Reprint of: Gamma radiation effect on Trichinella pseudospiralis and Trichinella spiralis infected wild boar meat.

Trichinellosis is a foodborne parasitic disease caused by Trichinella spp. Different methods, such as cooking, freezing and irradiation, have been suggested to inactivate the parasite in meat infected with Trichinella spp. The International Commission on Trichinellosis (ICT) recommends an irradiation dose of 0.3 kGy to inactivate Trichinella spp. larvae, but its effectiveness in all Trichinella species has not yet been demonstrated. Therefore, the objective of the present study was to determine the effectiveness of gamma radiation in treating wild boar meat to inactivate Trichinella pseudospiralis and Trichinella spiralis. Two wild boars (Sus scrofa) were each inoculated per os (PO) with 20,000 muscle larvae (ML) of Trichinella. One wild boar was inoculated with T. pseudospiralis and the other one with T. spiralis. Both wild boars were euthanized 20 weeks post infection (pi). A 250░g sample from each selected muscle type (side ribs, shoulder and upper forelegs) was obtained in duplicate from each animal. One group of samples was not irradiated (Gc; n░=░6) while the other group of samples was irradiated (Gt; n░=░6) at the Atomic Centre of the Argentinean National Commission of Atomic Energy (CNEA) with a minimum and maximum dose of 0.32-0.41 kGy. Twenty gram of each muscle from Gt and Gc were taken at 24░h, 7 days, 14 days and 21 days post-irradiation, and all samples were individually processed by means of artificial digestion. The ML were then inoculated into mice to evaluate the intestinal phase and the muscular phase. All recovered larvae from Gt and Gc samples showed integrity of the cuticle and active motility. Adult worms and ML were recovered from all mice inoculated with ML from Gc. However, no adult worms or ML were obtained in mice inoculated with ML from Gt. These results show the efficacy of irradiation to inhibit the development of T. pseudospiralis and T. spiralis in the host, which could possibly be extended to other non-encapsulated species, but further studies are needed to demonstrate this hypothesis.

Gamma radiation effect on Trichinella pseudospiralis and Trichinella spiralis infected wild boar meat.

Trichinellosis is a foodborne parasitic disease caused by Trichinella spp. Different methods, such as cooking, freezing and irradiation, have been suggested to inactivate the parasite in meat infected with Trichinella spp. The International Commission on Trichinellosis (ICT) recommends an irradiation dose of 0.3 kGy to inactivate Trichinella spp. larvae, but its effectiveness in all Trichinella species has not yet been demonstrated. Therefore, the objective of the present study was to determine the effectiveness of gamma radiation in treating wild boar meat to inactivate Trichinella pseudospiralis and Trichinella spiralis. Two wild boars (Sus scrofa) were each inoculated per os (PO) with 20,000 muscle larvae (ML) of Trichinella. One wild boar was inoculated with T. pseudospiralis and the other one with T. spiralis. Both wild boars were euthanized 20 weeks post infection (pi). A 250 g sample from each selected muscle type (side ribs, shoulder and upper forelegs) was obtained in duplicate from each animal. One group of samples was not irradiated (Gc; n = 6) while the other group of samples was irradiated (Gt; n = 6) at the Atomic Centre of the Argentinean National Commission of Atomic Energy (CNEA) with a minimum and maximum dose of 0.32 - 0.41 kGy. Twenty gram of each muscle from Gt and Gc were taken at 24 h, 7 days, 14 days and 21 days post-irradiation, and all samples were individually processed by means of artificial digestion. The ML were then inoculated into mice to evaluate the intestinal phase and the muscular phase. All recovered larvae from Gt and Gc samples showed integrity of the cuticle and active motility. Adult worms and ML were recovered from all mice inoculated with ML from Gc. However, no adult worms or ML were obtained in mice inoculated with ML from Gt. These results show the efficacy of irradiation to inhibit the development of T. pseudospiralis and T. spiralis in the host, which could possibly be extended to other non-encapsulated species, but further studies are needed to demonstrate this hypothesis.

Experimental infection with Toxocara cati in BALB/c mice, migratory behaviour and pathological changes.

Experimental inoculations of 1000 Toxocara cati larval eggs were carried out in 18 BALB/c mice. The T. cati eggs used for inoculation were collected from the faeces of naturally infected cats. Euthanasia was performed on two mice on days 1, 2, 3, 4, 5, 6, 14, 21 and 28 post-inoculation (p.i.). Tissue samples were taken for digestion and histopathology. Larvae were recovered from all infected mice and the average of all larvae recovered was 28.3% (95%; CI: 14.1-42.4). Maximum number was obtained from liver on days 1 and 2 p.i.; from the lung on day 2 p.i. and from the brain on day 28 p.i. In muscle, the recovery was high as from day 3 p.i., with the maximum obtained on day 28 p.i. Superficial foci of congestion and haemorrhage were macroscopically observed in the lungs between days 2 and 5 p.i. and in the brain between days 3 and 6 p.i. Microscopic lesions were observed in the liver between days 2 and 14 p.i., with periportal and subcapsule inflammatory infiltrates. In the lungs, haemorrhages and inflammatory infiltrates can be observed in the alveolar parenchyma, close to bronchioles and large blood vessels. In the brain, congestive areas without inflammatory reactions were seen. In muscle, the presence of inflammatory infiltrates and degenerated muscle can be observed surrounding a parasite larva. These same lesions were observed in myocardium and pericardium. The kidneys were congested with inflammatory infiltrates. The inflammatory cells present in all the tissues studied were lymphocytes, neutrophils and a few eosinophils. Formation of granulomas or signs of larva encapsulation were not observed. The migratory pattern of T. cati larvae in BALB/c mice and its tendency to become concentrated in the muscle reinforce the importance of the mouse as a paratenic host for the parasite's cycle in the environment.

Prevalence of Toxocara cati and other parasites in cats' faeces collected from the open spaces of public institutions: Buenos Aires, Argentina.

Toxocarosis is a worldwide parasitic infection that affects both cats and dogs. Toxocara cati (Schrank, 1788) syn. Toxocara mystax (Zeder, 1800) prevalence was studied in faeces from stray cats collected from the open spaces of public institutions of Buenos Aires city, both building and surrounding open spaces are fenced off. Of the 465 samples obtained from March to June of 2005, 58.3% were found to have parasite eggs. The following parasites were identified from the 271 positive samples: T. cati (61.2%), Cystoisospora spp. (20.3%), Trichuris spp. (17.0%), Toxascaris leonina (15.1%), Ancylostoma spp. (14%) and Aelurostrongylus abstrusus (2.6%). T. cati prevalence was 35.7% (95% confidence interval: 31.2-40.1), with a 42.2% single isolations. The most frequent combination was T. cati and Cystoisospora spp. (9%). More than half the areas studied showed over 40% prevalence. Seventy-one percent of the collected samples were fresh with a variable moist consistency and 29% were older with a dry consistency. A statistically significant association was found between sample consistency and presence of parasites (chi2 = 10.81; p = 0.001) as also between sample consistency and presence of T. cati (chi2 = 11.27; p = 0.0007). Moist consistencies were significantly different from the rest: consistency (wet or dry) versus parasites (z = 1.95; p = 0.02) (95% confidence interval: 0.004-0.203); consistency (wet or dry) versus T. cati (z = 3.25; p = 0.0006) (95% confidence interval: 0.075-0.254). The cat population that inhabits these public green spaces contaminates the environment, thus transforming them into dangerous spaces with a variable rate for the human population that spends time in these places.

Toxocara canis infections in a pig model: immunological, haematological and blood biochemistry responses.

The immunological, haematological and enzymatic responses to the inoculation in pigs of 100,000 embryonated eggs of Toxocara canis were studied. Fifteen females were inoculated and three remained as controls. Haematological values were analysed from day 7 p.i. until day 126 p.i. In the inoculated group, white blood cells were raised on day 14 p.i. and eosinophil values on days 7, 14, 21, 35 and 49 p.i. showing significant differences compared with controls (P < 0.05). Absolute eosinophil counts (per ml) presented two rises, the first on days 7, 14 and 21 p.i. and the second on days 35 and 49 p.i. Blood biochemistry was maintained within normal values. Serological examination by ELISA to determine antibody levels against Toxocara canis L2/L3 excretory-secretory (ES) antigens showed values higher than the positive cut-off (1:32) from day 7 p.i. and until the end of the study on day 126 p.i., presenting two peaks: one on day 28 p.i. and the second covering days 49 to 56 p.i. Western blots of sera of inoculated animals presented, from day 7 p.i., two polypeptide bands of 55 and 70 kDa MW and, from day 56 p.i., an additional band of 120 kDa MW, all of which persisted until the end of the study. Immunological responses were sustained over time. No direct correlation was observed between the rise in eosinophils and antibody titres. To validate the conclusions, more studies are required on the polypeptide bands.

Immunological and hematological response in experimental Toxocara canis-infected pigs.

The relationship between the immunological and hematological response to infection was studied in pigs inoculated experimentally with Toxocara canis. Two groups of four pigs were infected with doses of 1000 and 2000 infective eggs, respectively. Two uninfected animals were used as negative controls. Blood samples were collected from each pig once a week. Serological examination by ELISA to determine antibody levels against T. canis L2/L3 excretory-secretory (ES) antigens showed values higher than the positive cut-off point (1:32) for both the infected groups. These values increased from day 7 p.i. and remained high during the experimental period until day 56. Significant differences were recorded for the two inoculating doses (p