"Ixodiasis and lyme disease [Borreliosis] in the Saku district, Nagano prefecture [Japan]: Clinical and epidemiological studies."

"The incidence of tick bites is not rare in the farming and mountain villages in this country. The bite often makes a swelling as big as a large soybean. After the tick attached to the skin is removed, a small red spot appears at the very site of the bite. Then the red lesion starts expanding distally. In 1987, we reported seven such cases of erythema migrans (formerly called erythema chronicum migrans) in a paper entitled ""Statistics of Ixodid Tick Bites and Ixodiasis."" Incidentally, Baba et al. came up with a report of a case of Lyme disease which was developed after bites of Ixodes persulcatus in Myoko Heights. This report attracted attention becauseit was the first case ever reported in Japan. Since then, we have continued to investigate the incidence of the tick bites and Lyme disease in this country. The following is a summary of our findings thus far. Up until 1999, there were a total of 165 cases of ixodiasis, of which 16 were diagnosed as Lyme disease marked by erythema migrans. The year 1994 saw the largest number of victims of tick bites with 18. June was the peak month in which the largest 135 cases was registered. Age-wise, those aged 10 years or under were most prone to tick bites, accounting for 33 cases, followed by those in their 50s with 32 cases. The most common site of the bite was the abdomen with 99 cases. The back and the breast came second with 39 cases each. In 56 cases, the ticks were extracted by physicians ; in 94 other cases, the removal was done by picking ticks out of the skin by the victims themselves or their family members; and in seven ofher cases, the ticks simply dropped off before the victims realized it. The species of ticks identified include Ixodes persulcatus in 56 cases and Ixodes ovatus in 26 cases. We also report here the results of a questionnaire survey of employees at district forestry offices, a cohort at high risk of tick bites, and measurements of anti-Lyme disease Borrelia antibodies in serum."