Paron Dekumyoy

Gnathostomiasis: An Emerging Imported Disease

As the scope of international travel expands, an increasing number of travelers are coming into contact with helminthic parasites rarely seen outside the tropics. As a result, the occurrence of Gnathostoma spinigerum infection leading to the clinical syndrome gnathostomiasis is increasing. In areas where Gnathostoma is not endemic, few clinicians are familiar with this disease. To highlight this underdiagnosed parasitic infection, we describe a case series of patients with gnathostomiasis who were treated during a 12-month period at the Hospital for Tropical Diseases, London.

Distribution of Taenia saginata cysticerci in tissues of experimentally infected cattle

Bovine cysticercosis caused by Taenia saginata is a zoonotic disease warranting routine inspection measures for the postmortem detection of cysticerci (cysts) in beef destined for human consumption. Detection is based on gross examination of traditional carcass predilection sites, although there is evidence to suggest that examination of other sites may offer improvements in sensitivity. In order to evaluate the efficacy of current inspection protocols, this study determined the distribution and number of cysticerci in the tissues of experimentally infected cattle. Forty-two commercial beef cattle were divided into five groups of 5-12 animals each and inoculated with either 10,000, 5000, 1000, 100 or 10 T. saginata eggs. At time points ranging from 47 to 376 days post-inoculation (DPI), 10 animals inoculated with 5000 eggs were killed and the carcasses partitioned into 31 tissue sites. These consisted of the traditionally inspected tissue sites of heart, masseter and pterygoid muscles, tongue, oesophagus, and diaphragm (membranous and crura); as well as non-traditional sites of lung, liver and an additional 20 individual muscles or muscle groups. After performing the Canadian Food inspection Agencys (CFIA) routine inspection protocol for cysticerci on traditional tissue sites, tissues from all sites were cut into approximately 0.5 cm thick slices and the total number of parasitic cysts and cyst density (number of cysts/g of tissue) determined for each site. Traditional sites were similarly evaluated for the remaining 32 animals killed between 117 and 466 DPI. Sites were ranked based on cyst density. Infection was confirmed in 37 animals, of which only 20 were detected by routine inspection, and of which 7 harboured no cysts in traditional sites. For the animals in which additional non-traditional sites were evaluated, none yielded higher cyst densities than those traditionally inspected. When only traditional sites (for all animals) were compared, the heart ranked highest overall, although it was not significantly different from the masseter muscle, and was the most frequently affected site. The traditional site of oesophagus was one of the least rewarding of all sites for detection of cysticerci. The heart was confirmed as the preferred site for detection of bovine cysticercosis based on high cyst density and frequency of infection, and greater visibility of gross lesions due to the early inflammatory response in cardiac muscle. More extensive examination of the heart is recommended to improve detection of infected animals.

Outbreak of Trichinellosis Caused by Trichinella papuae, Thailand, 2006

In 2006, the Thailand Ministry of Public Health studied 28 patients from a village in northern Thailand. All had myalgia, edema, fever, and gastrointestinal symptoms; most had eaten wild boar. A muscle biopsy specimen from a patient showed nonencapsulated larvae with a cytochrome oxidase I gene sequence of Trichinella papuae.

Diagnostic values of IgG4 in human gnathostomiasis

The diagnostic values of immunoglobulin G subclass antibodies from patients with gnathostomiasis were assessed by immunoblot technique. Antigen was prepared from crude extracts of Gnathostoma spinigerum advanced third‐stage larvae obtained from naturally infected eels. The sera were obtained from 14 parasite‐confirmed gnathostomiasis cases, 63 patients with other helminthic infections and 13 healthy controls. Nine prominent IgG4 reactive bands appeared with molecular weights of 94, 51, 47, 43, 38, 24, 21, 20 and 15 kDa. The diagnostic sensitivity of each of the nine reactive bands ranged from 100% to 64.3% in 14 parasite‐confirmed gnathostomiasis cases. All (100%) confirmed cases recognized the 21 kDa antigenic band, but not other helminthic infections or parasite‐free control. Recognition of 21 kDa antigen in G. spinigerum advanced third‐stage larvae crude extracts is the most specific diagnostic marker for human gnathostomiasis, with 100% sensitivity and specificity. The 20 and 24 kDa protein bands were additional diagnostic bands for confirming diagnosis of infection where the 21 kDa band was faint. No specific binding of IgG1, IgG2, or IgG3 antibodies was observed in any sera from confirmed gnathostomiasis cases.

Imported cutaneous gnathostomiasis: report of five cases

Gnathostomiasis has rarely been described outside endemic countries. We report on a series of 5 patients (4 females, 1 male, mean age 42.2 years) who returned to France from South-East Asia and presented with cutaneous gnathostomiasis. The cutaneous lesions appeared within a mean period of 62 d (range 10-150 d) after return. They consisted of creeping eruptions in 3 patients (in addition one also had papules, one had nodules and hepatitis, and one had hepatitis; all 3 had profound asthenia) and recurring migratory swellings in 2 patients. The mean eosinophil count was 1546/mm3 (range 398-3245/mm3). Diagnosis was based on positive serological tests in 3 patients and seroconversion in 2 patients, and was confirmed by identification of Gnathostoma hispidum in a biopsy specimen from one of the seropositive patients. Albandazole (1-4 courses) was given as treatment. Recurrences may occur up to 24 months after apparent cure without reinfection. Gnathostomiasis should be considered when patients return from tropical countries and present with migratory swellings or creeping eruption that does not respond to the usual treatment for cutaneous larva migrans. Serological tests may be negative initially and thus need to be repeated to check for seroconversion. Treatment may require multiple courses of albendazole and a prolonged period of follow-up is necessary before cure can be confirmed.

Medullary Gnathostomiasis in a White Patient: Use of Immunodiagnosis and Magnetic Resonance Imaging

A 48-year-old French diplomat presented with a sensory-motor paraparesis of rapid onset, leading to paraplegia. Successive magnetic resonance image scans showed lesions of the thoracic spinal cord that were at different levels from one examination to the next. Specific anti-gnathostome antibodies were detected by means of enzyme-linked immunosorbent assay and Western blot test in both plasma and cerebrospinal fluid. Albendazole treatment prevented disease progression, but only partial regression of the neurologic symptoms was obtained.

The second outbreak of trichinellosis caused by Trichinella papuae in Thailand

A human trichinellosis outbreak caused by Trichinella papuae occurred in the Uthai Thani Province of Thailand in September 2007. A total of 34 villagers suffering at least one of the symptoms suggestive of trichinellosis, or those who were asymptomatic but had a history of ingesting raw wild pig meat, were enrolled in the study. Twenty-two villagers had ingested undercooked pork from a hunted wild pig (Sus scrofa). One patient with a severe clinical picture was hospitalised and more than 80 non-encapsulated larvae were detected in the muscle biopsy. The larvae were identified as T. papuae by molecular analyses of the mitochondrial cytochrome c oxidase subunit I (COI) gene and the expansion segment 5 (ES5) of the large subunit rRNA. Of the 34 suspected cases, 27 agreed to be subjected to haematological and serological tests. Immunoblot analysis using crude antigens from T. spiralis muscle larvae revealed anti-Trichinella IgG in 20 of the 26 serum samples (1 serum sample could not be analysed). All infected people were successfully treated with mebendazole; the one patient with severe symptomatology was treated successfully with prednisolone.

Systematics of the subfamily Haplorchiinae (Trematoda: Heterphyidae), based on nuclear ribosomal DNA genes and ITS2 region.

Phylogenetic relationships of 6 species in the trematode subfamily Haplorchiinae were analyzed using small and large subunit of ribosomal DNA genes (18S rDNA and 28S rDNA) and internal transcribed spacer subunit II (ITS2) region as molecular markers. Maximum Likelihood and Bayesian inference analyses of combined rDNAs and ITS2 indicated a close relationship between the genera Haplorchis and Procerovum, while these two genera were distinct from Stellantchasmus falcatus. These phylogenetic relationships were consistent with the number of testes but not with the characters of the modification of the seminal vesicle or of the ventral sucker. Although three Haplorchis spp. were, together with Procerovum, in the same cluster, their mutual topology was incongruent between rDNA and ITS2 trees. Phylogenetic analyses using other molecular markers with more species are necessary to work out solid phylogenetic relationships among the species in this subfamily.

The first workshop towards the control of cestode zoonoses in Asia and Africa.

The first workshop towards the control of cestode zoonoses in Asia and Africa was held in Asahikawa Medical University, Japan on 15 and 16 Feb 2011. This meeting was fully supported by the Asian Science and Technology Strategic Cooperation Promotion Programs sponsored by the Special Coordination Funds for Promoting Science and Technology, the Ministry of Education Japan (MEXT) for 3 years from 2010 to Akira Ito. A total of 24 researchers from 9 countries joined together and discussed the present situation and problems towards the control of cestode zoonoses. As the meeting was simultaneously for the establishment of joint international, either bilateral or multilateral collaboration projects, the main purposes were directed to 1) how to detect taeniasis/cysticercosis infected patients, 2) how to differentiate Taenia solium from two other human Taenia species, T. saginata and T. asiatica, 3) how to evaluate T. asiatica based on the evidence of hybrid and hybrid-derived adult tapeworms from Thailand and China, 4) how to evaluate T. solium and T. hyaenae and other Taenia species from the wild animals in Ethiopia, and 5) how to detect echinococcosis patients and 6) how to differentiate Echinococcus species worldwide. Such important topics are summarized in this meeting report.

Discovery of Opisthorchis lobatus (Trematoda: Opisthorchiidae): A New Record of Small Liver Flukes In the Greater Mekong Sub-Region

Abstract Metacercariae, morphologically similar to those of small liver flukes, were found to parasitize red-tailed snakehead fish, Channa limbata, collected from the city of Vientiane, Lao Peoples Democratic Republic. Adult worms that were recovered from experimentally-infected hamsters showed characteristics distinctly different from Opisthorchis viverrini, but closely similar to Opisthorchis lobatus, which was first reported in poultry (Anas sp.) from Pakistan. The present study aimed to redescribe O. lobatus based on the adult worms recovered from experimentally-infected hamsters. Additionally, it aimed to document the genetic relationships among O. lobatus and other opisthorchiid liver flukes using the mitochondrial cytochrome c oxidase subunit 1 (COI) gene and the internal transcribed spacer 2 (ITS2) region. DNA alignment of the O. lobatus and O. viverrini COI partial sequences (330 bp) showed 3.03% fixed differences (2.72% of amino acids changed) while the ITS2 region (350 bp) indicated a 0.86% difference for nucleotides. Species boundaries between the 2 parasites were determined by neighbor-joining analysis using the molecular sequence data. The phenogram confirmed that O. lobatus was distinctly different from O. viverrini, representing the first reported instance of O. lobatus in the Greater Mekong Sub-region (GMS) and the first record of C. limbata as the second intermediate host of a small liver fluke. Questions regarding human infection and the extent of the geographic distribution of these species should be investigated further.