Mosquito-borne Viral Disease in the U.S.

Most people are aware of the spread of the mosquito-borne viral disease, Zika, in many countries in South and Central America.  Worldwide, the most important disease transmitted by mosquitos is malaria.  Instead of being caused by a virus, however, malaria is caused by a parasite that infects the Anopheles mosquito. The World Health Organization (WHO) reports that 214 million cases of malaria occurred in 2015 with 438,000 deaths attributed to the disease.  The disease is passed on from a malaria-infected person to the next person via the mosquito bite.
 
The most common mosquito-borne viral disease globally is Dengue fever.  In 2015, nearly 2.4 million cases of this viral illness were reported by the WHO.  Both of these infections occur more commonly in tropical regions of the world. In the U.S., we are fortunate that local exposure to malaria has essentially been eliminated, and with the exception of a few cases affecting U.S. citizens living in topical settings such as Hawaii and Puerto Rico, nearly all dengue cases reported in the U.S. are acquired elsewhere by travelers or immigrants.

As of July 13^th of this year, the U.S. Centers for Disease Control (CDC) reports that there have been no locally acquired cases of Zika virus disease in the U.S. There have been, however, 1,305 travel-associated cases of this disease reported by the CDC in the U.S. since January 1, 2015. Infection with the Zika virus is usually quite mild.  A serious concern, however, is the link between a Zika virus infection in a pregnant woman and the development of microcephaly in newborns, a congenital defect of cranium and brain size resulting in profound neurological defects.

The most prevalent mosquito-borne diseases that develop from mosquito bites occurring in the U.S. include West Nile virus disease, Eastern Equine Encephalitis, Japanese encephalitis, and St. Louis encephalitis.

West Nile Virus Disease (WNVD) is primarily 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, blue jays, 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.  After reaching a peak at 9862 cases in 2003, the CDC reports that the number of cases appears to be decreasing.   Most people infected with West Nile virus will not have any symptoms. About 1 in 5 people who are infected will develop a fever and other symptoms. Less than 1% of those infected develop a serious, sometimes fatal, neurologic illness.

Eastern equine encephalitis (EEE) Most persons infected with the eastern equine encephalitis virus have no apparent illness with an average of 8 people per year developing a severe form involving inflammation of the brain (encephalitis).  Most cases have occurred in the Atlantic and Gulf Coast states.  Symptoms of EEE begin with the sudden onset of headache, high fever, chills, and vomiting. The illness may then progress into disorientation, seizures, or coma. EEE is one of the most severe mosquito-transmitted diseases in the United States with an approximately 33% mortality rate.

La Crosse encephalitis (LACV) causes inflammation of the brain (encephaltitis) in approximately 80 to 100 people in the U.S. each year. Most LACV infections, however, are much less severe.  Most cases of this disease have been reported from upper Midwestern, mid-Atlantic and southeastern states. Like the other illnesses being discussed, the risk for developing LACV is highest for people who live, work or recreate in woodland habitats, because of greater exposure to potentially infected mosquitoes.

St. Louis encephalitis virus infection primarily affects individuals living in eastern and central U.S. As with the other viral infections discussed, most people infected with this virus have no apparent illness. Severe neurological disease (often involving encephalitis, an inflammation of the brain) occurs more commonly in older adults. In rare cases, long-term disability or death can result. There is no specific treatment for SLEV infection; care is based on symptoms.

From the descriptions of these mosquito-borne viral illnesses affecting U.S. residents, several similarities become apparent: 

• Most people have no symptoms or are only mildly symptomatic.
• When symptoms do occur they are often similar in nature with headache, fever, chills, nausea, vomiting predominating.  
• A very small percentage of those infected will develop a more severe form of the disease, usually resulting in a brain infection (encephalitis) which is sometimes fatal.
• There is no specific treatment available for these infections.  Severe illnesses are treated by supportive therapy which may include hospitalization, respiratory support, IV fluids, and prevention of other infections.
• With the exception of a vaccine against the Japanese encephalitis virus (not typically given in the U.S.), immunizations are not available for these viral diseases.  
• Prevention measures for these illnesses center around avoiding mosquito bites
  • 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.

Sources for article:
West Nile Virus from the Centers for Disease Control and Prevention
Eastern Equine Encephalitis from the Centers for Disease Control and Prevention
Saint Louis Encephalitis from the Centers for Disease Control and Prevention
La Crosse Encephalitis from the Centers for Disease Control and Prevention

Avoiding "Picnic Poisoning"

Summertime is the perfect time of year for outdoor cookouts and picnics.  Unfortunately, food safety features that a home kitchen provides, such as temperature-controlled cooking, refrigeration, and washing facilities, are not always available when cooking or picnicking outdoors. This increases the risk of food poisoning, more accurately known as acute gastroenteritis. The most common causes for this are undercooking, spoilage or cross-contamination of food that is being prepared.  Let's look at some ways of minimizing these risks.

When shopping for picnicking foods:

• Shop last for foods that should remain cold, such as meats and poultry. The least amount of time spent in the shopping basket, the better. 
• To avoid contaminating other foods in the basket from meat juices place meat items in a separate bag.
•  If it will take a while to get the food into a refrigerator, you may want to take meats or perishables home in a cooler with ice.
• Once home, place perishables in the refrigerator right away.  If you are using cloth shopping bags, be sure and wash them regularly.

When prepping food for the picnic:

• Clean fresh fruits and vegetables under running water at home prior to packing for the picnic.
• Thaw frozen food in the refrigerator rather than at room temperature.
• Perishable foods should be transported in coolers with plenty of ice or cold packs to maintain a temperature of 40 degrees F or below.
• Consider using separate coolers for perishable foods and beverages.  The cooler with perishable food should be opened as infrequently as possible.

Prior to preparing food at the picnic site: 

• Wash hands, work areas, and utensils before preparing food.  You may even need to rewash your hands or utensils during food preparation if they come in contact with the uncooked food or juices. 
• If soap and water are not available, use a liquid hand sanitizer. Have plenty of clean utensils and platters available so that you avoid using the same platter and utensils for raw and cooked meats.

To assure that meats are cooked adequately (from the U.S. Food and Drug Administration):    

• Cook steaks, chops or roasts of beef, pork, lamb or veal to a minimum internal temperature of 145 °F as measured with a food thermometer before removing meat from the heat source. For safety and quality, allow meat to rest for at least three minutes before carving or consuming. For reasons of personal preference, consumers may choose to cook meat to higher temperatures.
• Cook all raw ground beef, pork, lamb, and veal to an internal temperature of 160 °F as measured with a food thermometer.
• Cook all poultry to a safe minimum internal temperature of 165 °F as measured with a food thermometer.

When serving food at the picnic:

• Don't put cooked food on the same platter that held raw meat or poultry. Any harmful bacteria present in the raw meat juices could contaminate safely cooked food.
• Foods like chicken salad (or anything containing mayonnaise) and desserts that include cream or other dairy products should be kept cold in a refrigerator or cooler until serving. Many dishes can be placed directly on ice, or in a shallow container set in a deep pan filled with ice on the serving table.
• Perishable food that sat out for longer than 2 hours (or less if the temperature is above 90 degrees) should be discarded.
• Grilled food can be kept hot until served by moving it to the side of the grill rack, away from the flame where it can overcook. When taking food off the grill, use a clean platter.

For many people, summertime is synonymous with cooking in the outdoors. Make sure to follow these simple rules for healthy and enjoyable outdoor dining.

Sources for article:
Eating Outdoors, Handling Food Safely from the U.S. Food and Drug Administration
Perfect Food Safe Picnics! from Foodsafety.gov

Is something lurking in our recreational water?

This summer, reports have emerged of a woman who died following an infection with "brain-eating" amoeba contracted while rafting at the U.S. National Whitewater Center in North Carolina and a man who contracted "flesh eating" bacteria after swimming in the Gulf of Mexico. What are these infections and how great a concern are they for the average person enjoying an outing on a lake, river or at the beach?

"Brain-eating" Amoeba

The scientific name for the organism commonly referred to as the "brain-eating" amoeba is Naegleria fowleri. Naegleria is a single-celled living organism that is commonly found in warm, fresh water lakes and rivers, particularly in the southern U.S. Rarely, Naegleria has been responsible for causing a brain infection called amoebic meningoencephalitis. Most cases appear to develop after water contaminated with the amoeba enters the nose while swimming or diving. There is currently no effective treatment for this infection and once it develops it is usually fatal. Fortunately, brain infections caused by Naegleria are very rare. In fact, in the 10 year period from 2006 to 2015 the Centers for Disease Control have reported only 37 cases in the U.S. Chlorine kills this amoeba so swimming in an adequately disinfected pool poses no risk of developing the infection. Since the organism does not live in salt water, there is no risk of developing this infection when swimming in the ocean.

"Flesh-eating" Infections:

The disease attributed to "flesh-eating" bacteria is known in medical terminology as necrotizing fasciitis. "Necrotizing" refers to the death of tissue. "Fasciitis" implies that the infection involves a deep layer of connective tissue (fascia) that surrounds muscles, nerves and blood vessels. No single strain of bacteria is designated as flesh-eating; instead this infection can be caused by several types of bacteria including Strep, Staph, and Vibrio. In most instances, infections with these organisms are relatively superficial and are not limb- or life-threatening. Fascia, however, is a deep tissue structure that is arranged in layers called "planes". Should the infection reach the fascia, rapid progression of the infection can occur as bacteria and the toxins that they produce spread between these fascial planes.

Most cases of necrotizing fasciitis begin with a break in the skin, such as a cut, puncture wound or surgical incision, that subsequently becomes infected. Having a condition that causes compromise of the immune system, such as diabetes, liver cirrhosis, or being on cancer chemotherapy increases the risk of developing this infection.
Necrotizing fasciitis is considered to be a rare disease that is not primarily contracted through exposure to contaminated recreational water. It is important, however, that any cut, scrape or puncture wound to the skin be cleaned thoroughly to avoid developing an infection. Also, you should avoid spending time in hot tubs, swimming pools, and natural bodies of water until infections are healed.

An even greater concern:

Symptoms suggesting the development of either of these conditions warrants immediate medical attention. Meningoencephalitis symptoms include headache, fever, nausea, vomiting, stiff neck, and confusion. The initial signs and symptoms of necrotizing fasciitis include pain, redness, and swelling at the site of the infection along with fever. In regard to concerns that swimming in natural bodies of water is hazardous, be aware that an even more serious concern is the risk of drowning. In the 10 year period between 2001 and 2010, there were over 34,000 drowning deaths in the U.S. The number of cases of "brain-eating" amoeba and "flesh-eating" bacteria infections associated with swimming in lakes, rivers and the ocean combined are only a small fraction of this number.

Sources for this article:

Necrotizing Fasciitis (Flesh-Eating Disease) from MedicineNet.com

Necrotizing Fasciitis: A Rare Disease, Especially for the Healthy from the Centers for Disease Control

Naegleria fowleri —Amebic Encephalitis from the Centers for Disease Control

Kent Davidson MD - Health Tip Content Editor
Reviewed and Approved by Charles W. Smith MD, Medical Director on 7-13-2016

Newer options for treating Type 2 Diabetes

The American Diabetes Association reports that in 2012, 29.1 million Americans, or 9.3% of the population, had diabetes. The great majority of these have Type 2 Diabetes (T2D), previously known as "adult onset" diabetes. Most people know that T2D is a metabolic disorder that is characterized by high blood sugar due to a relative lack of insulin, a hormone secreted by the pancreas that helps to regulate the level of glucose (sugar) in the body. In most cases, the initial treatment of T2D involves lifestyle measures such as weight reduction, healthy eating, and getting regular exercise.  

When these measures are insufficient to bring the hemoglobin A1C (a test that provides an average of blood sugar control over 2-3 months) into an acceptable range, the next step in treatment is usually taking a medication. Classes of medications that have been successfully used in treating T2D for a number of years include biguanides (metformin), sulfonylureas (DiaBeta, Glucotrol, Amaryl, others), thiazolidinediones (Avandia, Actos, others), and insulin.
 
Most authorities agree that of these, metformin is the best initial choice for treating TD2.  It works by increasing the body's sensitivity to insulin so that the reduced amount of insulin in the body is used more effectively.  Metformin is relatively inexpensive and is the only medication for diabetes shown in studies to reduce mortality and complications of the disease.

If A1C levels remain too high after several months of therapy, a second and sometimes a third medication is added. This medication could be from one of the previously mentioned classes drugs---sulfonylurea, thiazolidinedione, insulin----or could be one of the newer classes of drugs that have been developed to treat T2D.  In today's Health Tip, we'll look at several of the newer drugs developed for the treatment of T2D.  These go by the alphabet soup designation of:   SGLT2 inhibitors, GLP-1 receptor agonists, and DPP-4 inhibitors.

Sodium-glucose co-transporter 2 inhibitors (SGLT2)   This recently developed treatment for T2D works in a very clever way.  Under normal circumstances, the kidneys work to keep glucose, an important energy source for the body, in the blood stream instead of passing it into the urine. SGLT2 inhibitors (Invokana and Farxiga) allow a certain amount of glucose to pass into the urine, lowering blood glucose levels in the process. SGLT2 drugs do have the potential for causing side effects including urinary tract infections, genital yeast infections, and can lead to dehydration in someone taking a diuretic medication. Also, they are quite expensive, costing up to 400 dollars for a month's worth of medication.

Glucagon-like peptide 1 receptor agonists (GLP 1 RA)  This class of T2D medications includes the tradename products: Tanzeum, Trulicity, Byetta,  Bydureon, and Victoza.  They are all self-injectable, usually given once a day or once a week.  This class of drugs work by increasing insulin secretion and decreasing levels of a second hormone called glucagon. Glucagon normally has the opposite effect of insulin, raising blood sugar.  Beneficial effects of these medications include weight reduction, lowered blood pressure, and improvement in fat levels in the blood stream. The most common side effects with the GLP 1 RA class are nausea, vomiting, and diarrhea.  Like the other newer T2D drugs, these are quite expensive with one reported to cost up to 700 dollars per month.

Selective Dipeptidyl Peptidase-4 Inhibitors (DPP-4 Inhibitors)    Examples of DPP-4 inhibitors are sitagliptin (Januvia), saxagliptin (Onglyza) and linagliptin (Tradjenta). These drugs work by increasing levels of a hormone called incretin that signals the pancreas to release insulin. Like The SGLT2 drugs, they also inhibit the production of glucagon. Their effect on lowering A1C levels is fairly modest. They have been reported to cause severe inflammation of the pancreas (pancreatitis) and recently the U.S. Food and Drug Administration (FDA) warned that they may cause joint pain that can be severe and disabling.

As stressed in the Standards of Care in Diabetes from the American Diabetes Association, use of these and other medications for T2D should be individualized, taking into consideration the general health and underlying medical conditions of the person being treated.  They are most appropriately used after initiating treatment with metformin.  Since each class of drugs used to treat T2D has a different mechanism of action, this allows two, three and sometime four different drugs to be used together. At least for now the newer drugs represent a very expensive option in the treatment of T2D.  Less expensive medication options for treating T2D include metformin, sulfonylureas, and certain forms of insulin.  Even less expensive, and perhaps most important, are the life-style measures mentioned earlier in the article.

Sources for Article:
Type 2 Diabetes Treatment from Mayo Foundation for Medical Education and Research
GLP-1 receptor agonists: a review of head-to-head clinical studies from the National Library of Medicine
Management of Blood Glucose with Noninsulin Therapies in Type 2 Diabetes from the American Family Physician
Diabetes Management Guidelines from the National Diabetes Education Initiative

Kent Davidson MD - Health Tip Content Editor
Reviewed and Approved by Charles W. Smith MD, Medical Director on 7-6-2016