The Leander Paes syndrome is fast becoming a common Calcutta affliction. The tennis hero, say doctors, is just one among a growing list of patients laid low by tapeworms working their way up to the brain. And the germ of the problem often lies not in pork, but cucumber or leafy vegetables or even water.

Neurologists in town are concerned with the rapid rise in the incidence of neurocysticercosis — the condition in which tapeworms attack the brain — sometimes manifesting as convulsions or severe headaches or even causing permanent damage to vision.

But there are more worrying aspects to the disease than the mere rise in numbers, warn experts. Water and green, leafy vegetables — especially those grown in fields where human faeces is found — are fast becoming the most favoured route for tapeworms, not just pork.

Neurologists say they are now asking their patients to avoid raw and under-cooked vegetables. Salad ingredients like carrot, beetroot, tomato, lettuce, cauliflower, cabbage and even cucumber, they warn, are on the lookout list as they are eaten raw .

“Cold salads or those prepared without proper washing and cleaning have become the main source of infection nowadays,” stresses Tapas Banerjee, head of department (neuromedicine) of the National Neurosciences Centre (NNC), at Peerless Hospital. “Earlier, only pork-eaters were considered to be in the high-risk group.” Pork, of course, must still be boiled first and then cooked thoroughly before being consumed, warn doctors.

Neurocysticercosis is a parasitic infection of the central nervous system caused by tapeworms consumed — along with food — in larvae form. The eggs of the tapeworms make their way from the intestines to the bloodstream and, ultimately, to the brain. “The worms can wreak havoc inside the brain, depending on the site of invasion,” explains neurologist S.S. Nandi. “Lesion caused by neurocysts can affect sight, damage the spinal chord and even cause madness.”

Water, too, is not above suspicion when it comes to tapeworm trouble. NNC recently admitted a patient who had been infected thrice. “Initially, we were clueless,” says Banerjee. “Investigation revealed tapeworm eggs in the patient’s intestine and tests showed that the water the family was drinking was faecally contaminated.”