ABSTRACT The purpose of the study was to identify the endohelminths of the native fish Galaxias maculatus and Basilichthys australis in Lake Pullinque Chile, determine their prevalence, mean intensity, mean abundance, their zoonotic potential, describe new taxa for Chile, and evaluate the potential histopathological changes in parasitized samples of intestine of B. australis. Trematodes (Steganoderma szidati, Acanthostomoides apophalliformis, Tylodelphys sp, Posthodiplostomum sp) nematodes (Contracaecum sp, Camallanus corderoi and Eustrongylides sp) and the acanthocephalan Acanthocephalus tumescens was reported in G. maculatus. Tylodelphys sp presented the highest prevalence (97%) and mean abundance (21.1), while Posthodiplostomum sp showed the highest mean intensity (33.5). Trematodes (Limnoderetrema tolosai, Austrodiplostomum mordax and Tylodelphys destructor) and nematodes (Contracaecum sp, Hysterothylacium geschei and C. corderoi) were identified in B. australis. The highest prevalence (100%), mean intensity (71.9) and mean abundance (71.9) corresponded to L. tolosai. The histopathological study in B. australis showed adults of L. tolosai adhered to the surface of the intestinal mucosa, damaging the epithelium of the villi, and larvae of Contracaecum sp encapsulated and associated with mild congestion and few mononuclear cells in the connective tissue of the submucosa. All taxa were recorded for the first time in fish from Lake Pullinque. Eustrongylides sp and S. szidati were described for the first time in Chile being Eustrongylides sp the only potentially zoonotic taxon.

RESUMEN El propósito del estudio fue identificar los endohelmintos de los peces nativos Galaxias maculatus y Basilichthys australis en el lago Pullinque, Chile, determinar su prevalencia, intensidad media, abundancia media, su potencial zoonótico, describir los taxones nuevos para Chile y evaluar potenciales cambios histopatológicos en muestras parasitadas de intestino de B. australis. En G. maculatus se reportaron trematodos (Steganoderma szidati, Acanthostomoides apophalliformis, Tylodelphys sp, Posthodiplostomum sp), nematodos (Contracaecum sp, Camallanus corderoi y Eustrongylides sp) y el acantocéfalo Acanthocephalus tumescens. Tylodelphys sp presentó la mayor prevalencia (97%) y abundancia media (21.1), mientras que Posthodiplostomum sp mostró la mayor intensidad media (33.5). En B. australis se identificaron trematodos (Limnoderetrema tolosai, Austrodiplostomum mordax y Tylodelphys destructor) y nematodos (Contracaecum sp, Hysterothylacium geschei y C. corderoi). La mayor prevalencia (100%), intensidad media (71.9) y abundancia media (71.9) correspondieron a L. tolosai. El estudio histopatológico en B. australis mostró adultos de L. tolosai adheridos a la superficie de la mucosa intestinal, dañando el epitelio de las vellosidades, y larvas de Contracaecum sp encapsuladas y asociadas a una leve congestión y escasas células mononucleares en el tejido conectivo de la submucosa. Todos los taxones fueron registrados por primera vez en peces del lago Pullinque. Eustrongylides sp y S. szidati fueron descritas por primera vez en Chile, siendo Eustrongylides sp. el único taxón potencialmente zoonótico.

ABSTRACT The purpose of the study was to determine the prevalence of eukaryotic parasite eggs, larvae and cysts, as well as the number of helminth eggs or larvae per gram of dog faeces collected in the streets of the coastal towns of Niebla and Corral, in the south of Chile. The stool samples were processed by a combination of the qualitative methods of Modified Telemann and flotation with zinc sulphate solution, in addition to the quantitative method of Knight et al. (1972). The results showed that 85.1 and 92.3% of the samples were positive in Niebla and Corral, with no significant differences between localities. In both cities were identified eggs and larvae of Uncinaria stenocephala, Toxocara canis, Trichuris sp, Spirocerca sp, Capillariidae gen sp, and Taeniidae gen. sp, as well as oocysts of Cystoisospora canis and sporocysts of Sarcocystis sp, with the highest prevalence for U. stenocephala and Trichuris sp.

RESUMEN El propósito del estudio fue determinar la prevalencia de huevos, larvas y quistes de parásitos eucarióticos, así como el número de huevos o larvas de helmintos por gramo de heces de perros colectadas en calles de las localidades costeras de Niebla y Corral, en el sur de Chile. Las muestras de heces fueron procesadas mediante una combinación de los métodos cualitativos de Telemann modificado y flotación con solución de sulfato de zinc, además del método cuantitativo de Knight et al. (1972). El 85.1 y 92.3% de las muestras resultaron positivas en Niebla y Corral, sin diferencia significativa entre localidades. En ambas ciudades se identificaron huevos y larvas de Uncinaria stenocephala, huevos de Toxocara canis, Trichuris sp, Spirocerca sp, Capillariidae gen sp, y Taeniidae gen. sp, así como ooquistes de Cystoisospora canis y esporoquistes de Sarcocystis sp, siendo las prevalencias mas altas para U. stenocephala y Trichuris sp.

RESUMEN: La Región de Arica y Parinacota se caracteriza por ser una región agrícola ubicada en el Desierto de Atacama en el extremo norte de Chile. Su agricultura ha permitido desarrollar la economía de comunidades pre y post-hispánicas, las cuales se han asentado desde la época colonial en diferentes localidades de la región. Este artículo se centra en cómo las comunidades Aymaras del Valle de Lluta y la Precordillera de la Región de Arica y Parinacota han sido incluidas como parte de la población chilena, particularmente, desde el punto de vista social y económico. Además, se incluye una caracterización de los aspectos agronómicos de los principales poblados de esta zona, y la comercialización de productos agrícolas y ganaderos. Se debe considerar que la evolución de esta región tendría un impacto importante en la salvaguarda de la flora y fauna endémica por lo que es imperativo proteger el patrimonio genético de las especies locales y promover nuevas tecnologías que permitan la producción de productos comerciales de la Región de Arica. y Parinacota.

ABSTRACT: The Region of Arica and Parinacota is characterized as an agricultural region located in Atacama Desert at the extreme north of Chile. Its agriculture has allow developing the economy of pre- and post-Hispanic communities, which have been settled since colonial times at different locations in the region. This article is focused on how Aymara communities of Lluta Valley and Precordillera of Arica and Parinacota Region have been included as part of Chilean population, particularly, from social and economic point of view. Furthermore, a characterization of agronomic aspects of the main towns of this zone, and commercialization of agricultural and livestock is included. It must be considered that the evolution of this region would have an important impact in the safeguard on endemic flora and fauna so that it is imperative to protect the genetic heritage of local species and to promote new technologies which allow the production of commercial products from Arica and Parinacota Region.

ABSTRACT The purpose of this investigation was to determine the presence and prevalence of blastocystosis, a zoonosis caused by Blastocystis sp in free-range hens in homes of different localities in southern Chile, simultaneously verify human infection in at least one locality, and identify other infections by intestinal parasites in birds. Fresh fecal samples from hens and humans were collected and preserved in PAF fixative and processed by the PAFS method combined with a flotation phase with zinc sulfate solution. Blastocystis sp was detected in half of the homes and the average prevalence was 14.2% in the total of localities being greater in the rural area and in the locality of Teupa (p<0.05). The prevalence in humans was higher than in hens in the town of Ñancul (p<0.05), where the parasite was present in both hosts in 4 of 7 households. The prevalence of infection by Entamoeba gallinarum and the presence of Toxocara spp eggs was similar between localities, but the prevalences of Eimeria spp, Capillariidae gen. spp and Heterakis gallinarum /Ascaridia galli showed differences between localities (p<0.05). Only in Valdivia were observed samples with eggs of Trichostrongylidae gen. spp. The presence of blastocystosis in chicken was detected for the first time in Chile, suggesting its potential transmission to humans. The presence of Toxocara spp eggs in bird faeces suggests that they could act as environmental dispersers.

RESUMEN El propósito de esta investigación fue determinar la presencia y prevalencia de blastocystosis, zoonosis causada por Blastocystis sp, en gallinas criadas libremente en domicilios de localidades del sur de Chile. Las muestras de heces frescas de aves y humanos fueron colectadas con el fijador PAF y procesadas mediante el método del PAFS combinado con una fase de flotación con solución de sulfato de zinc. En la mitad de los domicilios se detectó Blastocystis sp en las aves con una prevalencia promedio de 14.2%, siendo mayor en la zona rural y en la localidad de Teupa (p<0.05). La prevalencia en humanos fue mayor que en las gallinas de la localidad de Ñancul (p<0.05), donde el parásito estuvo presente en ambos hospederos en 4 de 7 domicilios. La prevalencia de infección por Entamoeba gallinarum y presencia de huevos de Toxocara spp fue similar entre localidades, pero las prevalencias de Eimeria spp, Capillariidae gen. spp y Heterakis gallinarum /Ascaridia galli mostraron diferencias entre localidades (p<0.05). Solo en Valdivia se registraron muestras con huevos de Trichostrongylidae gen. spp. La presencia de blastocystosis en gallinas se detecta por primera vez en Chile sugiriéndose su potencial trasmisión hacia los humanos. La presencia de huevos de Toxocara spp en las heces de las aves sugiere que estas podrían actuar como dispersores ambientales.

ABSTRACT On the Chilean mistletoe “Quintral”, there has been limited literature, despite the fact the numerous uses and ubiquity amongst the Mapuche natives in Chile and Argentina. Therefore, our research group has carried out an exhaustive extraction with solvents of increasing polarity to Quintral flowers and leaves hosted in three different host species. With the extracts of different polarities, a phytochemical screening was performed, finding the presence of glycosides, sterols, terpenoids and quinones which are documented to convey different applications in cardiovascular or gastric afflictions. Likewise, the content of total phenols, total flavonoids and the reducing power of all the extracts were determined, displaying significant differences for the three varieties. Leaf and flower of the “Huayún Quintral” in methanol extracts gave the highest values of reducing power, while leaf and flower methanol extracts of “Maqui Quintral” showed the highest values for total phenols. Also observed are the lower polarity extracts from Quintral, contributing to the reducing capability by means of non-phenolic compounds.

The aim of this study was to evaluate the effect of the inclusion of Azolla on the diet of Japanese quails on voluntary intake, apparent nutrient digestibility and egg production. A total of 240 16-week old quail on the first third of egg laying were used. The birds were housed in 24 raised cages (10 per cage). A completely randomized design was used with four treatments: T1: 0%, T2: 5%, T3: 10% and T4: 15% inclusion of Azolla in the diet. Voluntary nutrient intake was higher in Azolla treatments (p<0.05). The lowest egg yield g/bird/day¹ was in T4 (p<0.0001) and the best feed conversion was in T1 and T2 (p<0.0001). The apparent digestibility of dry matter and organic matter showed no significant difference between treatments. The highest crude protein digestibility was in T1 (46.1%) and T2 (44.5%) (p<0.0001) and the highest for digestibility of neutral detergent fibre was in T2 (63.6%) (p=0.034). The incorporation of Azolla by 5% in the quail diet produces a similar effect in egg production and feed conversion than the control diet, which could be used as a non-conventional low-cost product.

El objetivo de esta investigación fue evaluar el efecto de la inclusión de Azolla en la dieta de codornices japonesas sobre el consumo voluntario, digestibilidad aparente de los nutrientes y producción de huevos. Se utilizaron 240 codornices de 16 semanas de edad iniciando el primer tercio de postura. Las aves se alojaron en 24 jaulas elevadas (10 aves por jaula). Se utilizó un diseño completamente al azar con cuatro tratamientos: T1: 0%, T2: 5%, T3: 10% y T4: 15% de inclusión de Azolla en la dieta por 60 días. El consumo voluntario de nutrientes fue mayor en los tratamientos con Azolla (p<0.05). El menor rendimiento de huevos g/ave/día¹ fue en T4 (p<0.0001) y la mejor conversión alimenticia fue en T1 y T2 (p<0.0001). La digestibilidad aparente de la materia seca y materia orgánica no mostró diferencia significativa entre tratamientos. La mayor digestibilidad de proteína cruda fue en T1 (46.1%) y T2 (44.5 %) (p<0.0001), y para fibra detergente neutra fue en T2 (63.6%) (p=0.034). La incorporación de Azolla en un 5% en la dieta de codornices produce un efecto similar en la producción de huevos y conversión alimenticia que la dieta control, pudiendo utilizarse como un producto no convencional de bajo costo.

Resumen Esta investigación tiene el propósito de evaluar y comparar a personas heterosexuales y homosexuales, con relaciones de pareja estables, respecto a los componentes de la teoría triangular del amor, tácticas de resolución de conflictos, ajuste con la pareja y bienestar psicológico. Participaron 157 adultos jóvenes chilenos, 77 homosexuales (30 lesbianas y 47 gays) y 80 heterosexuales (45 mujeres y 35 hombres). Se utilizaron la Escala de Ajuste Diádico, la Escala Triangular del Amor de Sternberg, la Flourishing Scale de Diener y el Conflict Resolution Style Inventory de Kurdek. Los resultados muestran algunas diferencias significativas en tácticas de resolución de conflicto, componentes del amor y ajuste en la pareja, según la orientación sexual; además existen diferencias entre las mujeres que conviven y no conviven.

Abstract The aim of this study was to evaluate and compare heterosexual and homosexual people who are in stable relationships, with respect to the components of the triangular theory of love: conflict resolution tactics, couple adjustment and psychological wellbeing. The participants were comosed of 157 young adults Chileans: 77 homosexuals (30 lesbians and 47 gay men) and 80 heterosexuals (45 women and 35 men). The instruments used were the Dyadic Adjustment Scale, the Sternberg’s Triangular Love Scale, the Flourishing Scale of Diener and Conflict Resolution Style Inventory of Kurdek. The results show that there are significant differences in some conflict resolution tactics, components of love between partners, and couple adjustment according to sexual orientation. In addition, there are also differences between women living and not living with a partner.

SUMMARY The frequency of anti-Toxocara spp. antibodies in individuals attended by the Centro de Salud Familiar in the coastal Niebla town, Chile, was related to the host and to environmental factors. IgG anti- Toxocara antibodies were detected with a commercial ELISA kit (SCIMEDX Corporation, USA). Samples with undetermined absorbance values were subjected to an additional ELISA standardized by the Instituto de Salud Pública, Chilean Health Ministry, a commercial ELISA (NOVATEC, Germany), and a commercial Western blot kit (LDBio Diagnostics, France). Hematological exams were performed using an automated blood counter and blood smears. Dog feces were collected from the ground along the main road in Niebla, including rural and urban locations. Ninety (25.4%) of the 355 examined individuals were positive by the ELISA test. The frequency of anti-Toxocara antibodies and the infection risk were significantly higher (p < 0.05) among those individuals ≥ 40 years old with respect to the 20-39 years old group, in individuals from rural locations, those who did not have a safe drinking water supply in the house or who presented blood eosinophilia. The proportion of positive samples of dog feces and the mean number of Toxocara canis eggs/g of feces in urban and rural areas were similar (p > 0.05).

Background: In a rapidly changing culture like ours, with emphasis on productivity, there is a strong need to find the meaning of health care work using learning instances that privilege reflection and face to face contact with others. The Diploma in Health and Humanization (DSH), was developed as an interdisciplinary space for training on issues related to humanization. Aim: To analyze the experience of DSH aiming to identify the elements that students considered key factors for the success of the program. Material and Methods: We conducted a focus group with DSH graduates, identifying factors associated with satisfaction. Transcripts were coded and analyzed by two independent reviewers. Results: DSH graduates valued a safe space, personal interaction, dialogue and respect as learning tools of the DSH. They also appreciates the opportunity to have emotional interactions among students and between them and the teacher as well as the opportunity to share personal stories and their own search for meaning. Discussion: DSH is a learning experience in which their graduates value the ability to think about their vocation and the affective interaction with peers and teachers. We hope to contribute to the development of face to face courses in the area of humanization. Face to face methodology is an excellent teaching technique for contents related to the meaning of work, and more specifically, to a group of learners that require affective communication and a personal connection of their work with their own values and beliefs.

Background: The Postgraduate Hospital Education Environment Measure (PHEEM) questionnaire, is a valid and reliable instrument to measure the educational environment (EE) in postgraduate medical education. Aim: To evaluate the EE perceived by the residents of a postgraduate training program using the PHEEM. Material and Methods: The PHEEM was applied in 2010-2011 in 35 specialty programs. We calculated their individual results and compared means of both global and individual domain scores of the PHEEM, by gender, university of origin and nationality. Cronbach's alpha coefficients and D study (Generalizability theory) were performed for reliability. Results: Three hundred eighteen residents were surveyed (75.7% of the total universe). The mean score of the PHEEM was 105.09 ± 22.46 (65.7% of the maximal score) which is considered a positive EE. The instrument is highly reliable (Cronbach's alpha = 0.934). The D study found that 15 subjects are required to obtain reliable results (G coefficient = 0.813). There were no significant differences between gender and university of origin. Foreigners evaluated better the EE than Chileans and racism was not perceived. The programs showed a safe physical environment and teachers with good clinical skills. The negative aspects perceived were a lack of information about working hours, insufficient academic counseling, and scanty time left for extracurricular activities. Conclusions: This questionnaire allowed us to identify positive aspects of the EE, and areas to be improved in the specialty programs. The PHEEM is a useful instrument to evaluate the EE in Spanish-speaking participants of medical specialty programs.

This article presents a model of familiar therapy useful at primary health care for the treatment of patients with somatization disorder or somatization. The objective is to describe a case of somatization disorder and an intervention form of Brief Family Therapy. The method included the recollection of clinical history and the application of Brief Family Therapy by two health professionals: a psychologist and a family doctor. The results showed symptomatology reduction and patient autonomy. The use of Brief Family Therapy with somatization disorder is discussed in primary care and the importance of improving the system resoluty.

En este artículo se presenta un modelo de Terapia Familiar que puede ser útil en la atención primaria para el tratamiento de pacientes somatomorfos o con trastornos somatomorfos. El objetivo fue describir un caso de trastorno somatomorfo y una forma de intervención a través de la Terapia Familiar Breve. El Método incluyo la recogida de la historia clínica y aplicación de la Terapia Familiar Breve por dos profesionales de la salud: psicólogo y médico de familia. Los resultados muestran una disminución de la sintomatología y recuperación de su competencia personal para funcionar autónomamente. Se discute el valor de la aplicación de la Terapia Familiar Breve o de corta duración en la atención de pacientes con trastornos somatomorfos y la importancia de usar estrategias que mejoren la resolutividad del sistema.

Several studies have revealed a variety of mechanisms of invasion of alien plant species. However, little is known on how those mechanisms and their associated effects on native species change across different life-cycle stages. Under controlled conditions, we assessed the interactions between the alien invasive species Centaurea solstitialis L. (Asteraceae) and two pioneer native species to the Chilean matorral; Baccharis linearis (Ruiz et Pav.) Pers. and B. paniculata DC. (Asteraceae). Competitive effects of the invader on natives were evaluated by combining different life-cycle stages: seed-seed, plant-seed, and plant-plant. Seed germination of C. solstitialis was explosive and much faster than that of the native species. The presence of C. solstitialis (individuals or seeds) did not affect negatively the seed germination of the two Baccharis species. However, the presence of C. solstitialis plants significantly decreased the total biomass oí Baccharis plants. Thus, the effect of C. solstitialis on Baccharis species depended on the life-cycle stage at which the interactions occurred. In the Chilean matorral, the early emergence of C. solstitialis could be an important invasion mechanism, enabling established plants to competitively displace late emerging seedlings of Baccharis species. The huge abundance of C. solstitialis in some disturbed matorrals suggests that seedling establishment of these two pioneer species could be limited.

Varios estudios han revelado una variedad de mecanismos de invasión en las plantas alóctonas. Sin embargo, aún se conoce poco sobre cómo tales mecanismos y sus efectos asociados cambian a través de diferentes estados del ciclo vida. En este estudio evaluamos, bajo condiciones controladas, el resultado de las interacciones competitivas entre la especie invasora Centaurea solstitialis L. (Asteraceae) y dos especies pioneras nativas del matorral chileno; Baccharis linearis (Ruiz et Pav.) Pers. y B. paniculata DC (Asteraceae). Estas interacciones fueron evaluadas combinando diferentes estados del ciclo de vida: semilla-semilla, planta-semilla y planta-planta. La germinación de C. solstitialis fue explosiva, siendo mucho más rápida que la de las especies nativas. La presencia de C. solstitialis (plantas o semillas) no disminuyó la germinación de las especies nativas de Baccharis. Sin embargo, la presencia de plantas establecidas de C. solstitialis disminuyó significativamente la biomasa de las plantas de Baccharis. Entonces, el efecto de C. solstitialis sobre las especies de Baccharis varió en función del estado del ciclo de vida en el cual las interacciones ocurrieron. En el matorral chileno, la emergencia temprana y explosiva de C. solstitialis podría ser un importante mecanismo de invasión, ya que aquellas plantas prontamente establecidas podrían desplazar competitivamente a las plántulas de Baccharis que emergen más tarde. La enorme abundancia de C. solstitialis en algunas zonas de matorral sugiere que el establecimiento de plántulas de estas dos especies pioneras podría estar siendo limitado.

Background: Cyanoacrylate can be used for incision closure with better esthetical results, less pain and lower incidence of infections. However, it could have a lower resistance to tension. Aim: To compare tensile strength of wounds closed with a non reabsorbable monofilament suture and octylcyanoacrylate. Material and Methods: Two skin incisions were done in the dorsal area of 20 rabbits. One incision was closed with nylon 5-0 with stitches every 0.5 cm and the other was closed with 2 layers of octylcyanoacrylate. Groups of nine rabbits were killed at seven and ten days after the procedure. A skin rectangle of the wound area was removed and the tensile force of the suture was measured with a specially devised instrument. A histological study of the incision was also done. Results: At seven days, tensile strength of sutures closed with cyanoacrylate and nylon were 9.65 + 2.72 and 9.28 + 2.38 Newtons, respectively, p=NS. At ten days, the figures were 10.98 + 4.8 and 9.08 + 3.58 Newtons respectively, p=NS. The histological study showed more inflammation, cellularity, fibrosis and vascular proliferation in sutures closed with nylon. Conclusions: No differences in tensile strength of sutures closed with cyanoacrylate or nylon were observed in this animal model. Sutures closed with nylon had a higher inflammatory reaction

Objetivo: Comparar la fuerza tensil de heridas cerradas mediante una sutura monofilamento no reabsorbible (nylon 5-0) y un polímero adhesivo (2-octylcianoacrilato). Material y Método: Estudio experimental. En incisiones de piel, utilizando conejos de la misma raza, se han realizado dos grupos de diez conejos, con dos incisiones cada uno, cerradas con 2-octycianoacrilato y con nylon 5-0 como control. Se ha valorado la fuerza tensil mediante un tensiómetro, en 2 tiempos: al 7º día (grupo I) y al 10° día (grupo II) post cirugía, y se ha tomado una muestra para análisis histológico. Los cálculos estadísticos se hicieron a través de prueba T-Student, y un p < 0,05 se tomó como significación estadística. Resultados: El valor medio de la fuerza tensil en el grupo I fue de 9,65 + 2,72 Newtons para las incisiones cerradas con 2-octylcianoacrilato y 9,28 + 3,28 Newtons para las cerradas con nylon 5-0, no existiendo diferencia estadísticamente significativa (P = 0,801). En el grupo II el valor medio de la fuerza tensil fue 10,98 +4,80 Newtons para las incisiones cerradas con 2-octylcianoacrilato, y 9,08 + 3,58 Newtons para las cerradas con nylon 5-0, no existiendo diferencia estadísticamente significativa (p = 0,357). El estudio histológico mostró mayor inflamación, celularidad, fibrosis y proliferación vascular en incisiones cerradas con nylon 5-0. Conclusiones: La sutura de piel realizada con el polímero adhesivo 2-octylcianoacrilato es tan resistente a la tracción como la realizada con la sutura monofilamento no reabsorbible nylon 5-0 y presenta menor reacción inflamatoria local al estudio histológico

Acanthostomoides apophalliformis (Trematoda: Cryptogonimidae) não causa mortalidade detectável no peixe Galaxias maculatus (Teleostomi: Galaxiidae) de Argentina do Sul. O "puyen", Galaxias maculatus, é um peixe nativo pequeno que habita a América do Sul e a Oceania. Acanthostomoides apophalliformis é um trematódeo digenético que parasita, freqüentemente, os "puyenes". O estudo atual foi conduzido para determinar se existe mortalidade induzida por parasito no população do "puyen" no lago Moreno, no sul de Argentina. Os dados de abundância do parasito e no grau de aggregação da distribuição de freqüência do parasito, sugerem a ausência de mortalidade induzida por A. apophalliformis em "puyenes".

The present study was conducted to determine if parasite induced mortality existed in a "puyen" population in Moreno Lake, southern Argentina. Data on both parasite abundance and degree of aggregation of parasite frequency distribution showed the absence of fish mortality induced by A. apophalliformis.