Parasitic worms found in dead rats in an Atlanta zoo pose “a possible threat” to humans, according to a study published in a U.S. Centers for Disease Control and Prevention (CDC) journal.
The parasite, Angiostrongylus cantonensis, also known as rat lungworm, can cause a rare type of brain infection in humans which can result in painful feelings in the skin, vomiting, stiff neck, headache, and nausea.
“Most infections of A. cantonensis resolve spontaneously over time without specific treatment because the parasite cannot survive for long in the human body. However, serious complications can rarely occur, leading to neurologic dysfunction or death,” the CDC notes.
An analysis of the rats’ tissue samples showed that seven of these creatures—over 20 percent—had A. cantonensis parasites in their heart, pulmonary artery, and brain tissues.
Rodents usually become infected with these parasites after ingesting “terrestrial gastropods,” a class of mollusks, the study said.
It warned that A. cantonensis in rat populations and other hosts in the greater Atlanta region can “pose a possible threat” to the health of human beings and animals.
Most human infection cases are reported from Asia. The discovery of the infection in wild brown rats in Georgia suggests that the parasite “has become established in a new area of the southeastern United States,” the study states.
A. cantonensis has been previously identified in rats in two states neighboring Georgia—Alabama and Florida.
The Infection
According to the CDC, humans can become infected with A. cantonensis by eating raw or undercooked snails or slugs infected with the parasite. Snails are eaten in certain cultures.Sometimes, children eat snails as part of a dare and end up getting infected. For instance, a boy from New Orleans became infected by swallowing a raw snail “on a dare” back in 1993. The child became ill a few weeks later, the CDC reported. The symptoms disappeared in about two weeks without treatment for the infection.
In addition to eating raw snails or slugs directly, people can also become infected by eating raw produce like lettuce, which may contain parts of a small slug or snail. Certain animals like frogs, crabs, and freshwater shrimp can also be infected with A. cantonensis. Eating them raw or undercooked can result in infections as well.
A. cantonensis infections usually do not have to be treated as the parasites die over time without any treatment, according to the CDC. Even those who end up developing eosinophilic meningitis—a brain infection—usually do not need antiparasitics, it notes.
“The most common types of treatment are for the symptoms of the infection, such as pain medication for headache or medications to reduce the body’s reaction to the parasite, rather than for the infection itself,” the CDC states. However, “patients with severe cases of meningitis may benefit from some other types of treatment.”
The agency advised people to avoid eating raw or uncooked snails or slugs, frogs, and shrimp or prawns. People who handle snails or slugs are recommended to wear gloves and wash their hands.
When handling fresh produce, it must be washed thoroughly. When traveling to regions where the parasite is known to be common, the CDC asks that people avoid eating uncooked vegetables.
Brain Parasites
The CDC’s study on A. cantonensis parasites is the latest in a series of brain-infecting parasite cases that have made headlines.Earlier in August, a 16-month-old boy from Arkansas died at a children’s hospital from an infection caused by the amoeba Naegleria fowleri.
Naegleria fowleri is an amoeba that lives in soil and warm fresh water like rivers, lakes, and hot springs. The organism causes primary amebic meningoencephalitis (PAM), a disease of the central nervous system.
Naegleria fowleri “is commonly called the ‘brain-eating ameba’ because it can cause a brain infection when water containing the amoeba goes up the nose. Only about three people in the United States get infected each year, but these infections are usually fatal,” the CDC states.
The child was “likely exposed” to the amoeba while playing in a splash pad, said the Arkansas Department of Health (ADH).
During her open biopsy, surgeons removed a “stringlike structure” from her brain which turned out to be a live Ophidascaris robertsi, a roundworm commonly found in carpet pythons. Scientists consider this to be the world’s first case of human infection by any species of Ophidascaris.
“Although visceral involvement is common in animal hosts, the invasion of the brain by Ophidascaris larvae had not been reported previously. The patient’s immunosuppression may have enabled the larvae to migrate into the central nervous system,” the scientists wrote in a journal published by the CDC.
