Host-induced phenotypic plasticity in Saccocoelioides lamothei Aguirre-Macedo and Violante-González, 2008 (Digenea: Haploporidae) a parasite of freshwater, brackish and marine fishes from Middle America

Saccocoelioides is a genus of trematodes associated with fishes from the Americas. In the current research, morphologically distinct specimens of Saccocoelioides spp. were collected from six countries in Middle America. Specimens were sequenced using three molecular markers, the domains D1-D3 of the large subunit (LSU) from the nuclear rDNA, the cytochrome c oxidase subunit 1 (cox1) and nicotinamide adenine dinucleotide dehydrogenase subunit 1 (nad1) from mitochondrial DNA. A total of 74 new sequences were compared and aligned with other sequences available in GenBank. Maximum likelihood and Bayesian inference analyses were inferred from the LSU and cox1 datasets, revealing unequivocally that all the specimens correspond to S. lamothei. A haplotype network was built with 119 sequences of the nad1 gene. The network detected 57 distinct haplotypes divided into three haplogroups. To explore morphological differences among samples of S. lamothei, 17 morphological features were measured from 53 specimens from three fish families: Eleotridae, Mugilidae and Gobiidae. Principal component analysis yielded three main polygons that corresponded with each family analysed, suggesting host-induced phenotypic plasticity. The current evidence suggests that S. lamothei infects at least five fish families along the Pacific coasts of Mexico, Guatemala, El Salvador, Honduras, Nicaragua and Costa Rica.

First case report of Metorchis orientalis from Black Swan

Metorchis orientalis belongs to the genus Metorchis of Opisthorchiidae, which mainly parasitizes in liver and bile ducts of waterfowl, causing liver dysfunction of the host. It has been reported that M. orientalis also infects humans. As a natural species in Australia and a popular ornamental animal, Black Swan (Cygnus atratus) has been imported into many countries. At present there has been no report of M. orientalis infection in Black Swan. In the present study M. orientalis infection in Black Swan was identified by a combination of different techniques, including morphological observation and molecular analysis. M. orientalis adults were found in the gallbladder and bile duct of a three-year-old female Black Swan, which was further confirmed by internal transcribed spacer (ITS) sequence analysis. In addition, the intermediate and definitive hosts of M. orientalis from the ‘Qing’ lake (a man-made lake in Changchun, China) that Black Swan lived were investigated and the infection route was preliminarily determined. Parafossarulus striatulus functioned as the first intermediate host which contained M. orientalis DNA, and fishes such as Pseudorasbora parva and Rhodeinae served as the second intermediate hosts with M. orientalis metacercariae in the fish flesh. M. orientalis eggs were found in the feces of three other Swans and six ducks that lived in the ‘Qing’ lake. This was the first reported case about M. orientalis infection of Black Swan. Our study described the course of the infection and provided new information about potential carriers and disseminators of M. orientalis.

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M. orientalis infection was firstly reported in Black Swan in China.

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P. striatulus served as the first intermediate host, P. parva and Rhodeinae as the second intermediate host. •Swans and ducks served as the definitive hosts.

Prevalence of Angiostrongylus cantonensis among different species of snails in the village of Bagong Sikat Muñoz, Nueva Ecija, Philippines and its associated risk factors for zoonotic transmission

Snails are good source of protein and one of the delicacies in majority of the areas in the Philippines. However, they may act as an intermediate host for several parasites such as Angiostrongylus cantonensis. This parasite is commonly found in South East Asia especially in agricultural countries like the Philippines. Hence, the present study aims to determine the prevalence of A. cantonensis in their intermediate host in Village Bagong Sikat, which is situated at the rice granary of the Philippines. A total of 947 snails were randomly collected within 50 m × 50 m transect line through handpicked method. The third larvae (L3) stage from the snails was recovered through artificial tissue digestion. Results showed that 173 out of 947 snails (18.27%) were found positive with A. cantonensis L3 larvae. Three species of snails were recovered having Melanoides tuberculata to have the highest prevalence of A. cantonensis (21.54%) followed by Pomacea canaliculata (17.75%) and Vivipara angularis (17.74%). Statistical analysis further showed that prevalence of A. cantonensis and the length of snails has no significant difference (p > 0.05). The species of snails collected and found infected in the present study are considered part of the delicacies of the locals in Nueva Ecija. Thus, these results highlight the need to raise awareness of the locals regarding the zoonotic potential of A. cantonensis, which are of public health importance.