemorrhagic fever
Description
Q: What is Ebola?
A: Ebola disease is a severe, often-fatal viral hemorrhagic fever found in humans and other primates. The disease is caused by an infection with Ebola virus, named after a river in the Democratic Republic of the Congo in Africa, where it was first recognized.

Q: Where is Ebola virus found in nature?
A: Its exact origin remains unknown. Researchers have been unsuccessful in determining the original source of infection and transmission.

On the basis of available evidence and the nature of similar viruses, researchers believe that Ebola disease is zoonotic (animal-borne) and is normally maintained in an animal host native to the African continent.

The virus is not known to be native to other continents, such as North America.

Q: What does hemorrhagic mean?
A: Hemorrhagic means causing bleeding.

Q: What are hemorrhagic fevers?
A: They are illnesses characterized by high temperature, internal bleeding and shock that occur primarily in tropical climates.

Q: Is Ebola a deadly disease?
A: Yes, the case fatality rates of Ebola infections in Africa have ranged from 50 to 90 percent.

Q: Have there been any cases of Ebola in the U.S.?
A: No human cases have been reported in the United States. Monkeys imported from Africa for research in the U.S. have died from the disease while in the country. Research workers associated with the diseased monkeys were infected with the virus but did not become ill.

Transmission
Q: How is the virus spread?
A: We don't know how humans initially contract the virus since we don't know what harbors the virus. Once the virus is in humans, however, it is spread through direct contact with bodily fluids from an infected person. It can also be spread through contaminated objects, such as needles.

Symptoms
Q: What are the symptoms of Ebola?
A: Flu-like symptoms occur within a few days following exposure. In most patients, flu-like symptoms include high fever, headache, muscle aches, stomach pain, fatigue and diarrhea.

• Some patients exhibit a sore throat, hiccups, rash, red and itchy eyes, and bloody vomit and diarrhea.
  
• Within a week of the infection, symptoms include chest pain, massive hemorrhaging and shock.
  

Treatment
Q: Is there any treatment for Ebola?
A: There is no standard treatment for Ebola, other than supportive therapy.

Q: If there is an outbreak of Ebola, how can I protect myself?
A: Avoid direct contact with an infected person's bodily fluids.

Q: Whom should I call if I think I've been exposed to Ebola?
A: Contact your doctor.

Bioterrorist Threat
Q: Why is Ebola considered a possible bioterrorist threat?
A: It is considered a possible threat because:

• Ebola virus, like the other viruses that cause viral hemorrhagic fevers, is highly infectious and can be aerosolized.
  
• The Ebola virus was assigned a high priority in the offensive biological warfare program of the former Soviet Union.
  
• It causes death in a high percentage of those clinically ill.

Lassa fever
Description
Q: What is Lassa fever?
A: Lassa fever is an acute animal-borne viral hemorrhagic fever.

Q: Where is Lassa fever found?
A: Lassa fever is found in various areas of West Africa. It has been recognized in Guinea, Liberia, Sierra Leone, as well as Nigeria. It is named after a village of northeast Nigeria.

Q: Which animal is a host for Lassa fever?
A: The host, or reservoir, of Lassa virus is a West African mouse.

Q: How serious a disease is Lassa fever?
A: In occasional epidemics of Lassa fever, the fatality rate can reach 50 percent.

• The disease, when it occurs naturally, is mild or has no observable symptoms in about 80 percent of the people infected with the virus. Overall about 1 percent of Lassa fever infections result in death.
  
• Approximately 15 percent of patients hospitalized with Lassa fever die from the illness.
  
• There is a high death rate among pregnant women.
  

Transmission
Q: How do people get Lassa fever from rodents?
A: The virus is transmitted to people in a number of ways:

• Aerosol or airborne transmission occurs when a person inhales tiny particles in the air contaminated with rodent excretions.
  
• Direct contact occurs from touching rodent urine or droppings or contaminated with rodent excretions. Cases also occur after eating food contaminated by rodent excretions or by the introduction of the virus through breaks in the skin (cuts or sores). Some cases occur after eating an infected rodent.
  
• Person-to-person contact with the blood, tissue, secretions or excretions of an individual infected with the Lassa virus can cause the disease. A person may also become infected by breathing in small airborne particles, which an already infected person produces through actions like coughing. Contaminated medical equipment, such as reused needles, can also spread the virus.
  

Symptoms
Q: What are the symptoms of Lassa fever?
A: The illness can begin with a gradual onset of fever, headache and tiredness. Additional symptoms include fever, sore throat, cough, abdominal and chest pain, nausea, vomiting, diarrhea and muscle pain. In severe cases, multiple body systems are affected. Symptoms include shock, fluid in lungs, bleeding, seizures, and swelling of the brain, face and neck.

Q: How long after exposure to Lassa do symptoms appear?
A: Symptoms usually show up six to 21 days after exposure.

Treatment
Q: Is there a treatment for Lassa fever?
A: Ribavirin, an antiviral drug, has been used with success in patients with Lassa fever. It is most effective when administered early in the course of the illness. Supportive care and treatment of complicating secondary infections are recommended.

Q: Is there a vaccine for Lassa fever?
A: No. However, research to find a vaccine is ongoing.

Q: How can I protect myself from Lassa fever during an outbreak?
A: Avoid person-to-person contact with known patients.

Q: If I suspect I've been exposed to the virus, what should I do?
A: Contact your doctor.

Bioterrorist Threat
Q: Why is Lassa considered a potential bioterrorist threat?
A: Like many of the viral hemorrhagic fevers, it is highly infections and can be aerosolized.

Marburg hemorrhagic fever
Description
Q: What is Marburg fever?
A: It is a rare, severe type of viral hemorrhagic fever, which affects both humans and non-human primates. It was first identified in 1967 in Germany and Serbia in Green monkeys imported from Africa for laboratory research. It is named after the German city Marburg.

Q: What is a "hemorrhagic fever"?
A: Hemorrhagic fevers are any group of fevers that occur primarily in tropical climates, characterized by high fever, internal bleeding and shock.

Q: Can you die from Marburg fever?
A: Yes. The fatality rate for Marburg is 25 percent.

Q: Where is Marburg virus found?
A: Marburg virus is indigenous to Africa, although its specific native geographical area within Africa is unknown. Early recorded outbreaks in European laboratories arrived with infected monkeys imported from Uganda.

Transmission
Q: How is Marburg fever contracted?
A: The host for Marburg fever is not known, so it is unknown how humans initially contract the disease. Once humans or primates have the disease, it is transmitted through direct contact with bodily fluids or the blood of an infected patient. It is also transmitted through objects contaminated with infectious blood or tissues.

Symptoms
Q: What are the symptoms of Marburg fever?
A: After an incubation period of five to 10 days, the onset of the disease is sudden and characterized by flu-like symptoms including fever, chills, headache and muscular pain or tenderness.

• Around the fifth day after the symptoms appear, a rash may break out. The rash is most prominent on the chest, back and stomach. Nausea, vomiting, chest pain, sore throat, abdominal pain and diarrhea may also occur.
  
• Symptoms become increasingly severe and may include jaundice, inflammation of the pancreas, severe weight loss, delirium, shock, liver failure, massive hemorrhaging and multi-organ failure.
  

Treatment
Q: Is there any treatment for Marburg fever?
A: There is no specific treatment for this disease except supportive hospital therapy.

Q: Are there any complications from Marburg fever?
A: Recovery is prolonged. There can be inflammation of the testes, spinal cord, eye, parotid gland or prolonged hepatitis.

Q: Whom do I contact if I suspect that I've been exposed to Marburg fever?
A: Contact your doctor.

Decontamination
Q: How can I keep from getting Marburg fever when there's an outbreak of the disease?
A: To prevent the spread of the virus from a known patient:

• Avoid direct physical contact with an infected patient's bodily fluids.
  
• Medical professionals treating the patients should protective gowns, gloves, masks and place the patient in strict isolation.

Bioterrorist Threat
Q: Why is Marburg fever considered a potential biological weapon?
A: Marburg fever is considered a potential biological weapon because the disease is highly infectious and was weaponized for a Soviet Union Biological Warfare program.

Smallpox (Updated 2/24/03)
Description
Q: What is smallpox?
A: Smallpox is a contagious and sometimes fatal infectious disease caused by the variola virus. The more common and more severe form of the disease is called variola major. Historically, about 30 percent of people with the variola major form of smallpox died.

The last case of smallpox in the United States was in 1949. The last natural case in the world occurred in Somalia in 1977. Routine vaccinations among the American public against smallpox stopped in 1972.

The variola virus that causes smallpox officially exists only in two laboratories in the world — in the U.S. and Russia. As there is concern that the virus could be used as a bioterrorism agent, federal, state and local governments are taking precautions to prepare for smallpox.

Even one case of confirmed smallpox would constitute a national public health emergency. A suspected case of smallpox should be immediately reported to the health department.

Transmission
Q: How is smallpox spread?
A: Smallpox is spread person-to-person through direct contact with respiratory droplets, aerosols, secretions and skin lesions of an infected person. Direct and fairly prolonged face-to-face contact (less than six feet for more than three hours) generally is required to spread smallpox from person-to-person. Although less common, it can be transmitted through contact with contaminated clothing or bedding. Animals or insects cannot spread smallpox.

Q: How long is someone infectious when they have smallpox?
A: People are contagious when the first rash appears, which often begins in the mouth and throat. A person remains contagious until the rash heals and the last smallpox scab falls off.

Symptoms
Q: What are the symptoms of smallpox and how soon after exposure do they appear?
A: After a person is exposed to the virus, symptoms usually begin within 12 to 14 days but can begin any time between seven and 17 days. The first symptoms include fever (101-104 degrees Fahrenheit), malaise (not feeling good), headache, backache, sometimes vomiting, and occasionally mental confusion. At this time, people are usually too sick to carry on their normal activities.

Two to four days after the first symptoms, a rash emerges. As the rash appears, the fever usually falls and the person may feel better. The rash begins in the mouth, spreads to the face, to the arms and legs (including hands and feet), and to the rest of the body within 24 hours. The rash first looks like raised bumps that then fill with a thick fluid and often have a depression in the center that looks like a belly button. Within five to 10 days, the bumps become sharply raised, round and firm pustules. Within two weeks, the pustules form a crust and become scabs. During the third week of the rash, the scabs fall off, leaving behind pitted scars.

Q: Smallpox sounds similar to chickenpox. How does smallpox differ from chickenpox?
A: There are several differences between the two diseases:

• The smallpox rash begins as small red spots on the tongue and in the mouth, then appears on the face, arms and legs, and then spreads in towards the trunk.
  
  
• The chickenpox rash begins on the trunk and then spreads out towards the arms and legs.
  
  
• Smallpox lesions are deeply embedded in the skin and develop at the same pace. On any part of the body, they appear identical.
  
  
• Chickenpox lesions are much more superficial and develop in groups at different rates. With chickenpox, scabs, vesicles and pustules are seen at the same time on the same part of the body.
  
  
• Chickenpox lesions are almost never found on the palms or soles, but smallpox lesions can appear on the palms or soles.
  

Treatment
Q: What is the treatment for smallpox?
A: Treatment consists of supportive care and relief of symptoms. No proven effective treatment exists to date, although there are some experimental antiviral medications that are being investigated.

Q: What is the smallpox vaccine?
A: The smallpox vaccine is a live virus vaccine made from a virus called vaccinia, which is a "pox"-type virus related to smallpox. The vaccine helps the body develop immunity to smallpox.

Q: Is it possible for people to get smallpox from the vaccination?

A: No. The smallpox vaccine does not contain smallpox virus and cannot spread or cause smallpox. However, the virus (vaccinia) in the vaccine is live and can spread from the vaccination site to other parts of the body or to other people. This can be prevented through proper care of the vaccination site, such as hand washing and careful disposal of used bandages.

Q: What is the length of protection?
A: Past experience indicates that the first dose of the vaccine offers protection from smallpox for three to five years, and perhaps as long as 10 years or more. If a person is vaccinated again later, immunity lasts even longer. Historically, the vaccine has been effective in preventing smallpox infection in 95 percent of those vaccinated.

Q: Can vaccination after exposure prevent the disease?
A: Vaccination within three days after exposure will prevent or significantly lessen the severity of smallpox symptoms in most people. Vaccination four to seven days after exposure likely offers some protection from disease or may lessen the severity of disease.

Q: Who should NOT get the smallpox vaccine?
A: People with any of the following conditions or people who live with someone with the following conditions should not get the smallpox vaccine unless exposed to the smallpox virus. People should consult with their physician on their health status.

• Weakened immune systems (e.g., HIV, AIDS, leukemia, lymphoma, other cancers, cancer chemotherapy, radiation therapy, high-dose corticosteroid therapy, other immune disorders, some severe autoimmune disorders, and medications to treat autoimmune disorders).
• Any history of eczema, atopic dermatitis (skin disease characterized by itchy, inflamed skin) or Darier's disease.
• Active skin conditions (e.g., burns, other wounds, impetigo, chickenpox, shingles, contact dermatitis, severe acne, herpes, psoriasis) (wait until these conditions have resolved).
• Women who are pregnant or planning to become pregnant within one month of vaccination.

In addition, people in the following categories should not receive the vaccine unless exposed to the smallpox virus:

• Women who are breastfeeding.
• Currently using steroid medications in eyes (wait until no longer using the medication).
• Allergic to the vaccine or any of its ingredients or have had a serious reaction to the vaccine in the past.
• Moderate or severe illness (wait until recovered).
• Are less than 18 years of age.
  

People who have been directly exposed to the smallpox virus should get the vaccine, regardless of their health status.

Q: What are the possible side effects from the smallpox vaccine?
A: The live vaccinia virus that is contained in the vaccine may cause mild reactions, such as rash, fever and head and body aches. Complications can occur if the vaccine site comes in contact with other parts of your body or even other people. The risk is minimized by covering the vaccine site and carefully washing hands after contact with the site until healed (up to three weeks).

Q: What are the chances of serious complications from the smallpox vaccine?
A: In the past, between 14 and 52 people per one million people vaccinated experienced potentially life-threatening reactions. Based on past experience, between 1 and 2 people per one million people vaccinated may die as a result of life-threatening reactions to the vaccine. People not recommended for vaccination may be at greater risk of severe complications.

Q: How is the vaccine given?
A: The smallpox vaccine is not given with a normal hypodermic needle and is not a typical shot. The vaccine is given using a bifurcated (two-pronged) needle that is dipped into and holds a droplet of the vaccine. The needle is used to poke the skin several times. The poking is not deep, but will cause a sore spot that will form a blister and eventually leave a small scar.

Q: Is the smallpox vaccine available?
A: President Bush has announced that volunteer health care providers and first responders will receive the smallpox vaccine as part of ongoing emergency preparedness efforts. The vaccine is currently not recommended for the general public. Routine smallpox vaccinations in the U.S. stopped in 1972. The last natural case of smallpox occurred in Somalia in 1977. The variola virus that causes smallpox officially exists in two laboratories, in the U.S. and Russia, but there is concern that it may be possessed by others and could be used as a bioterrorism agent, which is why federal, state and local governments are taking precautions to prepare.

Q: If a person is infected with smallpox and recovers, are they immune to the disease?
A: Yes, infection with the disease leads to lifelong immunity.

Q: How quickly will I be able to be vaccinated if an outbreak occurs?
A: In the event of an outbreak, the CDC and Virginia Department of Health have clear guidelines to swiftly provide vaccine to people exposed to this disease. The CDC maintains an emergency supply of the smallpox vaccine.

Q: What should I do if I suspect I have been exposed to smallpox?
A: Contact your doctor.

Q: How is the spread of smallpox stopped?
A: Vaccine and isolation are the strategies for stopping the spread of smallpox. Known patients should be placed in medical isolation so that they will not spread the virus. People who have come into close contact with smallpox patients should be vaccinated immediately and closely watched for symptoms of smallpox.

Bioterrorist Threat
Q: Is smallpox considered a potential biological weapon?
A: Yes, smallpox is considered a potential bioterrorism agent. It has been developed as a biological weapon and has been deemed a Category A bioterrorist agent by the CDC.

Q: Are we expecting a smallpox attack?
A: A smallpox attack is possible but not expected. However, recent events that included the use of biological agents as weapons heightened our awareness of the possibility of such an attack.

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