To confirm the usefulness of ear/hindfoot ratio (ear length/hindfoot length) in the identification of three house rats/mice, we measured ear/hindfoot ratio and tail ratio (tail length/head body length) for 45 black rats and 42 brown rats every seven days from 23 to 149 days of age. Ear/hindfoot ratio of 399 black rats, 142 brown rats, and 113 house mice carcasses were also measured. Ear/hindfoot ratios did not change significantly with growth in black rats and brown rats, and there was no overlap between species, but tail rates changed significantly and there was overlap between species. The maximum hindfoot length of house mice was 17.0 mm, and the minimum hindfoot length of black rats and brown rats was 19.5 mm and 25.0 mm. Ear/hindfoot ratio of the carcasses showed that the minimum value of black rats was 0.58 and the maximum value of brown rats was 0.55. These results indicate that, regardless of developmental stage, it should be possible to discriminate house mice from black rats and brown rats by hindfoot length and discriminate between black rats and brown rats by ear/hindfoot ratio.

We analyzed cases of tick bites that visited one dermatology clinic in Shizuoka Prefecture from 2016 to 2023. The age distribution of the 754 patients (346 males and 408 females) ranged from 0 to 97 years, with the largest number (240 cases) in their 70s. By tick species, Amblyomma testudinarium (AT) was the most common (717 cases), followed by Haemaphysalis longicornis (28 cases). The month with the highest number of cases was May (226 cases). As for the bite site, AT bites tended to be more common on the lower half of the body. Among the 717 cases of AT bites, 150 cases (20.9%) had erythema larger than 50 mm (tick-associated rash illness, TARI). ABO blood typing of each case showed no significant difference between AT bites and TARI cases. TARI cases were significantly more likely to have a history of tick bite. The success rate of tick removal methods in AT bites were significantly higher in the group using tick removal devices than in the groups using finger or tweezers. There were no cases of Japanese spotted fever or severe fever with thrombocytopenia syndrome after tick bites, suggesting that the risk of developing tick-borne infectious diseases is extremely low.

The highest distribution point of Blattella nipponica was 454 m above sea level on the slope of Mt. Daisen in Tottori Prefecture. Additionally, B. nipponica was widely distributed on the slopes of Mt. Daisen at altitudes below 454 m. Furthermore, to confirm the establishment of B. nipponica, we investigated its seasonal variation in emergence at three locations at different altitudes and found that it showed a univoltine life history, with overwintering of mainly 6th instar larvae. We also found that the 1st instar larvae of B. nipponica appeared in August and July at low and high altitudes, respectively, indicating differences in its seasonal prevalence depending on altitude. Considering its life cycle at high altitudes, we attempted to estimate the vertical distribution of the species on Mt. Daisen based on the lower developmental threshold temperature and thermal constant. The results were consistent with those of a distribution survey. This suggests that temperature limits the vertical distribution of B. nipponica on Mt. Daisen. These results suggest the importance of elucidating the life cycle of B. nipponica to estimate its distribution range. Furthermore, these results may be used to accurately estimate the horizontal distribution (northern limit) of B. nipponica.

The environment profoundly affects the gut microbiota of wild rodents, which are reservoirs of various infectious diseases. In the gut of wild rodents, parasites cohabitate and interact with the bacteria. Thus, monitoring the gut microbes is important for the prediction of future outbreaks of zoonosis, as well as the livestock infectious diseases. However, reports on the gut microbiome of wild rodents in Japan are limited. In the present study, we investigated the gut symbiosis of prokaryotes and eukaryotes in wild mice captured at the two sites around Lake Kahoku-gata in Ishikawa Prefecture, Japan. The diversity and composition of the microbiome differ between the locations around the same lake, highlighting the need to cover several sites, even in the same water system, for the precise prediction of possible zoonosis in the future.

The infection pathway of Japanese encephalitis was originally investigated in Japan, and it was found that herons carry the pathogen and that zoophilic Culex tritaeniorhynchus plays an important role in transmitting the virus from birds to pigs and then human. This scenario was thought to be applicable to Southeast Asian countries where rice paddy cultivation and pig breeding are common. However, there are Asian countries where pig breeding is rare. We asked if it is possible to follow any infection route of Japanese encephalitis without pigs as amplifying host in Bangladesh. We collected mosquitoes at night in places where pigs are not raised, including places where only humans are present as larger mammals. As a result, the occurrence of Cx. tritaeniorhynchus peaked in the winter when rice paddy cultivation is carried out and with abundant migrating birds. Culex tritaeniorhynchus was most frequently collected in cow sheds, but not a few were also collected in dormitory rooms where only humans sleep and wake up. Under these circumstances, we discuss effective measures to prevent Japanese encephalitis.

Old records and information newly found for Ornithomya fringillina, Hippobosca longipennis, and Lipoptena japonica (Hippoboscidae) in Japan and the Republic of Korea were presented.