Trichinella spiralis infection in pigs in eastern Bolivia

Summary Trichinellosis in pigs in Bolivia was first documented in 1993 following a small abattoir survey in a rural community in the Bolivian Altiplano. The present study investigated the presence of antibodies toTrichinella spiralis in pigs in the 2 largest departments in terms of pig production in Bolivia. Three geographically separate abattoir surveys were conducted to cover the major production areas in the Departments of Santa Cruz and Chuquisaca. Sera were tested using an enzymelinked immunosorbent assay. Of the 1,327 sera analysed from the 3 areas, 13·4% overall tested positive. Results from the 3 individual surveys varied from 10·2% seropositivity to 17·1 per cent. However, within each of the 3 sample areas, highly significant variation in seropositivity was encountered, with those areas with the most extensive production systems having the highest percentage of positive sera. Such variation is probably due to differences in nutrition with foraging and household waste being important components of pig diets in extensive production systems. The results of this study were similar to those obtained from the previous survey in the Altiplano and indicate that trichinellosis is present throughout Bolivia and is a potentially important public health problem.

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Infeccion PorTrichinella Spiralis En Cerdos En El Este De Bolivia

Resumen La triquinosis porcina fue detectada por primera vez en Bolivia en 1993 después de un estudio realizado en un matadero situado en una pequeña comunidad del altiplano. En est artículo se investigó la presencia de anticuerpos frente aTrichinella spiralis en cerdos en los 2 departamentos con una mayor cabaña porcina de Bolivia. Se estudiaron 3 matederos separados entre sí con objeto de cubrir las principales áreas productoras de cerdos en los departamentos de Santa Cruz y Chuquisaca. Se realizaron tests ELISA para detectar anticuerpos en el suero. De las 1327 muestras analizadas en total, el 13·4% fueron positivas. Los resultados obtenidos en cada matadero variaron entre el 10·2 y el 17·1% de seropositivos. No obstante, dentro de cada matadero se encontró una gran variabilidad, y aquellas áreas con sistemas de producción más extensivos fueron las que tuvieron porcentajes más altos de animales positivos. Esto se debe probablemente a diferencias en la alimentación, puesto que el pastoreo y el aprovechamiento de residuos domésticos son más importantes en los sistemas extensivos. Estos resultados son similares a los obtenidos anteriormente en otros estudios realizados en el altiplano e indican que la triquinosis está extendida en Bolivia y supone un peligro potencial para la salud humana.

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Infection ParTrichinella Spiralis Chez Des Porcs Dans L'est De La Bolivie

Résumé Des cas de trichinelloses chez des porcs en Bolivie ont été rapportés pour la première fois en 1993 après le suivi d'un petit abattoir d'une Communauté rurale de l'Altiplano bolivien. La présente étude s'intéressa à la présence d'anticorps contreTrichinella spiralis chez des porcs pour les 2 plus grands départements boliviens en terme de production porcine. L'étude de 3 abattoirs géographiquement distincts fut conduite pour couvrir les principales aires de production dans les Départements de Santa Cruz et de Chuqisaca. Les serums furent testés par ELISA. Parmi les 1327 serums analyses pour les 3 zones, 13,4% furent positifs. Les résultats de séropositivité pour les 3 zones varient entre 10,2% et 17,1%. Cependant, pour les 3 zones étudiées des variations trés significatives de séropositivité furent observées avec des pourcentages de séropositivité les plus élévés pour les zones ayant des systèmes de production extensive. De telles variations sont probablement dùes aux différences de nutrition par fourrage et déchets ménagés, principales composantes du régime alimentaire des porcs dans les systèmes de production extensive. Les résultats de cette étude furent similaires à ceux obtenus lors d'une étude précédente dans l'Altiplano, indiquant que la trichinellose est présente dans toute la Bolivie et apparait potentiellement comme un problème important de santè publique.

     

IgG response in guinea pigs to Trichinella spiralis infection

An enzyme-linked immunosorbent assay (ELISA) using excretory-secretory antigens was developed to study the dynamics of the IgG antibody response to varying levels of Trichinella spiralis infection in the guinea pig. Four groups of four Hartley guinea pigs each were infected with 1250, 250, 50 or 10 T. spiralis infective muscle larvae. They were bled every 15 days for 6 months and the IgG antibody response determined by ELISA. The time of seroconversion was dose dependent as the larger the dose, the earlier the response occurred. Significant differences in antibody response between the dose groups were evident at 30 days post-infection (P less than 0.05). Beyond 60 days post-infection, the response was similar in the four groups. The antibody response in the groups infected with 250 and 50 infective larvae was similar, but was significantly different from that of the high (1250) and low (10) dose groups from 30 days post-infection (P less than 0.01). Once seroconversion occurred, the antibody titer rose to the same level, irrespective of the initial dose. To compare the antibody response according to muscle larvae recovered, the guinea pigs were grouped into four categories: less than 10 larvae; 10-25 larvae, 50-80 larvae, greater than 100 larvae. A significant positive correlation (P less than 0.05) was observed at 60 days post-infection when these groups were compared.     

Concurrent infection with Trichinella spiralis and other helminths in pigs

The aim of this study was to investigate possible influence of different helmintosis in the development of Trichinella spiralis in experimental infected pigs. Forty-two Iberian pigs were allocated to six groups. Three groups were single inoculated with Ascaris suum, Metastrongylus apri or T. spiralis, respectively. Two groups were co-infected with T. spiralis and A. suum or T. spiralis and M. apri, respectively, while the last group included uninfected control pigs. Clinical signs were only observed in pigs with single or concurrent M. apri infections, with more severe respiratory symptoms in pigs with mixed M. apri infection. The number of A. suum and M. apri lung larvae, intestinal larvae of A. suum and adult M. apri were reduced in pigs with mixed Trichinella infections compared to pigs with single infections. In contrast, the number of liver white spots was higher in pigs with mixed infections. While T. spiralis muscular larval burdens were increased in pigs concomitantly infected with M. apri, they were reduced in pigs concomitantly infected with A. suum, compared to pigs receiving single infections with either of these helminths. Pigs with single or mixed A. suum infections showed higher eosinophil levels compared to the remaining groups. IgGt, IgG1, IgG2 and IgM against T. spiralis antigen could not be detected in pigs with single Ascaris or Metastrongylus infections, indicating that no cross-antibodies were produced. IgGt, IgG1 and IgM antibodies were detected earlier and generally at higher levels in mixed T. spiralis infections compared to single T. spiralis infections. The results suggest that T. spiralis had a low synergistic interaction with M. apri in concomitantly infected pigs, and an antagonistic interaction in concurrent infection with A. suum.     

同仁县隆务镇商品猪旋毛虫感染情况的调查

目的了解同仁县隆务镇猪肉旋毛虫感染情况。方法采集市场销售的猪肉膈肌脚393份,常规压片镜检,计数包囊。结果在检测的样品中,阳性18份,猪旋毛虫感染率为4．58％。结论同仁县隆务镇猪肉旋毛虫感染率较高,需要立即加强猪旋毛虫病防治工作。     

Peripheral blood mononuclear cell subsets during Trichinella spiralis infection in pigs

The immune response of 'Yugoslav meat breed' pigs inoculated with low doses of Trichinella spiralis muscle larvae was followed over two to nine weeks of primary infection, by analysing changes in peripheral blood mononuclear cell subsets, the development of a humoral antibody response and muscle larvae burden. During the course of the infection, infected animals showed a persistent elevation of both CD4+ and CD8+ T cell subsets from days 15 to 60 after the parasite exposure. During this time, the number of peripheral blood mononuclear cells expressing major histocompatibility complex class II antigens was also increased, while no significant differences were found in the number of circulating monocytes/macrophages and B cells over time. Humoral antibody responses to muscle larvae excretory-secretory products were evident as early as 41 days after infection, while the muscle larvae were recovered as early as 27 days after infection. The increased levels of CD4+ and CD8+ T cell subsets, as well as cells expressing major histocompatibility complex class II antigens in pigs exposed to T spiralis, may be indicative of some considerable alterations in cell subsets that are involved in the regulation of the swine immune response to this parasite.     

Inhibition of passive systemic anaphylaxis in guinea pigs by Trichinella spiralis infection

Thirty of 33 guinea pigs experimentally infected with Trichinella spiralis survived passive systemic anaphylactic reactions which were fatal for 32 of 33 uninfected controls. Guinea pigs were infected with viable excysted trichinella larvae 20 to 32 days before they and uninfected controls were sensitized by intracardiac injection of rabbit anti-bovine serum albumin. Animals were challenged 24 hours later by intracardiac injection of bovine serum albumin. Respiratory anaphylaxis was observed in all challenged animals. Protection from passive anaphylaxis in parasitized guinea pigs was most likely due to preemption of mast cell receptors by parasite-induced antibody with consequent blockage of passive sensitization.     

Vaccination of rats and pigs against Trichinella spiralis spiralis using the subspecies, T. spiralis nativa.

Rats and pigs were vaccinated against Trichinella spiralis spiralis either by feeding infective larvae of the subspecies, Trichinella spiralis nativa in musculature or by gavage. The number of larvae established in the musculature of vaccinated nonchallenged and vaccinated challenged rats and pigs were negligible and statistically comparable, while highly significant infections were established in the nonvaccinated challenged rats and pigs. High vaccination doses of T. spiralis nativa gave virtually complete protection to challenge with T. spiralis spiralis in pigs. The results of one trial in rats with a lower vaccination dose of larvae suggest that there is a minimal vaccination dose of larvae required to elicit marked resistance to challenge. The low numbers of muscle larvae established due to the high vaccination doses of larvae confirm the low infectivity of the subspecies, T. spiralis nativa in rats and pigs.     

Experimental Trichinella spiralis infection in sheep.

During susceptibility studies of non-specific hosts, three merino sheep were infected with 3000, 5000 or 7000 Trichinella spiralis larvae by gavage. Clinical, physiological and serological parameters were assessed during the experiment. On the 152nd day p.i., animals were necropsied and, using artificial digestion methods, numbers of Trichinella larvae in muscle tissues were determined. The most infected parts were masseters with 3122 larvae g-1 muscle, 5526 larvae g-1 muscle and 4058 larvae g-1 muscle and diaphragms with 2778 larvae g-1 muscle, 2725 larvae g-1 muscle and 2320 larvae g-1 muscle, for the 3000, 5000 and 7000 infection levels, respectively. A positive correlation between infective rate and circulating antibodies was observed using ELISA and latex agglutination (LA) test methods. Trichinella larvae from sheep applied by gavage to ICR mice developed to the muscle stage. No significant changes were found in the clinical and physiological parameters of infected animals. Our results confirm the high susceptibility of merino sheep to T. spiralis infection.     

Immunity to Trichinella spiralis muscle infection

Trichinella spiralis larvae establish chronic infections in skeletal muscles of immunocompetent hosts. Muscle infection is crucial to transmission and survival of the parasite in nature. Chronic infections by this highly immunogenic parasite are associated with modulation or escape from potentially destructive immune responses. This review summarizes our current knowledge of immunity to muscle infection with T. spiralis.     

Inoculation of pigs against Trichinella spiralis, using larval excretory-secretory antigens

Pigs were inoculated with Trichinella spiralis excretory-secretory products derived from short-term in vitro maintenance of infective muscle larvae. Intraperitoneal administration of excretory-secretory products in Freund's complete adjuvant or aluminum hydroxide induced moderate, but variable, degrees of immunity to challenge exposure in a nondose-dependent manner; IM administration of products in Freund's incomplete adjuvant was less successful. Inoculated pigs harbored fewer adult worms, and the fecundity of female worms (numbers of newborn larvae shed in vitro) recovered after challenge exposure was significantly lower (alpha = 0.05) than the fecundity of females recovered from control pigs. The degree of resistance in inoculated pigs was directly related to serotiter against excretory-secretory antigens, as determined in an enzyme-linked immunosorbent assay.     

A search for infections of Trichinella spiralis in New Zealand pigs

Abstract

Extract

Following the occurrence of one case of human trichinosis in New Zealand in 1931 (Lynch, 1932 Lynch, P. P. 1932. N.Z. med. J., 31: 216–216.  [Google Scholar]), a search was made for the larvae of Trichinella spiralis in the diaphragms of pigs. The examinations were made by pressing out pieces of muscle between two glass slides, and examining them under the microscope using a low-power objective. Samples from nearly 20,000 pigs were examined without any infections being found (N.Z. Dept. Agric, 1932 N.Z. Dept. Agric. 1932. Annual Report for 1931–32, : 57–57.  [Google Scholar]).     

Pathogenesis and serodiagnosis of experimental Trichinella spiralis spiralis and Trichinella spiralis nativa infections in cattle.

Trichinella spiralis spiralis infections were established in cattle by gavage and by feeding infected musculature in the ration. Trichinae were present in greatest numbers in masseter, tongue and diaphragm. Trichinella spiralis nativa had a low infectivity to cattle although a light infection was established in one cow by a heavy challenge. Cattle had an aversion to eating musculature unless it was camouflaged with molasses. Clinical signs of reluctance to eat and masticate were observed between 10 and 30 days postinfection. Eosinophil counts started to increase at seven days and peaked at about 30 days postinfection. By day 60 eosinophil counts returned to near preinfection levels but in animals examined greater than 90 days postinfection, the counts were variable. Focal lesions of eosinophilic myositis were observed up to about 90 days postinfection. Little cellular reaction was observed surrounding trichinae after muscle invasion and cyst development was completed except for cysts undergoing disintegration. Seroconversion occurred in all cattle examined between 7 and 14 days postinfection. Seroconversion was associated with IgG1 and IgG2 immunoglobulins. Peak levels of antibody occurred between 30 and 60 days. Cattle examined at 182 and 369 days postinfection showed a gradual decrease in antibody levels over time.     

Clinical, haematological and blood biochemical changes in goats after experimental infection with tick-borne fever

Tick-borne fever in goats caused by Ehrlichia (Cytoecetes) phagocytophila was characterised by high fever, dullness, anorexia, tachycardia and a slight to moderate inhibition of rumen motility. The animals developed a gradual decline in the total number of circulating white blood cells. There was a decrease in lymphocytes over a short period, followed by an increase. The number of neutrophils was higher on the 3rd day, causing considerable change in the lymphocyte:neutrophil ratios. The number of eosinophils increased slightly. Serum alkaline phosphatase (ALP) decreased during the febrile episodes, and a marked decline was observed in both plasma zinc and iron concentrations. Furthermore, there was a small but progressive decrease of haemoglobin and haematocrit values. Circulating endogenous pyrogen/leucocyte endogenous mediator could not be detected in plasma from febrile goats. Tick-borne fever was passively transmitted to kids with plasma obtained from these febrile animals.     

河池市屠宰猪旋毛虫感染状况调查

旋毛虫病是一种人畜共患的寄生虫病 ,可以通过动物的肉直接传染给人。旋毛虫病呈世界性分布 ,欧、美、亚、非均有。我国 1 965年首次报道了人的旋毛虫病之后 ,云南、西藏、黑龙江、吉林、河南、湖北等地也先后有人体感染的报道。动物旋毛虫的感染更为普遍 ,在我国感染较严重的省有福建、贵州、西藏、云南、湖北、河南、甘肃、辽宁、黑龙江等。其中猪的感染率高低不等 ,有的高达 50 %。自二十世纪 80年代以来 ,广西发生四起 (横县、邕宁、德保、南丹 )严重的旋毛虫感染事件 ,一百多人感染发病。其中 ,1 995年初德保有 64人感染 ,5人死亡。河…     

Differentiation of Trichinella spiralis spiralis and Trichinella spiralis nativa based on resistance to low temperature refrigeration.

A refrigeration technique to differentiate the subspecies, Trichinella spiralis spiralis and T. spiralis nativa is described. Trichinella spiralis spiralis trichinae in musculature do not survive 48 hours post-refrigeration at -32 degrees C while T. spiralis nativa will survive 72 hours and longer at the same temperature.     

Trichinella spiralis and Trichinella pseudospiralis mixed infection in a wild boar (Sus scrofa) of Germany

A wild boar (Sus scrofa) from the island Usedom in Mecklenburg-Western Pomerania (north-east Germany) was detected as Trichinella-positive during routine meat inspection. Encapsulated and non-encapsulated larvae were detected in the muscle tissue by trichinoscopy. In the diaphragm, 922 larvae per g were detected by artificial digestion. Muscle larvae displayed two different sizes of about 700 and 1100 microm. By a multiplex PCR analysis, larvae with a large size were identified as Trichinella spiralis, whereas those of a smaller size were identified as Trichinella pseudospiralis. This is the first finding of a mixed infection of T. spiralis and T. pseudospiralis in a naturally infected animal and it supports the tendency of more frequent detection of the non-encapsulated species T. pseudospiralis in Europe.