Distribution of muscle larvae and antibody dynamics in goats experimentally infected with Trichinella spiralis

Immune Correlates of Resistance to Trichinella spiralis Reinfection in Mice

The immune correlate of host resistance induced by reinfection of Trichinella spiralis remains unclear. In this study, we investigated immune correlates between the resistance and serum IgG antibody level, CD23⁺ IgM⁺ B cells, and eosinophil responses induced by T. spiralis reinfection. Mice were primarily infected with 10 or 100 T. spiralis larvae (10 TS, 100 TS), respectively, and after 4 weeks, they were challenge infected with 100 T. spiralis larvae (10–100 TS, 100-100 TS). Upon challenge infections, 10–100 TS mice induced significantly higher levels of T. spiralis-specific total IgG antibody responses in sera and antibody secreting cell responses in spleens compared to 100-100 TS mice, resulting in significantly reduced worm burdens in 10–100 TS mice (60% and 70% reductions for adult and larvae, respectively). Higher levels of eosinophils were found in mice primarily infected with 10 TS compared to those of 100 TS at week 8 upon challenge. CD23⁺ IgM⁺ B cells were found to be increased significantly in mice primarily infected with 10 TS. These results indicate that primary infection of 10 larvae of T. spiralis, rather than 100 larvae, induces significant resistance against reinfection which closely correlated with T. spiralis-specific IgG, eosinophil, and CD23⁺ IgM⁺ B cell responses.

An outbreak of trichinellosis by consumption of raw soft-shelled turtle meat in Korea

Trichinellosis transmission to humans via the consumption of reptile meat is rare worldwide. In Korea, however, 2 such outbreaks, possibly via consumption of soft-shelled turtle meat, have occurred in 2 successive years. In 17 August 2014, 6 patients were admitted to Wonju Severance Christian Hospital complaining of myalgia, fever, and headache. Eosinophilia was the indication of the initial laboratory results, and they were eventually diagnosed as trichinellosis by ELISA. All of the patients worked at the same company and had eaten raw soft-shelled turtle meat at a company dinner 10 days prior to their admission. They were treated with albendazole for 2 weeks, upon which all of their symptoms disappeared. This is the 8th report on human trichinellosis in Korea, and the second implicating raw soft-shelled turtle meat.

Trichinosis caused by ingestion of raw soft-shelled turtle meat in Korea

Reptiles, unlike mammals, have been considered to be unsuitable hosts of Trichinella spp., though larvae have been detected in their muscles and human outbreaks related to their consumption have, in fact, occurred. Herein we report 2 Korean cases of trichinosis, possibly transmitted via consumption of reptile meat. Both patients suffered from myalgia, headache, and facial edema. Laboratory examinations revealed leukocytosis with eosinophilia (54% and 39%, respectively) and elevated creatinine phosphokinase. ELISA was performed under the suspicion of trichinosis, showing positivity at the 29th and 60th day post-infection. Since they had consumed raw soft-shelled turtle meat, turtle was strongly suggested to be an infection source of trichinosis in Korea next to the wild boar and badger.

Antibody response against Trichinella spiralis in experimentally infected rats is dose dependent

Domestic pigs are the main representatives of the domestic cycle of Trichinella spiralis that play a role in transmission to humans. In Europe, backyard pigs of small household farms are the most important risks for humans to obtain trichinellosis. Rats might play a role in the transmission of Trichinella spiralis from domestic to sylvatic animals and vice versa. In order to be able to investigate the role of wild rats in the epidemiology of T. spiralis in The Netherlands, we studied the dynamics of antibody response after T. spiralis infections in experimental rats, using infection doses ranging from very low (10 muscle larvae, ML, per rat) to very high (16 000 ML per rat). To evaluate the feasibility of rats surviving high infection doses with T. spiralis, clinical and pathological parameters were quantified. Serological tools for detecting T. spiralis in rats were developed to quantitatively study the correlation between parasite load and immunological response. The results show that an infection dose-dependent antibody response was developed in rats after infection with as low as 10 ML up to a level of 10 000 ML. A positive correlation was found between the number of recovered ML and serum antibody levels, although specific measured antibody levels correspond to a wide range of LPG values. Serum antibodies of rats that were infected even with 10 or 25 ML could readily be detected by use of the T. spiralis western blot 2 weeks post infection. We conclude that based on these low infection doses, serologic tests are a useful tool to survey T. spiralis in wild rats.

Trichinella sp. in red foxes (Vulpes vulpes) from Catalonia, NE Spain

European legislation allows the official recognition of Trichinella-free pig holdings, provided Trichinella sp. infection is absent from humans and prevalence of Trichinella sp. infection in red foxes (Vulpes vulpes) is below 0.1% in the area, region or country. Tibialis anterior muscle samples from 1,319 red foxes captured in Catalonia (NE Spain) between 1998 and 2007 were analyzed for Trichinella sp. using the digestion method. Four foxes resulted positive (one in 1999, one in 2002 and two in 2006), accounting for a low prevalence (0.3%). However, this prevalence was concentrated in mountain or rural areas with a low sample size, reaching high local prevalences. The two positive samples in 2006 were characterized as Trichinella britovi, and a sylvatic cycle of trichinellosis seems to occur, at least in the rural insufficiently sampled regions of Catalonia. Overall, the results obtained do not currently allow the establishment of Trichinella-free pig holdings in the study area, but further research is needed to better know the prevalence and cycle of Trichinella sp. in Catalonia.

Humoral immune responses during experimental infection with Fascioloides magna and Fasciola hepatica in goats and comparison of their excretory/secretory products

This study investigated the humoral immune responses of goats experimentally infected with Fascioloides magna and Fasciola hepatica to F. magna excretory/secretory products (FmESP) or F. hepatica excretory/secretory products (FhESP), respectively. An enzyme-linked immunosorbent assay (ELISA) was used to determine serum antibody responses and for possible discrimination of F. magna and F. hepatica infections in goats. Comparison of ESPs of both flukes and evaluation of ESP antigenicity was also studied applying immunoblotting techniques. In all infected goats, antibody level was significantly increased (against negative control) since 2 weeks post infection (WPI). However, the dynamics of antibodies varied between F. magna and F. hepatica groups during the course of the infection. The cross-reaction of antibodies developed against F. magna and F. hepatica with ESP proteins was recorded by ELISA. The species-specific proteins 40, 120 kDa from FmESP and 80, 160 kDa from FhESP (with no antibody cross-reaction) were detected by two dimensional electrophoresis and immunoblot as the potential immunodiagnostic markers. Our results suggest that F. magna and F. hepatica infection could be distinguished by common immunological techniques based on species-specific antigen-antibodies interaction.