Dangerous 'Kissing' Bug Marches North in US - Medscape

Dangerous 'Kissing' Bug Marches North in US - Medscape
CDC: Vile 'Kissing Bugs' Appear to Be Moving North - The Weather Channel
Finding 'sweet spot' when deworming cattle - Beef Magazine

Posted: 29 Apr 2019 11:02 AM PDT

The CDC's recent report about a "kissing bug" identified in Delaware for the first time has sparked concerns as the potentially deadly bug marches its way north from Latin America through the Carolinas and beyond. Kissing bugs carry a parasite that causes Chagas disease, which can lead to serious heart and stomach problems.

So are we in for a summer invasion of these bloodsucking insects that are far from romantic?

Probably not, says kissing bug expert Rachel Curtis-Robles, PhD, a post-doctoral researcher and epidemiologist at Texas A&M University in College Station. Kissing bugs are nothing new. Eleven different species of the bugs — known as triatomine bugs — are in the U.S., the CDC says. And 28 states have reported them, the Texas A&M research team says. The bugs are also typically found in Mexico, Central America, and South America.

It's not the bug itself that causes the disease, but a parasite it may carry.

About 300,000 people with Chagas disease live in the U.S., but most were infected in parts of Latin America where the disease is most common. The likelihood of getting the infection in the United States is low, even if the bug is infected, the CDC says.

The news is a good reminder, experts agree, that people should be aware of the bug, what to do if bitten, and how to lessen the risk.

More on Kissing Bugs

Kissing bugs don't actually kiss. They got their nickname because they tend to bite people around the mouth or another part of the face, Curtis-Robles says. They are nocturnal, and your face is often the only body part exposed during sleep.

"They are attracted to the carbon dioxide we all breathe out," says Sarah Gunter, PhD, an assistant professor of pediatrics and Chagas disease researcher at the National School of Tropical Medicine, Baylor College of Medicine in Houston. And they are looking for blood as their meal.

But it's not the bite itself that transmits the parasite.

Here's the super-disgusting part: The bug bites and then defecates. "The parasite is in the feces," Gunter says. "If the feces from an infected insect gets into the wound, that is when we see an infection."

Transmission usually happens when a person accidentally rubs the feces into the bite wound or into a mucous membrane such as the eye or the mouth, the CDC says.

Identifying the bugs isn't simple, since there are a lot of look-alikes. Most species in the U.S. are mainly black or very dark brown, Curtis-Robles says. They have red, orange, or yellow "stripes" around their edges, thin antennae, and legs and a cone-shaped head.

Complicating the issue, most people don't report feeling a bite, Curtis-Robles says. Kissing bugs hang out indoors or out, preferring cracks and holes in older housing. Outdoors, they live beneath porches, in brush piles, or in rodent nests, outdoor dog houses, or chicken coops.

Possible Symptoms

Not everyone has symptoms. Some people have an allergic reaction to the saliva of the bug, the CDC says. They may have itching, swelling, hives, and severe redness.

There may be swelling if the parasite gets into the body through the skin or mucous membranes. Or it could cause swelling around the eye.

The infection eventually gets to the bloodstream, and it can affect the cells of the heart and digestive tract. "About one-third of people infected go on to the chronic form of the disease," Gunter says.

Complications of chronic Chagas disease may include heart rhythm problems that can cause sudden death, an enlarged heart that doesn't pump blood well, and an enlarged esophagus or colon that can cause problems with eating or passing stool.

"If someone is worried about being infected, they should first talk to their physician," Curtis-Robles says. A doctor can request blood tests to see if antibodies to the parasite are present. If infected, a patient may see an infectious disease specialist or a heart doctor for treatment with anti-parasitic drugs.

The bugs can also bite dogs, and they can get the same heart issues as people, but in a shorter timeline, Gunter says.

Happy Ending in Delaware

The insect found in Delaware, which had bitten a child as she watched television at night in her bedroom in July 2018, was sent to the CDC, which confirmed it was a kissing bug but found it negative for the parasite. The girl had no ill effects, according to a CDC report published April 19.

SOURCES:

Sarah Gunter, PhD, assistant professor of pediatrics and Chagas disease researcher, National School of Tropical Medicine, Baylor College of Medicine, Houston.

Rachel Curtis-Robles, PhD, post-doctoral researcher, epidemiologist, and co-founder of the Kissing Bug Citizen Science Program, Texas A&M University, College Station.

CDC: Morbidity & Mortality Weekly Report, April 19, 2019.

CDC: "Parasites — American Trypanosomiasis (also known as Chagas Disease)."

CDC: Vile 'Kissing Bugs' Appear to Be Moving North - The Weather Channel

Posted: 26 Apr 2019 11:30 AM PDT

CDC: 'Kissing Bugs' Might Be Spreading North

Twenty-nine states have reported encounters with Triatomine bugs, also known as 'kissing bugs.'
They get their name for their propensity to bite humans on the face and lips.
They can transmit a parasitic disease known as Chagas, which can lead to cardiovascular and gastrointestinal complications.

A disease-carrying-blood-sucking insect known as a "kissing bug" has spread to 29 states, including the latest sighting in Delaware, the Centers for Disease Control and Prevention reported last week.

The parents of a family in Delaware sought out the CDC in July 2018 to help identify a bug that had bitten their daughter while she was watching TV in her bedroom. The agency later identified the bug as Triatoma sanguisuga from a photo sent in by the family. It was the first reported encounter of a kissing bug in the state of Delaware, according to the CDC.

Typically found in warm climates in Asia, Africa, Australia, Latin America and the southern United States, Triatomine bugs, also known as cone-nosed bugs, vampire bugs, assassin bugs and blood suckers, are about twice the size of a penny and gets its name for its propensity for biting humans on their faces and lips.

There is documentation of kissing bugs in many states in records dating to the 1800s, according Texas A&M researchers. They are most common in the U.S. in New Mexico, Arizona and Texas.

Mostly active at night, the kissing bug feeds on the blood of mammals, bird and reptiles. They live in a wide variety of environmental settings but typically in the proximity of an animal upon which they can feed, the CDC reports. They also can be found in wooded areas, beneath porches, under cement, between rocky structures, in outdoor dog houses or kennels, in rock, wood and brush piles or beneath bark.

Twenty-nine states have reported sightings or encounters with 'kissing bugs.'

(CDC)

The bug can transmit a parasite known as Trypanosoma cruzi, which can lead to Chagas disease, a parasitic illness that can cause serious cardiac and gastrointestinal complications, Petty said,

While kissing bugs carrying Chagas disease is common in South and Central America, most types native to North America carry less risk of this disease, according to Western Exterminator.

The first case of Chagas disease in the United States was reported in 1955, Petty said.

Roughly 300,000 people with Chagas disease live in the U.S. today, mostly contracted from the Triatoma cruzi variety of kissing bug and mostly after being infected while living or traveling to parts of Central and South America.

The disease is transmitted through the bug's feces. If it defecates near an open bite, the infected feces can then be accidentally rubbed into the open wound. It can also infect humans via mucus membranes, including the eyes, nose or mouth.

Very few cases of Chagas disease contracted after being bitten in the U.S. have been documented. The aforementioned Delaware girl did not develop any symptoms of the disease, the CDC reported.

Petty said the likelihood of contracting the disease, even after being bitten by an infected bug, is unlikely.

"There are some areas in the United States where some triatomines are infected, but even in these areas, the likelihood of human Trypanosoma cruzi infection from contact with a triatomine bug in the United States is low," she told weather.com.

Early symptoms of Trypanosoma cruzi infection may include fever, fatigue, body aches, headache, rash, loss of appetite, diarrhea and vomiting. Since the symptoms mimic many other illnesses, it can be difficult to detect.

"If you suspect you have Chagas disease, consult your health-care provider. Or, to find a physician familiar with diagnosis and treatment of Chagas disease and other parasitic infections, ask your general practitioner or primary care physician for a referral," Petty said.

"You may also wish to consider visiting a physician who specializes in infectious diseases. To locate a clinician in your area, please visit the American Society of Tropical Medicine and Hygiene's Clinical Consultants Directory," she added.

Petty says preventive measures for travelers to Latin America include spraying infested dwellings with long-lasting insecticides, using bed nets treated with long-lasting insecticides, wearing protective clothing and applying insect repellent to exposed skin.

"Travelers should observe food and beverage precautions and avoid consuming salads, uncooked vegetables, unpeeled fruits and unpasteurized fruit juices," Petty added.

The CDC also recommends these precautions, which could limit exposure to humans and pets from kissing bugs in the United States:

Locate outdoor lights away from the home, dog kennels, chicken coops, and turn them off when not in use.
Remove trash, wood and rock piles from around the home.
Clear out any bird and animal nests around the home.
Seal cracks and gaps around windows, air conditioners, wall, roofs, doors and crawl spaces.
Tightly seal chimney flues when not in use.
Utilize screens that are on doors and windows.
Keep pets indoors at night and keep outdoor pet areas clean.
Consider having a licensed pest control professional inspect your home.
Do not squish or touch a suspected triatomine bug.
Instead, place it in a container and fill it with rubbing alcohol or freeze it before taking it to the health department.

It is unclear why the bugs appear to be moving north. Jacqueline Petty of the CDC told weather.com the bugs may have been in the north all along but increased awareness awareness about the bugs and about Chagas disease may have resulted in "an increase of bugs recognized or thought to be triatomines."

Finding 'sweet spot' when deworming cattle - Beef Magazine

Posted: 01 Apr 2019 12:00 AM PDT

Deworming cattle is easy, often providing significant economic return for relatively little cost.

Deworming cattle effectively and sustainably, though, is more complex than many believe. That has plenty to do with the apparent growing resistance of common internal cattle parasites to dewormers (anthelmintics).

Common parasites include Ostertagia ostertagi, which impact both young and mature animals. Cooperia sp. and Haemonchus placei are common calf parasites.

The three main classes of dewormer are macrocyclic lactones, benzimidazoles and imidazothiazoles.

There is no national statistic for anthelmintic resistance in beef cattle in the United States. However, various analyses, such as fecal worm egg count reduction trials, suggest growing parasite resistance to common anthelmintic classes. Globally, resistance is recognized as a key threat to grazing livestock.

"Anthelmintic resistance has been a recognized problem in small ruminants for decades. Now, there is increasing concern about resistance of cattle parasites to dewormers and the ability of cattlemen to continue to have cost-effective parasite control," explains Christine Navarre, DVM, Extension veterinarian at Louisiana State University.

This graphic shows how refugia, or drug-sensitive parasites, can be maintained in a herd. The presence of some drug-sensitive parasites decreases (dilutes) the proportion of resistant parasites within the parasite population on a ranch or farm. Graphic courtesy of FDA Center for Veterinary Medicine.

"Worldwide, there is documented anthelmintic resistance to all commercially available products in all of the important livestock parasites. But, the extent of the resistance in cattle varies from country to country and from ranch to ranch."

Test for resistance, and Navarre bets most cow-calf producers will find it in their herds; it's just a matter of how much. She's referring to the fecal egg count reduction test (FECRT), which helps determine efficacy for recent deworming treatments and provides the ability to estimate resistance.

"For $100, give or take, you can get some really good information," Navarre says. "It helps you to see where you are and how much of a resistance issue you have.

Plan your attack

"You've got to have this information to arm yourself in developing a plan … The key to parasite control is to deworm often enough, and at the right time, to minimize the economic impacts, while at the same time preventing the development of anthelmintic resistance," she says.

That's where it gets complicated, and why developing and executing a parasite control plan should be done with a producer's veterinarian.

Every operation and set of cattle is different. Effective plans will differ based on such things as cattle age, purpose and type.

"Many factors, including rainfall, environmental temperatures, pasture type, grazing management, age and immune status of animals, previous product use and anthelmintic resistance patterns all determine the severity of parasite problems on an individual ranch in a given year," Navarre says. "A unique parasite control program must be developed for each."

Never mind nutrition and overall herd immunity. As Navarre emphasizes, parasite control is just one part of a comprehensive herd health plan.

Even with testing, she cautions that diagnosing anthelmintic resistance can be difficult.

"This is a very complex and serious issue, and claims of resistance should not be made in haste or with very little evidence to support them. Conversely, if resistance is occurring, it needs to be documented," Navarre says.

"Resistance is often suspected when poor performance or clinical signs of parasitism don't improve following deworming. This can be caused by several things and should not be immediately interpreted as a failure of the anthelmintic product," she adds.

Simple things like guessing the weight of cattle for dosage, improper application, or figuring that stuff gathering dust on the back shelf is still good can all derail the intended outcome. In some cases, such misuse also contributes to resistance.

Then there's the parasite population left alone by deworming — referred to as refugia. Navarre says refugia are a key contributor to slowing down resistance, but likely for the exact opposite reason logic might suggest.

Leave some parasites to fight

"Refugia is the portion of the parasite population that is not selected by drug treatment; worms in refugia have a genetic makeup that make them susceptible to an anthelmintic," Navarre says. "The more refugia in a population, the more the resistance genes in a population are diluted, and the more effective the anthelmintic will be."

The notion of refugia is relatively new for some. In simpler and inexact terms, she says it's akin to leaving enough non-resistant parasites to breed with the resistant ones, thus slowing the progress of resistance.

Refugia can be on pastures. So, pasture type and management, as well as treatment timing, affect refugia.

"Historically, we have exploited those times of extreme heat or cold when Ostertagia larva cannot survive on pasture, and most of the total parasite burden is in the animal as hypobiotic larvae," Navarre explains.

"Deworming at this strategic time with products effective against inhibited larval stages can greatly decrease the overall parasite burden in a herd. However, it is a very effective way of eliminating refugia and may lead to resistance problems long term," she adds.

Similarly, Navarre notes that pasture rotation can control parasites, at least theoretically. But the timing of rotations is variable, depending on stocking density, age of cattle, time of year, recent rainfall and all of the rest. "Rotate pastures to maximize nutrition and pasture use, not to control parasites," she says.

Refugia can be maintained in the animals, too, by leaving some untreated. There is no cookie cutter for deciding which ones. It's ranch-specific and depends on myriad factors, including cattle age and purpose and results of the FECRT.

If it's a cow herd in the Gulf States, for example, Navarre says one approach to maintaining refugia is to leave the adult cattle untreated. Cattle up to 2 years old are commonly most susceptible to parasitic infection.

Conversely, the answer will be different for replacement heifers grazing permanent pasture.

Again, it goes back to developing a plan based on data provided by testing — at least for cattle remaining in the same operation. There's little to be gained from testing for a stocker operation bringing in calves from multiple sources and grazing them across the same pastures.

In that case, Navarre suggests a starting point is leaving 10% untreated. Based on limited economic research, she says the heaviest calves are the logical choice for the untreated group.

"The quickest way to get widespread anthelmintic resistance is to deworm an entire group of cattle and then put them on a clean pasture," Navarre says. "We have no refugia left on pasture, and we eliminate refugia in the animals. The only parasites left in the animals are resistant.

"When they reproduce, they will contaminate the pasture with an almost pure population of resistant parasites. There are no refugia on pasture to dilute the resistant worms," she explains.

One more thing when deworming: Navarre says two different classes of dewormer should be used at the same time. Also known as concurrent deworming, it boosts the odds of killing more resistant parasites, slowing resistance.

"But this must be in combination with a refugia program or you will be selecting for pure populations of multidrug resistant 'superworms,' " she says.

"Cattlemen should work with their veterinarian to find a balance between keeping overall parasite levels low enough to prevent economic losses, while at the same time retaining some refugia to slow the progression of anthelmintic resistance," Navarre emphasizes.

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