Catnip as Tick Repellent?

Ticks and Tick-Borne Diseases (González, J., et al.) has published “Repellency of novel catnip (Nepeta cataria) cultivar extracts against Ixodes scapularis and Haemaphysalis longicornis (Acari: Ixodida: Ixodidae)” in November 2022. In an effort to develop natural alternatives for commercial tick repellents, as effective or more effective than DEET, authors investigated the properties of two extracts derived from novel catnip cultivars, CR3 and CR9. Both extracts were tested for effectiveness to repel against both blacklegged ticks (Ixodes scapularis) and Asian longhorned ticks (Haemaphysalis longicornis).

Results of in-vitro assays showed that CR3 and CR9 extracts have similar repellency properties to DEET and, at a 20% concentration, both CR3 and CR9 extracts were 100% effective. Results also demonstrated that catnip extracts maintained repellent effectiveness for at least 8 hours. Interestingly, blacklegged ticks proved more sensitive to CR3 than DEET, and CR3 displayed an acaricidal effect on these ticks.   

Authors summarize that CR3 and CR9 catnip extracts show great promise as a natural and effective tick repellent that should be further developed and tested for their use on humans.

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Lyme Exposure Correlates with COVID Severity

Figure 4. From Science Reports, Szewczyk‑Dąbrowska, A., et al. (2022). “Risks in COVID-19 are linked to a history of tick bites and related infections.”

Scientific Reports, (Szewczyk-Dąbrowska, A., et al.), published “Correlation between COVID-19 severity and previous exposure of patients to Borrelia spp.” on September 24, 2022. Researchers found an association between the severity of the course of COVID infection in patients that also had evidence of past Lyme disease infection.

Investigators identified COVID-positive patients that also had exposure to Lyme through serological testing of patients’ blood for multi-antigens. They evaluated three groups of patients: patients with severe COVID requiring hospitalizations, those with asymptomatic-mild COVID, as well patients that had not been infected by COVID. Findings showed that patients with increased levels of Lyme IgG antibodies strongly correlated with increased COVID illness severity and hospitalizations. In fact, all hospitalized patients in the study tested IgG antibody positive for Borrelia spp

Though the understanding of this link is still not clear, evidence from this research suggests that previous Lyme disease infections play a role in COVID risk and severity of illness. The authors suggest that screening for Lyme antibodies may help assess patients that are at higher risk for hospitalization due to COVID.

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Understanding Red Blood Cell Modifications Caused by Babesia

BabesiaHassan Hakimi, et al., published “Advances in understanding red blood cell modifications by Babesia,” in PLOS Pathogens on September 15, 2022, to further investigate how the parasite invades and multiplies within red blood cells (RBCs) of mammalian hosts.

The researchers explain that to aid in their growth as obligate intracellular parasites, Babesia transmit various proteins to alter the RBC during infiltration and advancement. These proteins are believed to be vital to the survival of parasites and pathogenicity and, therefore, represent the targets of candidate drugs and vaccines. The accessibility of comprehensive genome sequences and the development of transfection systems for a number of Babesia species have facilitated the identification and functional categorization of exported proteins.

The article continues with a review of exported Babesia proteins, as well as an analysis of the roles they play, in the context of immune evasion, cytoadhesion, and nutrient uptake. The study concludes by highlighting potential forthcoming topics for further study and use in the field of tick-borne disease research.

For more information:

Read the study in PLOS Pathogens.

Read more about Babesia.

Q Fever

Dermacentor marginatus (sheep tick) CDC Pub. Health Image Lib.

Q fever is caused by Coxiella burnetti (Cb) bacteria. Disease can be tick-borne, but most cases result from inhaling Cb-containing dust or eating or drinking contaminated food.  Cattle, sheep, and goats are the primary reservoirs.

Although CDC does not indicate it can be a tick-borne disease on its Q fever page, other entities including NORD (National Organization for Rare Disorders) do indicate it can be tick-transmitted. 1, 2,3  CDC’s Public health Image Library, however,  does contain a picture of the ornate sheep tick, Dermacentor marginatus, with portion of caption “This ixodid hard tick species is known to be a vector for the tick-borne encephalitis virus complex as well as the bacterium, Coxiella burnetti , the cause of the disease known as Q Fever. ” 4

The Centers for Disease Control & Prevention, CDC,  indicates on its website that Coxiella burnetti has been previously weaponized for use in biological warfare and is considered a potential terrorist threat. 5

Symptoms include fever, severe headache, malaise, myalgia, chills and/or sweats, cough, nausea, vomiting, diarrhea, abdominal pain, chest pain, and may include endocarditis, encephalitis, pneumonia, hepatitis, splenomegaly. Acute symptoms include hepatitis and pneumonia or chronic endocarditis. IFA titers are used for diagnosis. Usually treated with doxycycline.  Chronic Q fever may be treated with doxycycline and hydroxychloroquine combination or other combinations. 

For More Information:

Citations for Q Fever to be a tick-borne disease

1 NORD https://rarediseases.org/rare-diseases/q-fever/,

2 https://emedicine.medscape.com/article/227156-overview;

3 Stephen R. Graves et al, AJGP VOL. 49, NO. 12, DECEMBER 2020

4 https://phil.cdc.gov/Details.aspx?pid=6289


 Citations for Coxiella burneti & biological warfare

5 https://www.cdc.gov/qfever/transmission/index.html#:~:text=livestock%2C%20or%20crops.-,C.,as%20a%20potential%20bioterrorism%20agent.



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Borrelia miyamotoi: Case Report in CT Patient

Deer tick on leaf

Elsevier, (Bobojama, S. B. et al.) published a case report, “Human Borrelia miyamotoi infection: A cause of persistent fever and severe hyperthermia in New England.” on September 6, 2022. This case report describes a patient from southwestern, Connecticut, a 75-year-old male, who was transported by ambulance to the emergency department (ED) after he had been found unresponsive at his home.

The man had a 3 day history of illness prior to this admission with symptoms including weakness, drowsiness, and eventually altered mental status. He also had rapid breathing and a relapsing fever with body temperatures reaching 106 °F.  In the ED he required active cooling with ice packs, and medications to reduce fever, antibiotics, and insertion of an endotracheal tube to protect his airway due to altered mental status and vomiting. 

Though the patient had no known history of a recent tick bite, his potential exposure to tick habitat initiated testing for common tick borne diseases (Lyme, babesia, anaplasma and ehrlichia). When these tests came back negative, testing for rare tick-borne diseases were then conducted. The patient was empirically treated with a combination of IV antibiotics and an antiviral for suspected meningitis/encephalitis while awaiting laboratory results. The patient showed positive results for Borrelia miyamotoi on PCR testing two days later. Borrelia miyamotoi is a relapsing fever spirochete transmitted by hard-bodied (ixodid) ticks. On day 5, the patient was discharged with plan for continued therapy with doxycycline for a total of 14 days. 

Authors recommend that Borrelia miyamotoi be considered in the differential diagnostics when high fever, headache, and altered mental status occurs in patients where the disease is endemic.

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Rickettsiosis Cases in the US Increasing

CDC Photo: Rocky Mountain spotted fever rash (Rickettsia rickettsii) on child’s face.

Vector-Borne and Zoonotic Diseases (Bishop, A. et al.) published “Increasing Incidence of Spotted Fever Group Rickettsioses in the United States, 2010–2018” on September 9, 2022. The authors of this study analyzed and summarized surveillance data (2010-2018) reported to the Centers for Disease Control and Prevention (CDC) through the National Notifiable Diseases Surveillance System on cases of spotted fever group Rickettsiosis. 

According to statistics collected, white males were at the highest risk. It is unclear how many cases were attributed to Rocky Mountain spotted fever (Rickettsia rickettsii), and how many were attributed to another spotted fever group, Rickettsioses. 

There were 36,632 reported cases of spotted fevers during the study period, with numbers indicating a significant increase in the incidence of this disease during the study period. Arkansas reported the highest incidence of cases and California the lowest. 

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Can Deer Ticks Transmit COVID?

The American Journal of Medicine, (Bakshi, C.S., et al.) published the pre-proof, “SARS-CoV-2 is Emerging in White-Tailed Deer and Can Infect and Spread Among Deer Mice Experimentally: What About Deer Ticks?” on August 16, 2022. Authors have found that a large number of white-tailed deer (Odocoileus virginianus) in the US have become infected with COVID-19. It is believed that this has occurred through reverse zoonosis in which the virus was transmitted to deer from infected humans.  

It is also noted in the study that deer mice (Peromyscus maniculatus) can be experimentally infected with COVID-19 and that these infected mice are capable of transmitting the virus to the same species.  It is unknown at this time whether deer mice or other mice have become infected with COVID-19 in the wild, though authors cite data that suggest that the omicron variant may have actually originated in mice. 

A question that remains is whether or not the deer tick (Ixodes scapularis) can become infected and then transmit COVID-19 to another host during feeding. Currently, only Powassan virus is known to be transmissible to humans through the bite of deer tick in the US. Authors have initiated tick collections in the Hudson Valley, NY, to attempt to answer questions regarding the vector competence of the deer tick and its potential role in the transmission of COVID-19. 

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Analysis of Human Babesiosis and Cardiac Complications

Anne Spichler-Moffarah, et al., published, “Cardiac Complications of Human Babesiosis” in Clinical Infectious Diseases on August 19, 2022. The article explains that many babesiosis patients have mild to moderate expressions of the disease, however, fatal circumstances can result. While cardiac issues are common, the comprehensive range of cardiac disease, as well as the rate of recurrence, risks, and patient outcomes are unknown. Consequently, the researchers performed a review of the records for patients who were admitted to Yale-New Haven Hospital from January 2011 to October 2021 with babesiosis and who were experiencing cardiac complications over the past decade.

Diagnosis was confirmed via the detection of Babesia parasites on thin blood smears and/or the use of polymerase chain reaction. The detection of Lyme disease and other tick-borne diseases was also documented.

The study included 163 enrolled patients, of which 32 (19.6%) had at least one cardiac complication while hospitalized. The most frequent cardiac issues were atrial fibrillation (9.4%), heart failure (8.6%), corrected QT interval prolongation (8.0%), and cardiac ischemia (6.8%).  It was noted that cardiovascular disease risk factors and preexisting cardiac conditions were not considerably associated with the occurrence of cardiac issues. The patient group with cardiac complications had increased incidences of high-grade parasitemia (>10%) (P < .001), lengthier hospital (P < .001) and intensive care unit stays (P < .001), and a greater death rate (P = .02) than the group with no cardiac complications.

Conclusions: complications caused by acute babesiosis are frequent and resulted in roughly one-fifth of this inpatient grouping. Additional studies will be required to uncover the correlation between babesiosis infections and cardiac complications.

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Persistent Babesiosis in Dogs

Pathogens, Theo Schetters, published “Mechanisms Involved in the Persistence of Babesia canis Infection in Dogs” on June 29, 2019. The researcher used controlled experimental infection with B. canis to observe events of infection and the eventual development of signs and symptoms of this parasitic disease in dogs. Very few parasites are detected in the blood of dogs infected with Babesia canis, even when canines present with severe clinical manifestation of disease.

The results of the study showed that B. canis-infected red blood cells accumulate in masses in the minute blood vessels, including capillaries, within body tissues of infected dogs.  This accumulation was shown to cause dilation of  these small vessels leading to variable clinical manifestations of disease, including changes in blood pressure.

The author states that vaccination against soluble parasite antigens (SPA) may potentially limit the rapid reproduction of the parasite which would result in less SPA being produced. Immunity would therefore be anti-parasite and not anti-disease, as hypothesized in previous studies.


Neurological & Hematological Manifestation of Babesiosis

Relapsing BabesiosisCureus, (Tejaswi V, et al.) published “Atypical Presentation of Babesiosis With Neurological Manifestations as Well as Hematological Manifestations” on July 13, 2022. In this article, authors present the atypical manifestations of babesiosis in 2 elderly patients who were both admitted for care with symptoms of confusion, cognitive impairment, slurred speech, ataxia, fever, myalgias and chills, urinary frequency, and urgency. Both patients had additional health issues, or comorbidities. Results of extensive work-ups revealed the possibility of hemolytic infections. Neither patient had a history of travel outside the US, nor did they recall tick bites. Because neither patient had traveled outside the US, babesiosis was suspected over malaria.

Both patients were treated for babesiosis, Lyme and anaplasmosis. The second patient was additionally treated for Mycoplasma infection. Authors observed improvement in cognition, speech within two days of treatment commencement. Both patients showed completely resolved hemolysis, parasitic load, and neurological manifestations after treatment follow-up.

Authors note that their review of literature produced little documentation regarding neurologic manifestations associated with babesiosis. They caution that it is imperative for clinicians to suspect babesiosis when hematologic and neurologic symptoms manifest, especially for people that reside in or have traveled to endemic areas.

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