Scientists study whether antioxidants protect against tick-borne illness
National Institute of Allergy and Infectious Disease to investigate
if increased intake of antioxidants can protect against tick-borne
illnesses.
Rocky Mountain spotted fever is a potentially life threatening tick-borne illness caused by the parasitic bacteria Rickettsia rickettsii. Over half of the cases in the US occur in the south-east Atlantic states, but the disease has also been documented throughout the Americas.
A similar bacteria, Rickettsia connorii, causes Mediterranean Spotted Fever (also called Boutonneuse fever), and is transmitted by dog ticks. The fever is endemic in many Mediterranean countries.
The majority of cases are recorded between April and August, which puts people who spend their summer holidays hiking in these areas at risk of contracting these disease.
While limiting exposure to ticks is the best preventative, researchers at the University of Rochester Medical Center, led by Sanjeev Sahni are investigating the role that antioxidants, like alpha-lipoic acid, vitamins C and E, and antioxidants found in green tea, might play in preventing the rickettsia bacteria.
The five-year study is supported by a grant of $2m from the National Institute of Allergy and Infectious Disease.
Previous research by Sahni has reported that cells undergo oxidative stress as a direct result of infection by R. rickettsii and R. connorii, and produce harmful free radicals, causing inflammation and other complications.
They hypothesised that antioxidants might serve as useful therapies after examining the damage to infected cells, as seen by electron microscopy, and through biochemical evidence proving oxidative stress.
Earlier experiments in which scientists infected cells with rickettsia bacteria and then exposed the cells to the potent antioxidant, alpha-lipoic acid, showed that the infected cells did, indeed, marshal a defence against the bacteria (Infection and immunity, 1998, Vol 66, pp 2290-2299).
Now Sahni, backed up by the million dollar funding, is to continue the search to see if increased intake of antioxidants from dietary or supplemental sources could offer protection from the diseases.
The Rochester researcher will also investigate what enzymes might boost the activity of antioxidants. The group, said Sahni, will study the process that occurs when infected cells express cyclooxygenase (Cox-2) and prostaglandins, which results in inflammation. This biological process is what causes the severe swelling in the limb that was bitten by a tick harboring the rickettsia bacteria.
The diseases are treatable with appropriate antibiotics but misdiagnosis can occur because the early symptoms are said to be similar to other less-serious viral infections.
The most common, and better known, tick-borne illness Lyme's Disease is caused by a different bacteria, Borrelia burgdorferi.
