Human Outbreak of Trichinellosis Caused by Trichinella papuae Nematodes, Central Kampong Thom Province, Cambodia.

In September 2017, a severe trichinellosis outbreak occurred in Cambodia after persons consumed raw wild pig meat; 33 persons were infected and 8 died. We collected and analyzed the medical records for 25 patients. Clinical signs and symptoms included myalgia, facial or peripheral edema, asthenia, and fever. We observed increased levels of creatine phosphokinase and aspartate aminotransferase-, as well as eosinophilia. Histopathologic examination of muscle biopsy specimens showed nonencapsulated Trichinella larvae. A Trichinella excretory/secretory antigen ELISA identified Trichinella IgM and IgG. Biopsy samples were digested and larvae were isolated and counted. PCR for the 5S rDNA intergenic spacer region and a multiplex PCR, followed by sequencing identified the parasite as Trichinella papuae. This species was identified in Papua New Guinea during 1999 and in several outbreaks in humans in Thailand. Thus, we identified T. papuae nematodes in humans in Cambodia.

The probable role of cannibalism in spreading Trichinella papuae infection in a crocodile farm in Papua New Guinea.

Between 2003 and 2007, 83 (50%) of 167 crocodiles (Crocodylus porosus) purchased as juveniles by a crocodile farm 3 or 4 years earlier from Kikori, Gulf Province, were found to be infected with Trichinella papuae. Between 2005 and 2007 infection was detected in a number of crocodiles at the farm obtained from six localities other than Kikori, as well as in a few animals born on the farm. Up to 2004, all juveniles at the farm, whether wild- or farm-born, were penned together; the practice was then stopped to prevent possible infection through cannibalism. The last infected animal from Kikori was seen in 2007, 4 years after the purchase of crocodiles from there ceased. The last non-Kikori infected crocodile was seen, also, in 2007. None of the 1972 crocodiles (comprising wild- and farm-born animals) tested from 2008 to 2013, using the digestion method, was infected with T. papuae. This indicates that infection of non-Kikori crocodiles was the result of cannibalism within the farm during the years up to 2004 when juvenile crocodiles were kept together, and that the farm is now free of the infection.

Susceptibility of laboratory rodents to Trichinella papuae.

Members of the genus Trichinella are small nematodes that can infect a wide range of animal hosts. However, their infectivity varies depending on the parasite and host species combination. In this study, we examined the susceptibility of 4 species of laboratory rodents, i.e., mice, rats, hamsters, and gerbils to Trichinella papuae, an emerging non-encapsulated Trichinella species. Trichinella spiralis and Trichinella pseudospiralis were also included in this study for comparison. Fifteen animals of each rodent species were infected orally with 100 muscle larvae of each Trichinella species. Intestinal worm burden was determined at day 6 and 10 post-inoculation (PI). The numbers of muscle larvae were examined at day 45 PI. The reproductive capacity index (RCI) of the 3 Trichinella species in different rodent hosts was determined. By day 6 PI, 33.2-69.6% of the inoculated larvae of the 3 Trichinella species became adult worms in the small intestines of the host animals. However, in rats, more than 96% of adult worms of all 3 Trichinella species were expelled from the gut by day 10 PI. In gerbils, only 4.8-18.1% of adult worms were expelled by day 10 PI. In accordance with the intestinal worm burden and the persistence of adults, the RCI was the highest in gerbils with values of 241.5±41.0 for T. papuae, 432.6±48 for T. pseudospiralis, and 528.6±20.6 for T. spiralis. Hamsters ranked second and mice ranked third in susceptibility in terms of the RCI, Rats yielded the lowest parasite RCI for all 3 Trichinella species. Gerbils may be an alternative laboratory animal for isolation and maintenance of Trichinella spp.

Susceptibility of Laboratory Rodents to Trichinella papuae

Members of the genus Trichinella are small nematodes that can infect a wide range of animal hosts. However, their infectivity varies depending on the parasite and host species combination. In this study, we examined the susceptibility of 4 species of laboratory rodents, i.e., mice, rats, hamsters, and gerbils to Trichinella papuae, an emerging non-encapsulated Trichinella species. Trichinella spiralis and Trichinella pseudospiralis were also included in this study for comparison. Fifteen animals of each rodent species were infected orally with 100 muscle larvae of each Trichinella species. Intestinal worm burden was determined at day 6 and 10 post-inoculation (PI). The numbers of muscle larvae were examined at day 45 PI. The reproductive capacity index (RCI) of the 3 Trichinella species in different rodent hosts was determined. By day 6 PI, 33.2-69.6% of the inoculated larvae of the 3 Trichinella species became adult worms in the small intestines of the host animals. However, in rats, more than 96% of adult worms of all 3 Trichinella species were expelled from the gut by day 10 PI. In gerbils, only 4.8-18.1% of adult worms were expelled by day 10 PI. In accordance with the intestinal worm burden and the persistence of adults, the RCI was the highest in gerbils with values of 241.5+/-41.0 for T. papuae, 432.6+/-48 for T. pseudospiralis, and 528.6+/-20.6 for T. spiralis. Hamsters ranked second and mice ranked third in susceptibility in terms of the RCI, Rats yielded the lowest parasite RCI for all 3 Trichinella species. Gerbils may be an alternative laboratory animal for isolation and maintenance of Trichinella spp.

Trichinellosis: a possible link between human infection and the traditional earth-oven or 'mumu' method of cooking in Morehead District, Western Province, Papua New Guinea.

OBJECTIVE: To investigate if the traditional method of cooking pig meat in an earth-oven or mumu, as practiced by people in Morehead District, Western Province, Papua New Guinea (PNG), could be a source of infection with Trichinella papuae and of the disease trichinellosis. PROCEDURE: As the locality lacks suitable river stones normally used in a mumu in PNG, people use various substitute materials, such as pieces of termite mounds, balls of dried clay and small rough stones. Samples of these were tested and compared with conventional mumu stones in their capacity to retain heat. RESULTS: None of the substitute materials tested was as efficient in retaining heat as the conventional mumu stones. CONCLUSIONS: Cooking pig meat in a mumu in Morehead District has the potential to be a source of infection with T. papuae. Loss of heat in a Morehead mumu is accelerated probably as the mumu is prepared on the surface of the ground and not in a shallow pit or depression as is the custom elsewhere in the country.