Introduction:
Angiostrongylus is a parasitic nematode that, depending on the species, can cause severe gastrointestinal or central nervous system disease in humans. The rat lungworm or Angiostrongylus cantonensis causes eosinophilic meningitis and is common in Southeast Asia and tropical Pacific islands. The parasite's recognized distribution has increased over time, and infections have been identified in other areas, such as Africa, the Caribbean, and the United States. Angiostrongylus costaricensis is found in Latin America and the Caribbean and causes eosinophilic gastroenteritis.
What Are Angiostrongylus Infections?
Two main species of Angiostrongylus can cause diseases in humans. The rat lungworm or Angiostrongylus cantonensis causes central nervous system (CNS) disease, while Angiostrongylus costaricensis causes abdominal disease. Third-stage Angiostrongylus larvae in or around snails, slugs, and other intermediate and paratenic hosts infect humans.
How Does Angiostongylus Cantonensis Cause Infections?
A. cantonensis has been observed to use a diverse range of rat species as definitive hosts, including black rats (Rattus rattus), brown rats (Rattus norvegicus), and cotton rats (Sigmodon hispidus). The gastropod intermediate hosts include Achatina species, Biomphalaria species, Bulinus species, Lymnaea species, and Pomaecea species. However, apart from humans, abnormal infections have been observed in various wild and domestic mammals and birds.
Humans may contract the parasite by eating raw or undercooked snails or slugs infected with it; they can also acquire it by eating raw produce containing a small snail, slug, or a portion of one. The larvae then migrate to the brain or, less frequently, the lungs, where they eventually die. Larvae may develop to the fourth or fifth stage in the human host, but they do not appear capable of fully maturing.
How Does Angiostongylus Costaricensis Cause Infections?
The hispid cotton rat (Sigmodon hispidus) is the primary definitive host for A. costaricensis, but adult worms have also been found in black rats (Rattus rattus), short-tailed zygodonts (Zygodontomys brevicauda), spiny pocket mice (Heteromys adspersus), and pygmy rice rats (Oligoryzomys fulvescens). Slugs from the Veronicellidae and Limacidae families are the most common intermediate hosts.
Abnormal abdominal infections have been documented in humans, nonhuman primates, and other mammals, including raccoons and one opossum. Humans are infected by consuming raw or undercooked gastropods containing third-stage larvae or by eating food contaminated with gastropod tissue or possibly larvae shed in slime. In humans, larvae migrate as expected, can reach sexual maturity, and lay eggs (and L1 larvae) (unlike A. cantonensis). The presence of larvae, adult worms, and eggs in the intestinal wall causes a local inflammatory response. This host reaction usually degrades parasites and eggs, which do not appear to be shed in human stool.
What Are The Symptoms Of Angiostrongylus Infections?
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Angiostrongylus cantonensis
The incubation period of A. cantonensis ranges from one day to more than six weeks on average. A. cantonensis illness typically lasts two to eight weeks but can last longer. People present with bacterial meningitis symptoms such as:
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Nausea.
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Vomiting.
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Neck stiffness.
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Headaches.
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Abnormal sensations of the arms and legs.
The eyes can sometimes be affected. Patients are tested for bacterial meningitis by taking a sample of the fluid surrounding the brain; the fluid does not contain high levels of the cells that help fight bacterial infections (polymorphonuclear leukocytes), as one might expect. Instead, eosinophils are found (this is known as eosinophilic meningitis), though these cells may be absent early or late in the disease's progression. Because the parasite cannot survive in the human body for long, most A. cantonensis infections resolve spontaneously over time. Serious complications, such as neurologic dysfunction or death, are uncommon.
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Angiostrongylus costaricensis
The incubation period is unknown, but it is thought to be several weeks to several months, possibly up to a year. A. costaricensis is most commonly found in the intestine (particularly the ileocecal region) and can cause:
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Abdominal pain.
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Fever.
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Nausea and vomiting.
Abdominal symptoms frequently mimic appendicitis, and infection is discovered after the appendix is surgically removed. In rare cases, larvae enter the abdominal cavity's mesenteric arteries and mature into adults, causing arteritis, infarction, thrombosis, and gastrointestinal bleeding. Adult worm eggs degenerate and lodge in capillaries, causing an inflammatory reaction. The immune system's reaction to adults, larvae, and eggs can cause a massive eosinophilic inflammatory response, including eosinophilic invasion of the intestinal wall and eosinophilic vasculitis. Deaths have been reported as a result of intestinal obstruction and perforation. Recurrent bouts of illness can last for several months. Most cases resolve on their own.
How Are Angiostrongylus Infections Diagnosed?
Diagnosis of Angiostrongylus infections can be difficult because no blood tests are readily available. However, a history of travel to areas where the parasite is known to be found and consumption of raw or undercooked snails, slugs, or possibly transport hosts (such as frogs, freshwater shrimp, or land crabs) in those areas are important clues that could lead to the diagnosis of infection. Another important finding is a high level of eosinophils (a type of blood cell that is elevated in the presence of a parasite, blood, or the fluid surrounding the brain). People must consult a doctor if they suspect any infection.
How Are Angiostrongylus Infections Treated?
Angiostrongylus infections have no specific treatment. However, there is some evidence that certain supportive treatments for A. cantonensis may reduce the severity of headaches and the duration of symptoms.
A. costaricensis infections usually resolve on their own, but surgical treatment may be required to remove inflamed intestine portions. Individuals experiencing symptoms should seek advice from their doctor.
How Can Angiostrongylus Infections Be Prevented?
To prevent Angiostrongylus infections, people who live in or travel to areas where the parasite is found should avoid eating raw or undercooked snails and slugs, freshwater shrimp, land crabs, and frogs, and monitor lizards, as well as potentially contaminated vegetables or vegetable juice. Snails, slugs, and rats found near houses and gardens should also be removed. After preparing raw snails or slugs, thoroughly wash the hands and utensils. If eating raw vegetables, thoroughly wash them.
Conclusion:
Angiostrongylus Infections can cause severe gastrointestinal or central nervous system disease in humans. Two main species of Angiostrongylus: Angiostrongylus cantonensis and Angiostrongylus costaricensis cause central nervous system (CNS) and abdominal diseases, respectively. Angiostrongylus infections have no specific treatment; therefore, eating raw or undercooked snails and slugs, freshwater shrimp, land crabs, frogs, and monitor lizards and potentially contaminated vegetables or vegetable juice must be avoided to prevent the disease.
