HIV / AIDS Disease Information

People have been warned about HIV and AIDS for over twenty years now. AIDS has already killed millions of people, millions more continue to become infected with HIV, and there's no cure – so AIDS will be around for a while yet.

AIDS is one of the biggest problems facing the world today and nobody is beyond its reach. Everyone should know the basic facts about AIDS.

What is AIDS?

AIDS (Acquired Immune Deficiency Syndrome) is a medical condition. People develop AIDS because HIV has damaged their natural defences against disease.

What is HIV?

HIV (Human Immunodeficiency Virus)
HIV is a virus. Viruses infect the cells that make up the human body and replicate (make new copies of themselves) within those cells. A virus can also damage human cells, which is one of the things that can make a person ill.

HIV can be passed from one person to another. Someone can become infected with HIV through contact with the bodily fluids of someone who already has HIV.

HIV stands for the 'Human Immunodeficiency Virus'. Someone who is diagnosed as infected with HIV is said to be 'HIV+' or 'HIV positive'.
Why is HIV dangerous?

The immune system is a group of cells and organs that protect your body by fighting disease. The human immune system usually finds and kills viruses fairly quickly.

So if the body's immune system attacks and kills viruses, what's the problem?

Different viruses attack different parts of the body - some may attack the skin, others the lungs, and so on. The common cold is caused by a virus. What makes HIV so dangerous is that it attacks the immune system itself - the very thing that would normally get rid of a virus. It particularly attacks a special type of immune system cell known as a CD4 lymphocyte.

HIV has a number of tricks that help it to evade the body's defences, including very rapid mutation. This means that once HIV has taken hold, the immune system can never fully get rid of it.

There isn't any way to tell just by looking if someone's been infected by HIV. In fact a person infected with HIV may look and feel perfectly well for many years and may not know that they are infected. But as the person's immune system weakens they become increasingly vulnerable to illnesses, many of which they would previously have fought off easily.

The only reliable way to tell whether someone has HIV is for them to take a blood test, which can detect infection from a few weeks after the virus first entered the body.

When HIV causes AIDS

A damaged immune system is not only more vulnerable to HIV, but also to the attacks of other infections. It won't always have the strength to fight off things that wouldn't have bothered it before.

As time goes by, a person who has been infected with HIV is likely to become ill more and more often until, usually several years after infection, they become ill with one of a number of particularly severe illnesses. It is at this point in the stages of HIV infection that they are said to have AIDS - when they first become seriously ill, or when the number of immune system cells left in their body drops below a particular point. Different countries have slightly different ways of defining the point at which a person is said to have AIDS rather than HIV.

AIDS is an extremely serious condition, and at this stage the body has very little defence against any sort of infection.

How long does HIV take to become AIDS?

Without drug treatment, HIV infection usually progresses to AIDS in an average of ten years. This average, though, is based on a person having a reasonable diet. Someone who is malnourished may well progress to AIDS and death more rapidly.

Antiretroviral medication can prolong the time between HIV infection and the onset of AIDS. Modern combination therapy is highly effective and, theoretically, someone with HIV can live for a long time before it becomes AIDS. These medicines, however, are not widely available in many poor countries around the world, and millions of people who cannot access medication continue to die.

How is HIV passed on?

HIV is found in the blood and the sexual fluids of an infected person, and in the breast milk of an infected woman. HIV transmission occurs when a sufficient quantity of these fluids get into someone else's bloodstream. There are various ways a person can become infected with HIV.
Ways in which you can be infected with HIV :
Unprotected sexual intercourse with an infected person Sexual intercourse without a condom is risky, because the virus, which is present in an infected person's sexual fluids, can pass directly into the body of their partner. This is true for unprotected vaginal and anal sex. Oral sex carries a lower risk, but again HIV transmission can occur here if a condom is not used - for example, if one partner has bleeding gums or an open cut, however small, in their mouth.
Contact with an infected person's blood If sufficient blood from an infected person enters someone else's body then it can pass on the virus.
From mother to child HIV can be transmitted from an infected woman to her baby during pregnancy, delivery and breastfeeding. There are special drugs that can greatly reduce the chances of this happening, but they are unavailable in much of the developing world.
Use of infected blood products Many people in the past have been infected with HIV by the use of blood transfusions and blood products which were contaminated with the virus - in hospitals, for example. In much of the world this is no longer a significant risk, as blood donations are routinely tested.
Injecting drugs People who use injected drugs are also vulnerable to HIV infection. In many parts of the world, often because it is illegal to possess them, injecting equipment or works are shared. A tiny amount of blood can transmit HIV, and can be injected directly into the bloodstream with the drugs.
It is not possible to become infected with HIV through :
sharing crockery and cutlery
insect / animal bites
touching, hugging or shaking hands
eating food prepared by someone with HIV
toilet seats

HIV facts and myths

People with HIV look just like everybody else
Around the world, there are a number of different myths about HIV and AIDS. Here are some of the more common ones :

'You would have to drink a bucket of infected saliva to become infected yourself' . . . Yuck! This is a typical myth. HIV is found in saliva, but in quantities too small to infect someone. If you drink a bucket of saliva from an HIV positive person, you won't become infected. There has been only one recorded case of HIV transmission via kissing, out of all the many millions of kisses. In this case, both partners had extremely badly bleeding gums.

'Sex with a virgin can cure HIV' . . . This myth is common in some parts of Africa, and it is totally untrue. The myth has resulted in many rapes of young girls and children by HIV+ men, who often infect their victims. Rape won't cure anything and is a serious crime all around the world.

'It only happens to gay men / black people / young people, etc' . . . This myth is false. Most people who become infected with HIV didn't think it would happen to them, and were wrong.

'HIV can pass through latex' . . . Some people have been spreading rumours that the virus is so small that it can pass through 'holes' in latex used to make condoms. This is untrue. The fact is that latex blocks HIV, as well as sperm - preventing pregnancy, too.

What does 'safe sex' mean?

Safe sex refers to sexual activities which do not involve any blood or sexual fluid from one person getting into another person's body. If two people are having safe sex then, even if one person is infected, there is no possibility of the other person becoming infected. Examples of safe sex are cuddling, mutual masturbation, 'dry' (or 'clothed') sex . . .

In many parts of the world, particularly the USA, people are taught that the best form of safe sex is no sex - also called 'sexual abstinence'. Abstinence isn't a form of sex at all - it involves avoiding all sexual activity. Usually, young people are taught that they should abstain sexually until they marry, and then remain faithful to their partner. This is a good way for someone to avoid HIV infection, as long as their husband or wife is also completely faithful and doesn't infect them.

What is 'safer sex'?

Safer sex is used to refer to a range of sexual activities that hold little risk of HIV infection.

Safer sex is often taken to mean using a condom for sexual intercourse. Using a condom makes it very hard for the virus to pass between people when they are having sexual intercourse. A condom, when used properly, acts as a physical barrier that prevents infected fluid getting into the other person's body.

Is kissing risky?

Kissing someone on the cheek, also known as social kissing, does not pose any risk of HIV transmission.

Deep or open-mouthed kissing is considered a very low risk activity for transmission of HIV. This is because HIV is present in saliva but only in very minute quantities, insufficient to lead to HIV infection alone.

There has only been one documented instance of HIV infection as a result of kissing out of all the millions of cases recorded. This was as a result of infected blood getting into the mouth of the other person during open-mouthed kissing, and in this instance both partners had seriously bleeding gums.

Can anything 'create' HIV?

No. Unprotected sex, for example, is only risky if one partner is infected with the virus. If your partner is not carrying HIV, then no type of sex or sexual activity between you is going to cause you to become infected - you can't 'create' HIV by having unprotected anal sex, for example.

You also can't become infected through masturbation. In fact nothing you do on your own is going to give you HIV - it can only be transmitted from another person who already has the virus.

Is there a cure for AIDS?
HIV medication can slow the progress of the virus

Worryingly, surveys show that many people think that there's a 'cure' for AIDS - which makes them feel safer, and perhaps take risks that they otherwise shouldn't. These people are wrong, though - there is still no cure for AIDS.

There is antiretroviral medication which slows the progression from HIV to AIDS, and which can keep some people healthy for many years. In some cases, the antiretroviral medication seems to stop working after a number of years, but in other cases people can recover from AIDS and live with HIV for a very long time. But they have to take powerful medication every day of their lives, sometimes with very unpleasant side effects.

There is still no way to cure AIDS, and at the moment the only way to remain safe is not to become infected.

Avian influenza Disease Information

How is avian influenza detected in humans?
Avian influenza cannot be diagnosed by symptoms alone, so a laboratory test is required. Avian influenza is usually diagnosed by collecting a swab from the nose or throat during the first few days of illness. This swab is then sent to a laboratory, where they will either look for avian influenza virus using a molecular test, or they will try to grow the virus. Growing avian influenza viruses should only be done in laboratories with high levels of protection. If it is late in the illness, it may be difficult to find an avian influenza virus directly using these methods. If this is the case, it may still be possible to diagnose avian influenza by looking for evidence of the body's response to the virus. This is not always an option because it requires two blood specimens (one taken during the first few days of illness and another taken some weeks later), and it can take several weeks to verify the results.

influenza to human health?
Two main risks for human health from avian influenza are 1) the risk of direct infection when the virus passes from the infected bird to humans, sometimes resulting in severe disease; and 2) the risk that the virus—if given enough opportunities—will change into a form that is highly infectious for humans and spreads easily from person to person.

How is avian influenza in humans treated?
Studies done in laboratories suggest that the prescription medicines approved for human influenza viruses should work in treating avian influenza infection in humans. However, influenza viruses can become resistant to these drugs, so these medications may not always work. Additional studies are needed to determine the effectiveness of these medicines.
Does seasonal influenza vaccine protect against avian influenza infection in people?

No. Seasonal influenza vaccine does not provide protection against avian influenza.

Should I wear a surgical mask to prevent exposure to avian influenza?
Currently, wearing a mask is not recommended for routine use (e.g., in public) for preventing influenza exposure. In the United States, disposable surgical and procedure masks have been widely used in health-care settings to prevent exposure to respiratory infections, but the masks have not been used commonly in community settings, such as schools, businesses, and public gatherings.

Can I get avian influenza from eating or preparing poultry or eggs?
You cannot get avian influenza from properly handled and cooked poultry and eggs.

There currently is no scientific evidence that people have been infected with bird flu by eating safely handled and properly cooked poultry or eggs.

Most cases of avian influenza infection in humans have resulted from direct or close contact with infected poultry or surfaces contaminated with secretions and excretions from infected birds. Even if poultry and eggs were to be contaminated with the virus, proper cooking would kill it. In fact, recent studies have shown that the cooking methods that are already recommended by the U.S. Department of Agriculture (USDA) and the Food and Drug Administration (FDA) for poultry and eggs to prevent other infections will destroy influenza viruses as well.

So to stay safe, the advice is the same for protecting against any infection from poultry:
Wash your hands with soap and warm water for at least 20 seconds before and after handling raw poultry and eggs.

Clean cutting boards and other utensils with soap and hot water to keep raw poultry from contaminating other foods.

Use a food thermometer to make sure you cook poultry to a temperature of at least 165 degrees Fahrenheit Consumers may wish to cook poultry to a higher temperature for personal preference.

Cook eggs until whites and yolks are firm.

The U.S. government carefully controls domestic and imported food products, and in 2004 issued a ban on importation of poultry from countries affected by avian influenza viruses, including the H5N1 strain. This ban still is in place.
We have a small flock of chickens. Is it safe to keep them?


Yes. In the United States there is no need at present to remove a flock of chickens because of concerns regarding avian influenza. The U.S. Department of Agriculture monitors potential infection of poultry and poultry products by avian influenza viruses and other infectious disease agents.

For additional information about avian influenza visit pandemicflu.gov.

What is the avian influenza A (H5N1) virus that has been reported in Africa, Asia, Europe, and the Near East?

Influenza A (H5N1) virus—also called "H5N1 virus"—is an influenza A virus subtype that occurs mainly in birds, is highly contagious among birds, and can be deadly to them.

Outbreaks of avian influenza H5N1 occurred among poultry in eight countries in Asia (Cambodia, China, Indonesia, Japan, Laos, South Korea, Thailand, and Vietnam) during late 2003 and early 2004. At that time, more than 100 million birds in the affected countries either died from the disease or were killed in order to try to control the outbreaks. By March 2004, the outbreak was reported to be under control.

Beginning in June 2004, however, new outbreaks of influenza H5N1 among poultry and wild birds were reported in Asia. Since that time, the virus has spread geographically. Reports of H5N1 infection in wild birds in Europe began in mid-2005. In early 2006, influenza A H5N1 infection in wild birds and poultry were reported in Africa and the Near East.

Human cases of influenza A (H5N1) infection have been reported in Azerbaijan, Cambodia, China, Djibouti, Egypt, Indonesia, Iraq, Kuwait, Lao People's Democratic Republic, Nigeria, Thailand, Turkey, and Vietnam. For the most current information about avian influenza and cumulative case numbers, see the World Health Organization Avian Influenza website.

What are the risks to humans from the current H5N1 outbreak?
H5N1 virus does not usually infect people, but more than 200 human cases have been reported. Most of these cases have occurred from direct or close contact with infected poultry or contaminated surfaces; however, a few cases of human-to-human spread of H5N1 virus have occurred.

So far, spread of H5N1 virus from person to person has been rare, limited and unsustained. Nonetheless, because all influenza viruses have the ability to change, scientists are concerned that H5N1 virus one day could be able to infect humans and spread easily from one person to another. Because these viruses do not commonly infect humans, there is little or no immune protection against them in the human population.

If H5N1 virus were to gain the capacity to spread easily from person to person, an influenza pandemic (worldwide outbreak of disease) could begin. No one can predict when a pandemic might occur. However, experts from around the world are watching the H5N1 situation in Asia and Europe very closely and are preparing for the possibility that the virus may begin to spread more easily from person to person.

How is infection with H5N1 virus in humans treated?
Most H5N1 viruses that have caused human illness and death appear to be resistant to amantadine and rimantadine, two antiviral medications commonly used for treatment of patients with influenza. Two other antiviral medications, oseltamivir and zanamavir, would probably work to treat influenza caused by H5N1 virus, but additional studies are needed to demonstrate their current and ongoing effectiveness.

Is there a vaccine to protect people from some strains of the H5N1 virus?
Yes. On April 17, 2007, the U.S. Food and Drug Administration (FDA) announced its approval of the first vaccine to prevent human infection with one strain of the avian influenza (bird flu) H5N1 virus. The vaccine, produced by sanofi pasteur, Inc., has been purchased by the federal government for the U.S. Strategic National Stockpile; it will be distributed by public-health officials if needed. This vaccine will not be made commercially available to the general public. Other H5N1 vaccines are being developed by other companies against different H5N1 strains. For more information about the sanofi pasteur, Inc. vaccine, visit http://www.fda.gov/bbs/topics/NEWS/2007/NEW01611.html. For information about other H5N1 and pandemic flu vaccine research activities visit http://www.pandemicflu.gov/research/index.html#vresearch.

What is the benefit of the FDA-approved H5N1 vaccine produced by sanofi pasteur Inc?
The H5N1 vaccine approved by the U.S. Food and Drug Administration (FDA) on April 17, 2007, was developed as a safeguard against the possible emergence of an H5N1 pandemic virus. However, since the H5N1 virus is not a pandemic virus since it does not transmit efficiently from person to person, the H5N1 vaccine is being held in stockpiles rather than being used by the general public . This vaccine aids H5N1 preparedness efforts in case an H5N1 pandemic virus were to emerge.

What does CDC recommend regarding H5N1 virus?
In February 2004, CDC provided U.S. public health departments with recommendations for enhanced surveillance ("detection") of H5N1 influenza in the country. Follow-up messages, distributed via the Health Alert Network, were sent to the health departments on August 12, 2004, February 4, 2005, and June 7, 2006; all three notices reminded public health departments about recommendations for detecting (domestic surveillance), diagnosing, and preventing the spread of H5N1 virus. The notices also recommended measures for laboratory testing for H5N1 virus.

Does CDC recommend travel restrictions to areas with known H5N1 outbreaks?
CDC does not recommend any travel restrictions to affected countries at this time. However, CDC currently advises that travelers to countries with known outbreaks of H5N1 influenza avoid poultry farms, contact with animals in live food markets, and any surfaces that appear to be contaminated with feces from poultry or other animals.

Is there a risk in handling feather products that come from countries experiencing outbreaks of avian influenza A (H5N1)?
The U.S. government has determined that there is a risk to handling feather products from countries experiencing outbreaks of H5N1 influenza.

There is currently a ban on the importation of birds and bird products from H5N1-affected countries in Africa, Asia, and Europe. The regulation states that no person may import or attempt to import any birds (Class Aves), whether dead or alive, or any products derived from birds (including hatching eggs), from the specied countries. This prohibition does not apply to any person who imports or attempts to import products derived from birds if, as determined by federal officials, such products have been properly processed to render them noninfectious so that they pose no risk of transmitting or carrying H5Nl and which comply with the U.S. Department of Agriculture (USDA) requirements. Therefore, feathers from these countries are banned unless they have been processed to render them noninfectious. Additional information about the import ban is available on the USDA website

Is there a risk to importing pet birds that come from countries experiencing outbreaks of avian influenza A (H5N1)?
The U.S. government has determined that there is a risk to importing pet birds from countries experiencing outbreaks of H5N1 influenza. CDC and USDA have both taken action to ban the importation of birds from areas where H5N1 has been documented. There is currently a ban on the importation of birds and bird products from H5N1-affected countries in Africa, Asia, and Europe. The regulation states that no person may import or attempt to import any birds (Class Aves), whether dead or alive, or any products derived from birds (including hatching eggs), from the specified countries (see Embargo of Birds from Specified Countries).

Can a person become infected with avian influenza A (H5N1) virus by cleaning a bird feeder?
There is no evidence of H5N1 having caused disease in birds or people in the United States. At the present time, there is no risk of becoming infected with H5N1 virus from bird feeders. Generally, perching birds (Passeriformes) are the predominate type of birds at feeders. While there are documented cases of H5N1 causing death in some Passeriformes (e.g., house sparrow, Eurasian tree-sparrow, house finch), in both free-ranging and experimental settings, none occurred in the U.S. and most of the wild birds that are traditionally associated with avian influenza viruses are waterfowl and shore birds.

What changes are needed for H5N1 or another avian influenza virus to cause a pandemic?
Three conditions must be met for a pandemic to start: 1) a new influenza virus subtype must emerge for which there is little or no human immunity; 2) it must infect humans and causes illness; and 3) it must spread easily and sustainably (continue without interruption) among humans. The H5N1 virus in Asia and Europe meets the first two conditions: it is a new virus for humans (H5N1 viruses have never circulated widely among people), and it has infected more than 190 humans, killing over half of them.

However, the third condition, the establishment of efficient and sustained human-to-human transmission of the virus, has not occurred. For this to take place, the H5N1 virus would need to improve its transmissibility among humans. This could occur either by "reassortment" or adaptive mutation.

Reassortment occurs when genetic material is exchanged between human and avian viruses during co-infection (infection with both viruses at the same time) of a human or another mammal. The result could be a fully transmissible pandemic virus—that is, a virus that can spread easily and directly between humans. A more gradual process is adaptive mutation,
where the capability of a virus to bind to human cells increases during infections of humans.

What is CDC doing to prepare for a possible H5N1 influenza pandemic?
CDC is taking part in a number of pandemic prevention and preparedness activities, including the following:
Providing leadership to the National Pandemic Influenza Preparedness and Response Task Force, created in May 2005 by the Secretary of the U.S. Department of Health and Human Services.
Working with the Association of Public Health Laboratories on training workshops for state laboratories on the use of special laboratory (molecular) techniques to identify H5 viruses.
Working with the Council of State and Territorial Epidemiologists and others to help states with their pandemic planning efforts.
Working with other agencies, such as the Department of Defense and the Veterans Administration, on antiviral stockpile issues.
Working with the World Health Organization (WHO) to investigate influenza H5N1 among people (e.g., in Vietnam) and to provide help in laboratory diagnostics and training to local authorities.
Performing laboratory testing of H5N1 viruses.
Starting a $5.5 million initiative to improve influenza surveillance in Asia.

Holding or taking part in training sessions to improve local capacities to conduct surveillance for possible human cases of H5N1 and to detect influenza A H5 viruses by using laboratory techniques.

Developing and distributing reagent kits to detect the currently circulating influenza A H5N1 viruses.

CDC has developed and is distributing the first FDA approved test for the detection of the H5 viruses that first emerged in Asia in 2003.

CDC also is working closely with WHO and the National Institutes of Health on safety testing of vaccine candidates and development of additional vaccine virus seed candidates for influenza A (H5N1) and other subtypes of influenza A viruses.

What animals can be infected with avian influenza A (H5N1) viruses?
In addition to humans and birds, we know that pigs, tigers, leopards, ferrets, and domestic cats can be infected with avian influenza A (H5N1) viruses. In addition, in early March 2006, Germany reported H5N1 infection in a stone marten (a weasel-like mammal). The avian influenza A (H5N1) virus that emerged in Asia in 2003 is evolving and it's possible that other mammals may be susceptible to infection as well. CDC is working closely with domestic and international partners to continually monitor this situation and will provide additional information to the public as it becomes available.

Can domestic cats be infected with avian influenza viruses?
While domestic cats are not usually susceptible to influenza type A infection, it is known that they can become infected and die (both experimentally and naturally) with avian influenza A (H5N1) viruses and, in a laboratory/research setting can spread the virus to other cats. It is not known whether domestic cats can spread the virus to other domestic cats under natural conditions.

How do cats become infected with avian influenza A (H5N1) viruses?
All of the cases of influenza A (H5N1) infection in domestic cats reported to date have been associated with H5N1 outbreaks among domestic poultry or wild birds and are thought to have occurred by the cat eating raw infected birds.

How commonly have cats been infected with avian influenza A (H5N1) viruses?
During the avian influenza A (H5N1) outbreak that occurred from 2003 to 2004 in Asia, there were only several unofficial reports of fatal infections in domestic cats. Studies carried out in the Netherlands and published in 2004 showed that housecats could be infected with avian influenza A (H5N1) and could spread the virus to other housecats. In these experiments, the cats became sick after direct inoculation of virus isolated from a fatal human case, and following the feeding of infected raw chicken. In February 2006, Germany reported that a domestic cat had died from influenza A (H5N1) infection. That cat lived in the northern island of Ruegen, where more than 100 wild birds are believed to have died of the disease. The cat probably got sick by eating an infected bird.

What about infection in large cats, like tigers?
Large cats kept in captivity have been diagnosed with avian influenza as well. In December 2003, two tigers and two leopards that were fed fresh chicken carcasses from a local slaughterhouse died at a zoo in Thailand. An investigation identified avian influenza A (H5N1) in tissue samples. In February and March 2004, the virus was detected in a clouded leopard and white tiger, respectively, both of which died in a zoo near Bangkok . In October 2004, 147 of 441 captive tigers in a zoo in Thailand died or were euthanatized as a result of infection after being fed fresh chicken carcasses. The cats are thought to have gotten sick from eating infected raw meat. Results of a subsequent investigation suggested that at least some tiger-to-tiger transmission occurred in that facility.

Can cats spread H5N1 to people?
There is no evidence to date that cats can spread H5N1 to humans. No cases of avian influenza in humans have been linked to exposure to sick cats, and no outbreaks among populations of cats have been reported. All of the influenza A (H5N1) infections in cats reported to date appear to have been associated with outbreaks in domestic or wild birds and acquired through ingestion of raw meat from an infected bird.

What is the risk to humans or other species from cats infected with avian influenza H5N1 virus?
There is no evidence to date that cats can spread H5N1 to humans. No cases of avian influenza in humans have been linked to exposure to sick cats, and no outbreaks among populations of cats have been reported. All of the influenza A (H5N1) infections in cats reported to date appear to have been associated with outbreaks in domestic or wild birds and acquired through ingestion of raw infected meat.

What is the current risk that a cat in the United States will become infected with influenza A (H5N1)?
As long as there is no influenza A (H5N1) in the United States, there is no risk of a U.S. cat becoming infected with this disease. The virus circulating in Asia, Europe and Africa has not yet entered the United States. CDC is working closely with domestic and international partners to continually monitor this situation and will provide additional information to the public as it becomes available.

If avian influenza A (H5N1) is identified in the United States, how can I protect my cat?
As long as there is no H5N1 influenza in the United States, at this time there is no risk of a U.S. cat becoming infected with this disease. In Europe, however, where H5N1 has been reported in wild birds, poultry, several cats, and a stone marten (a member of the weasel family), the European Center for Disease Prevention and Control has issued preliminary recommendations for cat owners living in H5N1-affected areas. Additionally, the Food and Agriculture Organization has produced guidance for areas where H5N1 HPAI has been diagnosed or is suspected in poultry or wild birds.

Cans dogs be infected with avian influenza?
While dogs are not usually susceptible to avian influenza viruses, the avian influenza A (H5N1) virus that emerged in Asia in 2003 has been documented to infect other carnivore species (e.g. cats, tigers, leopards, stone martens). This has raised concern that this strain of avian influenza A (H5N1) virus may be capable of infecting dogs. An unpublished study carried out in 2005 by the National Institute of Animal Health in Bangkok indicated that dogs could be infected with the virus, but no associated disease was detected. This limited information is not enough to determine definitively whether dogs are susceptible to the virus. CDC is coordinating with USDA, veterinary associations, and other partners domestically and internationally on this issue and will provide additional information to the public as it becomes available.

How would dogs be infected with avian influenza A (H5N1)?
There is not enough information available about avian influenza A (H5N1) infection in dogs to know how infection would occur. Affected domestic cats in Europe appear to have become infected by feeding upon raw infected poultry or wild birds. If dogs are susceptible to avian influenza A (H5N1), infection may be by the same route.

What is the current risk that a dog in the United States will become infected with avian influenza A (H5N1)?

As long as there is no influenza A (H5N1) in the United States, there is no risk of a U.S. dog becoming infected with this disease. The virus circulating in Asia, Europe and Africa has not yet entered the United States. CDC is working closely with domestic and international partners to continually monitor this situation and will provide additional information to the public as it becomes available.

Source: U.S. Centers for Disease Control and Prevention

Anthrax Disease Information

Anthrax is the disease caused by the bacterium Bacillus anthracis, which lives in soil. The bacterial cell lives as a hardy spore to survive harsh conditions. The spores germinate into thriving colonies of bacteria once inside an animal or person. Anthrax usually affects livestock far more than humans, but—as we know from the 2001 anthrax attacks in the United States—anthrax is feared as a modern biological weapon.

Anthrax occurs in three forms:
Cutaneous (affecting the skin)
Inhalational (in the lungs)
Gastrointestinal (in the digestive tract)
Cutaneous Anthrax

Cutaneous anthrax is the most common form of the disease. People with cuts or open sores can get cutaneous anthrax if they come in direct contact with the bacteria or its spores, usually through contaminated animal products. The skin will redden and swell, much like an insect bite, and then develop a painless blackened lesion or ulcer that may form a brown or black scab, which is actually dead tissue. Cutaneous anthrax responds well to antibiotics but may spread throughout the body if untreated. People who work with certain animals or animal carcasses are at risk of getting this form of the disease. Cutaneous anthrax is rare in the United States. According to the Centers for Disease Control and Prevention (CDC), the United States sees only one to two cases per year.
Inhalational Anthrax

When a person inhales the spores of B. anthracis, they germinate and the bacteria infect the lungs, spreading to the lymph nodes in the chest. As the bacteria grow, they produce two kinds of deadly toxins.

Symptoms usually appear 1 to 7 days after exposure, but they may first appear more than a month later. Fever, nausea, vomiting, aches, and fatigue are among the early symptoms of inhalational anthrax; it progresses to labored breathing, shock, and often death.

Historically, the mortality rate for naturally occurring inhalational anthrax has been 75 percent, even with appropriate treatment. But inhalational anthrax is rare. In the 2001 anthrax attacks, 11 people were infected with inhalational anthrax and 6 survived. Prior to 2001, the last known U.S. case was in 1976, when a California craftsman died after getting the infection from imported yarn contaminated with anthrax spores.
Gastrointestinal Anthrax

People can get gastrointestinal anthrax from eating meat contaminated with anthrax bacteria or their spores. Symptoms are stomach pain, loss of appetite, diarrhea, and fever. Antibiotic treatment can cure this form of anthrax, but left untreated, it may kill half of those who get it.

Gastrointestinal anthrax occurs naturally in warm and tropical regions of Asia, Africa, and the Middle East. There have been no confirmed cases of gastrointestinal anthrax in the United States, although a Minnesota farm family may have experienced symptoms of the disease in 2000 after eating meat from a steer that had anthrax.

Bacillus anthracis is a bacterium that lives in soil and has developed a survival tactic that allows it to endure for decades under the harshest conditions. An anthrax bacterial cell can transform itself into a spore, a very hardy resting phase which can withstand extreme heat, cold, and drought, without nutrients or air. When environmental conditions are favorable, the spores will germinate into thriving colonies of bacteria. For example, a grazing animal may ingest spores that begin to grow, spread, and eventually kill the animal. The bacteria will form spores in the carcass and then return to the soil to infect other animals in the future.

While its spore form allows the bacteria to survive in any environment, the ability to produce toxins is what makes the bacteria such a potent killer. Together, the hardiness and toxicity of B. anthracis make it a formidable bioterror agent. Its toxin is made of three proteins: protective antigen, edema factor, and lethal factor.
Protective antigen binds to select cells of an infected person or animal and forms a channel that permits edema factor and lethal factor to enter those cells.
Edema factor, once inside the cell, causes fluid to accumulate at the site of infection. Edema factor can contribute to a fatal build-up of fluid in the cavity surrounding the lungs. It also can inhibit some of the body’s immune functions.
Lethal factor also works inside the cell, disrupting a key molecular switch that regulates the cell’s functions. Lethal factor can kill infected cells or prevent them from working properly.
Bioterror Connection

In the fall of 2001, lethal anthrax bacteria were spread deliberately through the U.S. mail. Twenty-two people became ill, and five died. The perpetrator has not been caught.

Even before this bioterror attack, public health officials were concerned about the potential for such an event. In 1999, the Centers for Disease Control and Prevention (CDC) created lists of high-priority biological agents that terrorists could use to harm civilians. An expert panel of doctors and scientists classified Bacillus anthracis as a Category A bioterror agent. The NIAID list of Category A organisms includes those that pose the greatest threats to national security due to their ease of transmission, high rate of death or serious illness, potential for causing public panic, and the special public health measures an epidemic would require.

Since the creation of the CDC lists, public health officials and researchers have worked to plan and prepare for a possible bioterror attack. Following the 2001 anthrax attacks, federal funding for these efforts increased significantly.

If diagnosed early, anthrax is easily treated with antibiotics. Unfortunately, infected people often confuse early symptoms with more common infections and do not seek medical help until severe symptoms appear. By that time, the destructive anthrax toxins have already risen to high levels, making treatment difficult. Antibiotics can kill the bacteria, but antibiotics have no effect on anthrax toxins.

In 1970, the Food and Drug Administration (FDA) approved an anthrax vaccine for humans, which is licensed for limited use. The vaccine is currently used to protect members of the military and individuals most at risk for occupational exposure to the bacteria, such as slaughterhouse workers, veterinarians, laboratory workers, and livestock handlers. The vaccine does not contain the whole bacterium. Rather, it is made mostly of the anthrax protective antigen protein, so people cannot get anthrax infection from the vaccine.

Health experts currently do not recommend the vaccine for general use by the public because anthrax illness is rare and the vaccine has potential adverse side effects in some individuals. Researchers have not determined the safety and efficacy of the vaccine in children, the elderly, and people with weakened immune systems. Although the vaccine trials indicate that three to four doses of anthrax vaccine can generate significant protective immunity, the recommended vaccination schedule is six doses given over an 18-month period.

To quickly protect the public in the event of a bioterror attack, scientists are seeking to develop a new vaccine.

The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health, conducts and funds research to improve our ability to prevent, diagnose, and treat anthrax. Anthrax research was under way prior to the 2001 bioterror attack, but it has expanded significantly since then. New research findings are improving our understanding of how B. anthracis causes disease and how to better prevent and treat it.

Several biologic factors contribute to B. anthracis’ ability to cause disease. NIAID researchers and grantees are uncovering the molecular pathways that enable the bacterium to form spores, survive in people, and cause illness. Scientists envision this basic research to be the pathway to new vaccines, drugs, and diagnostic tools.
Natural history of anthrax

One goal of NIAID physician researchers is to look at the infectious disease process over time, from initial infection through the clinical course and beyond recovery. A small number of anthrax survivors from the 2001 attacks are enrolled in a long-term clinical study for this purpose. Many years of clinical observation are needed for this type of study to yield definitive results. Because the medical literature on anthrax does not include any findings regarding long-term complications in survivors, information gained in this study will be valuable to patients and healthcare workers.
Toxin biology

Scientists are studying anthrax toxins to learn how to block their production and action. Recently, NIAID-supported scientists have shown that protective antigen can bind edema factor and lethal factor at the same time, forming a greater variety of toxin complexes than were previously known. This finding could help researchers develop antitoxin therapies.

Previously, scientists discovered the three-dimensional molecular structure of the anthrax protective antigen protein bound to one of the receptors (CMG2) it uses to enter cells. Using a specific fragment of the CMG2 receptor protein, researchers have been able to block the attachment of protective antigen in test-tube experiments, thereby inhibiting all anthrax toxin activity.

NIAID-funded scientists also had synthesized a small cyclic molecule that blocks anthrax toxin in cell culture and in rodents. The molecule blocks the pore formed by anthrax protective antigen. Blocking the pore effectively prevents lethal factor and edema factor toxins from entering cells.

Scientists anticipate that these findings will lead to new and effective treatments.
Anthrax bacterium genome

Genes are the instructions for making proteins, which in turn build components of the cell or carry out its biochemical processes. The instructions that dictate how a microbe works are encoded within its genes. Bacteria keep most of their genes in a chromosome, a very long stretch of DNA. Smaller circular pieces of DNA called plasmids also carry genes that bacteria may exchange with each other. Because plasmids often contain genes for toxins and antibiotic resistance, knowing the DNA sequence of such plasmids is important.

Scientists have sequenced plasmids carrying the toxin genes of B. anthracis. In addition, researchers have sequenced the complete chromosomal DNA sequence of several B. anthracis strains, including one that killed a Florida man in the 2001 anthrax bioterror attack.

By comparing the DNA blueprints of different B. anthracis strains, researchers are learning why some strains are more virulent than others. Small variations among the DNA sequences of different strains may also help investigators pinpoint the origin of an anthrax outbreak.

Knowing the genetic fingerprint of B. anthracis might lead to gene-based detection mechanisms that can alert scientists to the bacteria in the environment or allow rapid diagnosis of anthrax in infected people. Variations between strains might also point to differences in antibiotic susceptibility, permitting doctors to immediately determine the appropriate treatment.

Scientists are now analyzing the B. anthracis genome sequence to determine the function of each of its genes and to learn how those genes interact with each other or with host-cell components to cause disease. Knowing the sequence of B. anthracis genes will help scientists discover key bacterial proteins that can then be targeted by new drugs or vaccines.
Spore biology

B. anthracis spores are essentially dormant and must “wake up,” or germinate, to become reproductive, disease-causing bacteria. Researchers are studying the germination process to learn more about the signals that cause spores to become active once inside an animal or person. Efforts are under way to develop models of spore germination in laboratory animals. Scientists hope those models will enable discoveries leading to drugs that block the germination process in B. anthracis spores.
Host immunity

People who contract anthrax produce antibodies to protective antigen protein. Similar antibodies appear to block infection in animals. Recent studies also suggest that some animals can produce antibodies to components of B. anthracis spores. Those antibodies, when studied in a test tube, prevent spores from germinating and increase their uptake by the immune system’s microbe-eating cells. These discoveries suggest that scientists might be able to develop a vaccine to fight both B. anthracis cells and spores.

Researchers also are studying how the immune system responds to B. anthracis infection. Part of the immune system response, known as adaptive immunity, consists of B and T cells that specifically recognize components of the anthrax bacterium. The other type of immune response—innate immunity—aims more generally to combat a wide range of microbial invaders and likely plays a key role in the body’s front-line defenses. Scientists are conducting studies of how those two arms of the immune system act to counter infection, including how B. anthracis spore germination affects individual immune responses.

In another study, NIAID-supported scientists have discovered a potential target for developing new measures to prevent and treat anthrax toxicity. Their study shows that a human gene called LRP6 plays a role in the delivery of anthrax toxins into cells. Antibodies directed against LRP6 protected cell cultures from anthrax lethal toxin. These results suggest that targeting LRP6 may prove useful in developing ways to protect against the effects of accumulated toxin.
Vaccine

NIAID is supporting research on next-generation anthrax vaccines designed to prevent infection using fewer doses than the currently licensed vaccine. The new vaccines, called recombinant protective antigen, or rPA vaccines, are based on the gene for just one anthrax toxin. These vaccines have been tested in rabbits and monkeys and have completed two phases of clinical trials in humans. The rPA vaccines appear to produce an effective immune response in people with intact immune systems. In general, the goal is to make rPA vaccines that are safer, more reliable, can be produced in large quantities, and may also be given to people with compromised immune systems.
Diagnostics

Research is under way to develop improved techniques for spotting B. anthracis in the environment and diagnosing it in infected individuals. As mentioned previously, a key part of that research is the functional genomic analysis of the bacterium, which should lead to new genetic markers for sensitive and rapid identification. Genomic analysis will also reveal differences in individual B. anthracis strains that may affect how those bacteria cause disease or respond to treatment.
Therapies

Following the discoveries of how the protective antigen and lethal factor proteins interact with cells, researchers are screening thousands of small molecules in hopes of finding an anti-anthrax drug. In addition, NIAID is working with FDA, CDC, and the Department of Defense to accelerate testing of collections of compounds for their effectiveness against inhalational anthrax. Many of those compounds already have been approved by FDA for other conditions and therefore could quickly be approved for use in treating anthrax, should they prove effective.

NIAID is also seeking new drugs that attack B. anthracis at different levels. These include agents that prevent the bacterium from attaching to cells, compounds that inhibit spore germination, and inhibitors that block the activity of key enzymes such as anthrax lethal factor. NIAID also will develop the capacity to synthesize promising anti-anthrax compounds in sufficient purity and quantity for preclinical testing.

NIAID-supported scientists have solved the structure of enzymes called sortases, which are known to anchor bacterial surface proteins to the cell walls. These enzymes may be essential to bacterial survival, and therefore could be an attractive potential target for therapies.

Scientists have designed a compound that blocks anthrax toxins from attaching to receptors on the surface of host cells in animal models. If the toxin cannot attach to and enter the cell, it is effectively neutralized. The new inhibitor is much more potent than current therapies and shows promise against some antibiotic-resistant strains as well. The general concept could also be applied to designing inhibitors for other pathogens.

Researchers have also found that human monoclonal antibodies protect against inhalation anthrax in three animal models. New anthrax therapies, such as monoclonal and polyclonal antibodies that can neutralize anthrax toxins, are being further developed.