Transmission Of Rat Lungworm Disease: Symptoms And Treatment

Rat lungworm disease is caused by roundworm called angiostrongylus cantonensis. The nematode (roundworm) resides in arteries of rat’s lung hence it is called rat lungworm. The larva of angiostrongylus cantonensis are excreted feces of rat. Snails and slugs act as intermediate hosts as they ingest this larva from the infected rat’s feces. Humans become infected with the worm when they eat raw or under-cooked snails and slugs. The larvae may also enter into human after eating unwashed vegetables especially lettuce as it is often contaminated with slugs.

Rat lungworm can cause cold and flu like symptoms or may be responsible for serious eosinophilic meningitis (inflammation of brain) which may sometimes cause death or permanent brain damage.

The disease is mostly found in Southeast Asia, Western Pacific Islands, etc. Most people do not require medical treatment as the parasite dies. Usually supportive treatment and analgesics are given to the patient to relieve headache.

Signs And Symptoms Of Rat Lungworm Disease

The symptoms of rat lungworm disease may differ from one person to another. Some infected people may not have any symptoms, while some may experience flu like symptoms. In few others the disease may be life threatening.

The symptoms develop 1 to 3 weeks after ingestion of the parasite. There is no specific time period and the symptoms may last for few days to few months.

The infected person may experience following symptoms:

  • Mild to moderate fever.
  • Severe headache with mild of high fever.
  • Vomiting
  • Stiffness of neck
  • Sensitivity to light
  • Tingling and painful sensation all over body.
  • Patient is extremely sensitive to touch.
  • Urine retention.
  • Temporary facial paralysis.
  • General paralysis
  • Coma and death in serious cases of meningitis.

Causes And Transmission Of Rat Lungworm Disease

Rat lungworm disease is caused by a nematode (roundworm) called A. Cantonensis. The disease spreads from rats as the adult worm resides in the pulmonary arteries of rats. Rats get infected when they eat the larvae of the worm. In infected rat the larvae becomes adult worm and it lays egg which are excreted through the rodent’s feces. Snails, slugs and fresh water prawns eat these larvae. Humans become infected when they eat either raw or under-cooked snails, slugs, which contain the infective rat lungworm larvae.

The disease is prevalent mainly in Southeast Asia, Pacific and Caribbean Island, and some parts of United States. Occurrence of this disease is more in Hawaii Island as various types of snails and slugs are found and carry the infective parasite in that area. The semi slug has tendency to climb and excrete its mucus on plants especially on home grown lettuce and other vegetables. Eating these contaminated food produce can also lead to rat lungworm disease. The definite host in this disease is rats. The intermediate host is snails and slugs.

Treatment For Rat Lungworm In Humans

Diagnosis of the disease is not easy and doctors rely on history of ingestion of common host such as snail and slugs, especially in areas predominantly suspected to be infected with the disease. Blood tests and cerebrospinal fluid examination often help in diagnosis of the condition, especially when high numbers of eosinophils are found.

There is no specific treatment of rat lungworm disease. Patients do not require any treatment because with passage of time the parasite dies. The parasite does not mature or reproduce in humans. Usually patient infected with this disease may need analgesics to alleviate headache. In case of eosinophilic meningitis patient may need careful observation in hospital with various medications according to the symptom manifestation.

Rat lungworm disease can be prevented by avoiding eating raw or under-cooked snails and slugs. Cleaning food produce properly is extremely important to reduce incidences of food borne illnesses.