Human gnathostomiasis is a food-borne zoonosis caused by a tissue nematode of the genus Gnathostoma. The disease is highly endemic in Asia, including Thailand. The freshwater swamp eel (Monopterus albus), the second intermediate host of the gnathostome nematode, has an important role in transmitting the infection in Thailand. Surveys on the infective larvae of Gnathostoma spinigerum based on morphological features in freshwater swamp eels have been performed continuously and reported in Thailand. However, there is still limited molecular data on intra-species variations of the parasite. In this study, a total of 19 third-stage larvae of morphologically identified G. spinigerum were collected from 437 liver samples of freshwater swamp eels purchased from a large wholesale market in Bangkok, Thailand. Molecular characterization based on mitochondrial cytochrome c oxidase subunit I (COI) sequences was performed to elucidate their genetic variations and phylogenetic relationship. Among the 19 infective larvae recovered from these eels, 16 were sequenced successfully. Phylogenetic analyses inferred from the partial COI gene showed the presence of three distinct COI haplotypes. Our findings confirm the presence of G. spinigerum as the main species in Thailand.
Human gnathostomiasis is an emerging food-borne parasitic disease caused by nematodes of the genus Gnathostoma. Currently, serological tests are commonly applied to support clinical diagnosis. In the present study, a simple and rapid filtration-based test, dot immune-gold filtration assay (DIGFA) was developed using a partially purified antigen of Gnathostoma third-stage larvae (L3). A total of 180 serum samples were tested to evaluate the diagnostic potential of DIGFA for gnathostomiasis. The diagnostic sensitivity and specificity were 96.7% (29/30) and 100% (25/25), respectively. The cross-reactivity with sera from other helminthiasis patients ranged from 0 to 4%, with an average of 1.6% (2/125). DIGFA using a partially purified L3 antigen was not only simple and rapid, but also more accurate than standard assays for the diagnosis of human gnathostomiasis. DIGFA may represent a promising tool for application in laboratories or in the field, without requiring any instrumentation.
The term 'tropical' refers to the region of the Earth lying between the Tropic of Cancer and the Tropic of Capricorn. Located between these equatorial parallels demarcating the Torrid Zone are several underdeveloped and developing countries: Thailand, the Philippines, Malaysia, Singapore, Indonesia, southern India, Sri Lanka, Brazil, Cuba, Ethiopia, Sudan and Nigeria, to name but a few considered to be 'tropical'. The climate in most of these countries is characterized by high temperatures and high humidity. The tropical climate and general state of socio-economic underdevelopment in such countries provide an ideal environment for pathogenic organisms, their vectors and intermediate hosts to flourish. Furthermore, the cultural habits and educational background of the people living in such countries expose them to pathogens and, when these people become infected, they readily become reservoirs for, or carriers of, those organisms. Ultimately, the adverse socioeconomic conditions of underdeveloped countries impede attempts to eradicate or control tropical diseases.
A thirty two year old taxi driver presented with cotnplaints of headache, nausea, vomiting and blurring of vision of the left eye of two days duration. He was found to have an acute anterior uveities and secondary glaucoma. On further examination patient was also found to have a neuroretinitis and phlebitis in the same eye. A worm was found in the anterior chamber and it was removed via a limbal incision under local anaesthesia. The worm-like structure sent to the Department of Parasitology was identified as Gnathostoma spinigerum. he patient was treated with topical eye drops and oral steroids at the same time to reduce the inflammation. No neurological symptoms were seen. The patient was not available for further evaluation and followup. KEYWORDS: Blurring of vision, Gnathostomiasis
The occurrence of adult Gnathostoma malaysiae in Rattus surifer and R. tiomanicus in Malaysia has been reported but there are no known reports on the host tissue reactions. This paper reports on the gross pathology caused by G. malaysiae in a red spiny forest rat, R. surifer and the tissue reactions caused. A tumor-like growth was located on the mid-stomach wall in a female rat captured in Gunung Bachock, Kelantan, Malaysia. This growth consisted of four tunnel-like structures containing sanguinopurulent fluid and leukocytes and this structure led into a central canal. The tissue surrounding the tumor was greatly inflamed and there was localized gastritis. The tunnel-like structure was surrounded by dense fibrotic tissue. The stomach wall was devoid of superficial epithelium and smooth muscle but mucinous glands were present. The midregion of the fibrotic scar contained eggs of G. malaysiae which had evoked a strong tissue reaction and were surrounded by pus. Blood vessels were empty, dilated and had undergone vasculitis and thrombosis.
The recovery of six adult Gnathostoma spinigerum Owen, 1936 from a civet cat, Prionodon linsang Hardwick, constitutes the second reported record of this parasite and the first authenticated case of adult worms found in a wild animal from Malaysia. The food habits of the infected P. linsang as an important link in the transmission of G. spinigerum in the intermediate and definitive hosts together with the probable distribution of this parasite are discussed.
The diagnosis and management of parasitic diseases of the central nervous system (CNS) is difficult, even for infectious diseases physicians and neurologists. Furthermore, few overviews of the spectrum of causative helminths and clinical syndromes have been published. In the present study, we review the seven most common parasitic diseases of the CNS: (i) cysticercosis, (ii) neuroschistosomiasis, (iii) paragonimiasis, (iv) angiostrongyliasis, (v) hydatid disease, (vi) sparganosis and (vii) gnathostomiasis. Major syndromes of parasitic disease of the CNS and their differential causes are discussed, including: (i) cystic lesions, (ii) enhancing granulomas (with and without creeping subcutaneous eruptions), (iii) eosinophilic meningoencephalitis and (iv) spinal cord disease. Specific risk factors that predispose to these infections are also discussed and particular attention is drawn to the situation in Australia.