The infection of marine diatom Coscinodiscus wailesii by a parasitic protist from the Yongho Bay of Busan, Korea was observed during the diatom bloom events in 2017 through 2018. The morphological and molecular features suggested that the parasitic nanoflagellate Pirsonia diadema was responsible for the infection. During the study period, the parasite prevalence ranged from 0.3% to 3.3%, and infected C. wailesii cells were observed only at surface seawater temperatures ranging between 10.9 and 19.9°C, although the host population appeared at temperatures above 25°C. The parasite and host system was successfully established as cultures. Using the cultures, we determined the morphological features over the infection cycle, parasite generation time, parasite prevalence as a function of inoculum size, and zoospore infectivity and survival time. The diatom C. wailesii was readily infected by the parasite P. diadema, with a parasite prevalence reaching up to 100% and a zoospore to host inoculum ratio above 20 : 1. The survival and infectivity of the parasite zoospores decreased with age. While the zoospores could survive up to 88 hours, they quickly lost their ability to infect after 48 hours. These results could lead to a better understanding of the biology and ecology of the parasitoid infecting the giant-sized diatoms in coastal waters.

A 37 years old male patient had suffered from fibrous nasal polyp for more than 10 years even though careful medical treatment, and recently aggravated with severe nasal stiffness and pain. In the radiological observation the lesion was continuously extended into the ipsilateral maxillary sinus by poly cystic radiopacities gradually destroying the anterior wall of antrum. During the Caldwell-Luc operation a cystic fibrous granulomatous tissue was removed, and its microsections showed multicystic and tunnel-like spaces, of which lumens were usually round and filled with parts of parasitic worm e xhibiting parasitic t eguments and eggs. The granulomatous l esion showed relatively mild inflammatory reaction with the infiltration of eosinophilic PMNs. The histological features of tunnel-like penetration of parasitic worms, and their teguments and eggs were competent with the diagnosis of sparganosis. Especially, although the patient had no experience of raw foods such as frog or snake, he used to drink the untreated natural stream water obtained in the mountain area of Gangwon prefecture in Korea. Therefore, the present study demonstrated a rare lesion of antral spanganosis, and we suppose that the frequent incident of oral sparganosis in Gangwon prefecture is possibly related to the usage of untreated stream water in the mountain area of Gangwon prefecture in Korea