Angiostrongylus cantonensis

Angiostrongylus cantonensis, commonly known as the rat lungworm, is a parasitic nematode (roundworm) that causes angiostrongyliasis, the most common cause of eosinophilic meningitis in humans. This condition arises when the parasite invades the central nervous system. Originating in Southeast Asia and the Pacific Basin, the parasite has spread to many other parts of the world, including the Hawaiian Islands, the Caribbean, and the American South.

Life Cycle

The life cycle of Angiostrongylus cantonensis involves two main hosts: rats, which serve as the definitive hosts, and snails or slugs, which act as intermediate hosts. Adult worms reside in the pulmonary arteries of rats, where females lay eggs. These eggs hatch into first-stage larvae, which migrate to the rat's throat, are swallowed, and then excreted in the feces. When snails or slugs come into contact with these larvae-infested feces, they become infected. The larvae develop into the third stage, which is infectious to mammals, within these intermediate hosts. Humans can become accidental hosts by ingesting raw or undercooked snails or slugs, or by consuming vegetables, fruits, or water contaminated with the larvae.

Symptoms and Treatment

In humans, Angiostrongylus cantonensis larvae can cause a rare type of meningitis (inflammation of the membranes surrounding the brain and spinal cord) known as eosinophilic meningitis. Symptoms may include severe headache, stiff neck, fever, nausea, vomiting, and neurological abnormalities. The severity of the disease can vary, and in some cases, it can lead to permanent brain damage or death.

Diagnosis is typically made through a combination of clinical symptoms, history of potential exposure, cerebrospinal fluid analysis showing eosinophilia, and sometimes serological tests. Treatment primarily focuses on relieving symptoms, as there is no specific treatment for the infection. In severe cases, antiparasitic drugs such as albendazole or mebendazole may be used, but their effectiveness is uncertain.

Prevention

Prevention of Angiostrongylus cantonensis infection involves avoiding consumption of raw or undercooked snails, slugs, frogs, and crustaceans. Proper washing and cooking of food items and avoiding contact with snails and slugs in endemic areas can significantly reduce the risk of infection.

Epidemiology

The distribution of Angiostrongylus cantonensis has expanded due to global trade and the movement of rats and intermediate hosts. Cases of angiostrongyliasis have been reported in Southeast Asia, the Pacific Islands, Africa, the Caribbean, and parts of the United States. Travelers to endemic areas are at risk, especially those consuming local raw or undercooked foods.

Research

Research on Angiostrongylus cantonensis is focused on understanding its life cycle, pathogenesis, and potential treatments. Studies on the development of vaccines and more effective diagnostic tests are ongoing.