ABSTRACT
To determine that Paragonimus sp. is actively transmitted in a tropical area of the Pacific region of Ecuador where human cases of pulmonary paragonimiasis have recently been documented, a total of 75 freshwater crabs were collected from 2 different streams in the Pedernales area of Manabí Province, Ecuador. All collected crabs were identified as Hypolobocera guayaquilensis based on morphological characteristics of the male gonopods. The hepatopancreas of each crab was examined by compressing it between 2 glass plates followed by observation under a stereomicroscope. Excysted Paragonimus metacercariae were detected in 39 (52.0%) crabs and their densities varied from 1 to 32 per infected crab. There was a positive relationship between crab size and metacercarial density. Sequences of the second internal transcribed spacer region of the ribosomal RNA gene of the Paragonimus metacercariae obtained in this study were identical to those of Paragonimus mexicanus deposited in the DDBJ/EMBL/GenBank database. Thus, the present study is the first to confirm that the crab species H. guayaquilensis is the second intermediate host of P. mexicanus in Manabí Province, Ecuador. Because this crab might be the possible source of human infections in this area, residents should pay attention to improper crab-eating habits related with a neglected parasitic disease, i.e., paragonimiasis.
Subject(s)
Humans , Male , Ecuador , Foodborne Diseases , Fresh Water , Genes, rRNA , Glass , Hepatopancreas , Metacercariae , Paragonimiasis , Paragonimus , Parasitic Diseases , RiversABSTRACT
Se estudió la infección por Paragonimus mexicanus en el rabipelado (Didelphis marsupialis) y cangrejo de agua dulce (Eudaniela garmani) en los municipios Sucre y Montes del Estado Sucre, Venezuela. Utilizando en la captura de ambas especies, trampas Sherman y redes de mano. En Sucre la prevalencia de parásitos fue 13,33% con una intensidad de 1,50 parásitos/rabipelado, y en Montes la prevalencia fue 31,88% e intensidad de 6,82 parásitos/rabipelado. En 634 cangrejos de Montes, la prevalencia de metacercarias fue 17,98% y 4,07 en 123 cangrejos de Sucre. En ambos municipios no hubo diferencias significativas entre prevalencia, intensidad y el sexo de los cangrejos, pero si una correlación positiva y significativa con la talla. En Sucre la intensidad de infección por individuo fue mayor (8,20) que en Montes (5,31). Se concluye que la infección fue más intensa en cangrejos hembras y en los de mayor talla. Estos resultados indican la existencia de un foco zoonótico en ambas áreas y la necesidad de continuar las investigaciones para determinar los elementos relevantes de esta interrelación parasitaria.
The Paragonimus mexicanus infection was studied in the opposum Didelphis marsupialis and crab Eudaniela garmani from the Sucre and Montes municipalities of Sucre State, Venezuela. In Sucre, prevalence of adult parasites in opposums was 13. 33% with an intensity of 1.50 parasites per individual; in Montes, prevalence was 31.88% with a parasite load of 6.82 parasites per host. Prevalence of metacercariae in crabs was 17. 98% in Montes and 4.07% in Sucre. No significant differences between prevalence, intensity and gender of the crabs was found in any of the two areas, but there was a positive and significant correlation with size. In Sucre, the crab parasite burden was higher, 8.20%, than in Montes, 5.31%. It was concluded that the intensity of infection was higher in female crabs and in those of a larger body size. These results indicate the existence of zoonotic contamination in both areas, and the need to continue investigating in order to determine relevant elements of this parasitic interrelation.
ABSTRACT
Paragonimiasis is a zoonotic disease in Mexico caused by adult digeneans of Paragonimus mexicanus species. Life cycle of this parasite involves two necessary intermediate hosts: a snail and a crab, and a mammal serving as the definitive host. Humans acquire the infection when eating raw or undercooked crabs infected by metacercariae. In March 2005, six opossums (Didelphis virginiana) were captured in Colima, Mexico. These opossums were euthanized in order to identify lesions caused by lung paragonimiasis. Infected lungs were processed and stained following the standard histological techniques. Four of the six opossums (67%) carried 25 adult parasites identified as P. mexicanus. The lung with the greatest number of parasites showed 13 multifocally distributed granulomas. The main histological changes were: infiltration of monocytes, lymphocytes, macrophages, plasma cells, epithelioid and giant cells, abundant neutrophils and eosinophils, as well as central necrosis of the eosinophilic granuloma. Likewise, interstitial pneumonia was observed due to the presence of eggs between the granuloma walls and alveolar spaces. This study represents the first description of the pulmonary lesions caused by P. mexicanus in wild mammals.
La paragonimiasis constituye una enfermedad zoonótica con origen en México por el digeneo adulto Paragonimus mexicanus. El ciclo de vida de esta especie involucra dos hospederos intermediarios obligatorios: un caracol y un cangrejo, así como un mamífero que actúa como hospedero definitivo. La infección humana ocurre a través de la ingestión de carne de cangrejo cruda o insuficientemente cocida, parasitada por metacercarias. En marzo de 2005, seis tlacuaches (Didelphis virginiana) fueron capturados en Colima, México; fueron sacrificados con el fin de extraer los pulmones mediante necropsia para identificar las lesiones ocasionadas por el parásito. Los pulmones parasitados fueron procesados y teñidos de acuerdo con las técnicas histológicas convencionales. Cuatro de los seis (67%) hospederos resultaron infectados por 25 gusanos adultos identificados como P. mexicanus. En un pulmón se encontraron hasta 13 granulomas, distribuidos multifocalmente. Los principales cambios histológicos fueron: infiltración inflamatoria de monocitos, linfocitos, macrófagos, células plasmáticas, epitelioides y gigantes, con abundantes neutrófilos y eosinófilos, así como necrosis central del granuloma eosinofílico. Asimismo, se observó neumonía intersticial debido a la presencia de huevos entre las paredes del granuloma y los espacios alveolares. Este estudio representa la primera descripción de lesiones pulmonares ocasionadas por P. mexicanus en mamíferos silvestres.