Centrocestus armatus is an intestinal parasite belonging to the family Heterophyidae. We developed an apparatus for recovering cercariae and clarified the infection dynamics of this parasite. To clarify the circadian rhythm of cercarial shedding in the summer season, we filtrated 30 l of river water every 2 h for 24 h. Cercariae were first detected between 06:00 and 08:00 h, increased over time to reach peak at 16:00 h and decreased thereafter, thus showing a single-peak pattern. In a survey of seasonal change, approximately 200 cercariae were contained in 1 l of river water during the summer season, while none were found during the winter. This cercarial shedding pattern appeared to be related to sunrise/sunset and water/atmosphere temperature. Therefore, we examined whether cercarial shedding was affected by light or temperature changes under laboratory conditions, and confirmed that both light and temperature were important factors for cercarial shedding. Light was a stronger factor than water temperature. Cercarial shedding of C. armatus occurred in response to temperature and light. The change in the number of juvenile metacercariae detected in fish brain corresponded with monthly detection rates of cercariae; however, the incidence of new infections decreased in August. This suggests that Nipponocypris temminkii contains a defense mechanism against new infections that may have hindered the increase in parasite infectivity. These results clarified the smooth infection from the first to the second intermediate host of C. armatus in the endemic river. Throughout the study period, fecal samples were collected from 19 kites, 114 herons, and three unidentified species. However, our results using C. armatus showed a low value of 1% in herons and 5% in kites. The infection dynamics of final host to first intermediate host need to be further investigated.

Infectious endocarditis (IE) concomitant with patent ductus arteriosus (PDA) is now considered rare because the early treatment of PDA in infancy has become standard. We report a case of PDA with IE diagnosed by computed tomography (CT). A 51-year-old man complained of arthralgia and numbness of the left extremities. He had fever of 39°C and left hemiplegia, and was referred to our hospital. A chest X-ray film showed infiltration in both lungs. CT revealed a mass lesion in the main pulmonary artery and a tubular connection between the main pulmonary artery and the aortic arch. Multiple small infarctions were also found in the brain, lungs, kidneys and spleen. Ultrasonic cardiography revealed a bi-leaflet aortic valve, and vegetations on the aortic and mitral valves. Staphylococcus aureus was detected by culture of an intravenous catheter tip. These findings suggested IE concomitant with PDA, and we started intravenous administration of antibiotics. However, congestive heart failure occurred due to severe aortic and mitral regurgitation 2 days after hospital admission, and therefore, we performed emergency surgery. The main pulmonary artery was incised after cardiopulmonary bypass was initiated. A 20-mm length of vegetation was found on the orifice of the PDA. The vegetation was removed and the PDA directly closed. Aortic and mitral valve replacement was then performed. The post-operative course was uneventful and his neurological symptoms did not exacerbate. No sign of IE recurrence was observed 2 years after the surgery. CT clearly showed PDA and vegetation in the main pulmonary artery, although ultrasonic cardiography did not. CT was useful to make a diagnosis of PDA with IE in the present case.

A 77-year-old man underwent aortic valve replacement with a Carpentier-Edwards Pericardial Magna (19 mm) for aortic stenosis. He presented with a low grade fever and congestive heart failure 6 months after the initial valve replacement. Staphylococcus aureus was detected in blood culture, and peri-valvular leakage was revealed by echocardiography. Prosthetic valve endocarditis was diagnosed and underwent re-aortic valve replacement with Medtronic Mosaic 21 mm bioprothesis. Six months after the re-do operation, perivalvular leakage was newly observed between the right and non-coronary cusps, which was opposite to endocarditis affected cusps. The peri-valvular leakage was considered to have resulted from the fragile valve annulus because he did not have fever, and repeated blood culture showed no bacterial growth. We performed a third surgery and repaired the leakage by adding sutures through the right atrium and the interventricular septum to avoid directly suturing the fragile annulus. The post-operative course was uncomplicated, and no sign of endocarditis nor perivalvular leakage was observed during 9-months of observation. It is considered that the aortic valve fixation sutures through the right atrium and inter-ventricular septum are useful alternatives for fragile aortic annulus after prosthetic valve endocarditis.

Chronic contained rupture of an abdominal aortic aneurysm （AAA） is a rare condition that can present with atypical symptoms, making diagnosis challenging. We report a case of chronic contained rupture of an AAA with vertebral destruction presenting as right lower extremity pain. A 78-year-old man with a history of mitral valve replacement and pyogenic spondylitis （L2-L3） presented with a two-month history of low back pain and a four-day history of right lower extremity pain and numbness. Computed tomography revealed a 61 mm diameter ruptured AAA with an irregular margin. Magnetic resonance imaging demonstrated vertebral destruction at L4-L5. The patient underwent open surgical repair with a rifampicin-soaked graft and debridement. Intraoperatively, a large defect was found at the posterior aspect of the aneurysm, exposing the destroyed vertebral bodies. Postoperatively, the patient required spinal immobilization for persistent neurological symptoms, which improved and the patient was discharged on postoperative day 55.