Tag Archives: mayla hsu

Lyme Arthritis: The Antibody Connection

by Mayla Hsu, Ph.D., Director of Research and Science, GLA

Lyme disease, caused by Borrelia burgdorferi bacteria, often leads to arthritis, with up to 60 percent of late-stage patients suffering from painful joints and swelling. Symptoms can persist for months and even years. Its suspected that a protein called arthritis-related protein (Arp), which is located on the surface of the Lyme bacteria causes these symptoms. Mice experimentally infected with B. burgdorferi develop arthritis symptoms that are resolved when the animals begin to make anti-Arp antibodies.

But an enduring medical mystery has been why these anti-Arp antibodies coincide with resolving Lyme arthritis but not any other aspect of Lyme disease. One reason could be that other proteins, also on the bacterial surface, may be protecting Arp and the bacteria from antibodies. And if those shielding proteins constantly adapt, they could be even more effective at protecting Arp.

It turns out that this shielding mechanism might be possible. Recent data reported by Abdul Lone and Troy Bankhead at Washington State University indicates that another bacterial surface protein known as  VlsE, may protect the bacteria from anti-Arp antibodies and act as a shield to prevent the immune system from fighting Lyme.

The mechanism of how VlsE defends the Lyme bacteria from Arp antibodies is an interesting story. Earlier work by this research team tested a mutant B. burgdorferi that lacks VlsE protein. This mutant was tested for its ability to infect and grow in immunodeficient mice. Growing the bacteria in mice (in vivo) is more informative than growing the bacteria in a test tube (in vitro), because a mouse has the complexity of an animal with multiple organ systems, and the bacteria disseminate through the body that has different cell types, a circulatory system and other features not found in vitro. Immunodeficient mice lack a functioning immune system, so growing bacteria in them allows observation of how the bacteria replicate unimpeded, in a complex animal system. 

In severe combined immunodeficient (SCID) mice, the VlsE-deficient mouse was capable of infection, showing no growth deficiency. However, if the animals were treated with anti-Arp antibodies, the animals were able to clear the infection.  This suggests that anti-Arp antibodies can stick to Arp on the bacteria and promote their destruction. In contrast, normal bacteria that have VlsE on their surface could not be cleared by anti-Arp antibodies in SCID mice. The contrast in bacterial clearance in the mice shows that VlsE somehow affects the clearance of bacteria by anti-Arp antibodies.

Next, the investigative team used microscopy to observe whether anti-Arp antibodies can stick to B. burgdorferi spirochetes when VlsE is also present on the bacterial surface. They found that although anti-Arp antibodies can bind to VlsE-negative bacteria, they cannot do so in VlsE-positive bacteria. This result suggests that VlsE may actually be a physical barrier that prevents anti-Arp antibodies from sticking to their target, the Arp protein. Precisely how VlsE does this is an interesting question. For example, are Arp and VlsE close together on the bacterial surface? Is VlsE larger or does it block only the specific epitopes, or subdomains that are bound by Arp antibodies?

Moreover, there were limits on VlsE-mediated protection of B. burgdorferi proteins. Control experiments indicated that VlsE may not block antibodies other than those targeting Arp. This was shown by using a blood serum (antisera) purified from mice infected with an Arp-negative, VlsE-negative bacteria. These antisera would lack antibodies against Arp and VlsE, but have antibodies against other B. burgdorferi proteins. Mice were pretreated with the Arp-negative, VlsE-negative antisera and then challenged with normal bacteria which had both Arp and VlsE. The normal bacteria could not infect, which showed that the presence of VlsE could not protect the bacteria from antibodies that target non-Arp bacterial antigens. This suggests that VlsE may only protect Arp, and not other Borrelia antigens.

Work by other investigators has shown that VlsE undergoes extensive antigen variation. The antibodies elicited by VlsE also change during disease course. So, the work of Lone and Bankhead raises questions about whether specific VlsE variants protect Arp, and if there is a correlation with disease stage and the onset of arthritis.

These findings are also important because they further highlight how, in addition to other immune dysfunctions, the bacteria have evolved multiple ways to specifically evade the humoral, or antibody-mediated immune response. Not only does the VlsE protein change during bacterial infection, providing a mechanism of immune evasion and persistence for the bacteria, but it may also protect other bacterial proteins from being targeted. Further studies will clarify how VlsE shields Arp.

And it is another piece of the puzzle of how B. burgdorferi may cause persistent arthritis. Previous findings implicated peptidoglycan, a different component of the bacterial cell wall. How these pieces fit together will explain disease outcomes and long-term symptoms.

Related Blogs:

Research POV: Lyme Arthritis and Peptidoglycan
Possible Clue to Lyme Arthritis Found in People’s Inflamed Joints


research pov_lyme arthritis_Peptidoglycan

Research POV: Lyme Arthritis and Peptidoglycan

Important study identifies the Borrelia burgdorferi peptidoglycan as an immunogen likely to cause Lyme arthritis in some patients


by Mayla Hsu, Ph.D., Director of Research and Science, GLA

A longstanding mystery in Lyme disease is why some antibiotic-treated patients continue to suffer long-term symptoms, while others recover. It is possible that a hyperactive immune system in some patients causes inflammation-related tissue damage. Another possibility is that the bacteria, Borrelia burgdorferi, may still be alive in compartments of the body that are not readily accessible to antibiotics, and the bacteria’s continued replication causes ongoing symptoms.

A recent article found that a component of the bacterial cell wall, peptidoglycan (PG), might be driving the persistent inflammation that causes Lyme arthritis even after antibiotic treatment. The authors, who include a GLA-funded researcher, found B. burgdorferi PG antibodies in the synovial fluid that surrounds the knees of Lyme arthritis patients, which is evidence of an ongoing immune response against bacteria or fragments of its cell wall. In contrast, they did not find significant antibodies against PGs of any other bacteria. A strength of this study is that they compared synovial fluid from Lyme arthritis patients with that of other types of non Lyme-related arthritis. Only Lyme arthritis patients had synovial fluid B. burgdorferi PG antibodies.

Blood was also collected from the same Lyme patients whose synovial fluid was studied. Here, they found that sera (serums) of Lyme arthritis patients also had PG antibodies, although the levels were much lower than in the synovial fluid. Moreover, Lyme arthritis patient sera had much higher levels of PG antibodies than any detected in control patient sera. These findings indicate a continued immune response against PG, particularly in the synovial joints, specifically against B. burgdorferi.

Another asset of this study was its analysis of patient samples both before and after antibiotic treatment. The authors designed a way to detect PG itself, not only antibodies, in synovial fluid and sera. Using this test, they could not find PG in control synovial fluid, nor in Lyme arthritis patient sera. However, it was present in 92% of Lyme arthritis synovial fluids, both before and after treatment with antibiotics; and this was true of patients who had been treated with oral as well as intravenous antibiotics. In addition, the amount of PG strongly correlated with the level of PG antibodies in the same synovial fluid samples. This finding suggests that the bacterial cell wall itself is present in the synovia of patients, and that its presence elicits antibodies against PG.

Peptidoglycan_figure for blog
Comparison of B. burgdorferi PG antibodies for serum and synovial fluid, from Lyme arthritis patients (red) and from controls (black) (healthy and non-Lyme arthritis)

Do these results mean that B. burgdorferi is actively replicating in the patients in whom PG or PG antibodies were found? Testing for bacterial DNA was done on synovial fluid and blood, both before and after antibiotic treatment. Although both compartments were often positive for bacterial DNA before therapy, almost all samples became negative after therapy. This finding suggests that PG and PG antibodies persisted even after eliminating actively replicating B. burgdorferi at these sites, but it does not rule out bacterial replication elsewhere, and leaves open the question of how bacterial cell wall components could remain long after the bacterial DNA is no longer detectable.

This study also identified proinflammatory cytokines in synovial fluid, which play an important role in mediating immune responses. In vitro, the addition of purified B. burgdorferi PG to cultured peripheral blood mononuclear cells (PBMCs) caused increased levels of inflammatory cytokines like TNFα, IL1α, and IFNγ. These and others were also significantly elevated in the synovial fluid of Lyme arthritis patients, suggesting a possible mechanistic link between PG and inflammation. Finally, injection of purified PG in mice resulted in ankle swelling and inflammatory changes that are consistent with the established mouse model for Lyme arthritis.

In sum, these results make a strong case that B. burgdorferi PG may be responsible for driving inflammation and continued symptoms in post-antibiotic Lyme arthritis. Whether it is also implicated in promoting other long-term symptoms remains to be seen. These findings open up a new avenue of inquiry that may yield fruitful insights that will help us to better understand and care for people suffering from persistent symptoms.

Learn more about GLA’s research initiatives and accomplishments:

Research Report
Published Research Findings
Current Grantees 
First Observational Study for Lyme Disease Treatment
Post-treatment Lyme: Two Million by 2020
Blog: Why Good Science is Crucial

tick-borne disease research

Requests for Tick-borne Disease Research Reach an All-Time High

by Mayla Hsu, Ph.D., Director of Research & Science, GLA

It is no surprise that when funding for research lags, associated progress in science and medicine slows. Perhaps no area of health research illustrates this fact better than that focusing on Lyme disease. Despite infecting at least 329,000 people in the U.S. each year, according to the CDC, and being known by the medical community for over 40 years, Lyme disease is still responsible for vast numbers of disabled and chronically ill sufferers. Global Lyme Alliance (GLA) has made great strides to fill the dearth of knowledge by funding high-level science, awarded to academic scientists for each of the past 20 years.

The current crop of grant applications are especially exciting in terms of their scientific breadth and depth. We have received 31 proposals from the U.S. and abroad, with 18 of them from researchers in Lyme-endemic U.S. states. The total amount requested was a record, totaling over $8 million, attesting to the strong interest in Lyme disease research among investigators. Of all the applicants, 25 (81%) have not previously been funded by GLA, which speaks to our growing acceptance and reputation among top researchers.

The applications received span a broad spectrum of research interests in the tick-borne disease field. Among them were creative ideas to improve Lyme disease diagnostics with new technologies which would allow more rapid and highly sensitive detection of Borrelia together with co-infecting microbes. Some proposals sought to study patient populations to better identify individuals with tick-borne infections and their co-morbidities. Support of biobanks to collect patient samples, in association with careful clinical data, was also requested. Some applications propose to study tick biology and environmental influences, and tick-bacteria interactions, which may reveal improved disease exposure prevention strategies. There were also inspiring applications for discovering and developing new potential treatments, and clinical science proposals which sought to understand the mechanisms of inflammation and pathology in organs targeted by Borrelia burgdorferi.

GLA’s rigorous process for evaluating grant applications, unique among Lyme disease nonprofits, is closely modeled on the peer-review guidelines used by the National Institutes of Health. Sixteen Scientific Advisory Board (SAB) members, consisting of scientists in industry and academia —who are all noted experts in medical research, immunology, and microbiology— are assigned applications in their respective fields of expertise.

Each application is then reviewed according to strict criteria. This process is followed by a series of discussions to ensure that only the most promising applications, directed by the most qualified and creative scientists, are funded. Throughout the grant selection process, GLA seeks those applications with a high likelihood of leading to evidence-based, validated scientific advances as a means of ensuring maximum potential effectiveness. The 2018-2019 grants will be announced in January 2019.

View GLA’s Lyme Disease Research Report

tick threats

Taking Stock of Tick Threats

by Mayla Hsu, Ph.D., Director of Research and Science, GLA

“Tickpocalypse!” “The Year of the Tick!” “A Tick-ing Time Bomb!” These are all recent clickbait headlines that cause us fear and anxiety. But how do we realistically and reasonably know the risk of acquiring tick-borne diseases? How can we anticipate that ticks will be in our neighborhoods?

There’s no doubt that Lyme disease and other illnesses spread by ticks are on the increase. As might be expected, climate change, land and habitat management, and human behavior are all variables that affect the degree of risk. The Centers for Disease Control and Prevention (CDC) has found that the geographic range of ticks is expanding, with the principal vector of Lyme disease, Ixodes or black-legged tick, now found in 49% of all US counties. The CDC has also shown that the number of counties with high Lyme disease incidence is growing. If areas previously unknown for ticks become suitable habitats for them, which is now occurring, we will need surveillance strategies that will dependably inform public awareness and prevention programs.

More than 40 years after Lyme disease was first identified, we now know that the life cycle of ticks depends on host species that provide the three blood meals needed for a tick’s major life transitions: (1) from larva to nymph, then (2) nymph to adult, and (3) so adult females can lay eggs. Small mammals like mice and chipmunks, as well as birds, deer and other animals are all host species for ticks. When not “questing”, or awaiting passing hosts from the tops of blades of grass, and when not attached to host animals, ticks are on the ground, where they spend most of their time.

We can measure tick abundance by directly counting ticks caught in traps or by cloth dragging, and identifying the tick species caught. Advantages to this are relative ease and lack of expensive technology. However, cloth dragging on the ground may be obscured by dense vegetation or trees. Another obvious limitation is that dragging may not sample large enough geographic areas. In addition, transient environmental variables like weather changes or time of day can affect tick trapping and drag capture outcomes.

Surveying animals is another way to measure tick prevalence. This can include counting ticks from domestic livestock or pets, or trapping wild animals such as mice. Wild host species can potentially serve as “sentinel” species, indicating tick abundance in the host’s native habitat. Generally, a good sentinel species would be an animal that can be caught and sampled readily, has a predictable geographic range, and is attractive to ticks. An example is the white-tailed deer, in which tick burden and pathogen load has been successfully studied in hunted animals.

Another example is wild pigs, whose large range can span various habitat types, and who can host varying species of ticks. In a recent study of 316 wild pigs in Florida, 1,023 adult ticks and only one nymph tick were collected. In contrast, 39 adults, 150 nymphs, and 2,808 larvae were found from dragging. This difference is likely because immature stages of ticks tend to quest lower than adults. Thus, larvae and nymphs are more likely to found than adults by dragging survey. In contrast, adult ticks may be more likely to be detected on hosts that have a medium to large body mass. Overall, these results suggest that complementary information was available from the two sampling methods. Together, cloth drags and sentinel species gave more complete information about tick abundance than each done separately.

With field data from cloth dragging and sentinel species, mathematical models can be built to predict whether tick populations in local neighborhoods are expected to be high or low. These calculations add data on elevation and weather patterns, including humidity, daily and seasonal temperature fluctuations, and precipitation. The type of habitats, whether agricultural, grassland, or forest, all composed of varying vegetation types, are also included in models.

Mathematical models were used to identify the highest densities of host-seeking nymph ticks in Minnesota. The study’s authors found that tick density increased as the proportion of agricultural land decreased, with the highest risk of host-seeking nymph ticks in the Minneapolis-St. Paul metropolitan area. Large swathes of western and southern Minnesota were found to be unsuitable for ticks, perhaps because such large rural areas are lacking in potential tick hosts. They also found that extremes of temperature and precipitation were identified as predictors of tick density.

Climate change will play a big role in tick habit expansion, with reports of ticks now emerging in Canada. Specialized mathematical models known as climate envelope models predict suitable new habitats for species. This type of model was used to determine whether a newly invasive tick, Haemaphysalis longicornis, would be predicted to expand in New Zealand. It was calculated that 75% of cattle farms in North Island and 3% of those in South Island will be suitable habitats for this tick, a concern because it transmits cattle anemia. This information will be important for gearing policy toward tick surveillance and reduction.

Ticks are an important concern for public health, environmental management, and agriculture. Only with reliable and valid research will we be able to accurately describe and anticipate future tick threats. This will be a rational first step toward effective control.

mayla hsuMayla Hsu, Ph.D.
Director, Research and Science
Global Lyme Alliance

Mayla manages GLA’s research grant program, working with the Scientific Advisory Board and creating viable partnerships to help advance the development of a reliable diagnostic test, effective treatments and ultimately a cure for Lyme.


tick table

pre-exposure prophylaxis, borrelia burgdorferi

Promising New Research: PrEPping for Ticks

by Mayla Hsu, Ph.D.
Director, Research and Science
Global Lyme Alliance

Stopping Lyme disease before it starts. Promising new research based on pre-exposure prophylaxis, or PrEP.


It’s frustrating that there are so few ways to protect ourselves from Lyme disease. We use tick repellents, rodent and deer control, and search for ticks on our bodies. But none of these are completely foolproof. What we need is creative approaches that go beyond fundamental tick-bite prevention. Now, there is intriguing news of a potentially novel method of pre-treating humans with a protective antibody. If the approach is eventually successful, it may become possible to prevent infection even after being bitten.

Promising new research published recently in the Journal of Infectious Disease, although still very preliminary, paves the way for new ways to protect ourselves from Lyme disease. This study used a technique called pre-exposure prophylaxis, or PrEP.

The studies were led by Dr. Mark Klempner at Mass Biologics and the University of Massachusetts Medical School. Lyme disease results when people are bitten by ticks infected with the bacterium called Borrelia burgdorferi. This research team found that pre-treating mice with antibodies that bind to Borrelia burgdorferi protected the mice from becoming infected after being bitten by infected ticks.

Two of the antibodies had dose-dependent effect, which means that when less antibody was pre-treated, fewer mice were protected. When more antibody was pre-treated, more mice were protected. This is strongly suggestive that the protective effect was due to the presence of the antibody. In contrast, a control antibody that does not recognize Borrelia failed to protect mice, who became infected.

Antibodies are proteins made by our immune systems to stave off infections. Some antibodies stick to bacteria and prompt immune cells to find and digest them. Other antibodies, once bound to bacteria, recruit defense proteins called complement proteins, which poke holes in microbes and kill them. Like a lock and key, antibodies recognize specific bacterial shapes, sticking only to precise locations on them. In other words, they direct immune defenses to highly specific places, leaving healthy bystander cells safely alone.

But not all antibodies work well. Initially, the research group immunized mice with OspA protein, which is on the outer surface of Borrelia burgdorferi. In response, hundreds of antibodies recognizing OspA were produced by the mice. But only four were able to promote the killing of Borrelia. In addition, these four antibodies targeted not only Borrelia burgdorferi, but also Borrelia garinii and Borrelia afzelii, two species of Borrelia bacteria that cause Lyme disease in Europe and Asia.

When the four antibodies were analyzed in depth, the team found that they all bound the purified OspA protein and recognized defined domains, or portions of OspA. Identifying these particular parts of OspA that are bound by the effective antibodies showed important potential targets for design of future vaccines or new Borrelia-targeted drugs. It was these four that were tested, and found effective at protecting mice from infection by Borrelia-harboring ticks.

The research results also suggest that certain parts of the OspA protein are common to all three species of Borrelia, even though there are other genetic differences between them. It shows that there might be a way to potentially block all three from infecting people. Naturally, this which would be enormously useful for people at risk for Lyme disease in other parts of the world as well as in the U.S.

Although a limited number of mice were studied, this data shows what is called  “proof-of-concept” that an antibody pre-treatment strategy might work to prevent infection by Lyme bacteria. The authors were careful to interpret their results cautiously, noting that we do not yet know whether the protection might last the duration of tick season, or even whether protection against all strains of Borrelia burgdorferi is possible.

These findings are only the beginning of a process for developing new preventive medicine and vaccines. Nonetheless, they are encouraging. They provide a rationale for continuing to develop this strategy, and raise the hope that another protective tool might eventually be available in our defense against Lyme disease.

Mayla Hsu, Ph.D.
Director, Research and Science
Global Lyme Alliance

Mayla manages GLA’s research grant program, working with the Scientific Advisory Board and creating viable partnerships to help advance the development of a reliable diagnostic test, effective treatments and ultimately a cure for Lyme.

Borrelia bacteria in the blood

GLA: Lyme Disease Research Symposium Highlights

by Mayla Hsu, Ph.D
Director of Research and Science, GLA

GLA hosts top researchers to discuss Lyme disease research.


How can we understand Lyme disease better? Are there drugs that can kill persistent bacteria? Why do some Lyme patients get well, while others remain sick? Questions like these were discussed at the 2017 Global Lyme Alliance Research Symposium, which was held March 31-April 1 in Greenwich, CT.

About 30 scientists from all over the United States met to share the latest data about Lyme disease. These were researchers who have received GLA grants, as well as Scientific Advisory Board members whose expertise spans both the clinical and basic sciences.

Norma Russo, board member, GLA; Dr. Ying Zhang, Johns Hopkins University
Norma Russo, board member, GLA; Dr. Ying Zhang, Johns Hopkins University

One highlight was the discussion of a new way of using the mouse model of Lyme disease, in which evidence of brain penetration by spirochetes has been found. In the past, this has not always been easy to demonstrate, and the new data will fuel further discovery of its direct effect on neurological infection and brain function.

Another area of discussion was focused on the 10-20% of Lyme disease patients who despite antibiotic therapy are not cured. Such patients often suffer debilitating pain, fatigue, and neurocognitive difficulties, which are termed post-treatment Lyme disease syndrome (PTLDS). Understanding the immune response in PTLDS patients and what causes a chronic inflammatory state is the subject of GLA-funded work, both in the mouse model as well as in the study of human subjects.

The search for more effective treatments for Lyme disease patients was also presented in talks and posters. The bacterium that causes Lyme disease is called Borrelia burgdorferi. When grown in the test tube and treated with antibiotics, some bacteria survive as persisters, which are very slow-growing bacteria. In patients, persisters may be the cause of long-lasting symptoms. Therefore, new drugs and drug combinations that directly target persister bacteria are a focus of research interest.

Lew Leone_Armin Alaedini
Lew Leone, board member, GLA: Dr. Armin Alaedini, Columbia University

The symposium wrapped up with a lively group conversation about the diagnostic blood test for Lyme disease, with widespread agreement that the existing two-tiered test recommended by the Centers for Disease Control is unacceptably insensitive. What it should be replaced with, however, is still being debated.

Overall, GLA was pleased to host this gathering of premier-level scientists. The newer research underway will in due course be published in high-quality, peer-reviewed scientific journals consulted by authorities in the tick-borne research field. We look forward to seeing the final results and to supporting ongoing studies.

The Mighty White-Footed Mouse

by Mayla Hsu, Ph.D., GLA Director of Research and Science

What makes the white-footed mouse more mighty than a lab mouse when it comes to tolerating Borrelia burgdorferi, the bacterium that causes Lyme disease?


When we think of mice, we envision cute furry rodents with big eyes and little feet, and we don’t usually associate them with disease. But when we discuss Lyme disease, we need to consider the wild, white-footed mouse because it is one of the most important reasons for the spread and continued existence of this illness.

Dr. Alan Barbour at the University of California at Irvine is a pioneer in tick-borne disease research and a Global Lyme Alliance grantee. He published a recent article that explained why it is important that we study Lyme disease in wild mice and not only in lab mice.

Peromyscus leucopus—the scientific name of the white-footed wild mouse—is abundant in North America, along with its close relative, Peromyscus maniculatus. Together, they act as natural hosts, or reservoirs, for numerous disease-causing microbes. This means that they provide a long-term home for pathogens to survive in nature. They are also blood meal sources for vectors, like ticks, which transmit the pathogens from one animal to another.

One reason why we should study Lyme disease in wild mice, Dr. Barbour writes, is because they are genetically quite distant from lab mice. Peromyscus mice are actually more closely related to hamsters and voles than to lab mice, which are genetically grouped with the black rat. The genetic distance between the species might explain why there are important differences in how wild mice and lab mice respond to pathogens like Borrelia burgdorferi, the bacterium that causes Lyme disease.

Capture of wild field mice indicates that compared to other small mammals, they are more heavily burdened by ticks. Although there is variation between different studies, up to 100% of these ticks have been found infected with B. burgdorferi. Dr. Barbour summarized studies showing that in the northeast and north-central United States, P. leucopus mice typically get infected during the spring and summer months. As part of their immune response, they produce antibodies in their blood that recognize OspC, a protein on the outside of the bacteria. This also occurs in lab mice and in humans infected with Lyme disease, suggesting that this part of the immune response is common to all three.

blog_mayla_white footed mouse_quoteBut what’s different about wild Peromyscus mice is that they exhibit no obvious pathology. In multiple studies, even though the bacteria could be recovered from the urinary bladder, kidney, heart, spleen, ears, tails and joints, there was no evident organ damage. There was no variation in the types of immune cells found in infected animals as compared to uninfected animals. Infected animals did not appear to differ in their body weight from uninfected ones, suggesting that there was no obvious impact on overall health. And the amount of time that Borrelia-infected P. leucopus mice spent running on their exercise wheels did not differ from the uninfected mice.

In contrast, lab mice, when challenged by Borrelia burgdorferi infection, typically develop arthritis, carditis, and joint inflammation. Studying infection in these animals is useful to understand how the bacteria cause disease and the dysfunction of the immune response, but that only tells part of the story.

It’s not well-understood why Peromyscus mice don’t get sick from Lyme bacteria, but we do have some clues. It has been speculated that B. burgdorferi infections have occurred for hundreds of years in North America. With time, it is likely that the host-pathogen relationship evolved into a balance allowing both of them to survive. While in the mouse, the pathogen has to reproduce to sufficient levels so that it can enter ticks and be transmitted from one animal to another.  But the pathogen can’t kill its host, or weaken it so that it can’t efficiently reproduce. The mouse host must live long enough to have progeny, in order to produce a new generation of hosts in which the pathogen can be maintained.

Somehow, Peromyscus mice are able to tolerate Borrelia infection without any obvious illness. If we study these animals, especially by comparing the immune response in both uninfected and infected mice, we may be able to learn much that might explain how Peromyscus mice avoid the damage caused by B. burgdorferi infection.

Podcast: Tick-Borne Co-Infections, Bartonella and Powassan Virus

Bartonella is a tick-borne co-infection. As with Lyme disease, its symptoms can be debilitating.


While the most common tick-borne infection is Lyme disease, infected ticks may carry more than one kind of microbe or disease producing organism that can make humans very sick. The microbes are called co-infections, the simultaneous infection of a host by multiple pathogenic or disease-producing organisms.

Dr. Mayla Hsu, GLA’s Director of Research and Science, and Dr. Harriet Kotsoris discuss Lyme and its co-infections in a recent podcast. Below is an excerpt of the podcast that focuses on Bartonella and the Powassan virus.

CLICK HERE to listen to the entire podcast.

Host: I’ve heard there’s a new tick-borne infection that’s somewhat controversial called Bartonella. Mayla would you like to tell us more about that?

Dr. Hsu: Sure. Bartonella is a bacterium that’s controversial in discussions of tick-borne illnesses because there is quite a lot of debate about whether it is actually spread by ticks and causes human disease. Now we know that it’s spread by fleas and body lice and sand flies, but ticks are a somewhat new idea that is gaining traction in some quarters. Bartonella is in domestic and wild animals and it causes various illnesses that we know about, such as cat scratch disease and trench fever, where people get bitten by fleas that are feeding on animals or by body lice. Now in recent years, Bartonella bacteria has been found in ticks in many countries around the world. The ticks do feed on host animals that carry Bartonella so it’s not surprising to find the bacterium in the ticks.

Humans with tick exposure, like hunters, have been found to have antibodies against Bartonella so that indicates they’ve been exposed, but whether Bartonella actually causes illness in healthy people is under debate. There’s no question that Bartonella is a big problem for people who are immuno-compromised and they can get sick, but even there we don’t know how much of it is acquired from tick bites versus flea bites. Now, if people do get Bartonella it’s diagnosed by looking for the DNA of the bacteria or by growing or culturing the bacteria, and then it is treated with antibiotics. Often the first symptom is striations or lines that look like stretch marks on the skin and it can progress into fever and lead to very serious illnesses including things like heart inflammation or endocarditis.

Host: A new class of microbe that is very different from the bacteria and parasites we’ve been hearing about are the viruses spread by ticks. Since they can’t be treated with antibiotics, should we be worried about them?

Dr. Hsu: The virus that is spoken about as transmitted by Ixodes or black-legged ticks, is the Powassan virus, which is also sometimes called deer tick virus. Powassan virus or deer tick virus are actually two different genetic lineages of very similar virus so let’s just call it Powassan virus. It was first described in the 1950s. Powassan virus can be very serious because in half of cases, 50% of cases, people have continued long-term neurological consequences and disability due to encephalitis, or inflammation of the central nervous system. The virus actually infects the brain. The fatality rate can be 10 to 20%, especially in the elderly, the immunocompromised or people with other health conditions.

The symptoms for Powassan virus are fever, vomiting, weakness, memory loss, and seizures. The diagnosis is made by doing a blood test or a spinal tap looking for antibodies against the virus. The treatment for Powassan virus is, as you said, it can’t be treated with antibiotics. They don’t work against the virus, so the treatment is mostly supportive. That is providing respiratory support, fluids, drugs to reduce brain swelling. Now, luckily Powassan virus is rare. There were 13 cases that were reported in 2013 to the CDC, so it’s actually not a really prevalent disease. It is found in actually a very low percentage of ticks, maybe three to 5% of ticks are co-infected with Lyme disease and Powassan virus, so it is there. It is present so we have to be concerned about it. Now overseas there are many more cases of a brain infection caused by ticks, there is tick-borne encephalitis, and that is also caused by a virus, a tick-borne encephalitis virus, that has been recorded and associated with serious illness.

Host: Obviously a lot of people haven’t heard of these co-infections spread by ticks, can you tell us about some of the major problems and how we cope with tick-borne diseases?

Dr. Hsu: One of the biggest issues is probably awareness. There are medical professionals who have heard of Lyme disease but may not have heard of these others.

Dr. Kotsoris:  Health authorities may not test for some of these if they’re unaware of them and then ordering the right diagnostic tests has to be done. The Lyme disease diagnostic by itself is highly inaccurate and so even getting that diagnosis is problematic. Without reliable molecular diagnostic techniques some tests are only available experimentally or at limited federal or state levels. Initial diagnosis is very difficult and you can’t sit around and wait for an antibody response, so physicians have to be better diagnosticians. They can not, as I said before, they can not sit around and wait for convalescent titers, antibody titers to indicate that the patient has had the infection. That’s four to six weeks after the initial infection. Until the FDA approves some of these experimentally available techniques, makes them more widely available to the frontline physician, we have to rely on clinical diagnosis.

Host: What about the treatment of tick-borne illnesses?

Dr. Kotsoris: It’s important to note the treatment for Lyme disease doesn’t cure the others necessarily, so proper diagnosis is critical to getting proper treatment that is specific for the co-infecting microbe. Also having two infections might make the symptoms tougher to treat. There are some research studies that indicate that co-infections actually make the illnesses more powerful individually. For example co-infections of Babesia and Lyme disease may make it harder to treat the patient than if he or she had only one of those.

Host: Are there other issues we should be thinking about with regard to tick-borne co-infections?

Dr. Hsu: I think there’s a lot we simply don’t know about the biology of co-infecting pathogens. For instance, we don’t understand a lot about how they grow in their host animals, more than one microbe. We don’t really understand how they get into a tick and how they survive in the tick, and very basic questions like infection of humans, from ticks to humans.

Host: Given all the lack of awareness, what kind of studies are needed to better understand and treat tick-borne diseases?

Dr. Hsu: There are some emerging illnesses now that are suspected of being caused by ticks but we don’t know for sure. We need more research. For instance, there’s a new illness that’s emerging called stari, S-T-A-R-I, and what that stands for is Southern Tick-Associated Rash Illness. We know that this is caused by a tick bite but we still don’t know what the pathogen or the microbe is that is responsible for the illness. Diagnosis, which we talked about is sometimes complicated. Some of the technology to diagnose some of these co-infections, like really sensitive molecular biology, looking for the DNA of the organism, is not readily available in some parts of the world.

Dr. Kotsoris: Travelers to other parts of the world may come home to the United States where the best of medical care is apparently available and doctors here may not know about those tick-borne illnesses, so education has to be a big part of it.

Host: Tick-borne diseases are a very big problem. Let’s hope that public health officials and the funding organizations take them seriously, especially since climate change is going to mean more sick people, more school and work absences, less productivity, and have a huge economic impact. Thank you for all the discussion today and thank you to all of you listeners.

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Tainted Transfusions: Why Screening Blood is More Important Than Ever

by Mayla Hsu, Ph.D., GLA Science Officer

The importance of screening for babesia in our blood supply is the focus of a new study published in the New England Journal of Medicine.


The last thing anyone wants from a blood transfusion is to get sick from an infectious microbe. Currently, the American Red Cross and other blood collection agencies screen for blood-borne pathogens like HIV and hepatitis viruses. But there is a malaria-like parasite called Babesia microti that can make us sick, and is not routinely screened for.

Spread by the same biting ticks that transmit Lyme disease, babesiosis can be self-limiting and asymptomatic in healthy adults. However, in the immunosuppressed–the elderly or those co-infected with Lyme disease–the illness, which is characterized by recurrent fevers and pain, can become severely debilitating and is potentially fatal. When blood from such infected patients is examined with a microscope, the parasite can be seen replicating inside red blood cells.

A new study published in the New England Journal of Medicine has shown that screening for babesia-infected blood is useful in reducing transfusion-acquired babesiosis. This research, conducted by the American Red Cross, analyzed blood donation samples obtained in Connecticut, Massachusetts, Minnesota, and Wisconsin, all states with high incidence of Lyme disease and babesiosis.


They found that after analyzing 89,153 blood samples, 335, or 0.38%, were positive for babesiosis, and these donations were removed from the blood supply. During the study period, which was from June 2012 to September 2014, there were 29 recorded cases of transfusion-acquired babesiosis. These came from blood that was not screened, and follow-up of the specific donor samples showed later that the source blood tested positive for Babesia.

When focused on Connecticut and Massachusetts, the researchers found that for screened blood, there were no transfusion-transmitted babesiosis cases in 75,331 blood donations. In contrast, with unscreened blood, there were 14 cases of babesiosis in 253,031 donations. This showed that blood donation screening was effective in preventing babesiosis transmission via blood transfusion.

Every year, about 1800 cases of babesiosis are reported to public health authorities, with 95% of cases in only 7 states. However, this is likely to be an undercount, due to low medical awareness and misdiagnosis of the disease. Presently, there is no Babesia blood donation screening test that has been approved by the Food and Drug Administration. This study and others like it will hopefully lead to such a test, by showing the vital importance of protecting our blood supply from a dangerous pathogen.

Tick-borne Infections on the Rise in Gray Wolves

by Mayla Hsu, Ph.D., GLA Science Officer

As the majority of emerging infectious diseases stem from wildlife, the rise of tick-borne Infections in gray wolves is a good indicator of the future of Lyme and other tick-borne diseases.


Wild gray wolves evoke images of unfettered nature and animals loping freely through forests and meadows. But a new study of wolf populations in northwest Wisconsin shows that a high percentage of them are actually infected with tick-borne infections, which suggests that they are potentially suffering ill health.

Many of us know that rodents like squirrels and mice, as well as larger animals like white-tailed deer, are hosts for Ixodes scapularis, the tick that transmits Lyme disease. The bacteria that cause Lyme disease (Borrelia burgdorferi), anaplasmosis (Anaplasma) and ehrlichiosis (Ehrlichia), grow in these host animals and colonize the ticks who bite them to take blood meals. When infected ticks then bite humans, we too become infected by the bacteria, and get sick.

Scientists analyzed 373 blood samples drawn from wild gray wolves between 1985 and 2011. Using the Snap 4Dx test, which is used by veterinarians to test for tick-borne illnesses in dogs, they looked for antibodies that recognize these microbes. Their presence indicates past exposure to the pathogens. Overall, they found antibodies to B. burgdorferi in 65.6% of animals, Anaplasma antibodies in 47.7% and Ehrlichia antibodies in 5.7%. These findings show that tick-borne pathogens are common in gray wolves in Wisconsin, and as expected, the American dog tick Dermacentor, and I. scapularis tick vectors that transmit them were routinely found on the animals.

While the sex of the wolves was unrelated to the percentage infected, their age was important. A higher proportion of adult wolves had B. burgdorferi, Anaplasma, and Ehrlichia antibodies than pups. This is unsurprising, since greater age means increased probability of being bitten by ticks. Also, adult wolves move greater distances, with greater exposure to questing ticks, compared to pups, who generally stay near their den.blog_tick-borne-gray-wolves-2

The research also showed a 50% increase in the prevalence of B. burgdorferi between 1985 and 2011 among gray wolves.  The counties in which wolf exposure has increased the most are among the Wisconsin counties in which human Lyme disease has also expanded the most.  By contrast, the prevalence of heartworm, a parasitic disease spread by mosquito bites, did not change during this time frame, suggesting that conditions favorable to ticks, but not mosquitoes, may be driving disease spread.

Why should we care about tick-borne diseases in wild wolves? They are free-ranging animals whose exposure to ticks is greater than that of pets or humans. They go places that we don’t go, and humans do not remove ticks from them as they do from domestic dogs. Thus, they can be regarded as sentinels of infectious diseases in wilderness spaces. Nationally, the Lyme disease epidemic in humans is expanding, particularly in the Northeast, Wisconsin and Minnesota. Several studies suggest that climate change may favor the growth of ticks and mosquitoes. So, information about vectors and microbes in wild animals everywhere will help us to plan and implement measures for safeguarding public health. In the last 75 years, 71.8% of emerging infectious diseases came from wildlife.

But aside from illnesses that we as humans may acquire, the health of gray wolves is important for another reason. They are predators and preserve ecosystem health, by preventing the overpopulation of prey species. Whether gray wolves become severely sick from tick-borne illness isn’t well known, with a few documented cases of captive wolves losing weight after Borrelia infection. So far, it appears that the wild wolf population, rebounding from near-extinction, has not been harmed by tick-borne microbes. However, we have a responsibility to remain vigilant to health threats to all species and in all habitats, not just our own.


Lyme Disease Prevention Needs Co-Operation, Not Isolation

by Hannah Staab and Mayla Hsu, Ph.D., GLA Science Officer

With the election of a new President in the United States, the heated rhetoric about reinforcing America’s southern border has ignored the critical need for international dialogue and mutual cooperation to control the spread of infectious diseases. Infectious pathogens do not respect national borders. As we have learned from Zika virus, both humans and animals can facilitate disease spread between countries, making the border areas between countries an important place for disease control. The U.S.-Mexico border zone can be considered a hotspot for diseases acquired from animals, such as Lyme disease and other tick-borne illnesses, whose spread may be promoted by factors including climate change, poverty, and migration.

A study conducted jointly by Mexican and American scientists found that Ixodes scapularis, the tick responsible for spreading Lyme disease, is present in the border area, and 45% of these ticks were infected with the Borrelia burgdorferi, the bacterium that causes Lyme. In Mexico, a survey of blood samples revealed that 6.4% of people living near the Texas border had antibodies for Lyme bacteria, while other regions in Mexico reported only 1.1% seropositivity. This region has a higher rate of Lyme disease and other tick-borne illnesses than anywhere else in Mexico, and reasons for this could include the high traffic of host animals, such as cattle and white-tailed deer that move through the area. Tick-borne diseases may also become more prevalent in this area due to climate change. Variables including rainfall, invasive vegetation and increasing temperature are shifting the habitat range of disease vectors like ticks as well as their mammalian hosts, and it’s speculated that Lyme disease incidence will increase in this border area. Poverty, which worsens difficulties in obtaining timely health care information and treatment, is not solely a Mexican problem: 15.9% of Texans live below the poverty level.

However, preventing the spread of disease to humans is not the only focus of tick control in this region. Rhipicephalus microplus is a species of tick usually found in sub-tropical regions, that often transmits Babesia bovis, a parasite that causes cattle fever. This infection causes potentially fatal anemia and wasting in cattle, and leads to devastating economic losses. The parasite is related to a similar tick-borne parasite, Babesia microti, that infects and sickens humans.

In the early 1900’s, the United States established the National Cattle Fever Tick Eradication Program, which eliminated virtually all cattle fever ticks. Still, these ticks remain abundant in Mexico, and to prevent their movement over the border, the United States Department of Agriculture created a Tick Eradication Quarantine Area (TEQA). Within the TEQA, stray, illegal and US-bound animals are inspected. In order to export cattle out of the quarantine area, they must be treated with acaricides, which are chemicals that kill ticks. Although this method has been very effective in keeping cattle fever out of Texas, the excessive use of acaricide has caused the ticks to adapt and become resistant.

A study by Busch et al. (2014) took tick samples from various locations in Texas and tested their resistance to multiple acaricides. These tests revealed that 15 out of 47 of the collections contained ticks that were resistant to acaricides. Eleven of 15 acaricide-resistant populations were collected outside of the TEQA, indicating the ticks were not contained. The authors concluded that despite the extensive actions to inhibit the spread of ticks into Texas, there were two dispersal mechanisms that led to these tick infestations. The first was frequent short-distance dispersal of acaricide-resistant ticks despite the precautions taken at the border. The second mechanism was the less frequent, long-distance dispersal from the TEQA, possibly mediated by humans, or carried on other host animals such as white-tailed deer.

Acaricide resistance is a major threat to the mechanisms that are currently in place to control tick populations. A study by Stone et al. (2014) examined the genetic mutations in ticks that are associated with acaricide resistance. They identified three single nucleotide polymorphisms that led to resistance in the sample population. Many communities on the Texas-Mexico border are concerned that their cattle will become infected with cattle fever, and without acaricides there are few weapons to battle the ticks. Studies like this will provide the knowledge necessary to enhance our tick control programs and prepare for future problems.

Protection of human and agricultural animal health will need research and testing on both sides of the border, as well as information sharing and collaborative implementation of vector control. In order to achieve this goal, it is necessary for the U.S. and Mexico to work together to stop the spread of tick-borne diseases.