A team of researchers at Stanford School of Medicine recently reported that the antihistamine loratadine and specifically its metabolite desloratadine may prove to be useful in treating Lyme disease. The disease is transmitted to humans by the bite of a tick infected with one of three closely related species of the Borrelia bacterium; Borrelia burgdorferi (sensu stricto), B afzelii and B garinii. In the UK, Lyme disease is usually caused by B afzelii and B garinii whereas in the USA B burgdorferi (sensu stricto) is more prevalent. The ticks are normally carried on deer and other small animals such as mice.
Lyme disease can affect any part of the body and causes flu-like symptoms, extreme tiredness, muscle pain, muscle weakness, joint pain, upset digestive system, headache, disturbances of the central nervous system and a poor sleep pattern. In some cases a characteristically shaped spreading ‘bull’s eye’ rash appears on the skin. The symptom pattern varies from person to person but often responds well to antibiotics such as doxycycline or amoxicillin. However, some victims have lingering symptoms of fatigue, pain or joint and muscle aches. This may be known as chronic Lyme disease although the term is controversial and post-treatment Lyme disease syndrome may be used instead.
Lyme disease has been around for a long time, perhaps since the last Ice Age. It has been known under various names in different countries and was even found to have been carried by the Neolithic mummy known as Ó¦tzi the Iceman discovered in the Italian Alps in 1991.
The new in vitro study in California funded by the Bay Area Lyme Foundation showed that loratidine was able to prevent manganese being transported through the cell wall of Borrelia burgdorferi so causing the bacteria to die. The bacteria requires manganese for vital metabolic processes and normally scavenges the body for trace metals like manganese in the blood. It has developed special adaptions called transport proteins on the cell walls which enable such trace metals to be carried into the cell. The specialised transport protein for Borrelia bacteria is Borrelia metal transporter A (BmtA) and the antihistamine appears to inhibit the process by which BmtA binds to manganese.
Lyme disease seems to be becoming more common. Public Health England (PHE) official estimates suggest there could be up to 3,000 new cases occurring in the UK every year while in the USA they reckon on 300,000 new cases annually. As current treatments for this potentially debilitating infection do not work for everyone and because the disease can offer many treatment challenges, this study offers encouraging insights to researchers and hope for those of us who live or work in those parts of the country where the ticks carrying the infection are prevalent.