The aetiology of an outbreak of haemorrhagic syndrome (HS) in a commercial broiler flock was examined. At a rearing farm, 596 of 6376 chicks (9.3%) in a flock were culled with depression and increased mortality from 12 to 26 days of age, with a peak at 16 to 19 days of age. Most of the affected chicks examined had haemorrhagic lesions of the muscles, atrophic changes of the lymphoid organs and aplastic bone marrow. Chicken anaemia agent (CAA) was isolated from the livers of all the 21 chicks examined. No fowl adenovirus was isolated. The present field case of HS coincides fairly well with the disease which is produced experimentally by CAA.

Populations of overwintering viruliferous Frankliniella occidentalis were evaluated in Tomato spotted wilt virus (TSWV)-affected green pepper fields in Bungo-Ohno City, Oita Prefecture, Japan. A survey of TSWV-infected weeds showed that the incidence of infection was low in weeds. Stellaria aquatica was infected frequently; however, the infections were considered secondary cases since S. aquatica appeared in the fields around late February to early March. In contrast, TSWV was frequently detected from green pepper fruits until they rotted. F. occidentalis primarily inhabited and reproduced on the green pepper fruits and moved to Lamium amplexicaule when the fruits rotted and subsequently spread to other weed species as young shoots or flowers appeared. The flying activity level of F. occidentalis rose in late February, and viruliferous F. occidentalis transmitted TSWV to green pepper plants. We concluded that TSWV-infected green pepper fruits discarded in greenhouses and fields are the major source of infection.

The acquisition efficiency of Tomato spotted wilt virus (TSWV) by Frankliniella occidentalis was examined using TSWV-infected Datura stramonium with various virus titres. TSWV quantities in leaves were measured using double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA) and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). The percentages of viruliferous F. occidentalis significantly correlated with DAS-ELISA and qRT-PCR values in the fed leaf piece. The detectable period of TSWV in viruliferous F. occidentalis adults trapped on sticky traps was also examined at various temperatures. At 25°C or less, TSWV could still be detected by DAS-ELISA in the bodies for at least 20 days after the capture of viruliferous F. occidentalis, although ELISA values had decreased gradually over time more rapidly at higher temperatures. The quantities of TSWV RNA detected by qRT-PCR rapidly decreased. The mean value decreased to half in a day, and reduced to 7.3% of the initial mean value after 14 days.

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