Gnathostomiasis- A Rare Nematode Infection: The Second Case Report in Bangladesh
1. Dr. Md. Mujibur Rahman 2. Dr. Md. Rashedul Moula
Source: Mymensingh Medical Journal
Gnathostoma, primarily an animal nematode, can infect human by the third stage larva by consumption of undercooked or raw fish, poultry, or pork. In Bangladesh gnathostomiasis is a very rare condition. The first case, an ocular infection by gnathostoma was reported in 2001 from Rangpur, a northern district. This is the second case report of gnathostomiasis which also is an ocular infection, occurred in an area of greater district of Rangpur. A female patient of 32 year of age of the northern district, Nilphamari has got infected with a species of Gnathostoma, manifested by the appearance of a live larva near the right lateral margin of anterior surface of iris of her right eye. The larva was removed surgically from her eye and the patient was cured from symptoms.
Pic: A and B: Larva of Gnathostoma sipinigerum in the anterior chamber of right eye of the female showing different shape in two pictures to note its movement.
In the month of May 2004, a 32 years old female patient of Nilphamari, a northern district of Bangladesh presented with slight pain, occasional blurred vision and redness of her right eye for the last 6 months. During this period she got symptomatic treatment with antibiotic drops and painkiller by local physician. Failing with this treatment she was referred to ophthalmologist. The affected eye was found slightly swollen. During slit lamp examination a motile worm was detected in the right eye. We observed the worm was of about 8-9 mm long, with one of its end fixed on the anterior surface of the right lateral area of iris. Assuming that the worm was emerging from that position. The other end was moving to and fro in the anterior chamber. From the experience of first case of gnathostomiasis, the worm was assumed to be another case of gnathostomiasis.
The worm was removed and collected in vial containing normal saline. The worm was examined under low power microscopy. It was cylindrical in shape, 7 mm in long with scaly spines allover the surface of its body. The head of the worm was searched and its morphology reveals that it was a larval stage of Gnathostoma species. The head was globular, separated from the body by a slightly constricted neck. The head was provided with four concentric rows of spines. The numbers of spines in each row were on average 40-45.The mouth opened on the center of the anterior ring. The morphology was similar with the first case and consistent with feature of Gnathostoma spinigerum. After removal of the worm the patient was cured completely in two weeks.
Occurrence of gnathostomiasis is very rare in Bangladesh and this is the second case noticed to us. However there may be other undiagnosed cases due lack of expectation or morphological knowledge of the nematode. Consumption of undercooked fish, poultry or pork is primary mode of infection. The patient has no history of taking such food but eating half-boiled egg is not uncommon in this area. Rare cases have shown that the third stage larval worm can penetrate through the skin and occupy the host in this mechanism. However, the way of infection in this case could not be assumed.
Brief on the nematode:
Gnathostoma spinigerum is best-understood species among all four species of human infection of Gnathostoma. Its definitive host is dogs, cats, tiger, lions etc. These animals harbor adult warms in their stomach wall and eggs released in the faeces. Cyclops, in fresh water ingests these ova and the larva develops up to early third stage form. Cyclops is eaten by fish (2nd intermediate host) or directly by definitive host. A wide variety of animals, including fish, bird and mammals serve as second intermediate host to Gnathostoma. The worm lodge in the gastric wall of definitive host; in second intermediate host (fish, poultry) and human, they lodge into other tissue and don't develop to their adult forms. Human can acquire larval warms by ingestion of definitive host (not common), second intermediate hosts, or first intermediate host. Since humans are "dead-end-hosts", the larva are unable to mature into adult-hood, thus they migrate throughout the body and can survive up to 10 years and encysted in any tissue.
Individuals infected with gnathostomiasis can develop symptoms as soon as 24 hours after ingestion of worm. These initial indicators can include malaise, fever, urticaria,
vomiting, diarrhea, and epigastric pain. Cases of gnathostomiasis have been observed in the lung, eye, face, genitourinary tract, GIT, auditory and CNS. Cutaneous gnathostomiasis is often diagnosed by the presence of migratory oedema of creeping eruptions. Oedema, localized swelling and skin abscesses are the more common indicators.
Visceral gnathostomiasis can take many forms and the parasites can be found in eye (intraocular), GI tract, lung ear, nose CNS etc. Migratory subcutaneous nodules are common with visceral gnathostomiasis. Presence of parasite in CNS and ocular area are very serious. Subarachnoid haemorrage, multiple types of encephalitis and hydrocephalus have all associated with gnathostomiasis involving CNS. Although it is understood how Gnathostoma are able to enter the eye, they have been known to damage sensory apparatus of the retina, leading to irreversible blindness.
Clinical presentation is the first key to recognizing gnathostomiasis. Migratory oedema or creeping eruption is visual sign of the presence of parasite. History of consumption of related food or traveling to endemic area can provide key information. A wide array of serological tests- precipitation, indirect fluorescent antibody, indirect agglutination and ELISA has been used for the detection of antibody against the parasite.
Albendazole, mebendazole and ivermectin have been shown to be effective against gnathostomiasis but the treatment of choice is often surgical removal of the parasite. Recommended adult dose of albendazole is 400mg twice daily for 21 days in gnathostomiasis where surgery could not be done.
So far we know, except two cases, no case of Gnathostomiasis has been reported in Bangladesh. The two cases were of ocular infection. It would be easier to find any parasite when it comes in a hollow organ like eye than in other parts of the body like liver, kidney, muscle, under skin, in brain or other area. As study shows that the most common manifestation of gnathostomiasis is dermal lesion. But so far, not a single case of dermal or other type has been reported in Bangladesh. It should not mean that except ocular infection, Gnathostoma infection is not present here. This may be due to lack of proper diagnosis due to the ignorance about the nematode. So this article may create awareness among the health personals about the parasite and help to diagnose the infection earlier and thus to avoid serious complications due to involvement of internal organs like CNS, eye or auditory area by the parasite.
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