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Bartonella quintana is a gram-negative bacterium causing trench fever, an illness historically acquired by soldiers during World War I. More recently, outbreaks of trench fever have been reported in those experiencing homelessness in the United States, France, Russia, and Tokyo, as well as in children in Nepal and persons in Ethiopia. Reports of B. quintana infection outside of Tokyo are rare in Japan. The aim of this study was to examine body lice and blood obtained from people staying in shelters in Osaka (2009-2010) for B. quintana via polymerase chain reaction and enzyme-linked immunosorbent assays. Day laborers were defined as homeless individuals and shelter residents in this study. We detected genes of B. quintana in body lice by PCR and antibodies against B. quintana. The positive rate of B. quintana genes was 6/10 (60%) in body lice and the seroprevalence (IgG) of B. quintana was 4/10 (40%). This demonstrates that trench fever was endemic in people staying in shelters in Osaka in 2009-2010., (© The Author(s) 2023. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

Aedes albopictus (Skuse) (Diptera: Culicidae) is distributed widely and is common in much of Japan. In Japan, female adults begin to bite in between April and June, except in the southern subtropics where the mosquito has no dormant period. It is difficult to estimate the first Ae. albopictus biting day because it varies annually depending on the location. Over several years, we surveyed the mosquitoes at different locations that covered a range of warmer to cooler areas of Japan. We found an association between the timing of first biting day by Ae. albopictus and spring temperature. In spring months, the strongest correlation was found with mean April temperatures, followed by March. Based on these data, it may, therefore, be possible to apply a simple formula to predict the timing of the first biting day at various geographical locations in Japan. Forecasting maps were created using a simple prediction formula. We found that the first biting day for Ae. albopictus changed depending on early spring temperatures for each year. There was an approximate 20-d difference in first biting day between years with warmer and cooler springs. This prediction model will provide useful insight for planning and practice of Ae. albopictus control programs, targeting larvae and adults, in temperate regions globally., (© The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America.)

Superinfection exclusion is generally defined as a phenomenon in which a pre-existing viral infection prevents a secondary viral infection; this has also been observed in infections with mosquito-borne viruses. In this study, we examined the superinfection exclusion of the vertebrate-infecting flaviviruses, Japanese encephalitis virus (JEV) and dengue virus (DENV), by stable and persistent infection with an insect-specific flavivirus, Culex flavivirus (CxFV), in a Culex tritaeniorhynchus Giles cell line (CTR cells). Our experimental system was designed based on the premise that wild Cx. tritaeniorhynchus mosquitoes naturally infected with CxFV are superinfected with JEV by feeding on JEV-infected animals. As a result, we found no evidence of the superinfection exclusion of both JEV and DENV by pre-existing CxFV infection at the cellular level. However, JEV superinfection induced severe cytopathic effects on persistently CxFV-infected CTR cells. These observations imply the possibility that JEV superinfection in CxFV-infected Cx. tritaeniorhynchus mosquitoes has an adverse effect on their fitness., (© The Author 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.)

Calliphora nigribarbis Vollenhoven is a possible mechanical transmitter of highly pathogenic avian influenza. Based on laboratory tests, we evaluated the efficacy of a long-lasting permethrin-treated mosquito netting, known as the Olyset net, for the prevention of this species entering livestock barns. Flies were trapped in Olyset net cages, and two statistics for knockdown and lethal efficacies were obtained. Median knockdown time in the cage (KT50) was estimated to be 341 s for females, and median lethal time after exposure to the mesh (LT50) was estimated to be 30 s and <15 s for females and males, respectively. These LT50s were faster than those measured for anesthetized stationary flies brought in contact with the Olyset net (> 120 s for both sexes),indicating that a fly's spontaneous contact with the Olyset net accelerates insecticide adhesion. The rate of permethrin adhesion to C. nigribarbis after its spontaneous contact with the Olyset net was estimated to be 3.7 ng/s for females, in reference to the 50% lethal dose (LD50) value (112 ng/female), which was obtained from the topical application bioassay of permethrin. The lethality exhibited after brief spontaneous contact with the Olyset net suggests its potential utility in poultry farms against C. nigribarbis invasion.

To investigate the possible spread of West Nile virus (WNV) into Japan, we carried out entomological surveillance for flaviviruses at migratory bird stopover sites in Hokkaido, Japan, during 2003-2006. A total of 3,826 mosquitoes, identified as 15 species in five genera, were collected and 2,465 of these were grouped into 123 pools that were assayed for cytopathic effects on mosquito and mammalian cell cultures and for flavivirus RNA by reverse transcription-polymerase chain reaction using flavivirus universal primer sets for fragments of the NS3 and NS5 genes. Neither WNV nor other mosquito-vertebrate transmitted flaviviruses were detected in mosquitoes collected at any of the sites in Hokkaido, but five Culex flaviviruses and one novel Aedes galloisi flavivirus were identified from Culex pipiens L. s. l. and Aedes galloisi Yamada, respectively. Genetic and phylogenetic analyses based on the partial NS5 nucleotide sequences classified Aedes galloisi flavivirus with the insect flavivirus, but distant from Cell fusing agent, Kamiti river virus, and Culex flaviviruses, showing <74% sequence identities. Polymerase chain reaction-based bloodmeal analysis of 79 females showed that all of the Aedes and Ochlerotatus mosquitoes fed on mammals (deer and humans), whereas, Cx. pipiens s. l. mosquitoes fed on both of avian (ducks and sparrows, 85.7%) and mammalian hosts (dog, 14.3%). We suggest that to date WNV has not become established in Japan.

To evaluate the vectorial capacity of mosquitoes for viruses in Japan, the host-feeding habits of the mosquitoes were analyzed by sequencing polymerase chain reaction-amplified fragments of the cytochrome b and 16S ribosomal RNA regions of the mitochondrial DNA of 516 mosquitoes of 15 species from seven genera that were collected from residential areas during 2003-2006. Culex pipiens L. and Aedes albopictus Skuse were the most commonly collected species in urban and suburban residential areas. Anautogenous Culex pipiens pallens Coquillett was distinguished from the autogenous Cx. pipiens form molestus Forskal using a polymerase chain reaction-based identification method. Both Cx. p. pallens and Cx. p. form molestus exhibited similar host-feeding habits, broadly preferring avian (50.0 and 42.5% of avian, respectively) and mammalian (38.6 and 45.0% of avian, respectively) hosts, such as tree sparrows, ducks, and humans. Conversely, Ae. albopictus exhibited a highly mammalophilic and anthropophilic feeding pattern, with 84.2% feeding on mammalian hosts and 68.5% of these on humans. We concluded that in Japan, Cx. pipiens might play a significant role in the avian-to-mammal transmission of viruses, such as West Nile virus, whereas Ae. albopictus might play a role in the human-human transmission of dengue and Chikungunya viruses.

In a previous study, the highly pathogenic avian influenza (HPAI) H5N1 viruses were isolated from blow flies collected at the Tamba Town of Kyoto prefecture during the outbreak period in March 2004. In this study, we carried out virus exposure experiments to investigate whether the H5N1 virus would survive in a blow fly, Calliphora nigribarbis. The virus exposure experiments showed that the H5N1 influenza virus was isolated from the crop and intestine of C. nigribarbis for at least 24 h, and the viruses remained viable with titers ranging from 0.5 to 4.63 TCID50. This result suggests that C. nigribarbis could possibly transport the H5N1 virus over a distance of 2 km, which is the distance they can migrate within 24 h.

Pyrethroid insecticides play very important roles in the control of pediculosis, which is caused by human head louse (Pediculus humanus capitis De Geer) worldwide. The development of head louse resistance to pyrethroid pediculicides has become a global issue during the last two decades. Pyrethroid resistance is associated with amino acid substitutions in the alpha-subunit of the para-sodium channel gene; these substitutions are termed kdr-like mutations. The frequencies of four mutations (D11E, M815I, T929I, and L932F) in the sodium channel gene were studied in human head louse colonies collected from Japan by using SNaPshot method. A total of 630 head lice collected from 282 infested people were analyzed, and it was found that 55 lice of 19 colonies homozygously or heterozygously possessed kdr-like genes, in which the four mutations existed concomitantly. This suggested that the quadruple mutant haplotype is a common feature of the kdr genes of pandemic head lice. The frequencies of the occurrence of resistant genes in the total individuals tested and resistant gene-carrying colonies were 8.7 (55/630) and 6.7% (19/263), respectively. Because the resistant gene was detected in the colonies collected from 11 of the 22 prefectures surveyed, it is speculated that resistant head lice are already spread extensively in Japan. This was the first large-scale survey of pyrethroid resistant head lice in Japan.

Culex pipiens complex is the significant vector mosquito of West Nile virus. To take stock of the current situation of insecticide susceptibilities and design an ideal mosquito control strategy, we collected Culex pipiens pallens Coquillet, Culex pipiens form molestus Forskal, and Culex quinquefasciatus Say from fields in Japan and conducted bioassays for five larvicides (fenitrothion, temephos, etofenprox, diflubenzuron, and pyriproxyfen) by using a larval dipping method. Among five insecticides tested, obvious reduced susceptibilities were observed for etofenprox, which is the only pyrethroid compound registered as a larvicide in Japan. Twenty-two of 56 colonies exhibited a >10% survival rate at the etofenprox concentration of 5.7 microg/ml, which is a 10 times higher concentration of the working solution. The LC50 of a colony collected from Fukuoka prefecture for etofenprox exceeded 60 microg/ml (resistance ratio >2,307), and this colony also exhibited cross-resistance to other pyrethroids, permethrin (299-fold) and phenothrin (1,200-fold). The insect growth regulators diflubenzuron and pyriproxyfen were found to be sufficiently effective enough to control Culex larvae present, but decreased sensitivities to these insecticides were slightly detected in some colonies of Cx. p. form molestus collected from urban areas. Several etofenprox-resistant colonies of Cx. p. form molestus exhibited simultaneously decreased susceptibilities to other insecticides, including temephos, diflubenzuron, and pyriproxyfen.

Two cDNA sequences encoding Drosophila Ace-orthologous and -paralogous acetylcholinesterase precursors (AO- and AP-AChE precursors, respectively), were identified from the body louse, Pediculus humanus humanus L. In vitro inhibition studies with an insecticide-susceptible body louse strain exhibited a simplex inhibitory response of AChE. The I50 values of fenitroxon and carbaryl were estimated to be 2.2 and 1.9 microM for the susceptible lice, respectively. The mRNA level of AP-AChE gene was 3.1- and 9.3-fold higher than that of AO-AChE gene in the abdomen and the combined parts of the head and thorax, respectively, suggesting, due to its abundance, the potential significance of the AP-AChE isoform in Pediculus human lice in association with the efficacy of AChE-targeting pediculicides.

Trench fever is a body louse-borne disease caused by Bartonella quintana Brenner. The recent status of louse infestation in Nepalese children is not well known. We collected head and body lice, Pediculus humanus capitis De Geer and Pediculus humanus humanus L., respectively, from 30 children, including 11 cases of double infestation with both head and body lice. Detection of B. quintana in both louse species identified was carried out by polymerase chain reaction (PCR). PCR products with B. quintana DNA sequences were detected in both head and body lice from two children as well as in body lice derived from two other children. These results demonstrate that head lice may also play a role in the transmission of trench fever.

We experienced a case of Dermatobia hominis infestation from South America. Here we discuss imported cases of D. hominis in Japan with literature.

The dispersal pattern of the widow spider Latrodectus hasseltii (Araneae: Theridiadae), in Osaka Prefecture, Japan, was analyzed from accumulated survey data of spider distribution. All confirmed infested points from 1996 to 2002 were plotted on a map, and infested points in each survey year were connected with the nearest previously confirmed points. Expansion patterns of the confirmed habitats were analyzed by year and dispersion distances were classified by using spider diagram, one of method of geographical information system spatial analysis. L. hasseltii moves by walking step by step on the ground, mainly in coastal areas during early stages of infestation, and also can be conveyed over distances by various vehicles, mainly in inland areas. These analyses show L. hasseltii does not move by ballooning.

We report detection of Bartonella quintana Brenner, the pathogenic agent of trench fever, from body lice, Pediculus humanus L., infesting homeless people in Tokyo by polymerase chain reaction. Two of 12 (16.7%) homeless were infested with Bartonella-positive body lice. From the current status of the recent increase of homeless people in many large cities of the developed countries, a medical examination of homeless people should be carefully performed in the consideration of trench fever. Sampling of body lice from clothing of homeless people is recommended for quick and accurate diagnosis of trench fever through the detection of B. quintana DNA.