Gnathostomiasis
Gnathostomiasis /lat. gnathostomosis/ is a natural zooanthroponosis from the group of nematodes with a fecal-oral transmission mechanism of the causative agent. It is characterized by polymorphic and clinical manifestations.
About 1000 cases of the disease are known. They are registered primarily in Thailand, but also in India, Indonesia, Myanmar, Malaysia, the Philippines, Japan, China, Bangladesh and Israel. The disease is characterized by infectious outbreaks in nature. People living in the coastal areas get sick, regardless of their belonging to certain population groups.
What are the causes?
The cause of the disease is the small or medium-sized nematode Gnathostoma spinigerum, parasitizing the digestive tract of vertebrates.
After developing in water at a temperature of 27 – 31 °C, after a few days they form the larvae, which are swallowed by freshwater crustaceans inhabiting the regions mentioned above.
They are eaten by intermediate hosts such as fish, frogs and birds, in which the larvae form cysts.
The larvae of Gnathostoma spinigerum cause eosinophilic meningitis in humans, migratory swellings on the skin, damage to the eyes and internal organs.< /p>
Pathogenesis
A person usually becomes infected by consuming uncontaminated water, meat, fish, frogs or birds. Parasitism through the skin is also possible.
The natural susceptibility of people to this nematode has not been established, the same applies to the duration of the incubation period.
When parasitizing humans, the larvae migrate through the stomach wall to the liver, and then spread to the subcutaneous fat tissue and other organs and tissues. Therefore, the clinical manifestations are diverse and depend on the localization of the parasite.
The most common manifestations of parasitic invasion are – “creeping” rash, subcutaneous nodules, migrating swellings and abscesses. Of the deep disorders, the most characteristic are gastrointestinal and brain disorders.
What are the symptoms?
Clinical manifestations are usually associated with the migration of a single larva into the skin, internal organs, central nervous system or eyeball.
During the migration, local inflammatory reactions, pain, cough, hematuria accompanied by fever and eosinophilia can be observed.
If the skin is affected, painful and itchy migratory swellings appear – the distal parts of the limbs and eyelids are especially often affected.
Manifestations usually disappear after a week, however, they often recur for many years. Affecting the eyeball is a serious danger to vision.
When the central nervous system is affected, eosinophilic meningitis with encephalomyelitis develops. This severe complication is due to the migration of the larvae along the nerve trunks and inside the central nervous system.
Attacks of excruciating sharp pains, paresthesias of the buttocks and limbs are characteristic, which may be followed by paraplegia. Affecting the brain with focal hemorrhages and necrosis often ends in death.
Diagnosis
Establishment of migrating swellings against the background of pronounced eosinophilia combined with a corresponding epidemiological history usually makes it possible to make the diagnosis of gnathostomiasis. But it is possible that the parasitic invasion is widespread and progresses without previous skin manifestations.
In the latter case, eosinophilic cytosis, blood, or xanthochromia were found during examination of cerebrospinal fluid. However, helminth larvae are practically never found in it.
Treatment of gnathostomiasis
The best method of diagnosis and treatment at the same time is the surgical removal of the parasite from the subcutaneous tissues and eyes. But unfortunately, this is rarely feasible.
Albedanzole is sometimes effective – 400-800 mg internally for a period of 21 days. In case of central nervous system involvement, symptomatic treatment is recommended, usually including glucocorticoids.
