Introduction:
More than 25 Capillaria species have been identified in mammals, birds, fish, amphibians, and reptiles. However, only four of them are found in humans. They include Capillaria aerophila, Capillaria hepatica, Capillaria plica, and Capillaria philippinensis. Furthermore, Capillaria hepatica and Capillaria philippinensis are the two species of nematodes causing hepatic and intestinal capillariasis, respectively. These infections have curative treatments but, if neglected, are fatal.
How Do We Get Infected With Capillariasis?
Capillaria hepatica is a parasite found in the liver of monkeys, dogs, and rodents, which can cause liver cirrhosis (end stage disease of liver) in these animals. When carnivores eat these infected animals, the eggs are ingested and excreted through the carnivore’s feces. The contact of this fecal matter with the soil makes it infective in around 30 days affecting other organisms later. If humans ingest them, the eggs travel to the liver and grow into worms. Capillaria philippinensis can be found in freshwater fish. When humans eat these undercooked or raw parasite-containing fish, larvae travel and mature into worms in the intestine. The female worms release the eggs, which get excreted in the fecal matter. When the fecal matter reaches water bodies, another cycle begins after the fish ingests infected feces.
Is Capillariasis Contagious?
Capillaria hepatica can get transmitted among humans through eggs deposited in fecal matter, contaminating the soil. However, Capillaria philippinensis is not transmitted from person to person as it requires an intermediate host. But in the case of adult Capillaria philippinensis, the eggs released by worms hatch into larvae and cause hyperinflation in the intestine.
Where Are Capillariasis More Common?
The cases of hepatic capillariasis are rare but have been reported worldwide and do not have a specific region of disease spread. But, intestinal capillariasis is frequently reported in the Philippines, Thailand, Columbia, and other Asian countries.
What Are the Signs and Symptoms of Capillariasis?
When only one worm of Capillaria hepatica infects humans, no signs and symptoms are present. When multiple worms are present, fever with a temperature above 40 degrees Celsius, anemia, hypereosinophilia, hepatomegaly, and hepatitis. In this condition, the eggs are deposited in the liver parenchyma, which forms granuloma and necrosis. The presence of the condition is often underestimated as there are no specific clinical signs, and diagnosis is difficult.
When an individual is first infected with Capillaria philippinensis, The infection begins as a gastrointestinal disease, and a protein-losing enteropathy can cause cardiomyopathy, emaciation (malnutrition leading to extreme thinness), cachexia (substantial weight and muscle loss), and eventually death. The fatality rate of intestinal capillariasis is around 10 percent.
How to Diagnose Capillariasis?
Capillaria hepatica can be identified by taking a liver biopsy, in which adult worms or eggs can be demonstrated. A needle biopsy and autopsy after death could also help. However, examining a stool sample cannot diagnose this parasitic infection.
In Capillaria philippinensis, a small intestine and stool samples biopsy can help diagnose where eggs, larvae, or adult worms can be identified. However, embryonated eggs are typically visible in the fecal samples, whereas embryonated ones can be identified only during severe infections. Therefore, serological testing does not help identify Capillaria philippinensis.
How Is Capillariasis Treated?
Capillaria hepatica is a rare infection, and its clinical presentation is limited. However, steroids to treat hepatic inflammation and for expelling the worms, anthelmintics, such as Thiabendazole and Albendazole, are used.
When it comes to treating Capillaria philippinensis, Mebendazole and Albendazole are used.
How to Prevent Capillariasis?
As capillariasis is identified to spread through eggs in the fecal matter, proper disposal and hygiene are crucial. A few preventive measures include
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Proper management of the disposal system of fecal matter to prevent animals from reaching them, further preventing contamination of water and food supplies.
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Maintaining hand hygiene after working in the soil and before taking food.
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Children must be made aware of handwashing to prevent infection.
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Fruits and vegetables must be washed before intake.
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Avoid eating undercooked or raw fish. The Food and Drug Administration recommends cooking fish at least 63 degrees Celsius to kill the existing parasites.
How Does Capillariasis Infection Affect Animals?
The species of Capillaria affecting dogs and cats are Capillaria plica, Capillaria aerophilous, and Capillaria boehmi. They affect the animals' bladder wall, portions of the kidney, lungs, trachea, nasal passages, and sinuses.
Route of Infection: The species of Capillaria in the bladder and respiratory tract of animals usually get released in the environment in the urine and cough expels, respectively. The spread of the infection from this stage may be direct or with an intermediate host. For example, the eggs released in the environment can be ingested by the animals directly, or the earthworms can ingest these eggs, which are then eaten by other animals, thereby getting infected.
Signs of Capillaria: In most cases, dogs do not show significant clinical symptoms. But if they occur, it depends on the specific species affecting them. For example, Capillaria plica affecting the bladder wall and portions of the kidney can lead to bloody urine and straining urination. In addition, Capillaria aerophilous affects the lungs and trachea and can cause shortness of breath, coughing, and wheezing. Finally, Capillaria boehmi affects the nasal passages and sinuses, causing nasal discharge and sneezing.
Diagnosis: The parasite can be identified by urinalysis, fecal examination, X-ray, and rhinoscopy.
Treatment: Dewormers such as Fenbendazole, Ivermectin, and Milbemycin treat animals with Capillaria infection.
Transmission to Humans: There are chances of humans getting infected with Capillaria species from animals, especially if proper hygiene practices are not followed with infected pet animals at home. Hence, it is necessary to wear protective wear when disposing of fecal matter.
Conclusion:
Capillariasis is an alarming condition affecting vital organs, such as the liver and intestine. If an individual is exposed to the risk factors and suspected of establishing the infection, it's better to consult a physician immediately because if the condition is left untreated, it turns fatal. Following hygienic measures can prevent susceptibility to infection. Therefore, stay hygienic and away from infections.