HARD SCIENCE ON LYME: Another journalist with only half the story

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.

In his interview with Terry Gross on Fresh Air, journalist Michael Specter says that patients are desperate and that “chronic Lyme” is “more comforting” for them to grab onto than a vague, incurable diagnosis of post-treatment Lyme disease, the preferred IDSA terminology – and a concept that is “recognized,” he points out. He thinks he is being sympathetic and doesn’t seem to realize how condescending and very offensive this sounds to Lyme patients.

The FDA gave its blessing to Lyme tests that miss as many as half the cases or more. The CDC thinks this should be good enough for patients. But patients insist on tests with better sensitivity from specialty labs in spite of having to pay out of pocket. Why is the government trying to prevent them from using all the tools in the arsenal when failure to diagnose has profound, life-altering consequences?

It is important to understand mechanisms of persistence in tick-borne diseases.  Microbes use different mechanisms to evade the immune system and survive. A study by Anthony Barbet of the University of Florida describes the mechanisms by which babesiosis and anaplasmosis persist in animals.  He notes that many vector-borne diseases remain resistant and states: "Some of the most intransigent of these are infections that induce a 'carrier' state, where the animal remains infected, is still able to transmit organisms to the vector, but may show disease symptoms intermittently or not at all. Indeed, it may be difficult to detect the infection by classical means."  He points to Babesia and Anaplasma as prime examples of this type of persistence and discusses how new and sensitive molecular diagnostic methods have made it possible to demonstrate that "a typical infection course consists of numerous relapsing peaks of organisms separated by time periods when they are not detected."

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.