Hantavirus, who's at risk?

The Centers for Disease Control (CDC) recently announced that up to 10,000 people who visited Yosemite National Park this summer were at risk for developing an infection caused by Hantavirus.  Most of these potential victims stayed in the Park’s tent-cabins that, unbeknownst to Park authorities, had been infested with mice that carry the potentially fatal virus.  Since the span of time from exposure to development of symptoms can take as long as 5 weeks, those who may have been exposed were warned to watch carefully for symptoms and to see their doctors at the first sign of infection.

Hantavirus may be carried by several species of rodents including the deer mouse, the white-footed mouse, the rice rat, and the cotton rat.  The virus causes no harm to the host rodent but if contracted by humans can cause a deadly disease called Hantavirus pulmonary syndrome (HPS).  Initially identified in the “4-corners” region of the American southwest, Hantavirus has now been reported in more than 24 states in the continental United States, Canada, and South America.

Most often, Hantavirus infections develop in humans after they have inhaled the virus following disturbance of an infected mouse’s nest or when urine or droppings containing the virus are stirred up and released into the air.  Direct transmission after touching contaminated nesting materials or droppings and then touching eye, nose, or mouth can also occur.

Who’s at risk:  Hantavirus infections can occur in anyone who comes in contact with contaminated mouse droppings, urine, saliva, or nesting materials.  Activities that place someone at particular risk include:

• Living or sleeping in houses or outbuildings that are infested with mice or rats infected with the Hantavirus.  This is particularly true if the structure has been closed for a period of time.
  
• Using mice-infested trail shelters or the tent-cabins such as those at Yosemite National Park, when camping or hiking.
  
• Housekeeping that involves cleaning up mice droppings.  This may be a problem particularly in the winter when mice tend to seek shelter indoors.  Vacuuming dropping or nesting materials is not recommended since this could release the virus into the air.
  
• Working in mouse infested areas, such as crawl spaces, attics, basements, or between walls of the house.  Plumbers, utility workers, and pest-control personnel may be at particular risk while working in these areas.

What are the symptoms of a Hantavirus infection?  Symptoms typically develop between 1 and 5 weeks following exposure to the virus. Initially, people manifest flu-like symptoms, including fever, muscle aches, vomiting and diarrhea.  This can progress rapidly to HPS that causes cough, extreme shortness of breath, and shock (circulatory collapse).  In its most severe form, HPS progresses to kidney failure and death.

How are Hantavirus infections diagnosed?  Since the onset of HPS can develop fairly quickly, it is important to see your doctor if you think that you could be infected.  Flu-like symptoms, along with a history of exposure to potentially infected rodents, should alert the doctor to the possibility of this infection.  In addition to a physical exam checking particularly for lung involvement, laboratory testing including a complete blood count (looking especially at the number and type of infection-fighting white blood cells), kidney and liver function tests, and an x-ray of the chest are typically done.  Confirmation of a Hantavirus infection can be done by looking for antibodies to the virus or with a special test known as polymerase chain reaction (PCR).

Can Hantavirus infections be cured?  Not always, in fact, up to 50% of people with HPS die.  Current treatment is primarily supportive in nature by providing intravenous fluids, oxygen, and if necessary, mechanical breathing.  With certain complications of HPS, an anti-viral medication known as ribavirin may be used, although it has not been shown to be effective in all cases.

Prevention of Hantavirus infections: The CDC has offered the following recommendations for people to help avoid contracting this infection:

• When opening an unused cabin, shed, or other building, open all the doors and windows, leave the building, and allow the space to air out for 30 minutes.
  
• Return to the building and spray the surfaces, carpet, and other areas with a disinfectant.  Leave the building for another 30 minutes.
  
• Spray mouse nests and droppings with a 10% solution of chlorine bleach or similar disinfectant. Allow it to sit for 30 minutes.  Using rubber gloves, place the materials in plastic bags.  Seal the bags and throw them in the trash or an incinerator. Dispose of gloves and cleaning materials in the same way.
  
• Wash all potentially contaminated hard surfaces with a bleach or disinfectant solution.  Avoid vacuuming until the area has been thoroughly decontaminated.  Then, vacuum the first few times with enough ventilation.  Surgical masks may provide some protection.

For a complete rundown of ways and measures for avoiding mouse or rat infestations including how to keeping mice out of your home, how to safely trap and remove mice, and how to clean up mouse nest and droppings, go to the CDC’s website for more information.

Back-to-School Backpacks

Backpacks have become the most popular means for school age children to carry their books and school supplies.  And in fact, when used correctly, a properly designed backpack is an excellent way to carry the necessities of the school day.  Unfortunately, thousands of children each year experience back pain related to use of school backpacks that are too heavy or used incorrectly.  It appears that public awareness of backpack related back injuries has helped to reduce its incidence.  With the start of the new school year, however, it is worth offering a reminder to parents and children of ways to prevent these from occurring.

Choose the right backpack - Be sure that the backpack is the appropriate size for the child. A well-designed backpack will include wide, padded straps to reduce strain on the shoulders and spine.  A chest (sternum) strap and waist belt will help distribute the load over the entire trunk.  Some of the best ergonomically designed backpacks are made by companies that specialize in equipment for hiking (Jan Sport, Osprey, North Face, etc.).  Additionally, salespersons in outdoor specialty shops can be helpful in making sure that the backpack fits appropriately.  Straps that compress the contents of the backpack will stabilize the load and keep it closer to the back.  If carrying heavy loads is unavoidable, a convertible backpack with wheels may be a consideration.  Reflective material to enhance visibility is an important safety feature for children who walk at dusk or after dark.

Wear the backpack properly - A proper fitting backpack rests evenly in the middle of the back, rather than hanging below the level of the lower back or waist.  Both shoulder straps should be used rather than just one.  Shifting the weight of the backpack to one side by using only one strap alters back symmetry, which can lead to neck and back strain.  This advice also applies to backpacks that are designed with only one strap that crosses the front of the body.  When walking a significant distant, encourage your children to use the chest and sternum strap.

Avoid overloading - Most experts recommend that children carry no more than 15% of their body weight in their packs.  For a 50 pound child, this would mean that the backpack and its contents should not weigh more than 7.5 pounds.  This amount would double to 15 pounds for a 100 pound child.  One way of gauging this is to weigh the child with and without the backpack on the bathroom scales.  More weight than this can cause compression of the discs that serve as cushions between the bones of the spine and cause excessive curvature of the spine.  Studies have shown that the amount of back pain reported by children increases along with the load in the backpack.  Parents can help to reduce the weight in their child's backpack by seeing that only those items needed for the school day are packed.  Unnecessary books or items (cell phones, music devices, video games, etc.) should be left at home.

Consider alternatives -  Whenever possible, children should use lockers or their desks during the school day to minimize the load carried in the backpack during the school day.  If there is an option, purchase paperback, rather than hard-bound books in order to decrease the weight of the books that are being carried.  Only those textbooks that are needed for completing homework should be brought home in the backpack.  If unavoidable due to the number or weight of required textbooks, a second set could be purchased for use at home.

Back pain in children should not be ignored.  Since backpack-related back pain is so common, however, parents should consider this as a possible explanation for their child's problem.  A few of the symptoms or signs that could indicate that a backpack may be responsible for the child's pain include:

•  Back pain that is present when wearing a backpack but goes away when removed.
  
•  Excessive back curvature or alteration of posture when wearing a backpack
  
•  Numbness or tingling affecting the arms or legs
  
• Struggling due to excessive weight when putting on or removing the backpack.

Following the recommendations for proper use of the backpack will, in many cases, take care of the problem.  Back pain in children deserves medical attention if it persists despite these measures, inhibits normal activities, requires regular medication, or affects sleep habits.

Avoiding West Nile Virus Disease

Over the past decade, the incidence of West Nile virus disease (WNV) was highest in 2006 when 4269 cases were reported with 177 deaths attributed to this illness.  This year, a total of 693 cases of WNV have been reported to the Centers for Disease Control (CDC), resulting in 26 deaths.  While these numbers are lower than in 2006, it's important to know that the number of cases of WNV reported so far this year is the highest reported through the second week of August.  Almost certainly, we can expect to see more infections and deaths from this potentially preventable disease.  Let's take a closer look at this  illness and measures that can protect you and your family.

How do humans contract this illness?  Most often, WNV is spread by the bite of a mosquito that has fed on an infected bird.  Over 300 species of birds have been found to be infected with the West Nile virus including common songbirds, crows, blackbirds, bluejays, doves, and pigeons.  Once a bird becomes infected, a mosquito can then transfer the virus from the bird's blood stream to humans, setting the stage for the infection.  In a very small number of cases, WNV also has been spread through blood transfusions, organ transplants, breastfeeding and even during pregnancy from mother to baby.

What Are the Symptoms of WNV?  Four out of five individuals who are infected with WNV will have no symptoms at all.  Twenty percent of those infected will develop West Nile Fever which is characterized by mild fever, headache, and body aches, nausea, vomiting, swollen lymph glands and/or a skin rash on the chest, stomach and back.  Less than 1% of those infected will develop a serious form of the disease associated with inflammation of the brain and spinal cord.  This is known as West Nile Encephalitis or West Nile Meningitis.  Symptoms of these include severe headache, high fever, neck stiffness, stupor, disorientation, coma, tremors, convulsions, muscle weakness, and paralysis.

How is WNV Infection Treated?  As with most viral illnesses, there is no specific treatment available for WNV infection.  Fortunately, most people recover from the illness in a few days to weeks without complications.  In the more serious cases, hospitalization is usually required for supportive treatment such as intravenous fluids and assistance with breathing.  In these individuals long-term problems may develop such as seizures, memory loss, personality changes, paralysis, tremors, and walking or balance problems. As previously noted, in a small percentage of cases, the infection can be fatal.

What can be done to Prevent WNV?  There is no vaccine available to prevent WNV.  Simply stated, the best way to prevent WNV is to avoid mosquito bites.  This does not mean that you or your family should not go outside for the entire summer, but that you should consider taking the following precautions to avoid being bitten by mosquitoes:

• When outdoors, use an insect repellent that contains an EPA-approved active ingredient such as DEET, Picaridin, IR3535, and Oil of Lemon Eucalyptus.
  
• Since mosquitoes are most active at dusk and dawn, along with using a repellent, consider wearing long sleeves and pants during these times.
  
• Be sure that your window and door screens are intact.
  
• Remove sources of standing water around the home that serve as mosquito breeding sites.

Are insect repellants safe to use?  DEET and Picaridin are considered to be "conventional repellents", derived from chemical sources.  Oil of Lemon Eucalyptus (PMD) and IR3535 (e.g. Avon Skin-So-Soft with IR3535) come from natural materials and are classified by the EPA as "biopesticide repellents".  Any of these products will provide safe and effective protection against mosquito bites when used according to labeled instructions.  The EPA has provided the following instruction when using insect repellents:

• Follow the label directions to ensure proper use.
  
• Repellents should be applied only to exposed skin and/or clothing. Do not use under clothing.
  
• Store insect repellents safely out of the reach of children.
  
• Do not apply near eyes and mouth, and apply sparingly around ears.
  
• When using sprays, do not spray directly into face; spray on hands first and then apply to face.
  
• Never use repellents over cuts, wounds, or irritated skin.
  
• Do not spray in enclosed areas. Avoid breathing a spray product, and do not use it near food.
  
• When using on children, apply to your own hands and then put it on the child.
  
• After returning indoors, wash treated skin and clothes with soap and water.

The CDC reports that as of this week, 43 states have seen WNV in people, birds, or mosquitoes.  Most of the infections affecting humans have occurred in three states---Texas, Mississippi, and Oklahoma.  Since the incidence of WNV peaks in late August and September, we appear to be on pace for a record year.  By taking the measures described above, the risk of being bitten by mosquitoes and exposed to the West Nile can be significantly reduced.