Updated

An unusual rise in syphilis cases has health officials investigating why Tulare County residents are getting the sexually transmitted disease at a higher rate than in other counties.

Preliminary California Department of Public Health data shows that about half the syphilis cases in the San Joaquin Valley in 2007 came from Tulare County, which had 30 cases for the year.

Tulare County health officer Dr. Karen Haught said the county had 21 cases in 2006 and 14 in 2005.

Haught said most of those infected used methamphetamine or had sexual contact with meth users, who are more likely to engage in risky behavior.

State health officials said 1.2 of 100,000 people in the Valley's seven counties had the disease in 2007 compared to 4.6 of every 100,000 people in Tulare County.

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