European all-cause excess and influenza-attributable mortality in the 2017/18 season: should the burden of influenza B be reconsidered?

OBJECTIVES: Weekly monitoring of European all-cause excess mortality, the EuroMOMO network, observed high excess mortality during the influenza B/Yamagata dominated 2017/18 winter season, especially among elderly. We describe all-cause excess and influenza-attributable mortality during the season 2017/18 in Europe. METHODS: Based on weekly reporting of mortality from 24 European countries or sub-national regions, representing 60% of the European population excluding the Russian and Turkish parts of Europe, we estimated age stratified all-cause excess morality using the EuroMOMO model. In addition, age stratified all-cause influenza-attributable mortality was estimated using the FluMOMO algorithm, incorporating influenza activity based on clinical and virological surveillance data, and adjusting for extreme temperatures. RESULTS: Excess mortality was mainly attributable to influenza activity from December 2017 to April 2018, but also due to exceptionally low temperatures in February-March 2018. The pattern and extent of mortality excess was similar to the previous A(H3N2) dominated seasons, 2014/15 and 2016/17. The 2017/18 overall all-cause influenza-attributable mortality was estimated to be 25.4 (95%CI 25.0-25.8) per 100,000 population; 118.2 (116.4-119.9) for persons aged 65. Extending to the European population this translates into over-all 152,000 deaths. CONCLUSIONS: The high mortality among elderly was unexpected in an influenza B dominated season, which commonly are considered to cause mild illness, mainly among children. Even though A(H3N2) also circulated in the 2017/18 season and may have contributed to the excess mortality among the elderly, the common perception of influenza B only having a modest impact on excess mortality in the older population may need to be reconsidered.

Temporal variation in the effect of heat and the role of the Italian heat prevention plan.

OBJECTIVES: The aim of the article is to evaluate the temporal change in the effect of heat on mortality in Italy in the last 12 years after the introduction of the national heat plan. STUDY DESIGN: Time series analysis. METHODS: Distributed lag non-linear models were used to estimate the association between maximum apparent temperature and mortality in 23 Italian cities included in the national heat plan in four study periods (before the introduction of the heat plan and three periods after the plan was in place between 2005 and 2016). The effect (relative risks) and impact (attributable fraction [AF] and number of heat-related deaths) were estimated for mild summer temperatures (20th and 75th percentile maximum apparent temperature [Tappmax]) and extreme summer temperatures (75th and 99th percentile Tappmax) in each study period. A survey of the heat preventive measures adopted over time in the cities included in the Italian heat plan was carried out to better describe adaptation measures and response. RESULTS: Although heat still has an impact on mortality in Italian cities, a reduction in heat-related mortality is observed progressively over time. In terms of the impact, the heat AF related to extreme temperatures declined from 6.3% in the period 1999-2002 to 4.1% in 2013-2016. Considering the entire temperature range (20th vs 99th percentile), the total number of heat-related deaths spared over the entire study period was 1900. CONCLUSIONS: Considering future climate change and the health burden associated to heat waves, it is important to promote adaptation measures by showing the potential effectiveness of heat prevention plans.

Brenneria salicis Associated with Watermark Disease Symptoms on Salix alba in Italy.

From 1999 to 2010, withering of white willow was observed on trees growing along roads or irrigation canals in Torino, Alessandria, and Vercelli provinces of Italy, with incidence varying from 15, 25, and 30%, respectively. In spring and autumn 2008, six samples from withering branches with bark cankers were collected. On the bark surface near the cankers, iridescent traces of dried ooze were found. Tissues immediately below the cankers were dark with water-soaked, olive-colored edges. In some cases, the xylem appeared affected. Small fragments taken from the affected tissue on both edges of bark alterations and darkened vessels were crushed into mortars with sterile saline. Ten-fold serial dilutions (10-1, 10-2) were also performed. Aliquots of 0.1 ml were plated on nutrient agar and incubated at 25°C for 4 days. Bacterial colonies were ivory to white, circular, and bright, with a diameter of ~2 mm. Isolates were negative for Gram staining, presence of arginine dehydrolase, oxidase, phenylalanine deaminase, urease, hydrolysis of gelatin and starch, nitrate reduction, acidity from d-arabinose, cellobiose, lactose, maltose, trehalose, xylose, and pectinolytic activity on potato slices; positive for the presence of catalase and levan, fermentative metabolism of glucose, acid production from aesculin, l-arabinose, dextrose, d-galactose, inositol, d-mannitol, α-methylglucoside, raffinose, salicin and sucrose, H2S production from cysteine, and bright yellow pigment production on autoclaved potato tissue. They were not fluorescent on King's medium B and did not induce hypersensitivity reaction on tobacco leaf. Similar results were obtained with Brenneria salicis control strain, LMG 6089, except for acid production from α-methylglucoside (negative) and l-arabinose (negative). Acid production from α-methylglucoside has been reported for the Japanese strains of B. salicis, which do not produce acidity from inositol (4). Genomic DNA was extracted (1) from three isolates, and PCR reactions were performed with Es1A and Es4B primers (2) that amplify a 553-bp fragment from the 16S rDNA of B. salicis. The isolates showed a PCR product of expected size, like the positive control LMB 6089. On the basis of colony features, biochemical tests, and the PCR assay, we conclude that the isolates belong to B. salicis, a pathogen reported in Belgium, Germany, Great Britain, the Netherlands, Hungary, Japan, and New Zealand (2,3) but, as well as watermark disease symptoms, never previously reported in Italy. In summer 2009, pathogenicity tests were performed by inoculating young, white willow plants with B. salicis suspensions of ~1 to 2 × 109 CFU/ml placed with a syringe at the intersection of 1-year-old branches on the trunk. However, a year later, no symptoms of disease have been noted on the inoculated plants. According to the literature, pathogenicity tests rarely lead to the expected results because the bacterium can survive for many years in latent form, breaking out only when proper environmental conditions occur (3). Also the tests with B. salicis LMG 6089 gave negative results. Further investigation is necessary to clarify the relationships between this bacterium and the environment in causing withering of white willows in Piedmont. References: (1) W. P. Chen and T. T. Kuo. Nucleic Acids Res. 21:2260, 1993. (2) L. Hauben et al. Appl. Environ. Microbiol. 64:3966, 1998. (3) M. Maes et al. Environ. Microbiol. 11:1453, 2009. (4) Y. Sakamoto et al. Plant Pathol. 48:613, 1999.

Plant-pathogenic bacteria as biological weapons - real threats?

At present, much attention is being given to the potential of plant pathogens, including plant-pathogenic bacteria, as biological weapons/bioterror weapons. These two terms are sometimes used interchangeably and there is need for care in their application. It has been claimed that clandestine introduction of certain plant-pathogenic bacteria could cause such crop losses as to impact so significantly on a national economy and thus constitute a threat to national security. As a separate outcome, it is suggested that they could cause serious public alarm, perhaps constituting a source of terror. Legislation is now in place to regulate selected plant-pathogenic bacteria as potential weapons. However, we consider it highly doubtful that any plant-pathogenic bacterium has the requisite capabilities to justify such a classification. Even if they were so capable, the differentiation of pathogens into a special category with regulations that are even more restrictive than those currently applied in quarantine legislation of most jurisdictions offers no obvious benefit. Moreover, we believe that such regulations are disadvantageous insofar as they limit research on precisely those pathogens most in need of study. Whereas some human and animal pathogens may have potential as biological or bioterror weapons, we conclude that it is unlikely that any plant-pathogenic bacterium realistically falls into this category.

First Report of Syringae Leaf Spot Caused by Pseudomonas syringae pv. syringae on Tomato in Italy.

In the spring of 2006 and 2007, grafted and nongrafted tomato plants (scion cv. Cuore di Bue, rootstock Lycopersicon lycopersicum × L. hirsutum cv. Beaufort) displaying stem and petiole necrosis were observed in many commercial greenhouses in the Piedmont of northern Italy. Initial symptoms that developed 2 to 10 days after transplanting consisted of water-soaked circular lesions (2 to 3 mm in diameter) on stems and petioles. These lesions eventually coalesced into brown-to-black areas as much as 1 cm in diameter. In some cases, necrotic areas progressed from stem petioles to leaf tissues. Thereafter, plants wilted and died within a few days. In some greenhouses, more than 80% of young plants exhibited symptoms and production was severely reduced. Two to three sections of symptomatic tissue from stems and petioles from 20 affected plants were surface disinfested in 0.5% NaOCl for 1 min and repeatedly washed in sterile deionized water. Samples were macerated in nutrient yeast dextrose broth, streaked onto nutrient yeast dextrose agar (NYDA), and incubated at 22 ± 1°C for 48 h. Light yellow colonies typical of Pseudomonas spp. were consistently isolated on NYDA. All colonies fluoresced under UV light when grown on King's B medium (3). Colonies were levan positive, oxidase negative, potato soft rot negative, arginine dihydrase negative, and tobacco hypersensitivity positive (LOPAT test; group Ia). In addition, all isolates were positive for arbutin and aesculin hydrolysis and utilized erythitol, but not adonitol, l(+)-tartrate or dl-homoserine as a carbon source. The isolates also caused severe necrotic lesions on lemon fruits and lilac leaves (4). The bacterial colonies were identified as Pseudomonas syringae pv. syringae (1). Also, repetitive-sequence PCR using the BOXA1R primer indicated that the isolates belong to pattern 4 of P. syringae pv. syringae (4). The pathogenicity of three isolates was tested twice by growing the bacterium in nutrient broth shake cultures for 48 h, pelleting the suspension, resuspending the cell pellet in sterile water to a concentration of 106 CFU/ml, and spraying 35-day-old healthy tomato plants (cv. Cuore di Bue) with the inoculum. Ten grafted and 10 nongrafted plants were inoculated, and the same number of plants was sprayed with sterile nutrient broth as a control. After inoculation, plants were covered with plastic bags for 48 h and placed in the greenhouse at 22 ± 1°C. Six days postinoculation, stem lesions, similar to those seen in the field, and leaf spots were observed on all bacteria-inoculated plants, but not on the controls. Leaf tissues did not develop symptoms. Isolations were made from the lesion margins and the resulting bacterial colonies were again identified as P. syringae pv. syringae. To our knowledge, this is the first report of Syringae leaf spot caused by P. syringae pv. syringae in Italy as well as in Europe. A bacterial spot of tomato caused by P. syringae pv. syringae has been reported in the United States (2). References: (1) A. Braun-Kiewnick and D. C. Sands. Pseudomonas. Page 84 in: Laboratory Guide for the Identification of Plant Pathogenic Bacteria. 3rd ed. N. W. Schaad et al., eds. The American Phytopathological Society, St. Paul, MN, 2001. (2) J. B. Jones et al. Phytopathology, 71:1281, 1981. (3) E. O. King et al. J. Lab. Clinic. Med. 44:301, 1954. (4) M. Scortichini et al. Plant Pathol. 52:277, 2003.

Characterization of Erwinia amylovora strains from different host plants using repetitive-sequences PCR analysis, and restriction fragment length polymorphism and short-sequence DNA repeats of plasmid pEA29.

AIMS: The three main aims of the study were the assessment of the genetic relationship between a deviating Erwinia amylovora strain isolated from Amelanchier sp. (Maloideae) grown in Canada and other strains from Maloideae and Rosoideae, the investigation of the variability of the PstI fragment of the pEA29 plasmid using restriction fragment length polymorphism (RFLP) analysis and the determination of the number of short-sequence DNA repeats (SSR) by DNA sequence analysis in representative strains. METHODS AND RESULTS: Ninety-three strains obtained from 12 plant genera and different geographical locations were examined by repetitive-sequences PCR using Enterobacterial Repetitive Intergenic Consensus, BOX and Repetitive Extragenic Palindromic primer sets. Upon the unweighted pair group method with arithmetic mean analysis, a deviating strain from Amelanchier sp. was analysed using amplified ribosomal DNA restriction analysis (ARDRA) analysis and the sequencing of the 16S rDNA gene. This strain showed 99% similarity to other E. amylovora strains in the 16S gene and the same banding pattern with ARDRA. The RFLP analysis of pEA29 plasmid using MspI and Sau3A restriction enzymes showed a higher variability than that previously observed and no clear-cut grouping of the strains was possible. The number of SSR units reiterated two to 12 times. The strains obtained from pear orchards showing for the first time symptoms of fire blight had a low number of SSR units. CONCLUSIONS: The strains from Maloideae exhibit a wider genetic variability than previously thought. The RFLP analysis of a fragment of the pEA29 plasmid would not seem a reliable method for typing E. amylovora strains. A low number of SSR units was observed with first epidemics of fire blight. SIGNIFICANCE AND IMPACT OF THE STUDY: The current detection techniques are mainly based on the genetic similarities observed within the strains from the cultivated tree-fruit crops. For a more reliable detection of the fire blight pathogen also in wild and ornamentals Rosaceous plants the genetic features of deviating E. amylovora strains have to be studied in detail.

First Report of Bacterial Leaf Spot Caused by Pseudomonas cichorii on Phlox paniculata in Italy.

Phlox paniculata L. (fall phlox) is a perennial garden species belonging to the Polemoniaceae family. During the spring of 2003 and 2004, leaf spot symptoms were observed on fall phlox plants in some private gardens in the Biella area (northern Italy). Lesions were first observed on leaves at the collar level and later on the entire plant. Lesions started as water-soaked areas, which in few days developed on the upper side of the leaves into irregular, shrunken, reddish brown spots from 1 to 2 mm in diameter. Lesions on the lower surface sometimes had a translucent halo. In many cases, the leaves were completely withered. Disease was particularly severe during the spring and fall and its incidence ranged from 10 to 25%. No fungal structures were observed within the lesions. Small fragments of tissue from affected leaves were macerated in nutrient yeast dextrose broth (NYDA), and dilutions of the resulting suspension were streaked onto NYDA and potato dextrose agar (PDA). Isolations were made from at least 25 leaves. Plates were maintained at 22 ± 1°C for 48 h. No fungi were isolated from the spots on NYDA or PDA. Colonies typical of Pseudomonas species were consistently isolated on NYDA. Isolates were negative for levan, potato soft-rot (pectolytic activity), and arginine dehydrolase while positive for oxidase and hypersensitivity on tobacco leaves. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of whole-cell protein analysis (1) indicated that the bacterium isolated was similar to Pseudomonas cichorii (Swingle) Stapp NCPPB 943 and 3283 strains. On King's medium B, (2) a typical fluorescent pigment was produced. The pathogen was identified as Pseudomonas cichoriii. Pathogenicity of 10 colonies was tested by growing inoculum in nutrient-broth shake cultures for 48 h, suspending bacterial cultures in water, diluting to 106 CFU/ml, and spraying 10 1-year-old healthy plants of P. paniculata. Ten control plants were sprayed with sterile nutrient broth. Inoculated and control plants were kept covered with plastic bags for 72 h. After 8 days in a growth chamber at 20 ± 1°C, leaf spots identical to those observed in the field developed on leaves of inoculated plants. Control plants remained symptomless. The pathogenicity test was repeated once. Bacteria were reisolated from the spots and identified as P. cichoriii. To our knowledge, this is the first record of bacterial leaf spot of Phlox paniculata in Italy as well as in the world. References: (1) D. H. Bergey et al. Bergey's Manual of Determinative Bacteriology. Williams and Wilkins, Baltimore, MD, 1994. (2) E. O. King et al. J. Lab. Clin. Med. 44:301, 1954.

First Report of Bacterial Leaf Spot Caused by Pseudomonas syringae pv. viburnii on Viburnum sargentii in Italy.

During the spring of 2003, plants of Viburnum sargentii, a species mostly used in gardens as low-maintenance hedges, showing symptoms unlike those of known diseases were observed in some private gardens in the Biella area (northern Italy). Lesions on leaves were the only symptoms seen. Lesions started as water-soaked, circular areas that in 4 days developed into irregular, shrunken, brown spots from 2 to 4 mm in diameter. The core of older lesions appeared somewhat transparent. Leaves dried up completely 3 weeks after symptoms were first seen. No fungal structures were observed in lesions. Microscopic examination of affected leaf tissues revealed abundant bacterial ooze from the cut margin of lesions. Small fragments of tissue from affected leaves were macerated in nutrient yeast dextrose broth (NYDA) and dilutions of the resulting suspension were streaked onto NYDA and potato dextrose agar (PDA). Isolations were made from at least 25 leaves. Plates were maintained at 22 ± 1°C for 48 h. Slightly yellow colonies typical of Pseudomonas species were consistently isolated on NYDA. No fungi were isolated from the spots on NYDA or PDA. Levan production, oxidase production, pectinolytic activity, arginin dihydrase production, and tobacco hypersensitivity (LOPAT) were tested. Strains were positive for levan and negative for oxidase, arginine dihydrolase, and nitrate reductase. Strains did not rot potato slices but induced a hypersensitive reaction on tobacco leaves. Protein analysis (1) indicated that the bacterium isolated was similar to Pseudomonas syringae pv. viburnii NCPPB 1921. The pathogen was identified as Pseudomonas syringae pv. viburnii (2,3). Pathogenicity of 10 colonies was tested by growing inoculum in nutrient broth shake cultures for 48 h, suspending bacterial cultures in water, diluting to 106 CFU/ml, and spraying five 1-year-old healthy plants of Viburnum sargentii. Five control plants were sprayed with sterile nutrient broth. Inoculated and control plants were kept covered with plastic bags for 72 h. After 7 days in a growth chamber at 20 ± 1°C, leaf spots identical to those observed in the field developed on leaves of inoculated plants. Control plants remained symptomless. The pathogenicity test was repeated once. Strains were isolated from the spots and identified as P. syringae pv. viburnii. To our knowledge, this is the first record of bacterial leaf spot of Viburnum sargentii in Europe. A bacterial spot on Viburnum opulus, V. tomentosum, and V. dentatum was reported in the United States (4). References: (1) D. H. Bergey et al. Bergey's Manual of Determinative Bacteriology. Williams and Wilkins, Baltimore, MD, 1994. (2) J. W. Pscheidt et al. Diseases of Woody Ornamentals and Trees in Nurseries. The American Phytopathological Society, St. Paul, MN, 2001. (3) N. W. Schaad. Laboratory Guide for Identification of Plant Pathogenic Bacteria. The American Phytopathological Society, St Paul, MN, 1998 (4) H. H. Thornberry and H. W. Anderson. Phytopathology 21:907, 1931.