Red light eradicating ticks and bacteria with photodynamic therapy.

Shedding Light on Tick-Borne Diseases: How Photodynamic Therapy Could Be a Game Changer

Samir D’Costa in Health & Wellness November 2025 • 4 min read.

"Could light therapy be the new frontier in treating rickettsial infections? Discover how photodynamic therapy offers hope in the fight against tick-borne illnesses and antibiotic resistance."

Tick-borne diseases are a growing concern worldwide, affecting outdoor enthusiasts, pet owners, and even those just spending time in their backyards. Rickettsiae, the bacteria responsible for many of these infections, are transmitted through tick bites and can lead to a range of illnesses, from mild discomfort to severe health complications. As these diseases become more prevalent and antibiotic resistance rises, innovative treatment options are urgently needed.

Traditional treatments for rickettsial infections primarily rely on antibiotics. However, the overuse of antibiotics has led to increasing resistance, making these drugs less effective over time. This has spurred researchers to explore alternative therapies that can combat these infections without contributing to the growing problem of antibiotic resistance.

One such promising approach is photodynamic therapy (PDT). PDT involves using a non-toxic photosensitizer along with harmless visible light to generate reactive oxygen species that kill bacteria. This method has shown promise in treating various infections and is now being investigated for its potential in combating tick-borne diseases.

The Science Behind Photodynamic Therapy

Red light eradicating ticks and bacteria with photodynamic therapy.

Photodynamic therapy (PDT) is emerging as a powerful tool in the fight against various infections, including those caused by tick-borne bacteria. The process is elegantly simple yet remarkably effective. First, a photosensitizer, a non-toxic substance, is applied to the infected area. This photosensitizer is designed to be absorbed by the targeted cells, in this case, the rickettsiae-infected cells.

Next, the area is exposed to a specific wavelength of light, typically red light, which activates the photosensitizer. Upon activation, the photosensitizer interacts with the oxygen molecules present in the cells to produce reactive oxygen species (ROS). These ROS, such as singlet oxygen and free radicals, are highly toxic to the bacteria. They damage the bacterial cells by oxidizing essential cellular components, leading to their destruction. The beauty of this approach lies in its targeted action; the photosensitizer is selectively absorbed by the infected cells, minimizing damage to the surrounding healthy tissue.

Key advantages of PDT for treating rickettsial infections:

Targeted Action: Selectively destroys infected cells.
Reduced Antibiotic Reliance: Minimizes the risk of antibiotic resistance.
Low Toxicity: Uses non-toxic photosensitizers and visible light.
Broad-Spectrum Potential: May be effective against various types of bacteria.

A recent study published in the journal Photodiagnosis and Photodynamic Therapy explored the effectiveness of PDT on Vero cells infected with Rickettsia slovaca, a bacterium known to cause tick-borne lymphadenopathy (TIBOLA). The researchers used methylene blue as the photosensitizer and red light for activation. The results were striking: after treatment, there was a significant reduction in the number of viable R. slovaca bacteria. Specifically, quantitative RT-PCR showed a 96% reduction in bacterial load 48 hours after treatment. Even more impressively, a pretreatment with red light before infection resulted in a 99% reduction.

Future Directions and Implications

The findings of this study open up exciting possibilities for the treatment of tick-borne diseases. While further research is needed, PDT shows promise as a safe, effective, and low-cost alternative to traditional antibiotic treatments. By reducing our reliance on antibiotics, we can help combat the growing problem of antibiotic resistance and protect the effectiveness of these crucial drugs for future generations.

About this Article -

This article was crafted using a human-AI hybrid and collaborative approach. AI assisted our team with initial drafting, research insights, identifying key questions, and image generation. Our human editors guided topic selection, defined the angle, structured the content, ensured factual accuracy and relevance, refined the tone, and conducted thorough editing to deliver helpful, high-quality information.See our About page for more information.

This article is based on research published under:

DOI-LINK: 10.1016/j.pdpdt.2018.09.018, Alternate LINK

Title: Low-Cost Light-Induced Therapy To Treat Rickettsial Infection

Subject: Pharmacology (medical)

Journal: Photodiagnosis and Photodynamic Therapy

Publisher: Elsevier BV

Authors: Eva Špitalská, Zdenko Špitalský, Zoran Markovic, Katarína Štefanidesová, Ľudovít Škultéty

Published: 2018-12-01

Everything You Need To Know

How does photodynamic therapy (PDT) work to combat tick-borne diseases?

Photodynamic therapy (PDT) is a treatment that uses a non-toxic photosensitizer and visible light to generate reactive oxygen species, which are toxic to bacteria. The photosensitizer is absorbed by infected cells, and when exposed to light, it produces these reactive oxygen species that damage and kill the bacteria. This approach targets infected cells while minimizing harm to surrounding healthy tissue.

What are the current treatments for rickettsial infections, and what are their limitations?

The traditional treatment for rickettsial infections primarily relies on antibiotics. However, the overuse of antibiotics has led to increased antibiotic resistance, making them less effective over time. The rise of antibiotic resistance has prompted the exploration of alternative therapies like photodynamic therapy (PDT) to combat these infections.

What did the study on Rickettsia slovaca reveal about the effectiveness of photodynamic therapy (PDT)?

The recent study in *Photodiagnosis and Photodynamic Therapy* used methylene blue as a photosensitizer and red light to treat Vero cells infected with *Rickettsia slovaca*, the bacterium that causes TIBOLA. The study demonstrated a significant reduction in the number of viable *R. slovaca* bacteria, with a 96% reduction in bacterial load 48 hours post-treatment. Pretreatment with red light before infection even resulted in a 99% reduction.

What are the advantages of using photodynamic therapy (PDT) over traditional antibiotic treatments for rickettsial infections, and what are the limitations?

Photodynamic therapy (PDT) offers several key advantages for treating rickettsial infections. It provides targeted action by selectively destroying infected cells, reduces reliance on antibiotics (minimizing antibiotic resistance), exhibits low toxicity through the use of non-toxic photosensitizers and visible light, and demonstrates broad-spectrum potential, suggesting effectiveness against various types of bacteria. However, PDT's effectiveness can vary based on the specific bacteria, photosensitizer used, and light source, necessitating further research to optimize its application.

What are the broader implications of using photodynamic therapy (PDT) to treat tick-borne diseases beyond just individual patient care?

The implications of photodynamic therapy (PDT) extend beyond just treating current tick-borne diseases. By offering a low-cost alternative to antibiotics, PDT could significantly help in combating the growing global issue of antibiotic resistance. Widespread adoption of PDT could preserve the effectiveness of antibiotics for future generations, ensuring that these crucial drugs remain viable options for severe bacterial infections. Further research is needed to fully realize its potential.