Tourists catch meningitis worm

The tourists were visiting Jamaica

A rare form of meningitis caused by worm infestation - normally associated with east Asia - was picked up by tourists in Jamaica.

The New England Journal of Medicine reported how the group of 12, from the US, fell ill after visiting the Caribbean.

It is thought they got infected by eating unwashed salad in a restaurant there.

Meningitis is normally linked to bacterial or viral infection - it refers simply to symptoms caused by inflammation of the membrane surrounding the brain, rather than the cause.

The culprit here was the worm Angiostrongylus cantonensis - also known as the rat lungworm.

A rat infested with the worms will produce eggs which hatch out in the lungs - young larvae are then passed out in the lungs.

They can survive for up to two weeks in water.

To survive, they must infect a snail or slug, inside which they mature further and become infectious to humans.

If humans eat anything carrying slime from these molluscs, then they are at risk.

The larvae then burrow through the gut wall, and are carried around the bloodstream until they reach the central nervous system.

They then congregate in the spinal cord and brain, eventually reaching the membrane surrounding it.

Each is half a centimetre long - and a major infection may involve thousands.

Symptoms

This causes typical meningitis symptoms such as severe headache, back and neck stiffness, aversion to bright lights, nausea, vomiting and vertigo.

If the patient has eaten large numbers of worms - perhaps from consuming an infected snail - then the infection can be serious, and may even result in death.

Nine of the 12 patients affected had to be hospitalised because of the infection, but all made a full recovery.

Investigators could not track down the exact source of the outbreak - but feel it could be a Caesar salad eaten by all of the patients at a restaurant on the island.

Rat infestation

This theory was supported by the fact that the worm was found in rats caught on Jamaica.

It comes as a slight surprise, as the majority of cases are associated with south east Asia and the Pacific Basin - and the report warned that doctors and health officials should be on the lookout for more cases throughout the Caribbean, Cuba, Puerto Rico, and even parts of the southern US such as New Orleans.

Angiostongylus expert Dr George Joshua, from the London School of Tropical Hygiene and Medicine, said: "If you consume a large number of parasites, it can be serious.

"Pretty much every human case is associated with eating snails, but if an affected mollusc crawled about on your salad, you could get it like that."