FORT WORTH (KRLD) - As the number of Texans sickened by the cyclospora infection continues to grow, tracking the source of the outbreak is moving painstakingly slow.
More than 200 Texans have been diagnosed with the illness, 41 of them in Tarrant and 32 in Dallas County.
While health officials in Nebraska and Iowa have traced their outbreaks to salad mix served at local Olive Garden and Red Lobster restaurants and supplied by a Mexican farm, Texas authorities say the common source for the sickness has eluded them.
"We have not been lucky in that regard, as far as finding a good cluster here in our county. We are looking for the smoke, so we can trace back to the gun," said Russ Jones, Tarrant County chief epidemiologist.
That smoking gun has been tough to find, in part because of the long incubation time of the illness. Symptoms of cyclosporiasis may not show up for 14 days after the parasite was ingested in contaminated food or water. In many cases, those symptoms can be relatively mild and may not prompt an immediate doctor's visit, according to Chris Van Dusen from the State Health Department. When the symptoms reoccur and patients do visit the doctor, several weeks may have passed since exposure.
"We are asking people to think back, 'What did you eat? Two, three, four weeks ago?' It's not as easy for people to answer that. Frankly it just takes some time…it's a lot of shoe leather detective work," said Van Dusen.
The process with each patient can be a lengthy one. Then, health officials must combine that information to find clusters of people who may have dined at the same restaurant or shopped at the same grocery store around the same time.
"It really involves interviewing people, asking them to fill out questionnaires, and going back and interviewing people to determine where they ate, where they bought groceries, what type of food," said Van Dusen.
Thorough washing of all fresh produce is recommended as a way to prevent cyclospora infection, but even that does not completely eliminate the risk.
"To decrease the risk of eating fresh produce it is important to thoroughly rinse your fruits and vegetables several times," said Dr. Christopher Perkins, Dallas County Health and Human Services medical director. "Even when cooking vegetables, it is critical to clean them beforehand."
Already the number of cyclospora cases reported in Dallas County over the past couple of months nearly triples the number of cases reported over the past 12 years. Only 12 cases have been reported in Dallas County since 2001.
However, Van Dusen says looking at the number of cases reported most recently, there may be a light at the end of the tunnel.
"Of the illnesses that have been reported to us, the last onset date was in late June. We haven't seen any more recent," he said. "Our peak was several weeks ago, so it may be that we are on the downslope of this or it may be that we are going to get more cases reported."
Nationwide, nearly 470 people in 16 states have been sickened by the cyclospora infection.
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