Trichinella spiralis y Trichinella patagoniensis: cinética de desialización eritrocitaria / Trichinella spiralis and Trichinella patagoniensis: kinetics of erythrocyte desialization / Trichinella spiralis e Trichinella patagoniensis: cinética de dessialização eritrocitária

El objetivo del trabajo fue estudiar la cinética de desialización eritrocitaria producida por larvas infectantes de Trichinella spiralis y Trichinella patagoniensis. Se trabajó con 7 suspensiones eritrocitarias incubadas con 1.000±200 larvas musculares/mL, durante 2 horas, tomando muestra al tiempo inicial y cada 15 minutos. Los respectivos eritrocitos controles se incubaron de la misma manera con solución salina. Se aplicaron el método de titulación por Polibrene calculando el CexpST y un análisis de varianza (ANOVA) con las comparaciones múltiples según Tukey. Los resultados mostraron que el valor promedio de CexpST disminuyó con el aumento del tiempo de incubación, para ambas especies. En el tratamiento con T. spiralis no hubo diferencias significativas entre el valor medio del coeficiente a tiempo 60 y 75 minutos, mientras que con T. patagoniensis, a 45 y 60 minutos. Todas las restantes diferencias fueron significativas. La comparación entre los tratamientos, para cada uno de los tiempos, mostró que al tiempo inicial el coeficiente promedio no difirió entre las especies, pero que a todos los otros tiempos fue significativamente menor en la incubación de los eritrocitos con T. spiralis. Se concluye que la relación hospedador-parásito que se establece en ambos casos es distinta y probablemente también la capacidad de adaptación y de daño al hombre.

The objective of this work was to study the kinetics of erythrocyte desialization produced by infective larvae of Trichinella spiralis and Trichinella patagoniensis. It was performed on 7 erythrocyte suspensions incubated with 1,000±200 muscle larvae/ mL for 120 minutes, taking samples at the initial time and every 15 minutes. The respective control erythrocytes were incubated in the same way with saline solution. The Polybrene Titration method calculating the CexpST and variance analysis (ANOVA) with the multiple comparisons according to Tukey were applied. The results showed that the average value of CexpST decreased with the increase in incubation time, for both species. There were no significant differences between the mean value of the coefficient at 60 and 75 minutes in the treatment with T. spiralis, while neither were there any differences between 45 and 60 minutes in the incubation with T. patagoniensis. All other differences were significant. The comparison between the two treatments, for each of the times, showed that at the initial time the average coefficient did not differ between the species, but at all other times it was significantly lower in the incubation of the erythrocytes with T. spiralis. It is concluded that the parasite host relationship that is established in both cases is different and probably also is the ability to adapt and cause harm to man.

O objetivo do trabalho foi estudar a cinética de dessialização eritrocitária. produzida por larvas infectantes de Trichinella spiralis e Trichinella patagoniensis. O trabalho foi feito com 7 suspensões eritrocitárias incubadas com 1.000±200 larvas musculares/mL por 2 horas, colhendo amostras no tempo inicial e a cada 15 minutos. Os respectivos eritrócitos-controle foram incubados da mesma forma com solução salina. Foi aplicado o método de titulação por Polibreno calculando o CexpST e também uma análise da variância (ANOVA) com as comparações múltiplas de acordo com Tukey. Os resultados mostraram que o valor médio de CexpST diminuiu com o aumento do tempo de incubação para ambas as espécies. No tratamento com T. spiralis não houve diferenças significativas entre o valor médio do coeficiente no tempo 60 e 75 minutos, ao passo que com T. patagoniensis, aos 45 e 60 minutos. Todas as diferenças restantes foram significativas. A comparação entre os tratamentos, para cada um dos tempos, mostrou que no tempo inicial o coeficiente médio não diferiu entre as espécies, mas que em todos os outros tempos foi significativamente menor na incubação dos eritrócitos com T. spiralis. A conclusão é que a relação hospedeiro-parasita, estabelecida em ambos os casos, é diferente e provavelmente também a capacidade de adaptação e dano ao homem.

Survival of Trichinella papuae muscle larvae in a pig carcass maintained under simulated natural conditions in Papua New Guinea.

In Papua New Guinea, Trichinella papuae, a non-encapsulated species, is circulating among wild and domestic pigs and saltwater crocodiles. Since an important phase of the life cycle of nematodes of the genus Trichinella is the time of survival of infective larvae in decaying muscle tissues of the hosts, the carcass of a pig, experimentally infected with larvae of T. papuae, was exposed to the environmental conditions of Papua New Guinea to establish how long these larvae would survive and remain infective to a new host. Larvae retained their infectivity in the pig carcass up to 9 days after slaughtering, during which time the temperature within the carcass reached 35.0 degrees C on 2 days; the average relative humidity was 79.0%. A low number of larvae survived up to day 14 after the pig was killed, when the carcass temperature reached 38.0 degrees C, but they lost their infectivity to laboratory mice. This result suggests that the larvae of T. papuae can survive in a tropical environment for a time, favouring their transmission to a new host in spite of the lack of a collagen capsule.

Seroprevalence of Trichinella in slaughter pigs in Kathmandu Valley, Nepal.

The aim of the present study was to determine the Trichinella seroprevalence in slaughter pigs in Kathmandu Valley, Nepal. Serum samples were obtained from 400 pigs at 4 major slaughterhouses and tested for Trichinella antibodies by ELISA using larval excretory-secretory (E/S) antigen. Four were positive and one was equivocal, giving a Trichinella seroprevalence of 1% (95% CI: 0.27 - 2.54). On titration, all positive and equivocal samples had titers greater than 1:80. Upon re-examination the equivocal sample failed to give a positive ELISA result. The pigs were from four major areas of Nepal, Kathmandu Valley, eastern Nepal, Terai and adjoining areas of the valley. Positive results were found from only Kathmandu Valley and adjoining areas. There was no significant difference in the prevalence between areas (p = 0.43). All four positive samples were from indoor managed pigs. The Trichinella seroprevalence determined in this study deserves a direct demonstration of the parasites for proof of the presence of Trichinella in Nepal and to discover the species and infection sources.

Muscle fiber selectivity of Trichinella spiralis and Trichinella pseudospiralis (1983).

The biceps, semimembranosus, biceps femoris, and soleus muscles of female Rockland Wistar mice infected with either 1,000 Trichinella spiralis or 1,000 Trichinella pseudospiralis larvae were removed on days 12, 14, 16, and 18 post-infection (PI), sectioned and stained histochemically for their myosin ATPase activity. Light microscopic examination of the sections revealed that larvae of T. spiralis invade only the slow twitch muscle fibers, and those of T. pseudospiralis invade both the fast twitch and the slow twitch fibers. In sections obtained from mice infected with either parasite and killed on days 16 and 18 PI, identification of the majority of the infected fibers as fast twitch or slow twitch was not possible due to pathological modification of infected fibers.

Trichinosis: A recent outbreak in Northern Thailand.

During April, 1973, and outbreak of trichinosis occurred in Mae Sruay District, Chiang Rai Province, about 900 kilometers north of Bangkok, Thailand. Thirty-one persons were involved, of whom 27 (20 males, and 7 females), ranging in age from 9 to 72 years, were questioned. One adult female died before being brought to hospital. All subjects gave a history of having consumed raw pork in the form of "lahb" and "nahm", favourite dishes of the northern Thai. Beginning the third week after exposure, all developed fever and myalgia. Other less common complaints were diarrhoea and oedema of extremities and palpebral skin. Leucocytosis was revealed in 37% and 55% had eosinophilia exceeding 20%. Nineteen patients had hookworm and Opisthorchis infections. About 63% were skin test positive with Trichinella antigen. Eight patients were admitted to hospital; muscle biopsy was done on one serious case and trichina larvae were detected.