Lychee Hazard

This week the Centers for Disease Control (CCD) came out with a warning about lychee fruit. A mysterious, cyclically recurrent epidemic of life-threatening seizures in children in Muzaffarpur, India was finally linked to a cause. And that cause turned out to be consumption of unripe lychee fruit.

The District Official Website of Muzaffarpur proclaims that this “‘The Land Of Leechi’ was created in 1875 for the sake of administrative convenience …. Now it has won international encomiums for its delicious Shahi Leechi and China Leechi” (http://muzaffarpur.bih.nic.in/). We can glean from this that: 1. Lychee is big in that part of India (an imported crop, not native to the area) and 2. Not only are there multiple ways to spell lychee (the CDC prefers litchi), but that encomium can be used beyond the name of a Led Zeppelin tribute album.

The CDC report was anything but a booster for the lychee agribusiness. Their team studied two seasons of the illness in Muzaffarpur. The disease attacks children, causing seizures and other nervous system derangement (encephalopathy). Oddly, the illness outbreaks came on abruptly always at the same time of year, just as quickly fading away. The timing coincides with the lychee growing season. In 2013, 4 in every 10 cases were fatal; in 2014, three in 10. And there were hundreds of children made ill (http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6403a1.htm).

Although initially a viral agent was suspected, sophisticated testing failed to demonstrate any infectious cause. It turns out that unripe lychee fruit naturally contains a chemical called methylenecyclopropylglycine that can be shown in experimental animals to cause low blood sugar. A common laboratory finding in the poisoned children was exactly that: lie-threatening low blood glucose (hypoglycemia). The CDC‘s detective work in India solved the mystery of a similar disease that has been plaguing Vietnam, also in its lychee-growing area. There the syndrome was called Ac Mong, meaning bad nightmares. Not unreasonably, investigators in Vietnam also hypothesized that the problem was infectious, suspecting that the connection might be to virally-contaminated bats feeding on lychees (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3559149/).

Another connection has been made that, in hindsight, seems obvious. This is not the first outbreak of childhood illness with seizures and low blood sugar that has been reported by the CDC. Back in 1992, they provided details on a syndrome also known also “Jamaican vomiting sickness.” That illness, also potentially fatal, is caused by eating unripe ackee fruit, which is a botanical relative of lychee. Unripe ackee contains its own natural toxin called hypoglycin that also dangerously lowers blood sugar (http://www.cdc.gov/mmwr/preview/mmwrhtml/00015987.htm). The vomiting illness is also endemic in West Africa, where ackee fruit originated before it was brought to the New World in the 1800s.

Sometimes ripe exotic fruits can be a problem too. Star fruit (carambola), it seems, also can cause severe adverse neurologic effects too, but this appears to be limited to persons with underlying kidney disease. Recent experimental data suggest that another specific natural toxin, caramboxin, may be the culprit.

It’s not clear what all this will do for lychee’s appeal. Although a delicacy in Asia, in the U.S. it once was relegated to the desert option closing out a mediocre meal that began with a sumptuous pu-pu platter. All that has changed and lychee is now the stuff of which trendy martini dreams are made on. Ripe lychee fruit does not present any known hazard, nor apparently does the fruit of its close relatives, rambutan and longan. Your martini is safe. Nonetheless, there is a certain irony in food writer Kimlai Yingling’s Huffington Post blog posting from almost exactly a year ago, “What Is the Difference Between the Lychee, Rambutan and Longan?” (http://www.huffingtonpost.com/kimlai-yingling/lychee-rambutan-and-longa…) wherein she observes, “Lychee martinis have been hitting the scene for a few years now and remain a pretty popular beverage, but there is definitely more to the lychee than meets the eye.”