The prevailing infection of Schistosoma japonicum and other zoonotic parasites in bubaline reservoir hosts in the ricefield of lake ecosystem: the case of Lake Mainit, Philippines.

Bovines are important reservoir hosts of schistosomiasis, placing humans and animals in rice fields areas at risk of infection. This study reported the prevailing infection of zoonotic parasites from bovine feces in the rice fields adjacent to Lake Mainit, Philippines. Formalin Ethyl Acetate Sedimentation was performed on 124 bovine fecal samples from rice fields and documented eggs and cysts from seven parasites: Schistosoma japonicum, Fasciola gigantica, Ascaris sp., Strongyloides sp., Balantidium coli, coccidian oocyst and a hookworm species. Among these parasites, F. gigantica harboured the highest infection with a 100% prevalence rate, followed by hookworms (51.61%), B. coli (30.64%) and S. japonicum (12.09%), respectively. The intensity of infection of S. japonicum eggs per gram (MPEG = 4.19) among bovines is categorized as 'light.' Bovine contamination index (BCI) calculations revealed that, on average, infected bovines in rice fields excrete 104 750 S. japonicum eggs daily. However, across all ricefield stations, bovines were heavily infected with fascioliasis with BCI at 162 700 F. gigantica eggs per day. The study reports that apart from the persistent cases of schistosomiasis in the area, bovines in these rice fields are also heavily infected with fascioliasis. The study confirms the critical role of bovines as a reservoir host for continued infection of schistosomiasis, fascioliasis and other diseases in the rice fields of Lake Mainit. Immediate intervention to manage the spread of these diseases in bovines is recommended.

Prevalence of Schistosoma japonicum in bovines and Oncomelania hupensis quadrasi from ricefields surrounding Lake Mainit, Philippines.

Schistosomiasis is a parasitic disease caused by blood flukes of the genus Schistosoma and involves bovines and snails as a reservoir and intermediate hosts, respectively. This disease is endemic in Lake Mainit, Philippines, as early as 1947. The study was conducted to determine the prevalence of Schistosoma infection in ricefields adjacent to Lake Mainit by collecting Oncomelania hupensis quadrasi snails and bovine fecal samples which are then subjected to laboratory examination and analysis. A total of 345 O. quadrasi individuals and 32 bovine fecal samples were collected from six barangay rice field stations adjacent to Lake Mainit from February and July 2020. Among the six barangays, Alipao had the highest prevalence of Schistosoma in O. quadrasi (39.71%), followed by San Isidro (28.3%), Matin-ao (18%), Poblacion (15%), and Magpayang (2.5%). No Oncomelania snails were collected in the ricefields of Cuyago. Schistosoma japonicum had an overall prevalence of 14.71% in all the bovines sampled, where Cuyago had the highest prevalence (50.0%) followed by Alipao (33.33%). The intensity of infection of Schistosoma eggs per gram (MPEG = 0.70) among bovines is categorized as light. Bovine contamination index calculations revealed that, on average, infected bovines in Lake Mainit excrete ~ 55,000 S. japonicum eggs per day. The study confirms the important role of bovines as a reservoir host for schistosomiasis. The presence of both infected bovines and O. quadrasi in ricefields makes this agricultural venue an important nidus of S. japonicum emergence in Lake Mainit. An integrated approach of mass drug administration (MDA) of praziquantel, implementation of a bovine vaccine-directed control program, and providing farmers with mechanized farm equipment are highly recommended to minimize the risk of exposure and infection to schistosomiasis in rice fields adjacent to the lake.

Histological and ultrastructural characteristics of the testis of the invasive suckermouth sailfin catfish Pterygoplichthys disjunctivus (Siluriformes: loricariidae) from Marikina River, Philippines.

The histological and ultrastructural features of the testis of the invasive suckermouth sailfin catfish Pterygoplichthys disjunctivus rapidly proliferating in Marikina River, Philippines were characterized during the fish's 2010-2011 reproductive season. The germinal compartment of the testes was composed of anastomosing tubules with cysts undergoing synchronous development. Spermatogenic cells were along the length of the testes indicate it to be of the unrestricted spermatogonial type. The spermatozoon is classified as type 1 ect aquasperm devoid of acrosome, has rounded nucleus, and a long flagellum - characteristics necessary for external fertilization. Male P. disjunctivus was reproductively active during half of the year-long study with peak spawning during the most rainy months (June-August) and prolonged recrudescence during the dry months (February-May). Results from this study form a histological baseline to describe the gonad dynamics and reproduction of this invasive fish species as well as provide possible means of mechanical control to curb the population of the fish in this river.