Hepatitis A virus (HAV) is a common infectious agent that causes acute hepatitis worldwide. Since the incubation period of HAV infection is about one month, it is difficult to identify the source of infection based only on medical interviews. Molecular epidemiological analysis of HAV isolated from patients can help to reveal the infection route and to identify diffuse outbreaks caused by common food vehicles. In the present study, samples were collected from 108 cases notified to the active epidemiological investigation system in Tokyo between 2016 and 2017. Samples found to be HAV-positive by semi-nested RT-PCR were subjected to sequencing and phylogenetic analysis; the results were analyzed together with the epidemiological data. HAV was detected in 99 out of 108 cases. Phylogenetic analysis showed that the 99 HAV strains were divided into 91 of genotype IA, two of IB, and six of IIIA. The 91 HAV strains typed as IA were further divided into four main line­ages, IA-1, IA-2, IA-3, and IA-4, each with a unique epidemiological background. Our nucleotide sequence database of HAV and epidemiological background data will be helpful to investigate sources of infection and the epidemiology of hepatitis A cases in the future.

Polymorphism in the mitochondrial gene ND5 enables the determination of the order, a taxonomic rank, of many insects from the 5 major insect orders—Diptera, Hymenoptera, Hemiptera, Coleoptera, and Lepidoptera. DNA nucleotide sequences of multiple species were determined and more than 19 nucleotides characteristic of each order were identified; this makes it possible to discriminate insects at the order level more precisely and easily than when using conventional techniques.

Chocolate and cocoa are manufactured from cacao beans produced by the cacao tree (Theobroma cacao). These products may contain cadmium (Cd), which originates from contaminated soil. Here, we surveyed the Cd concentrations in dark chocolate, milk chocolate, white chocolate and cocoa powder products purchased at retail stores in Japan, using inductively coupled plasma mass spectrometry. The Cd concentrations in these chocolate and cocoa powder products ranged from 0.00021 to 2.3 mg/kg and from 0.015 to 1.8 mg/kg, respectively. A weak positive correlation was found between the Cd concentration and the content of cocoa solids stated on the product labels. A comparison between these results and the maximum levels (MLs) set by the European Union revealed that the Cd concentrations in chocolate and cocoa powder products on the Japanese market exceeded the MLs for eight of the 180 chocolate products and 26 of the 140 cocoa powder products.

The aluminium (Al) content of Japanese confectionery and foods containing flour was investigated. Some of these items were investigated in previous studies, which examined foods that made use of baking powder containing aluminium potassium sulfate (Alum). Al was detected in 41 of the 123 samples at levels ranging from 0.01 (limit of quantitation) to 0.40 mg/g. The detection rate of Al in almost all confectionery (except Japanese confectionery) was decreased as compared with previous studies. However, the detection rate of Al in Japanese confectionery and foods containing flour was high. For 4 of the 41 samples tested, consuming one serving once a week would result in an Al intake exceeding the PTWI for young children (body weight=16 kg).