The Rise of Vector - Borne Diseases

The Rise of Vector- Borne Diseases By: Max Schochet It’s something out of a scary Hollywood movie. Insects carrying deadly diseases threatening the world’s public health. Vector-borne diseases or VDB’s have increased significantly over the years, causing more than 700,000 deaths annually. VDBs are transmitted to humans through insect bites (called vectors) that carry the diseasecausing pathogens. Vectors include mosquitoes, ticks and flies and here in Massachusetts there is` a growing and alarming problem.

“This is actually a serious issue,” says Dr. Catherine Brown, State Epidemiologist and State Public Health Veterinarian at the Massachusetts Department of Public Health.

Illnesses from mosquito, tick, and flea bites have more than tripled from 2004 to 2016, according to the Centers for Disease Control and Prevention (CDC).

Why is it happening The exact reason for the spread of vector-borne diseases is not completely clear but experts say there are two main contributing factors; climate change and suburbanization.

“Climate change has altered the natural environment and longstanding ecological relationships,” says Kate Fowler, Press Officer with Center for Disease Control and Prevention (CDC).

“Since vector-borne diseases have strong environmental links, we expect that changes in seasonality and location may occur. We don’t know what those changes will be, but we know that climate is only one of several very important factors that influence the distribution and occurrence of vector-borne diseases.”

In Massachusetts, changes in climate are having a major impact on mosquito borne diseases in including West Nile Virus and Eastern Equine Encephalitis also known as Triple E. “We know that mosquitos carrying West Nile virus tend to increase when the temperatures are warmer than average,” says Dr. Brown, adding that significant rain events separated by droughts in hotter temperatures increase the population of mosquitoes that spread West Nile Virus.

Tick-borne diseases are skyrocketing and some experts say at epidemic proportions. In 2017, state and local health departments reported a record number of cases to CDC. Massachusetts is one of the states with the most reported cases of tick-borne diseases. Counties in the state have the highest rates of Lyme Diseases in the US. But unlike mosquitoes, diseases carried by ticks spread differently.

“The increases that we've seen in the diseases carried by that black legged tick over the last 20, 30 years (in Massachusetts) is probably due to changes in land use patterns that have impacted the animal population that the ticks feed off of,” says Dr. Brown.

Another key driver to the tick surge in the northeast, is the reforestation of land that used to be farmland.

“Suburban development in these areas has increased the spread of these germs because people, ticks, deer, and tick hosts such as mice and chipmunks are in close contact,” says Fowler.

The new threat But as bad as these diseases are, there is another threat, as new even more dangerous diseases are emerging.

“I think one place where we can say climate change probably really is going to have an impact is with the introduction of new species of vectors,” says Dr. Brown.

Powassan virus, which is carried by the black legged tick, can cause brain swelling, meningitis, encephalitis and death in a short amount of time. Although this disease is rare, there have been reported cases in Southeastern Massachusetts.

26-year-old Tucker Lane knows about Powassan all too well. In 2014, he was out in his backyard in West Barnstable, when he noticed two ticks on his hip. Lane who grew up on Cape Cod had been around ticks his entire life. He removed the two ticks as he normally would.

“I really didn’t think much about it,” said Lane.

A short time later, he developed a headache that continued to get worse. He also experienced hot and cold sweats, nausea, blurry vision and shortness of breath. Lane drove to a hospital, but doctors couldn’t figure out what was wrong with him.

“They accused me of abusing opioids and gave me Narcan,” said Lane.

Lane eventually got worse. He lost consciousness and was not breathing. The local hospital rushed him to Brigham and Women’s Hospital in Boston. With 48 hours, Lane was in a coma.

“My brain functions were to the point that they didn't think I was gonna live or not have brain damage,” he said.

The one-week later Lane woke up from his coma. He survived and recovered from near death.

It wasn’t until his follow up visit to the doctor, he got a shocking diagnosis, Powassan Virus.

“When I left the hospital, I had to learn to walk and eat again.”

"His cognition was very altered," recalled Dr. Jennifer Lyons, director of neurological infections and inflammatory diseases at Brigham & Women's Hospital in Boston, in a WCVB web article. " "There are very few medications that we have to treat viruses, in general," she said. "And for Powassan virus, specifically, we have no specific antidote."

According to the CDC Powassan Virus has a 10-15 percent fatality rate and long-term sequelae can occur in approximately 50% of patients. A Powassan infection can occur in just 15 minutes, significantly shorter than the 36 to 48 hours it can take for Lyme.

Lane was one of the lucky ones. He has no long-term side effects from Powassan Virus.

“Doctor’s say it was a miracle,” said Lane.

Emerging diseases are a huge concern globally, nationwide and in Massachusetts. The Lone Star Tick is another species from the southeastern region of the U.S. gradually moving toward the northeast.

“Warming temperatures are probably allowing that the population of that species to move northward. But we also have a turkey population explosion and so now there's more food for that type of tick to feed off of so the populations are growing,” says Dr. Brown.

Lone Star cause of host of diseases like ehrlichiosis (a bacterial illness that causes flu-like symptoms), tularemia (a rare infectious disease that attacks the skin, eyes, lymph nodes and lungs), Heartland virus disease (symptoms include headache, nausea, diarrhea, and muscle or joint pain). and southern tick-associated rash illness (STARI). It can also cause an allergy to red meat.

“This tick has a painful bite and causes severe inflammation which is why if exposed to this tick bite it has severe ramifications,” said Dr. Goudarz Molaei, a Connecticut Agricultural Station research scientist quoted in an article published by NBC CT last year.

Experts say to expect more of the Lone Star ticks in Massachusetts. Dr. Stephen Rich, the director of the Laboratory of Medical Zoology at UMass Amherst where they have been collecting ticks in Massachusetts since 2006 said there was a significant increase in a 2016.

In a 2016 article by the Lowell Sun, Dr. Rich said that in roughly 10 years his lab has been collecting ticks, 81 Lone Stars have been found -- 70 since April 2014.

And ticks are not just a warm weather problem. They seem to be active all year round.

“They are evolving and deepening the ability to survive in temperatures cooler than where it originally came from,” says Dr. Brown.

The Asian Tiger Mosquito which comes from southeast Asia is also traveling northward and is now in Massachusetts. This aggressive mosquito can transmit harmful diseases like Zika virus, West Nile Virus, Dengue Fever and Chikungunya fever, a debilitating joint disease, with outbreaks already reported in Asia, Africa and Italy.

The Asian Tiger Mosquito is active all year long and has been adapting to cooler, temperate regions, where they hibernate over winter. Mosquito eggs can survive in colder temperatures. They can even tolerate snow, temperatures below freezing and can be seen in the winter.

So, how do we stop this onslaught of vector-borne diseases?

“If I knew that, I would retire by and the very wealthy,” says Dr. Brown.

“Unfortunately our ability to control populations is actually pretty limited. There's a lot of research going on right now aimed specifically at that issue. But there is is no solution. She adds.”

Dr. Brown says that there are just so many disease carrying insects, that there's no way to get enough pesticide chemicals saturated into the environment all at once to kill everything.

“I mean it's just not possible. Wouldn't it be advisable either on many levels. But you know there would likely be unintended consequences to that,” she says.

But experts agree knowledge, awareness and prevention are the keys to keeping us safe.

Prevention and solutions Before going outdoors, where protective clothing. · Use a chemical repellent with DEET, permethrin or picaridin · Another option are essential oils or oil of lemon eucalyptus · Wear light-colored protective clothing. · Tuck pant legs into socks. · Avoid tick-infested areas

Know how to spot a tick.

Ticks are different sizes and the smallest one can be the size of a poppy seed.

A single tick will progress through four stages of development including egg, larva, nymph, and adult. The nymph tick is most active in the spring through the summer months.

Check for ticks on your clothing and on your entire body.

Be sure to check under the arms, in and around the ears and inside the belly button.

Check all around your head, skull and hair. Finally check your waist, groin area and between your toes. Make sure you shower soon after being outdoors.

If you find a tick, carefully remove it with a tweezer.

Here are the recommended steps on How to remove a tick from the CDC: 1. Use fine-tipped tweezers to grasp the tick as close to the skin’s surface as possible.

2. Pull upward with steady, even pressure. Don’t twist or jerk the tick; this can cause the mouth-parts to break off and remain in the skin. If this happens, remove the mouth-parts with tweezers. If you are unable to remove the mouth easily with clean tweezers, leave it alone and let the skin heal.

3. After removing the tick, thoroughly clean the bite area and your hands with rubbing alcohol or soap and water.

4. Never crush a tick with your fingers. Dispose of a live tick by putting it in alcohol, placing it in a sealed bag/container, wrapping it tightly in tape, or flushing it down the toilet.

Know the symptoms: Symptoms will vary depending upon the type of insect that has bitten you. Common symptoms of tick- borne diseases may include: · fever · chills · headache · sore muscles · skin rash · nausea · a red spot or rash near the site · pain or swelling near the site bite · A full body rash Common treatment for Lyme Disease are antibiotics.

To prevent mosquitos: Use insect repellent. · DEET · Picaridin (known as KBR 3023 and icaridin outside the US) · IR3535 · Oil of lemon eucalyptus (OLE) · Para-menthane-diol (PMD) · 2-undecanone Dump out any standing water near your home.

Stay indoors during dusk and dawn.

Reversing the trend of vector-borne diseases is a major challenge. There are some vaccinations for diseases like yellow fever, Japanese encephalitis, tick-borne encephalitis, tularemia, plague, but they are not widely used.

Vaccine prospects for major vector-borne diseases are not good. With the exception of malaria, few other vectorborne diseases have funding for vaccine research. Innovative tools to tackle vector-borne diseases are much needed.