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Researchers Fear Spread of Canine Vector-Borne Diseases

May 10, 2011 | 11,486 views
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Sick Cocker SpanielAt the Bayer Animal Health-sponsored 6th Canine Vector Borne World Forum held recently in France, researchers called for greater awareness of canine vector borne diseases (CVBD) and the danger they pose to both animals and humans.

The vectors that transmit these diseases are parasites such as fleas, flies, mosquitoes and ticks.

Per Veterinary Practice News:

“A number of the CVBDs cause real suffering and even death in dogs, and many CVBDs represent a zoonotic risk,” said Dwight Bowman, Ph.D., a professor of parasitology at Cornell University’s College of Veterinary Medicine. “It’s vital that veterinarians and pet owners everywhere understand the seriousness of the threats posed, and take action to prevent transmission of these diseases.”

Attendees of the forum are concerned serious diseases like Tick-Borne Encephalitis (TBE) are being underestimated and underreported. TBE is an example of a potentially life-threatening infection that has moved beyond its usual geographical boundaries into Europe and Asia.

Because CVBDs are spreading into new regions of the world, forum attendees feel veterinarians should consider testing for rare or exotic infections during diagnosis of sick animals.

Dr. Becker's Comments:

Being aware and informed of the existence of diseases like Tick-Borne Encephalitis and other CVBDs is a good thing.

In my experience, experts in parasitology like those present at the 6th Canine Vector Borne World Forum are earnest in their desire to bring attention to diseases many of us have never heard of or been concerned about.

Being aware and informed, however, shouldn’t lead to an overreaction in terms of protecting your dog or yourself from exotic or rare vector borne infections. And a full understanding of the situation must encompass some knowledge of who sponsors events like the forum in France.

Bayer Animal Health, backer of the parasite conference, is a pharmaceutical giant. This company is in the business of making and selling chemical parasite preventives and other drugs.

Drug companies are very aware of how consumers react to news of, for example, the spread of a scary, exotic disease. And as luck would have it, they often have drugs for sale that help prevent or treat the symptoms of that very disease.

Let’s take a closer look at the three CVB diseases mentioned in the Veterinary Practice News article:

  • Tick-borne encephalitis (TBE)
  • Babesiosis
  • Leishmaniasis.

Tick-Borne Encephalitis (TBE)

TBE is a human virus of the central nervous system which most often appears as meningitis (inflammation of the membrane around the brain and spinal cord), encephalitis (inflammation of the brain) or meningoencephalitis (inflammation of both the brain and meninges).

The disease is transmitted by ticks. The primary hosts are rodents; humans are ‘accidental’ hosts. Most infections occur between April and November (high tick activity months). It’s also possible to become infected by drinking raw milk from cows, goats or sheep.

Person-to-person transmission is extremely rare, occurring through either blood transfusion or breastfeeding. Transmission from infected mother to fetus has occurred.

After exposure from a tick bite, it takes from seven to 14 days for symptoms to appear (less time after milk-borne transmission). Signs of infection can include:

  • Fever
  • Loss of appetite
  • Headache and muscle aches
  • Nausea and/or vomiting
  • General feeling of malaise

In about 20 to 30 percent of those infected, a week or so after initial symptoms subside, a second phase of the disease presents with central nervous system-related symptoms characteristic of meningitis, encephalitis, or meningoencephalitis. TBE is more severe in adults than in children, with the highest incidence in people over 50.

Permanent neuropsychiatric damage from TBE occurs in 10 to 20 percent of people with the infection. Fatalities are rare (one to two percent of sufferers), with death occurring five to seven days after development of neurologic symptoms.

TBE is a significant problem in many areas of Europe, the former Soviet Union, and Asia. The disease is underreported, with several thousand cases reported each year.

According to the CDC:

Over the last 30 years, the geographic range of TBEV and the number of reported TBE cases have increased significantly. These trends are likely due to a complex combination of changes in the ecology and climate, increased human activity in affected areas, and increased recognition.

The CDC’s assessment of risk to travelers:

  • The overall risk of acquiring TBE for an unvaccinated visitor to an endemic area during the TBEV transmission season has been estimated at 1 case per 10,000 person-months of exposure.
  • Most TBEV infections result from tick bites acquired in forested areas through activities such as camping, hiking, fishing, bicycling; collecting mushrooms, berries, or flowers; and outdoor occupations such as forestry or military training. The risk is negligible for persons who remain in urban or unforested areas and who do not consume unpasteurized dairy products.

Babesiosis

Babesiosis disease is transmitted by ticks and is found worldwide, with most cases reported along coastal areas in the northeastern U.S. The disease is often present with only mild or no symptoms, so it’s difficult to assess the true incidence of infection.

For the majority of people infected with babesiosis, the disease is mild. However, according to the National Institute of Allergy and Infectious Diseases, it has the potential to be very serious and even fatal, particularly in the elderly, those without a spleen, organ transplant patients and people with suppressed immune systems.

Babesiosis is typically transmitted to humans through the bite of an infected deer tick – the same tick that transmits Lyme disease.

There are usually no symptoms of infection, but when they do occur, it is within one to four weeks after transmission. Illness can last for several weeks and can include:

  • Fatigue and weakness
  • Headache; muscle aches
  • Chills and fever; sweating
  • Nausea and vomiting

According to the CDC, because Babesia parasites destroy red blood cells, babesiosis can cause hemolytic anemia, a type of anemia that can lead to dark-colored urine and jaundice.

When babesiosis is serious, symptoms include:

  • Severe breathing problems and acute respiratory distress syndrome
  • Low blood pressure
  • Heart problems
  • Kidney failure

Canine Babesiosis

Babesia infections also occur in dogs. Young dogs suffer more serious symptoms, and Greyhounds, Pit Bull Terriers and American Staffordshire Terriers appear to the most susceptible breeds.

Just as with people, a babesiosis infection can have very mild or no symptoms or it can be very serious. Severity depends on the species of Babesia parasite involved and on the dog’s immune system. U.S. babesia strains appear to cause a milder form of the disease than species found elsewhere in the world.

Canine babesiosis symptoms may come and go as the disease runs its course, and can include:

  • Pale gums and tongue
  • Fever
  • Weakness; lethargy
  • Orange or red urine
  • Jaundice
  • Enlarged lymph nodes; enlarged spleen

A severe infection can affect multiple organ systems like the lungs, GI tract, kidneys and the nervous system.

Diagnosis of the canine form of babesiosis is challenging, and drugs to treat the infection are not always effective and carry serious side effects. In many cases, drug treatment may relieve symptoms but not clear the parasite from the dog’s system. The dog remains infected and the infection can flare up during periods of stress or immune system imbalance.

Leishmaniasis

Leishmaniasis is caused by the bite of the sand fly. Despite what the name implies, sand flies aren’t found on the beach, but in gardens, around homes out in the country, in parks and wooded areas.

Sand fly distribution in the U.S. is unknown, however, we do know the flies are most active between dusk and dawn.

There are two primary forms of the disease in people:

  • Cutaneous leishmaniasis affects the skin and mucus membranes, usually starting at the site of the sandfly bite.
  • Visceral leishmaniasis, also known as the systemic form of the disease, affects the entire body. It presents from two to eight months after a sandfly bite, and in fact, most people don’t remember they even had a bite or skin sore. This is the more serious form of the disease – it causes damage to the immune system and can lead to life-threatening complications.

Leishmaniasis has been reported on every continent except Antarctica and Australia. Closest to the U.S., cases have been reported in South America, Mexico, and in military personnel returning from the Persian Gulf.

According to the CDC:

The distribution is world-wide, but 90% of visceral leishmaniasis cases occur in India, Bangladesh, Nepal, Sudan, Ethiopia and Brazil, while 90% of cutaneous leishmaniasis cases occur in Afghanistan, Algeria, Iran, Saudi Arabia, Syria, Brazil, Colombia, Peru and Bolivia.

Symptoms of cutaneous leishmaniasis may include:

  • Skin sores and ulcers
  • Ulcers on the gums, tongue, lips, nose and inside the nose
  • Stuffy and running nose; nosebleeds
  • Difficulty breathing
  • Difficulty swallowing

The visceral form of infection affects children and adults differently.

Adults usually run a fever for anywhere from two weeks to two months, and experience feelings of fatigue, weakness and loss of appetite. Children infected with the disease normally have sudden onset vomiting, diarrhea, fever and a cough.

Other symptoms can include:

  • Abdominal discomfort
  • Night sweats
  • Skin changes like scaling and darkening
  • Hair loss
  • Weight loss

Canine Visceral Leishmaniasis

The visceral form of this disease can be very serious and often fatal when it infects our canine companions.

Most dogs are infected by the bite of a sandfly. Very rarely, a healthy dog can acquire the disease after close contact with an infected dog, or puppies of an infected mother can be born with it.

Dogs that acquire leishmaniasis may never develop symptoms, or they may have symptoms that come and go, including:

  • Chronic weight loss; severe muscle atrophy
  • Conjunctivitis and other eye abnormalities (anterior uveitis, retinitis, ocular lesions)
  • Loss of hair on the face
  • Swollen lymph nodes
  • Polyarthritis

If the infection is severe and systemic, additional symptoms can include skin lesions, epistaxis (severe bleeding from the nose), anemia, swollen joints and limbs, lameness and renal failure.

According to the Companion Animal Parasite Council (CAPC), prevalence and geographic distribution of the disease is as follows:

  • Leishmania infantum/chagasi is endemic in much of the Mediterranean basin (e.g., Italy, Spain and Portugal), the Balkans, central and southwest Asia, north and northwest China, north and sub-Saharan Africa, and parts of Central and South America.
  • Visceral leishmaniasis is occasionally diagnosed in the United States in dogs of any breed imported from southern Europe or South America where the infection is endemic.
  • Since the 1980s, locally acquired infection has been reported in kenneled foxhounds, and infection is now recognized in foxhounds from many eastern U.S. states and Canadian provinces.

Just as leishmaniasis a more serious disease in dogs, it is also more resistant to treatment than human infection, and relapses are common

To date, there is no drug that consistently cures the disease in canines. Certain drugs can suppress and sometimes cure the infection.

Safe Parasite Prevention Measures for Your Dog

Fleas, ticks and other parasites are attracted first to unhealthy animals. One of the most important things you can do to make your dog unappealing to bugs is to keep her optimally healthy.

  • A high quality, species-appropriate diet is the foundation upon which your pet’s good health and long life must be built.
  • In addition, you now have a safe, natural alternative to chemical pest preventives – Natural Flea and Tick Defense. For more information, view my recent video to learn just how special and effective this
  • Natural, food-grade diatomaceous earth helps to remove parasites from your pet’s body. Never apply the powder to the face or near the eyes.
  • Fresh garlic can be given to dogs to prevent internal as well as external parasites. Work with your holistic vet to determine a safe amount for your pet’s body weight.

Another common sense step to reduce or eliminate exposure to parasites is to steer clear of tick-infested areas, perform tick checks on your dog often (daily or more often if necessary), and if you’re in a region where leishmaniasis is endemic you’ll want to remain indoors between dusk and dawn when sand flies are most active.

Hopefully after reading this information you have a better understanding of three somewhat exotic canine vector borne diseases.

You now know their prevalence among both humans and dogs, the conditions under which you and your pet are most likely to pick up one of these infections, and steps you can take to prevent exposure to a CVBD.

[+] Sources and References

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