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Phocine distemper outbreak, The Netherlands, 2002.

Rijks JM, Van de Bildt MW, Jensen T, Philippa JD, Osterhaus AD, Kuiken T - Emerging Infect. Dis. (2005)

Bottom Line: During the 2002 phocine distemper epidemic, 2,284 seals, primarily harbor seals (Phoca vitulina), were found stranded along the Dutch coast.Stranding pattern varied with age, sex, state of decomposition, wind, and location.Cumulative proportion of deaths (54%) was comparable to that in the first reported epidemic in 1988.

View Article: PubMed Central - PubMed

Affiliation: Dutch Wildlife Health Center, Rotterdam, The Netherlands.

ABSTRACT
During the 2002 phocine distemper epidemic, 2,284 seals, primarily harbor seals (Phoca vitulina), were found stranded along the Dutch coast. Stranding pattern varied with age, sex, state of decomposition, wind, and location. Cumulative proportion of deaths (54%) was comparable to that in the first reported epidemic in 1988.

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Related in: MedlinePlus

Spatial and temporal distribution of seal strandings in the Netherlands during the 2002 phocine distemper virus epidemic. A) Spatial distribution of seal strandings and proportion of seals necropsied at each location. The diameter of each pie chart corresponds to the number of seals stranded at a particular location. The names of the Wadden Sea islands have been abbreviated (Tx, Texel; V, Vlieland; Ts, Terschelling; A, Ameland; S, Schiermonnikoog; R, Rottumeroog and Rottumerplaat). B) Weekly stranding rate of all stranded harbor seals and effect of age category on weekly stranding rate.
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Figure 1: Spatial and temporal distribution of seal strandings in the Netherlands during the 2002 phocine distemper virus epidemic. A) Spatial distribution of seal strandings and proportion of seals necropsied at each location. The diameter of each pie chart corresponds to the number of seals stranded at a particular location. The names of the Wadden Sea islands have been abbreviated (Tx, Texel; V, Vlieland; Ts, Terschelling; A, Ameland; S, Schiermonnikoog; R, Rottumeroog and Rottumerplaat). B) Weekly stranding rate of all stranded harbor seals and effect of age category on weekly stranding rate.

Mentions: Seal strandings were reported to a central telephone service. Live stranded seals were rehabilitated or euthanized. Dead stranded seals were collected for necropsy during which species, sex, standard body length, and state of decomposition were determined. Seals were divided into age categories, based on sex and standard body length (7): male juveniles (age <1 yr; length <95 cm), subadults (1 yr < age <4 yr; 95 cm < length <140 cm), or adults (age >4 yr; length >140 cm); female juveniles (age <1 yr; length <90 cm), subadults (1 yr < age <3 yr; 90 cm < length <130 cm), or adults (age >3 yr; length >130 cm) (Table 1).Of 1,315 seals that underwent necropsy, complete data were obtained for 1,096 harbor seals (Phoca vitulina) (Table 1). These seals originated from the entire Dutch coast, except from the islands Rottumeroog and Rottumerplaat, where they were buried; from the island of Texel, where they were collected for a different study; and from the mainland coasts of North Holland and South Holland, where only a few seals were submitted for necropsy (Table 1, Figure 1A). Because seals on which a necropsy was performed represented 56%–73% of the stranded seals in the remaining locations (Table 1, Figure 1A) and had a similar-shaped epidemic curve to that of stranded seals (Figure A1), they were considered representative of stranded seals. The daily wind factor was calculated by multiplying average daily wind force at Den Helder, North Holland (obtained from the Royal Netherlands Meteorological Institute [KNMI]), with its coefficient. Coefficients were positive for winds north of the line west-southwest–east-northeast, negative for winds south of this line, and ranged from 0, when the wind direction was parallel to this line, to 4, when at right angles to it. To analyze the effect of spring tide, the number of strandings on the day of spring tide and the 2 subsequent days was compared to the number of strandings on other days. We used the χ2 test for categorical comparisons and linear trends, and Mann-Whitney U and Kruskal-Wallis tests for temporal scales, with pair-wise comparison for the variables that showed significant overall effect (SPSS for Windows, SPSS Inc., Chicago, IL, USA). For stranded seals with missing observations, age category, sex, and state of decomposition were imputed by using data on seals that underwent necropsy and had been stranded in the same location and on the same or closest weekly date.


Phocine distemper outbreak, The Netherlands, 2002.

Rijks JM, Van de Bildt MW, Jensen T, Philippa JD, Osterhaus AD, Kuiken T - Emerging Infect. Dis. (2005)

Spatial and temporal distribution of seal strandings in the Netherlands during the 2002 phocine distemper virus epidemic. A) Spatial distribution of seal strandings and proportion of seals necropsied at each location. The diameter of each pie chart corresponds to the number of seals stranded at a particular location. The names of the Wadden Sea islands have been abbreviated (Tx, Texel; V, Vlieland; Ts, Terschelling; A, Ameland; S, Schiermonnikoog; R, Rottumeroog and Rottumerplaat). B) Weekly stranding rate of all stranded harbor seals and effect of age category on weekly stranding rate.
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Related In: Results  -  Collection

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Figure 1: Spatial and temporal distribution of seal strandings in the Netherlands during the 2002 phocine distemper virus epidemic. A) Spatial distribution of seal strandings and proportion of seals necropsied at each location. The diameter of each pie chart corresponds to the number of seals stranded at a particular location. The names of the Wadden Sea islands have been abbreviated (Tx, Texel; V, Vlieland; Ts, Terschelling; A, Ameland; S, Schiermonnikoog; R, Rottumeroog and Rottumerplaat). B) Weekly stranding rate of all stranded harbor seals and effect of age category on weekly stranding rate.
Mentions: Seal strandings were reported to a central telephone service. Live stranded seals were rehabilitated or euthanized. Dead stranded seals were collected for necropsy during which species, sex, standard body length, and state of decomposition were determined. Seals were divided into age categories, based on sex and standard body length (7): male juveniles (age <1 yr; length <95 cm), subadults (1 yr < age <4 yr; 95 cm < length <140 cm), or adults (age >4 yr; length >140 cm); female juveniles (age <1 yr; length <90 cm), subadults (1 yr < age <3 yr; 90 cm < length <130 cm), or adults (age >3 yr; length >130 cm) (Table 1).Of 1,315 seals that underwent necropsy, complete data were obtained for 1,096 harbor seals (Phoca vitulina) (Table 1). These seals originated from the entire Dutch coast, except from the islands Rottumeroog and Rottumerplaat, where they were buried; from the island of Texel, where they were collected for a different study; and from the mainland coasts of North Holland and South Holland, where only a few seals were submitted for necropsy (Table 1, Figure 1A). Because seals on which a necropsy was performed represented 56%–73% of the stranded seals in the remaining locations (Table 1, Figure 1A) and had a similar-shaped epidemic curve to that of stranded seals (Figure A1), they were considered representative of stranded seals. The daily wind factor was calculated by multiplying average daily wind force at Den Helder, North Holland (obtained from the Royal Netherlands Meteorological Institute [KNMI]), with its coefficient. Coefficients were positive for winds north of the line west-southwest–east-northeast, negative for winds south of this line, and ranged from 0, when the wind direction was parallel to this line, to 4, when at right angles to it. To analyze the effect of spring tide, the number of strandings on the day of spring tide and the 2 subsequent days was compared to the number of strandings on other days. We used the χ2 test for categorical comparisons and linear trends, and Mann-Whitney U and Kruskal-Wallis tests for temporal scales, with pair-wise comparison for the variables that showed significant overall effect (SPSS for Windows, SPSS Inc., Chicago, IL, USA). For stranded seals with missing observations, age category, sex, and state of decomposition were imputed by using data on seals that underwent necropsy and had been stranded in the same location and on the same or closest weekly date.

Bottom Line: During the 2002 phocine distemper epidemic, 2,284 seals, primarily harbor seals (Phoca vitulina), were found stranded along the Dutch coast.Stranding pattern varied with age, sex, state of decomposition, wind, and location.Cumulative proportion of deaths (54%) was comparable to that in the first reported epidemic in 1988.

View Article: PubMed Central - PubMed

Affiliation: Dutch Wildlife Health Center, Rotterdam, The Netherlands.

ABSTRACT
During the 2002 phocine distemper epidemic, 2,284 seals, primarily harbor seals (Phoca vitulina), were found stranded along the Dutch coast. Stranding pattern varied with age, sex, state of decomposition, wind, and location. Cumulative proportion of deaths (54%) was comparable to that in the first reported epidemic in 1988.

Show MeSH
Related in: MedlinePlus