Introduction:
The nematode Angiostrongylus, often known as the rat lungworm, completes its life cycle by parasitizing both rats (ultimate host) and snails or slugs (intermediate host). In 1933, it was discovered in China after being isolated from rat pulmonary arteries; the first incidence in humans, which serve only as accidental hosts, was reported in 1945. Consumption of infected mollusks is the human infection route. Epidemiological data suggest that prawns, frogs, lizards, and contaminated vegetables are transmission vectors. Human infections with A. cantonensis have been recorded most frequently from Southeast Asia. However, this disease first appeared in the Pacific immediately following World War II, then spread to the Caribbean, and is now threatening South America. At least a few thousand instances have been recorded from all around the world so far.
What Is Angiostrongyliasis Cantonensis?
Angiostrongyliasis, commonly known as neural angiostrongyliasis or rat lungworm, is a brain and spinal cord illness. It is caused by Angiostrongylus cantonensis, a parasitic nematode (roundworm parasite). Adult A. cantonensis is exclusively found in rodents. However, diseased rodents excrete worm larvae in their feces. Therefore, snails, slugs, and other animals can get infected by consuming their larvae.
How Does Angiostrongyliasis Cause Eosinophilic Meningitis?
A. cantonensis is one of the most common reasons people get eosinophilic meningitis. The larvae get into the blood and lymph vessels of the digestive system and move to organs in the circulatory system. The larvae of A. cantonensis move into the brain and spine, changing into young, immature adults several days to weeks after infection. In humans, the worms rarely go to the pulmonary arteries, unlike in rats, which are permissive final hosts. So, the main symptoms are inflammation in the central nervous system (CNS). Even though A. cantonensis infection changes the way cytokines and chemokines are expressed in brain tissue in a big way; the exact way larvae die is still unknown. Interleukin was the first part of the killing machine that was found. This cytokine makes more eosinophils and makes them more active. The other eosinophils kill the larvae and cause more swelling.
What Are the Signs and Symptoms of This Disease?
The symptoms and signs displayed by the individuals can vary. The onset of symptoms may be subtle at first, but they may become more distinct as time passes.
- After getting the infection, some people may feel stomach pain and throw up. Later on, neurological symptoms like headaches may emerge.
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Fever, sensitivity to light, muscle soreness, weariness, and insomnia are all non-specific symptoms. Constant headache, neck stiffness and pain, tingling or burning skin, double vision, bowel or bladder issues, seizures, and so on may all be more specific symptoms.
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Fever, irritability, sleepiness, lethargy, gastrointestinal symptoms, muscle twitching, convulsions, and weakness in the limbs and arms may all be exacerbated in children. In addition, people may go symptom-free for a few days to weeks before experiencing a flare-up of neurologic symptoms.
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The duration of the symptoms varies from person to person but is typically between two and eight weeks.
What Are the Diagnostic Tests for Angiostrongyliasis Cantonensis?
It might be challenging to diagnose sickness caused by A. cantonensis infestation without a thorough history of the patient's exposure to the parasite and the presence of symptoms. Confirmation of eosinophilic meningoencephalitis strengthens the presumptive diagnosis. Eosinophilic meningitis can be diagnosed when signs of high intracranial pressure and an increase in eosinophil count are present. Eosinophilic meningitis is far more challenging to diagnose than other types of meningitis, and A. cantonensis is a common cause of this condition. To check for adult or developing A. cantonensis worms, a spinal tap or cerebrospinal fluid (CSF) sample is required. Unfortunately, over half of the infected people have no detectable levels of A. cantonensis in their cerebrospinal fluid (CSF). Likewise unreliable are the current approaches for detecting individual antigens linked to A. cantonensis. This has led to the development of immuno-PCR and the investigation of other methods for detecting antigen-antibody responses. Furthermore, a rapid dot-blot ELISA test is available for efficient and inexpensive on-site diagnosis of A. cantonensis.
How Is Angiostrongyliasis Cantonensis Treated?
Meningitis caused by A. cantonensis is treated with painkillers and frequent removal of CSF to lower pressure in the central nervous system (CNS). Corticosteroids can reduce the number of times a therapeutic lumbar puncture is needed because it causes parasite antigens to be released into the body. In addition, anthelmintic therapy may make inflammation worse. However, most people get better independently and have no lasting effects.
There is no specific way to treat an infection caused by A. cantonensis. Most infections go away on their own. However, if a person has an A. cantonensis infection, antihelminthic therapy may not be effective as the reactions to dying worms may worsen with therapy.
If antihelminthic treatment is needed, Albendazole is the best choice, and treatment should start early in the disease's course, within three weeks of exposure.
How To Prevent Angiostrongylus Cantonensis Infection?
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Preventing incidental hosts (dogs, birds, horses, etc.) from consuming mollusks and paratenic hosts.
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Do not consume water when dead snails have been discovered.
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Local cases should be reported to public health centers to reduce further consumption of infected intermediate hosts and keep the source contained.
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It is essential to raise public knowledge about the dangers of eating undercooked crabs, snails, slugs, and prawns.
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Because the danger of infection arises from the consumption of the vectors, raw snails or slugs, crabs, and shrimp should be avoided. Furthermore, raw snail slugs may be accidentally included in uncooked meals such as salads. Washing hands should be done while preparing food.
Conclusion
Since this parasite is found all over the world and its hosts (rats and mollusks) make up a significant population, it would be extremely difficult, if not impossible, to completely remove it from the natural environment. However, the transmission pathway of this parasite to humans can be reasonably easily blocked by educating the general public not to eat raw or undercooked snails, frogs, lizards, or any other potential intermediate or paratenic hosts from endemic regions. This will prevent the spread of the parasite.
