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Anthrax | Hantavirus | Norovirus | West Nile Virus

Anthrax
Hantavirus
Norovirus
What are the symptoms of illness caused by noroviruses?
What is the name of the illness caused by noroviruses?
How serious is norovirus disease?
How do people become infected with noroviruses?
When do symptoms appear?
Are noroviruses contagious?
Who gets norovirus infection?
What treatment is available for people with norovirus infection?
Can norovirus infections be prevented?
West Nile Virus

Anthrax
Q.
What personal protective equipment (PPE) should I wear?
A.
OSHA, CDC, NIOSH, EPA, and the FBI have developed a matrix in consultation with the U.S. Postal Service. You can find the Matrix following site: http://www.osha.gov/bioterrorism/anthrax/matrix/index.html. It supports the modified level C approach we've discussed for the majority of incidents.

Q.
What is the causative (etiologic) agent of anthrax?
A.
Bacillus anthracis, a large (1-1.5 x 3-5um) Gram positive bacillus that forms spores (1 x 1.5um). The name of the organism is derived from the Greek word for coal (anthrakis) because the disease causes black, coal-like lesions.

Q.
Where is the organism found?
A.
The causative agent of anthrax is a common inhabitant of soils worldwide, especially in areas where farm animals have become infected.

Q.
How is the disease transmitted?
A.
Transmission of anthrax occurs by either inhalation of spores causing pulmonary infections, physical contact with spores usually in contaminated soil or animal tissues causing cutaneous (skin) lesions, or, in rare occasions, by consumption of contaminated meat or water. Of these modes of transmission, inhalation is the most deadly, with mortality rates of over 85 percent.

Q.
Can the disease be transmitted person-to-person?
A.
There is no indication that anthrax can be transmitted person-to-person.

Q.
Do cases normally occur in the United States?
A.
Historically, only 18 cases were reported in the United States between 1900 and 1978. No cases were reported in the United States from 1978 until this last month's terrorist acts. An accidental release of anthrax spores from a biowarfare facility in the former Soviet Union in 1979 resulted in at least 79 cases and 68 deaths.

Q.
How many organisms are needed to cause illness?
A.
It has been estimated that it takes an exposure of 2,500 to 55,000 spores to kill 50% (LD50) of the exposed individuals.

Q.
How long before symptoms appear? (incubation period)
A.
Disease onset, in the Soviet Union experience, occurred 2 to 43 days after exposure. Initial symptoms are non-specific, lasting from a few hours to a few days, and include fever, headache, vomiting, chills, weakness, and abdominal and chest pains. The second stage, sometimes following a brief remission is characterized by sudden fever, shortness of breath (dyspnea), perspiration (diaphoresis), shock, delirium, turning blue (cyanosis) usually followed by death, which can occur within hours.

Q.
Is anthrax a newly discovered disease?
A.
No, anthrax has been around for centuries. See the CNN link below for a timeline of anthrax.

Hantavirus

Q.

What are the recommended procedures for clean up of rodent droppings, urine and nesting materials. My park personnel are concerned that hantavirus is a big problem here.

A.

While hantavirus is a currently a significant problem in the western United States, to date, it is not nearly as significant a disease in eastern United States. However, clean ups of rodent droppings, rodent urine or nesting materials should be treated the same way.

General procedures for clean up include:

  • Open up buildings and completely air out prior to the commencement of the clean up process
  • Wear latex (or other suitable material) rubber gloves for all clean ups. No other special clothing or respirators are needed for this level of clean up.
    • Disinfect gloves prior to removal
  • Thoroughly wet contaminated areas with detergents or liquid to deactivate the virus. Most general purpose disinfectants and household detergents are effective. However, a hypochlorite solution prepared by mixing 1 and 1/2 cups of household bleach in 1 gallon of water may be used in place of commercial disinfectant. (CDC recommend the use of a 1:10 bleach solution or a solution of diluted general disinfectant such as lysol).
    • When using the chlorine solution, avoid spilling the mixture on clothing or other items that may be damaged.
    • Hydrogen peroxide or alcohol-based cleaners are not recommended for disinfection.
  • No dry sweeping or vacuuming of materials. You do not want to stir up the settled materials.

Special, enhanced precautions should be taken when cleaning up a cabin or other similar structure where:

  • a known Hantavirus Pulmonary Syndrome (HPS) case has occurred or
  • there is evidence of a very heavy rodent infestation.

Usually, a HEPA-equipped vacuum, disposable coveralls (e.g. Tyvek™) and properly-fitted respiratory protection is used in these types of clean up procedures.

For details on clean up procedures in the National Park Service, consult the Hantavirus Infection Interim Recommendations for Risk Reduction


Norovirus
Source: Centers for Disease Control and Prevention Norovirus Web Site (with updates)
For general information - Norovirus Information Sheet
Q. What are noroviruses?
A.

Noroviruses are a group of viruses that cause the "stomach flu," or gastroenteritis (GAS-tro-en-ter-I-tis), in people. The term norovirus was recently approved as the official name for this group of viruses. Several other names have been used for noroviruses, including:

  • Norwalk-like viruses (NLVs)
  • caliciviruses (because they belong to the virus family Caliciviridae)
  • small round structured viruses.

Viruses are very different from bacteria and parasites, some of which can cause illnesses similar to norvirus infection. Viruses are much smaller, are not affected by treatment with antibiotics, and cannot grow outside of a person's body.


Q. What are the symptoms of illness caused by noroviruses?
A.

The symptoms of norovirus illness usually include nausea, vomiting, diarrhea, and some stomach cramping. Sometimes people additionally have a low-grade fever, chills, headache, muscle aches, and a general sense of tiredness. The illness often begins suddenly, and the infected person may feel very sick. The illness is usually brief, with symptoms lasting only about 1 or 2 days. In general, children experience more vomiting than adults. Most people with norovirus illness have both of these symptoms.


Q. What is the name of the illness caused by noroviruses?
A.

Illness caused by norovirus infection has several names, including:

  • stomach flu - this "stomach flu" is not related to the flu (or influenza), which is a respiratory illness caused by influenza virus.
  • viral gastroenteritis - the most common name for illness caused by norovirus. Gastroenteritis refers to an inflammation of the stomach and intestines.
  • acute gastroenteritis
  • non-bacterial gastroenteritis
  • food poisoning (although there are other causes of food poisoning)
  • calicivirus infection

Q. How serious is norovirus disease?
A.

Norovirus disease is usually not serious, although people may feel very sick and vomit many times a day. Most people get better within 1 or 2 days, and they have no long-term health effects related to their illness. However, sometimes people are unable to drink enough liquids to replace the liquids they lost because of vomiting and diarrhea. These persons can become dehydrated and may need special medical attention. This problem with dehydration is usually only seen among the very young, the elderly, and persons with weakened immune systems. There is no evidence to suggest that an infected person can become a long-term carrier of norovirus.


Q. How do people become infected with noroviruses?
A.

Noroviruses are found in the stool or vomit of infected people. People can become infected with the virus in several ways, including:

  • eating food or drinking liquids that are contaminated with norovirus;
  • touching surfaces or objects contaminated with norovirus, and then placing their hand in their mouth;
  • having direct contact with another person who is infected and showing symptoms (for example, when caring for someone with illness, or sharing foods or eating utensils with someone who is ill).

Persons working in day-care centers or nursing homes should pay special attention to children or residents who have norovirus illness. This virus is very contagious and can spread rapidly throughout such environments.


Q. When do symptoms appear?
A. Symptoms of norovirus illness usually begin about 24 to 48 hours after ingestion of the virus, but they can appear as early as 12 hours after exposure.

Q. Are noroviruses contagious?
A.

Noroviruses are very contagious and can spread easily from person to person. Both stool and vomit are infectious. Particular care should be taken with young children in diapers who may have diarrhea.How long are people contagious?

People infected with norovirus are contagious from the moment they begin feeling ill to at least 3 days after recovery. Some people may be contagious for as long as 2 weeks after recovery. Therefore, it is particularly important for people to use good handwashing and other hygienic practices after they have recently recovered from norovirus illness.


Q. Who gets norovirus infection?
A. Anyone can become infected with these viruses. There are many different strains of norovirus, which makes it difficult for a person's body to develop long-lasting immunity. Therefore, norovirus illness can recur throughout a person's lifetime. In addition, because of differences in genetic factors, some people are more likely to become infected and develop more severe illness than others.

Q. What treatment is available for people with norovirus infection?
A.

Currently, there is no antiviral medication that works against norovirus and there is no vaccine to prevent infection. Norovirus infection cannot be treated with antibiotics. This is because antibiotics work to fight bacteria and not viruses.

Norovirus illness is usually brief in healthy individuals. When people are ill with vomiting and diarrhea, they should drink plenty of fluids to prevent dehydration. Dehydration among young children, the elderly, the sick, can be common, and it is the most serious health effect that can result from norovirus infection. By drinking oral rehydration fluids (ORF), juice, or water, people can reduce their chance of becoming dehydrated. Sports drinks do not replace the nutrients and minerals lost during this illness.


Q. Can norovirus infections be prevented?
A.

Yes. You can decrease your chance of coming in contact with noroviruses by following these preventive steps:

  • Frequently wash your hands, especially after toilet visits and changing diapers, before eating or preparing food.
  • Carefully wash fruits and vegetables, and steam oysters before eating them.
  • Thoroughly clean and disinfect contaminated surfaces immediately after an episode of illness by using a bleach-based household cleaner.
  • Immediately remove and wash clothing or linens that may be contaminated with virus after an episode of illness (use hot water and soap).
  • Flush or discard any vomitus and/or stool in the toilet and make sure that the surrounding area is kept clean.

Persons who are infected with norovirus should not prepare food while they have symptoms and for 3 days after they recover from their illness. Food that may have been contaminated by an ill person should be disposed of properly.


West Nile Virus
Source: Centers for Disease Control and Prevention West Nile Virus Web Site (with updates)
For general information - West Nile Virus Information Sheet
Q.
What is West Nile encephalitis?
A.

"Encephalitis" means an inflammation of the brain and can be caused by viruses and bacteria, including viruses transmitted by mosquitoes. West Nile encephalitis is an infection of the brain.


Q.

How many cases of West Nile encephalitis in humans have occurred in the U.S.?

A.
In 1999, 62 cases of severe disease, including 7 deaths, occurred in the New York area. So far in 2002, there have been at least 112 cases, including 5 deaths in Louisiana. Cases have been identified in Alabama, Arkansas, Illinois, Mississippi, and Texas.

Q.

I understand West Nile virus was found in "overwintering" mosquitoes in the New York City area in early 2000. What does this mean?

A.
One of the species of mosquitoes found to carry West Nile virus is the Culex species, which survive through the winter, or "overwinter," in the adult stage. That the virus survived along with the mosquitoes was documented by the widespread transmission the summer of 2000.

Q.

Do the findings indicate that West Nile virus is established in the Western Hemisphere?

A.
Yes. Each year since its initial emergence of 1999, West Nile virus has been found in more states and further west - as far as the South Dakota border with Montana and Wyoming.

Q.

Is the disease seasonal in its occurrence?

A.
In the temperate zone of the world (i.e., between latitudes 23.5° and 66.5° north and south), West Nile encephalitis cases occur primarily in the late summer or early fall. In the southern climates where temperatures are milder, West Nile virus can be transmitted year round.

Q.
What precautions are needed to prevent a recurrent outbreak?
A.
Active sampling for West Nile virus (i.e., surveillance) in mosquito and bird populations will greatly enhance state and local governments' early detection systems. When the first virus activity is detected in a community, prior to the occurrence of human disease, rapid mosquito control measures, such as targeted application of adulticides and larvicide, should be implemented. (see Suggested Guidelines for Phased Response to West Nile Virus Surveillance Data)

Q.
How do people get West Nile encephalitis?
A.
By the bite of mosquitoes infected with West Nile virus.

Q.

What is the basic transmission cycle?

A.
Mosquitoes become infected when they feed on infected birds, which may circulate the virus in their blood for a few days. Infected mosquitoes can then transmit West Nile virus to humans and animals while biting to take blood. The virus is located in the mosquito's salivary glands. During blood feeding, the virus may be injected into the animal or human, where it may multiply, possibly causing illness.

Q.

If I live in an area where birds or mosquitoes with West Nile virus have been reported and a mosquito bites me, am I likely to get sick?

A.
No. Even in areas where mosquitoes do carry the virus, very few mosquitoes- less than 1%-are infected. If the mosquito is infected, less than 1% of people who get bitten and become infected will get severely ill. The chances you will become severely ill from any one mosquito bite are extremely small.

Q.

Can you get West Nile encephalitis from another person?

A.
No. West Nile encephalitis is NOT transmitted from person-to-person. For example, you cannot get West Nile virus from touching or kissing a person who has the disease, or from a health care worker who has treated someone with the disease.

Q.

Besides mosquitoes, can you get West Nile virus directly from other insects or ticks?

A.
Infected mosquitoes are the primary source for West Nile virus. Although ticks infected with West Nile virus have been found in Asia and Africa, their role in the transmission and maintenance of the virus is uncertain. However, there is no information to suggest that ticks played any role in the cases identified in the United States.

Q.

How many types of animals have been found to be infected with West Nile virus?

A.
Although the vast majority of infections have been identified in birds, through September 2000 CDC has received reports of WN virus infection in horses, cats, bats, chipmunks, skunks, squirrels, domestic rabbits, and raccoons.

Q.

Can you get West Nile virus directly from birds?

A.
There is no evidence that a person can get the virus from handling live or dead infected birds. However, persons should avoid barehanded contact when handling any dead animals and use gloves or double plastic bags to place the carcass in a garbage can.

Q.

How does West Nile virus actually cause severe illness and death in humans?

A.
Following transmission by an infected mosquito, West Nile virus multiplies in the person's blood system and crosses the blood-brain barrier to reach the brain. The virus interferes with normal central nervous system functioning and causes inflammation of brain tissue.

Q.

What proportion of people with severe illness due to West Nile virus die?

A.
Among those with severe illness due to West Nile virus, case-fatality rates range from 3% to 15% and are highest among the elderly. Less than 1% of those infected with West Nile virus will develop severe illness.

Q.

If a person contracts West Nile virus, does that person develop a natural immunity to future infection by the virus?

A.

It is assumed that immunity will be lifelong; however, it may wane in later years.


Q.

Is there a vaccine against West Nile encephalitis?

A.
No, but several companies are working towards developing a vaccine.

Q.

What can I do to reduce my risk of becoming infected with West Nile virus?

A.

The following precautions are recommended to reduce the risk of WN virus infection:

· Stay indoors at dawn, dusk, and in the early evening.
· Wear long-sleeved shirts and long pants whenever you are outdoors.
· Spray clothing with repellents containing permethrin or DEET since mosquitoes may bite through thin clothing.
· Apply insect repellent sparingly to exposed skin. An effective repellent will contain 35% DEET (N, N-diethyl-meta-toluamide). DEET in high concentrations (greater than 35%) provides no additional protection.
· Repellents may irritate the eyes and mouth, so avoid applying repellent to the hands of children.
· Whenever you use an insecticide or insect repellent, be sure to read and follow the manufacturer's DIRECTIONS FOR USE, as printed on the product.
Note: Vitamin B and "ultrasonic" devices are NOT effective in preventing mosquito bites.


Q.

Where can I get more information on mosquito repellents?

A.
Visit the American College of Physicians Web site: "Mosquitoes and mosquito repellents: A clinician's guide" (Mark S. Fradin, MD. Annals of Internal Medicine. June 1, 1998;128:931-940). You can also find information on insect repellents containing DEET at the Environmental Protection Agency (EPA) Web site.

Q.

Where can I get information about the use of pesticide sprays that are being used for mosquito control?

A.
The federal agency responsible for pesticide evaluation is the Environmental Protection Agency (EPA). See their Web site for detailed answers to the questions about pesticides used for mosquito control.

Q.

Who is at risk for getting West Nile encephalitis?

A.
All residents of areas where virus activity has been identified are at risk of getting West Nile encephalitis; persons older than 50 years have the highest risk of severe disease.

Q.

What are the symptoms of West Nile encephalitis?

A.
Most infections are mild, and symptoms include fever, headache, and body aches, occasionally with skin rash and swollen lymph glands. More severe infection may be marked by headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, paralysis, and, rarely, death.

Q.

What is the incubation period in humans (i.e., time from infection to onset of disease symptoms) for West Nile encephalitis?

A.
Usually 3 to 15 days.

Q.

I think I have symptoms of West Nile virus. What should I do?

A.
Contact your health care provider if you have concerns about your health. If you or your family members develop symptoms such as high fever, confusion, muscle weakness, and severe headaches, you should see your doctor immediately.

Q.

How do health care providers test for West Nile virus?

A.
Your physician will first take a medical history to assess your risk for West Nile virus. People who live in, or traveled to areas where West Nile virus activity has been identified are at risk of getting West Nile encephalitis; persons older than 50 years of age have the highest risk of severe disease. If you are determined to be at high risk and have symptoms of West Nile encephalitis, your provider will draw a blood sample and send it to a commercial or public health laboratory for confirmation.

Q.

How is West Nile encephalitis treated?

A.
There is no specific therapy. In more severe cases, intensive supportive therapy is indicated, often involving hospitalization, intravenous fluids, airway management, respiratory support (ventilator), prevention of secondary infections (pneumonia, urinary tract, etc.), and good nursing care.

Q.

Do birds infected with West Nile virus die or become ill?

A.
In the 1999 New York area epidemic, there was a large die-off of American crows. Through September 2000, West Nile virus has been identified in at least 70 species of birds found dead in the United States. The public identified most of these birds through reporting of dead birds.

Q.

How can I report a sighting of dead bird(s) in my area?

A.
Please contact your state or local health department.

Q.

Can West Nile virus cause illness in dogs or cats?

A.
There is a published report of West Nile virus isolated from a dog in southern Africa (Botswana) in 1982. West Nile virus has been isolated from several dead cats in 1999 and 2000. A serosurvey of dogs and cats in the epidemic area showed a low infection rate.

Q.

Can infected dogs or cats be carriers (i.e., reservoirs) for West Nile virus and transmit the virus to humans?

A.
West Nile virus is transmitted by infectious mosquitoes. There is no documented evidence of person-to-person, animal-to-animal, or animal-to-person transmission of West Nile virus. Veterinarians should take normal infection control precautions when caring for an animal suspected to have this or any viral infection.

Q.

How do dogs or cats become infected with West Nile virus?

A.
The same way humans become infected-by the bite of infectious mosquitoes. The virus is located in the mosquito's salivary glands. During blood feeding, the virus is injected into the animal. The virus then multiplies and may cause illness. Mosquitoes become infected when they feed on infected birds, which may circulate the virus in their blood for a few days. It is possible that eating dead infected animals such as birds could infect dogs and cats, but this is unproven.

Q.

Can a dog or cat infected with West Nile virus infect other dogs or cats?

A.
No. There is no documented evidence that West Nile virus is transmitted from animal to animal.

Q.
How long can a dog or cat be infected with West Nile virus?
A.
The answer is not known at this time.
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