HARDSCIENCEONLYME: Horse Treated for Lyme Improves, Relapses, then Dies

Researchers have recently discovered that another species of Borrelia transmitted by deer ticks causes illness. The species, Borrelia miyamotoi, was discovered in Japan in 1995, but occurs in Asia, Europe and North America as well. A new study confirms that B. miyamotoi causes human disease "including relapsing disease that may last for months and may not respond to inappropriate antimicrobial drug therapy." Because B. miyamotoi is transmitted by an array of ixodid ticks and can be passed via the ovaries from one tick generation to the next, it "greatly expands the potential geographic distribution of this disease". The study notes that further investigation of possible B. miyamotoi infection in humans is warranted wherever I. pacificus, I. persulcatus, I. ricinus, and I. scapularis ticks are found.

One of the hot topics in Lyme disease is whether the bacteria that causes Lyme disease persists. There are a lot of factors that go into proving this, but one is whether there is a “plausible biological mechanism for persistence.” What this means is whether there is a mechanism in biology that might allow the bacteria to survive. Simply put, the Infectious Diseases Society of America says there isn’t and other researchers disagree. The most recent article on this subject is from Straubinger, who is best known for his research on persistence in dogs. The highlights of the study after the jump. . .

David Leiby, of the Red Cross, has declared the risk of blood transfusion for Babesia microti to be unacceptably high. Babesia microti is a coinfection of Lyme disease that is transmitted primarily by ticks. Over the past 30 years, between 70-100 cases of transfusion transmitted Babesia have been reported, with at least 12 fatalities. Although the need to screen for the parasite which lives in red blood cells is now recognized as urgent, the method of screening blood has yet to be determined and several obstacles remain before screening practices are adopted. However, according the Leiby, failure to screen is "no longer a viable alternative". The abstract to the article follows the jump. . .

A group of researchers, (Swei, Ostfeld, Lane, and Briggs), did a study on the western fence lizard recently that produced some interesting results. The life cycle of the tick involves three stages and three blood meals. Ticks are born without the Lyme disease bacteria. However, they may acquire it during their first blood meal (as larval ticks), their second blood meal (as nymphal ticks) or their third blood meal (as adult ticks). Lizards host up to 90% of larval and nymphal I. pacificus ticks. Western fence lizards (as well as the southern alligator lizard) are not competent hosts for Lyme disease bacteria. This means they cannot transmit Lyme disease to feeding ticks. But even better, their immune system actively kills the Lyme spirochete in ticks that feed on them. So a tick that feeds on one of these lizards will take its next blood meal without the bacteria that transmits Lyme disease. This eliminates the risk of people contracting Lyme disease from the ticks that have previously fed on the lizard and reduces the infection rate of the ticks generally in the area. You would think that the number of infected ticks would go up in the absence of the lizard that kills the Lyme bacteria. Not so. . . Find out why after the leap.

I had to post this image and encourage anyone interested in biofilms to go visit the website that hosts this interactive introduction to biofilms. Some of you know that biofilms have been implicated in Lyme disease. Drs. McDonald and Sapi recently published on this topic. The gist of the matter is that biofilms may be one of the ways in which bacteria persist in the body. They can provide a protective covering that antibiotics cannot penetrate. It’s a pretty esoteric subject matter, but this website describing how they work is pretty down home. Give it a visit if you get a chance. And, kudos to the University of Montana for making this available to folks like us who just need simple explanations so we know how things work! The link is after the jump.

I thought I would share a few prevention practices identified at the Institute of Medicine Lyme disease workshop as effective by Dr. Mathew Liang of Harvard Medical School. One idea focused a study in Nantucket by Daltroy (2007) on an educational outreach method. The 5-year study randomized 29,000 people traveling by ferry to Nantucket and exposed the study group to an entertainment-based information session about Lyme disease and steps to prevent it. Participants also received a card with a Braille dot on it the size of a tick and a plastic shower card similar to those used for breast self-exam, tweezers, and a map of the island where ticks were prevalent. The study showed a reduction in Lyme disease in the group who received the message, both among year round residents and among visitors, who constitute a high-risk population.