Progeria

Overview

Progeria (pro-JEER-e-uh), also known as Hutchinson-Gilford syndrome, is an extremely rare, progressive genetic disorder that causes children to age rapidly, starting in their first two years of life.

Children with progeria generally appear normal at birth. During the first year, signs and symptoms, such as slow growth and hair loss, begin to appear.

Heart problems or strokes are the eventual cause of death in most children with progeria. The average life expectancy for a child with progeria is about 13 years. Some with the disease may die younger and others may live longer, even up to 20 years.

There's no cure for progeria, but ongoing research shows some promise for treatment.

Symptoms

Usually within the first year of life, growth of a child with progeria slows markedly, but motor development and intelligence remain normal.

Signs and symptoms of this progressive disorder include a distinctive appearance:

• Slowed growth, with below-average height and weight
• Narrowed face, small lower jaw, thin lips and beaked nose
• Head disproportionately large for the face
• Prominent eyes and incomplete closure of the eyelids
• Hair loss, including eyelashes and eyebrows
• Thinning, spotty, wrinkled skin
• Visible veins
• High-pitched voice

Signs and symptoms also include health issues:

• Severe progressive heart and blood vessel (cardiovascular) disease
• Hardening and tightening of skin on the trunk and extremities (similar to scleroderma)
• Delayed and abnormal tooth formation
• Some hearing loss
• Loss of fat under the skin and loss of muscle mass
• Skeletal abnormalities and fragile bones
• Stiff joints
• Hip dislocation
• Insulin resistance

When to see a doctor

Progeria is usually detected in infancy or early childhood, often at regular checkups, when a baby first shows the characteristic signs of premature aging.

If you notice changes in your child that could be signs and symptoms of progeria, or you have any concerns about your child's growth or development, make an appointment with your child's doctor.

Causes

A single gene mutation is responsible for progeria. The gene, known as lamin A (LMNA), makes a protein necessary for holding the center (nucleus) of a cell together. When this gene has a defect (mutation), an abnormal form of the lamin A protein called progerin is produced and makes cells unstable. This appears to lead to progeria's aging process.

Unlike many genetic mutations, progeria is rarely passed down in families. The gene mutation is a rare, chance occurrence in the majority of cases.

Other similar syndromes

There are other progeroid syndromes that do run in families. These inherited syndromes cause rapid aging and a shortened life span:

• Wiedemann-Rautenstrauch syndrome, also known as neonatal progeroid syndrome, starts in the womb, with signs and symptoms of aging apparent at birth.
• Werner syndrome, also known as adult progeria, begins in the teen years or early adulthood, causing premature aging and conditions typical of old age, such as cataracts and diabetes.

Risk factors

There are no known factors, such as lifestyle or environmental issues, which increase the risk of having progeria or of giving birth to a child with progeria. Progeria is extremely rare. For parents who have had one child with progeria, the chances of having a second child with progeria are about 2 to 3 percent.

Complications

Children with progeria usually develop severe hardening of the arteries (atherosclerosis). This is a condition in which the walls of the arteries — blood vessels that carry nutrients and oxygen from the heart to the rest of the body — stiffen and thicken, often restricting blood flow.

Most children with progeria die of complications related to atherosclerosis, including:

• Problems with blood vessels that supply the heart (cardiovascular problems), resulting in heart attack and congestive heart failure
• Problems with blood vessels that supply the brain (cerebrovascular problems), resulting in stroke

Other health problems frequently associated with aging — such as arthritis, cataracts and increased cancer risk — typically do not develop as part of the course of progeria.

Diagnosis

Doctors may suspect progeria based on signs and symptoms characteristic of the syndrome. A genetic test for LMNA mutations can confirm the diagnosis of progeria.

A thorough physical exam of your child includes:

• Measuring height and weight
• Plotting measurements on a normal growth curve chart
• Testing hearing and vision
• Measuring vital signs, including blood pressure
• Looking for visible signs and symptoms that are typical of progeria

Don't hesitate to ask questions. Progeria is a very rare disease, and it's likely that your doctor will need to gather more information before determining next steps in caring for your child. Your questions and concerns can help your doctor develop a list of topics to investigate.

Treatment

There's no cure for progeria, but regular monitoring for heart and blood vessel (cardiovascular) disease may help with managing your child's condition.

During medical visits, your child's weight and height is measured and plotted on a chart of normal growth values. Additional regular evaluations, including electrocardiograms and dental, vision and hearing exams, may be recommended by your doctor to check for changes.

Certain therapies may ease or delay some of the signs and symptoms. Treatments depend on your child's condition and symptoms. These may include:

• Low-dose aspirin. A daily dose may help prevent heart attacks and stroke.
• Other medications. Depending on your child's condition, the doctor may prescribe other medications, such as statins to lower cholesterol, drugs to lower blood pressure, anticoagulants to help prevent blood clots, and medications to treat headaches and seizures.
• Physical and occupational therapy. These therapies may help with joint stiffness and hip problems to help your child remain active.
• Nutrition. Nutritious, high-calorie foods and supplements can help maintain adequate nutrition.
• Dental care. Dental problems are common in progeria. Consultation with a pediatric dentist experienced with progeria is recommended.

Potential future treatment

Current research seeks to understand progeria and identify new treatment options. Some areas of research include:

• Studying genes and the course of the disease to understand how it progresses. This may help identify new treatments.
• Studying ways to prevent heart and blood vessel disease.
• Performing human clinical trials using drugs known as farnesyltransferase inhibitors (FTIs), such as lonafarnib, which were developed for treating cancer, but may be effective for treatment of progeria by helping with weight gain and increased flexibility of blood vessels.
• Testing other drugs for treatment of progeria.

Lifestyle and home remedies

Here are some steps you can take at home to help your child:

• Make sure your child stays well-hydrated. Dehydration can be more serious in children with progeria. Be sure your child drinks plenty of water, especially during an illness, with activity or in hot weather.
• Provide frequent, small meals. Because nutrition and growth can be an issue for children with progeria, giving your child smaller meals more often may help increase calorie intake. Add healthy, high-calorie foods and snacks or supplements as needed.
• Provide opportunities for regular physical activity. Check with your child's doctor to learn which activities are appropriate for your child.
• Get cushioned shoes or shoe inserts for your child. The loss of body fat in the feet can cause discomfort.
• Use sunscreen. Use a broad-spectrum sunscreen with an SPF of at least 15. Apply sunscreen generously, and reapply every two hours — or more often if your child is swimming or perspiring.
• Make sure your child is up to date on childhood immunizations. A child with progeria isn't at increased risk of infection, but like all children, is at risk if exposed to infectious diseases.
• Provide learning and social opportunities. Progeria won't affect your child's intellect, so he or she can attend school at an age-appropriate level. Some adaptations for size and ability may be needed.
• Make adaptations. You may need to make some changes at home that enable your child to have some independence and to be comfortable. These can include household changes so that your child can reach items such as faucets or light switches, clothes with special closures or in special sizes, and extra padding for chairs and beds.

Coping and support

Learning that your child has progeria can be emotionally devastating. Suddenly you know that your child is facing many difficult challenges and a shortened life span. For you and your family, coping with the disorder involves a major commitment of physical, emotional and financial resources.

Some helpful resources include:

• Support network. Your health care team, family and friends can all be a valuable part of your support network. Also, ask your doctor about self-help groups or therapists in your community. Your local health department, public library and trustworthy sources on the internet may be helpful in finding resources.
• Support groups. In a support group, you'll be with people who are facing challenges similar to yours. If you can't find a progeria support group, you may be able to find a group for parents of children with chronic illness.
• Other families dealing with progeria. The Progeria Research Foundation may be able to help you connect with other families coping with progeria.
• Therapists. If a group isn't for you, talking to a therapist or clergy member may be beneficial.

Helping your child cope

If your child has progeria, he or she is also likely to increasingly feel different from others as the condition progresses. Over time, fear and grief will likely increase as awareness grows that progeria shortens life span. Your child will need your help coping with physical changes, special accommodations, other people's reactions and eventually the concept of death.

Your child may have difficult but important questions about his or her condition, spirituality and religion. Your child may also ask questions about what will happen in your family after he or she dies. Siblings may have these same questions.

For such conversations with your child:

• Ask your doctor, therapist or clergy member to help you prepare.
• Consider input or guidance from friends you meet through support groups who've shared this experience.
• Talk openly and honestly with your child and his or her siblings, and offer reassurance that's compatible with your belief system and appropriate to the child's age.
• Recognize when your child or his or her siblings might benefit from talking to a therapist or clergy member.

Preparing for your appointment

It's likely that your family doctor or your child's pediatrician will notice signs and symptoms of progeria during regular checkups. After evaluation, your child may be referred to a medical genetics specialist.

Here's some information to help you prepare for your appointment.

What you can do

To get ready for your appointment, make a list of:

• Any signs and symptoms your child has been experiencing, and for how long.
• Your child's key medical information, including recent illnesses, any medical conditions, and the names and dosages of any medications, vitamins, herbs or other supplements.
• Questions you want to ask the doctor.

Some basic questions to ask the doctor may include:

• What is likely causing my child's signs and symptoms?
• Are there any other possible causes?
• What kinds of tests does my child need?
• Are treatments available for this condition?
• What are the complications of this condition?
• Are my other children or family members at increased risk of this condition?
• Are there clinical trials underway for which my child may be eligible?
• Do you recommend that my child see a specialist?
• How can I find other families who are coping with this condition?

What to expect from your doctor

Your doctor is likely to ask you a number of questions. Be ready to answer them to reserve time to go over points you want to focus on.

• When did you first notice that something may be wrong?
• What signs and symptoms have you noticed?
• Has your child been diagnosed with any notable diseases or conditions? If so, what was the treatment?
• How is your family coping?

Alzheimer's disease

Overview

Alzheimer's disease is a progressive disorder that causes brain cells to waste away (degenerate) and die. Alzheimer's disease is the most common cause of dementia — a continuous decline in thinking, behavioral and social skills that disrupts a person's ability to function independently.

The early signs of the disease may be forgetting recent events or conversations. As the disease progresses, a person with Alzheimer's disease will develop severe memory impairment and lose the ability to carry out everyday tasks.

Current Alzheimer's disease medications may temporarily improve symptoms or slow the rate of decline. These treatments can sometimes help people with Alzheimer's disease maximize function and maintain independence for a time. Different programs and services can help support people with Alzheimer's disease and their caregivers.

There is no treatment that cures Alzheimer's disease or alters the disease process in the brain. In advanced stages of the disease, complications from severe loss of brain function — such as dehydration, malnutrition or infection — result in death.

Symptoms

Memory loss is the key symptom of Alzheimer's disease. An early sign of the disease is usually difficulty remembering recent events or conversations. As the disease progresses, memory impairments worsen and other symptoms develop.

At first, a person with Alzheimer's disease may be aware of having difficulty with remembering things and organizing thoughts. A family member or friend may be more likely to notice how the symptoms worsen.

Brain changes associated with Alzheimer's disease lead to growing trouble with:

Memory

Everyone has occasional memory lapses. It's normal to lose track of where you put your keys or forget the name of an acquaintance. But the memory loss associated with Alzheimer's disease persists and worsens, affecting the ability to function at work or at home.

People with Alzheimer's may:

• Repeat statements and questions over and over
• Forget conversations, appointments or events, and not remember them later
• Routinely misplace possessions, often putting them in illogical locations
• Get lost in familiar places
• Eventually forget the names of family members and everyday objects
• Have trouble finding the right words to identify objects, express thoughts or take part in conversations

Thinking and reasoning

Alzheimer's disease causes difficulty concentrating and thinking, especially about abstract concepts such as numbers.

Multitasking is especially difficult, and it may be challenging to manage finances, balance checkbooks and pay bills on time. These difficulties may progress to an inability to recognize and deal with numbers.

Making judgments and decisions

The ability to make reasonable decisions and judgments in everyday situations will decline. For example, a person may make poor or uncharacteristic choices in social interactions or wear clothes that are inappropriate for the weather. It may be more difficult to respond effectively to everyday problems, such as food burning on the stove or unexpected driving situations.

Planning and performing familiar tasks

Once-routine activities that require sequential steps, such as planning and cooking a meal or playing a favorite game, become a struggle as the disease progresses. Eventually, people with advanced Alzheimer's may forget how to perform basic tasks such as dressing and bathing.

Changes in personality and behavior

Brain changes that occur in Alzheimer's disease can affect moods and behaviors. Problems may include the following:

• Depression
• Apathy
• Social withdrawal
• Mood swings
• Distrust in others
• Irritability and aggressiveness
• Changes in sleeping habits
• Wandering
• Loss of inhibitions
• Delusions, such as believing something has been stolen

Preserved skills

Many important skills are preserved for longer periods even while symptoms worsen. Preserved skills may include reading or listening to books, telling stories and reminiscing, singing, listening to music, dancing, drawing, or doing crafts.

These skills may be preserved longer because they are controlled by parts of the brain affected later in the course of the disease.

When to see a doctor

A number of conditions, including treatable conditions, can result in memory loss or other dementia symptoms. If you are concerned about your memory or other thinking skills, talk to your doctor for a thorough assessment and diagnosis.

If you are concerned about thinking skills you observe in a family member or friend, talk about your concerns and ask about going together to a doctor's appointment.

Causes

Scientists believe that for most people, Alzheimer's disease is caused by a combination of genetic, lifestyle and environmental factors that affect the brain over time.

Less than 1 percent of the time, Alzheimer's is caused by specific genetic changes that virtually guarantee a person will develop the disease. These rare occurrences usually result in disease onset in middle age.

The exact causes of Alzheimer's disease aren't fully understood, but at its core are problems with brain proteins that fail to function normally, disrupt the work of brain cells (neurons) and unleash a series of toxic events. Neurons are damaged, lose connections to each other and eventually die.

The damage most often starts in the region of the brain that controls memory, but the process begins years before the first symptoms. The loss of neurons spreads in a somewhat predictable pattern to other regions of the brains. By the late stage of the disease, the brain has shrunk significantly.

Researchers are focused on the role of two proteins:

• Plaques. Beta-amyloid is a leftover fragment of a larger protein. When these fragments cluster together, they appear to have a toxic effect on neurons and to disrupt cell-to-cell communication. These clusters form larger deposits called amyloid plaques, which also include other cellular debris.
• Tangles. Tau proteins play a part in a neuron's internal support and transport system to carry nutrients and other essential materials. In Alzheimer's disease, tau proteins change shape and organize themselves into structures called neurofibrillary tangles. The tangles disrupt the transport system and are toxic to cells.

Risk factors

Age

Increasing age is the greatest known risk factor for Alzheimer's disease. Alzheimer's is not a part of normal aging, but as you grow older the likelihood of developing Alzheimer's disease increases.

One study, for example, found that annually there were two new diagnoses per 1,000 people ages 65 to 74, 11 new diagnoses per 1,000 people ages 75 to 84, and 37 new diagnoses per 1,000 people age 85 and older.

Family history and genetics

Your risk of developing Alzheimer's is somewhat higher if a first-degree relative — your parent or sibling — has the disease. Most genetic mechanisms of Alzheimer's among families remain largely unexplained, and the genetic factors are likely complex.

One better understood genetic factor is a form of the apolipoprotein E gene (APOE). A variation of the gene, APOE e4, increases the risk of Alzheimer's disease, but not everyone with this variation of the gene develops the disease.

Scientists have identified rare changes (mutations) in three genes that virtually guarantee a person who inherits one of them will develop Alzheimer's. But these mutations account for less than 1 percent of people with Alzheimer's disease.

Down syndrome

Many people with Down syndrome develop Alzheimer's disease. This is likely related to having three copies of chromosome 21 — and subsequently three copies of the gene for the protein that leads to the creation of beta-amyloid. Signs and symptoms of Alzheimer's tend to appear 10 to 20 years earlier in people with Down syndrome than they do for the general population.

Sex

There appears to be little difference in risk between men and women, but, overall, there are more women with the disease because they generally live longer than men.

Mild cognitive impairment

Mild cognitive impairment (MCI) is a decline in memory or other thinking skills that is greater than what would be expected for a person's age, but the decline doesn't prevent a person from functioning in social or work environments.

People who have MCI have a significant risk of developing dementia. When the primary MCI deficit is memory, the condition is more likely to progress to dementia due to Alzheimer's disease. A diagnosis of MCI enables the person to focus on healthy lifestyle changes, develop strategies to compensate for memory loss and schedule regular doctor appointments to monitor symptoms.

Past head trauma

People who've had a severe head trauma have a greater risk of Alzheimer's disease.

Poor sleep patterns

Research has shown that poor sleep patterns, such as difficulty falling asleep or staying asleep, are associated with an increased risk of Alzheimer's disease.

Lifestyle and heart health

Research has shown that the same risk factors associated with heart disease may also increase the risk of Alzheimer's disease. These include:

• Lack of exercise
• Obesity
• Smoking or exposure to secondhand smoke
• High blood pressure
• High cholesterol
• Poorly controlled type 2 diabetes

These factors can all be modified. Therefore, changing lifestyle habits can to some degree alter your risk. For example, regular exercise and a healthy low-fat diet rich in fruits and vegetables are associated with a decreased risk of developing Alzheimer's disease.

Lifelong learning and social engagement

Studies have found an association between lifelong involvement in mentally and socially stimulating activities and a reduced risk of Alzheimer's disease. Low education levels — less than a high school education — appear to be a risk factor for Alzheimer's disease.

Complications

Memory and language loss, impaired judgment, and other cognitive changes caused by Alzheimer's can complicate treatment for other health conditions. A person with Alzheimer's disease may not be able to:

• Communicate that he or she is experiencing pain — for example, from a dental problem
• Report symptoms of another illness
• Follow a prescribed treatment plan
• Notice or describe medication side effects

As Alzheimer's disease progresses to its last stages, brain changes begin to affect physical functions, such as swallowing, balance, and bowel and bladder control. These effects can increase vulnerability to additional health problems such as:

• Inhaling food or liquid into the lungs (aspiration)
• Pneumonia and other infections
• Falls
• Fractures
• Bedsores
• Malnutrition or dehydration

Prevention

Alzheimer's disease is not a preventable condition. However, a number of lifestyle risk factors for Alzheimer's can be modified. Evidence suggests that changes in diet, exercise and habits — steps to reduce the risk of cardiovascular disease — may also lower your risk of developing Alzheimer's disease and other disorders that cause dementia. Heart-healthy lifestyle choices that may reduce the risk of Alzheimer's include the following:

• Exercise regularly
• Eat a diet of fresh produce, healthy oils and foods low in saturated fat
• Follow treatment guidelines to manage high blood pressure, diabetes and high cholesterol
• If you smoke, ask your doctor for help to quit smoking

Studies have shown that preserved thinking skills later in life and a reduced risk of Alzheimer's disease are associated with participating in social events, reading, dancing, playing board games, creating art, playing an instrument, and other activities that require mental and social engagement.

Coronavirus

A new Chinese coronavirus, a cousin of the SARS virus, has infected hundreds since the outbreak began in Wuhan, China, in December. Scientist Leo Poon, who first decoded the virus, thinks it likely started in an animal and spread to humans.

"What we know is it causes pneumonia and then doesn't respond to antibiotic treatment, which is not surprising, but then in terms of mortality, SARS kills 10% of the individuals," Poon, a virologist at the School of Public Health at The University of Hong Kong, said.

It's not clear how deadly the Wuhan coronavirus will be, but fatality rates are currently lower than both MERS and SARS. Experts stress that it will change as the outbreak develops.

The World Health Organization offered guidance to countries on how they can prepare for it, including how to monitor for the sick and how to treat patients. Here's what you should know about coronaviruses.

What is a coronavirus

Coronaviruses are a large group of viruses that are common among animals. In rare cases, they are what scientists call zoonotic, meaning they can be transmitted from animals to humans, according to the US Centers for Disease Control and Prevention.

Coronavirus symptoms

The viruses can make people sick, usually with a mild to moderate upper respiratory tract illness, similar to a common cold. Coronavirus symptoms include a runny nose, cough, sore throat, possibly a headache and maybe a fever, which can last for a couple of days.

For those with a weakened immune system, the elderly and the very young, there's a chance the virus could cause a lower, and much more serious, respiratory tract illness like a pneumonia or bronchitis.

There are a handful of human coronaviruses that are known to be deadly.

Middle East respiratory syndrome, also known as the MERS virus, was first reported in the Middle East in 2012 and also causes respiratory problems, but those symptoms are much more severe. Three to four out of every 10 patients infected with MERS died, according to the CDC.

Severe acute respiratory syndrome, also known as SARS, is the other coronavirus that can cause more severe symptoms. First identified in the Guangdong province in southern China, according to the WHO, it causes respiratory problems but can also cause diarrhea, fatigue, shortness of breath, respiratory distress and kidney failure. Depending on the patient's age, the death rate with SARS ranged from 0-50% of the cases, with older people being the most vulnerable.

The Wuhan coronavirus is currently thought to be more mild than SARS and MERS and takes longer to develop symptoms. Patients to date have typically experienced a mild cough for a week followed by shortness of breath, causing them to visit the hospital, explains Peter Horby, professor of emerging infectious diseases and global health at the University of Oxford. So far, around 15% to 20% of cases have become severe, requiring, for example, ventilation in the hospital.

How it spreads

Viruses can spread from human contact with animals. Scientists think MERS started in camels, according to the WHO. With SARS, scientists suspected civet cats were to blame. Officials do not yet know what animal may have caused the current outbreak in Wuhan.

When it comes to human-to-human transmission of the viruses, often it happens when someone comes into contact with an infected person's secretions, such as droplets in a cough.

Depending on how virulent the virus is, a cough, sneeze or handshake could cause exposure. The virus can also be transmitted by touching something an infected person has touched and then touching your mouth, nose or eyes. Caregivers can sometimes be exposed by handling a patient's waste, according to the CDC.

Human-to-human transmission has been confirmed for the Wuhan coronavirus, but experts are now trying to understand who is transmitting it most, who is at most risk and whether transmission is occurring mostly in hospitals or in the community. SARS and MERS were largely transmitted inside hospitals, Horby said. Some people are also considered to be "superspreaders."

Who is affected?

MERS, SARS and the Wuhan coronavirus appear to cause more severe disease in older people, though uncertainty remains around the latest outbreak. Of the cases of Wuhan coronavirus reported so far, none are yet confirmed to be among children, Horby said. The average age is people 40 or over, he said.

Coronavirus treatment

There is no specific treatment, but research is underway. Most of the time, symptoms will go away on their own and experts advise seeking care early. If symptoms feel worse than a standard cold, see your doctor.

Doctors can relieve symptoms by prescribing a pain or fever medication. The CDC says a room humidifier or a hot shower can help with a sore throat or cough.

Drink plenty of fluids, get rest and sleep as much as possible.

Should you worry about the Wuhan coronavirus?

The Wuhan coronavirus fatality rate is lower than for SARS and MERS, but still comparable to the 1918 Spanish flu pandemic, explains Neil Ferguson, professor of mathematical biology at Imperial College London.

"It is a significant concern, globally," Ferguson says, noting that we don't fully understand the severity.

Ferguson believes the fatality rate is likely to be lower due to an "iceberg" of milder cases we are yet to find, but he highlights that novel viruses spread much faster through a population.

How can you can prevent it?

There is no vaccine to protect against this family of viruses, at least not yet. Trials for a MERS vaccine are underway. The US National Institutes of Health is working on a vaccine against the new virus, but it will be months until clinical trials get underway and more than a year until it might become available.

You may be able to reduce your risk of infection by avoiding people who are sick. Try to avoid touching your eyes, nose and mouth. Wash your hands often with soap and water and for at least 20 seconds.

Awareness is key. If you are sick and have reason to believe it may be the Wuhan coronavirus due to travel to the region or coming into contact with someone who has been there, you should let a health care provider know and seek treatment early.

Cover your mouth and nose when you cough or sneeze, and disinfect the objects and surfaces you touch.

If traveling to China, be aware of symptoms and avoid live animal markets, which is where the latest outbreak began in Wuhan.

Coronavirus and pregnancy

In pregnant women, the more severe versions of MERS and SARS coronaviruses can be serious. There are cases in which a woman infected with MERS had a stillbirth, a 2014 study showed.

SARS-associated illnesses were linked to cases of spontaneous abortion, maternal death and critical maternal illness, a 2004 study found.

Coronavirus and cats, dogs and other animals

Pets can catch coronaviruses and the infections can become severe. Sometimes the viruses can lead to deadly diseases. One can cause feline infectious peritonitis in cats and something called a pantropic canine coronavirus can infect cats and dogs, according to a 2011 study.

Cats can catch SARS, but none of the infected cats developed symptoms, according to the study. The feline coronavirus typically is asymptomatic, but can cause mild diarrhea. Feline infectious peritonitis, or FIP, can cause flu-like symptoms for a cat, but can also be more serious for cats and can cause organ failure, but it is not contagious and will not spread from animal to animal or person to person.

Pantropic canine coronavirus that can impact cats and dogs can be fatal to dogs, studies show.

These particular dog and cat viruses don't seem to spread to human