Archive for the ‘Transmission’ Category

Know Your Ticks

Know your ticks

Easy to read table shows the most common ticks found in the U.S. that transmit pathogens to humans.
Note: only a partial list. To learn more about tick-bite prevention and how to be Tick AWARE, click here

Click here to download the Tick Table

Tick Table

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Remember, in Wisconsin, ticks are found in every county in the state. Researchers are also finding them in bright, open, mowed lawns.

What is Powassan Virus?


what is powassan virus
The Powassan virus is a tick-borne illness transmitted by the same tick that harbors the Lyme disease bacterium. Although it is still considered rare, the number of cases is growing and if contracted the virus can have devastating and long-lasting effects.

In their article “Underrecognized Tickborne Illnesses: Borrelia Miyamotoi and Powassan Virus,”  Della-Giustina et al. explain what is the Powassan virus and why it’s raising concerns.  

“We chose to review the Powassan virus because it only requires 15 min. of tick attachment for transmission, and the sequelae of the neurologic disease are devastating, in addition to a 10% mortality rate.”¹

What is Powassan virus?

The Powassan virus (POW) is a tick-borne flavivirus that is related to other viruses including: dengue, yellow fever, West Nile encephalitis, and tick-borne encephalitis (primarily found in Europe). “Flaviviruses are a group of single stranded RNA viruses that cause severe endemic infection and epidemics on a global scale.”²

In recent years, other viruses transmitted by ticks have been identified including the Heartland virus (phlebovirus) and the Bourbon virus (thogotovirus).

POW is very similar genetically to the deer tick virus and the clinical presentations are identical.
How was it discovered?

Powassan was first discovered in the brain of a young child.

“Powassan virus is named for the Ontario, Canada, town where it was first isolated from the brain of a 5-year-old boy who died of severe encephalitis in 1958,” the authors write.

Where is it?

The second case was reported in New Jersey (1970) and then another in eastern Russia (1978). Although, there have been no reported cases in other countries, the virus has been identified in a growing number of states.

In 2019, 13 U.S. states reported cases: Connecticut, Indiana, Massachusetts, Maine, Minnesota, North Carolina, North Dakota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, and Wisconsin.

Ticks infected with Powassan virus can transmit the disease in only 15 minutes, causing long-lasting neurologic problems in some individuals, in addition to a 10% mortality rate.

How is the virus transmitted?

The Powassan virus is carried and transmitted by Ixodes scapularis ticks, also known as deer ticks or blacklegged ticks. These ticks can also transmit Borrelia burgdorferi, the bacteria which causes Lyme disease.

“Although many flaviviruses have mosquitos as competent vectors, there is no evidence of human POW virus disease transmitted by mosquitos,” the authors point out.

How fast can Powassan virus be transmitted?

Very fast. “Transmission in mice has been shown to occur within 15 min. of I. scapularis attachment,” the authors write.

This rapid transmission occurs because the virus is already present in the salivary glands, compared to other non-viral tick-borne diseases where the pathogen is typically harbored in the tick’s mid-gut.

What is the typical clinical presentation?

“Few people who become infected with the POW virus have clinically significant disease,” the authors write.

However, in some cases, “a Powassan infection can lead to disorientation, headache, neck stiffness, fever up to 40°C, clonus, ocular, and other motor palsies, obtundation and convulsions, and can mimic herpes simplex encephalitis.”

Can Powassan virus be serious?


“Approximately 50% of cases result in lasting hemiplegia, memory problems, and muscle wasting,” the authors explain.

“Ten percent of cases are fatal.”

Are there tests for it?

A PCR test is only positive in early stages of a Powassan infection. “IgG by enzyme-linked immunosorbent assay is the mainstay of diagnosis, but confirmation requires specialized testing,” write the authors.

Why are co-infections important?

Treatable tick-borne co-infections may be present. The authors describe a patient with a combination of Powassan encephalitis, Lyme carditis, and Babesia.

Yoon and colleagues described the case of a 17-year-old young man who died waiting for a Powassan virus test.³  He was not treated for a co-infection with Lyme disease. His autopsy showed Borrelia spirochetes, which cause Lyme disease, in his heart and liver. He also had PCR evidence of spirochetes in his brain and lungs.

What is the treatment for a Powassan infection?

There is no treatment for a Powassan virus infection other than supportive care.

  1. Della-Giustina D, Duke C, Goldflam K. Underrecognized Tickborne Illnesses: Borrelia Miyamotoi and Powassan Virus. Wilderness Environ Med. Jun 2021;32(2):240-246. doi:10.1016/j.wem.2021.01.005
  2. Chong HY, Leow CY, Abdul Majeed AB, Leow CH. Flavivirus infection-A review of immunopathogenesis, immunological response, and immunodiagnosis. Virus Res. 2019 Dec;274:197770. doi: 10.1016/j.virusres.2019.197770. Epub 2019 Oct 15. PMID: 31626874.
  3. Yoon EC, Vail E, Kleinman G, et al. Lyme disease: a case report of a 17-year-old male with fatal Lyme carditis. Cardiovasc Pathol. Sep-Oct 2015;24(5):317-21. doi:10.1016/j.carpath.2015.03.003



Regarding transmission time – ALL pathogens can reside in the salivary glands of ticks due to partial feeding, which will result in quicker transmission times, but this fact is continually downplayed:

It’s also important to note that minimum transmission times have NEVER been established:  Within this important letter, Lyme advocate Carl Tuttle shows rapid transmission has occurred in under 4 hours:

  1. Clinical evidence for rapid transmission of Lyme disease following a tick bite:
  2. B. Patmas, MA, Remora, C. Disseminated Lyme Disease After Short-Duration Tick Bite. JSTD 1994; 1:77-78:
  3. Lyme borreliosis: a review of data on transmission time after tick attachment:  The claims that removal of ticks within 24 hours or 48 hours of attachment will effectively prevent LB are not supported by the published data, and the minimum tick attachment time for transmission of LB in humans has never been established.
  4. Regarding Tick Attachment Times –
There are about 5 to 10 percent of infected ticks that have a generalized infection, including salivary glands and saliva at the time of attachment. In such cases, transmission of spirochetes would and does occur immediately at time of attachment.” —Willy Burgdorfer

According to this study by Coppe Labs, right here in Wisconsin, 85% of Powassan infected ticks come from Northern Wisconsin. Another study by Coppe showed that when 95 patients were tested for suspected tick-borne disease, 66% showed evidence of current or prior Lyme infection.  Of those patients, 17% had serologic evidence of acute POWV infection, demonstrating that POWV may affect more patients than we know.

For more on Powassan:

After a Tick Bite, How Long For Disease Transmission?



A single tick bite can transmit several diseases. But investigators continue to debate how long a tick must be attached before it can transmit the Lyme disease bacterium. While many believe a tick must be attached for at least 36 to 48 hours before transmission can occur, others say it can happen within several hours.

People often ask: How long does it take for disease transmission to occur after a tick bite? According to investigators, Lyme disease may be transmitted faster if the tick previously fed on another host.

In a 2014 article entitled “Lyme borreliosis: a review of data on transmission time after tick attachment,” Michael J Cook explored the topic. “It is frequently stated that the risk of infection is very low if the tick is removed within 24 to 48 hours with some claims that there is no risk if an attached tick is removed within 24 hours or 48 hours.”

However, in animal models, Cook found, “transmission can occur in less than 16 hours, and the minimum attachment time for transmission of infection has never been established.”

Have you been bitten by a partially fed tick?

Investigators suggest that transmission time may be shorter if a tick has already fed on a host. A study by Shih and colleagues, found that, “Partially fed nymphal ticks transmit spirochetal infection more rapidly than do ticks that have never been attached to a host.”¹

So, how quickly a tick can transmit Lyme disease may depend on whether the tick had been partly fed BEFORE it attached to its second host.

Shih et al. demonstrated that partially fed nymphal ticks (84%) were capable of transmitting spirochetes to a non-infected mouse within 24 hours. The authors discovered it took less time for an infected nymphal deer tick to transmit Lyme spirochetes to a mouse if the tick was partially fed.

Ticks spontaneously detach from hosts

Individuals may mistakenly believe that once a tick bites it will remain attached throughout the entire feeding or until it is removed. But this isn’t the case.

In the mouse study, Shih found that ticks can spontaneously detach during the feeding process. And this action can profoundly impact the time it takes for spirochetes to infect the host.

“Virtually all nymphal ticks that previously had fed for 16 hours reattached efficiently.”¹

“We found that nymphs do detach spontaneously from free-ranging mice in the laboratory, perhaps as frequently as 15% of the time,” the authors report.

“Indeed, about [one tenth] of questing nymphs in nature seem to be distended, and reattachment by partially fed sub-adult ticks commonly occurs.”

In the laboratory, partially fed ticks would reattach to a second host and commence feeding. “Virtually all nymphal ticks that previously had fed for 16 hours reattached efficiently.”

What happens in partially fed ticks?

The tick attaches to a host, feeds and the Lyme bacteria multiply rapidly in the tick’s mid-gut. Normally, the tick eliminates all of the bacteria, leaving behind only those spirochetes that survive in the mid-gut before they molt into an adult.

But, in a partially fed tick, spirochetes multiply in the mid-gut and then move to the salivary glands.

If the tick bites again, the spirochetes residing in the salivary glands can be transmitted more quickly. “Partially fed nymphs [ticks] are able to reattach to another host and Lyme disease spirochetes may be transmitted by partially fed nymphs more rapidly than by nymphs that have not already fed.”

Pet owners: be wary

Their findings are particularly relevant to people who own pets. “These partially fed ticks may already have acquired spirochetal infection and avidly seek other hosts,” writes Shih.

“Pet ownership appears to be a risk factor for human Lyme disease, and this may reflect contact with ticks that have detached from a cat or dog within the household.”

If an unfed tick attaches it can take up to 36 hours to transmit the Lyme spirochetes to a mouse, Shih claims. “The chain of events that culminates in migration of the spirochetes from the gut of the tick to its salivary apparatus begins within the first day of attachment and requires at least another day for completion.”

Note: The study by Shih and colleagues was conducted only with mice and has not been replicated with humans.

UPDATED: June 22, 2021

  1. Shih CM, Telford SR, 3rd, Pollack RJ, Spielman A. Rapid dissemination by the agent of Lyme disease in hosts that permit fulminating infection. Infect Immun, 61(6), 2396-2399 (1993).


For more:

Tick Season 2021: Why Researchers Are Focusing on Staten Island Backyards

Tick season 2021: Here’s why researchers are focusing on Staten Island backyards

STATEN ISLAND, N.Y. — For the last four years, researchers from Columbia University have been studying the rise in tick populations and Lyme disease on Staten Island — and the work continues this summer as they drag for ticks, set up hair traps and place trail cameras in residents’ backyards.

The researchers are studying both parks and residential areas to better understand the ecology of ticks and the risk of tick-transmitted diseases in urban environments. And ticks are now being found across all of Staten Island, not just in the southernmost parts.

Most notably, the Asian longhorned tick continues to spread across the borough.

(See link for article)



For more on Diuk-Wasser’s work.

Tick Research Lab of Pennsylvania Weekly Newsletter



The continued advice to sit around and “watch for signs of infection” is not helping patients. ILADS recommends consideration of prophylactic treatment for ALL black legged tick bites with a minimum of 20 days of doxycycline.

It’s also important to remember that Lyme is just the tip of the spear and ticks transmit 19+ pathogens, some of which can be transmitted within minutes. Also, other types of ticks transmit disease as well and need to be considered.

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