| Summary Information |
| Diseases /
List of Parasitic Diseases
/ Disease summary |
| Alternative Names |
- Filarial worm infection
- Connective tissue worm infection
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| Disease Agents |
Dirofilaria
ursi (synonym Dirofilaria desportesi).
- Dirofilaria ursi were described for the first time, found in the abdominal
cavity of bears Ursus torquuatus japonicus (Selenarctos thibetanus japonensis i.e.
Ursus thibetanus - Asiatic black bear) from
Kiso, Nagano Prefecture, Japan. (J409.9.w1)
- They were 21-220 mm long; the nerve ring was 0.31-0.35 from the anterior end, body 0.37-0.45 mm broad at this point.
(J409.9.w1)
- Distinguished from the heartworm Dirofilaria immitis by
having more preanal papillae per row (4-9, average 7, versus 4-5,
average 4), the presence of longitudinal cuticular ridges, and a more
posterior placement of the vulva. (J11.61.w1)
- Transmitted by mosquitoes. (J345.3.w2)
- Dirofilaria desportesi was found in a black bear from Ontario, Canada.
(J30.30.w1) This was later considered
synonymous with
Dirofilaria ursi. (J345.3.w2)
- Males were 79-85 mm long, 0.25-0.29 mm wide at the level of the nerve ring, which was 0.28-0.31 mm from the anterior end. The anterior oesophagus measured 0.40-0.49 mm, the posterior oesophagus measured 0.67-0.82 mm. The right spicule measured 0.15-0.17 mm and the left spicule 0.35-0.50 mm and alated.
(J30.30.w1)
- Females measured 188-231 mm, and 0.30-0.40 mm wide at the level of the nerve ring, 0.30-043 mm from the anterior. The anterior oesophagus was 0.46 mm long, the posterior oesophagus 0.70-0.94 mm.
(J30.30.w1)
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| Infectious
Agent(s) |
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| Non-infectious
Agent(s) |
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| Physical
Agent(s) |
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| General Description |
- Dirofilaria ursi can be found in the abdominal cavity and subcutaneous tissues
of bears (B336.51.w51,
J1.11.w11, J345.3.w2)
and in the submucosa of the oesophagus. (J345.3.w2)
- Microfilariae are found in the blood. (J345.3.w2)
- This nematode is considered to be nonpathogenic. (B336.51.w51)
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| Further Information |
Occurrence
- Dirofilaria ursi were described for the first time from the abdominal
cavity of bears Ursus torquuatus japonicus (Selenarctos thibetanus japonensis, i.e.
Ursus thibetanus - Asiatic black bear) from
Kiso, Nagano Prefecture, Japan. (J409.9.w1)
- Dirofilaria ursi occurs in bears throughout Canada and the northern USA.
(J1.11.w11)
- Adult Dirofilaria ursi were found in connective tissue and the peritoneal cavities of Ursus americanus - American black
bears from Michigan and Minnesota. During April to September, Dirofilaria sp. microfilariae were detected in the blood of all 47 bears
examined. (J1.11.w11)
- Dirofilaria ursi were found in 57% of Ursus americanus - American black
bears during a study in Quebec, Canada, June 1971-November 1972.
(J1.13.w11)
- In two hunter-killed bears, adult Dirofilaria ursi were found in connective tissue around the aorta, kidneys and
rectum. Microfilaria of Dirofilaria ursi were found in blood
of Ursus americanus - American black
bears in northern Wisconsin during the summers of 1974 and 1975. (J1.14.w9)
- Dirofilaria ursi were found in the perioesophageal region of the thoracic inlet in
one of 91 bears during a study in northwestern Alberta, Canada, May 1976-September 1977.
(J1.15.w10)
- Dirofilaria ursi were found (two specimens) in the oesophagus
and tracheal connective tissue of a male Ursus thibetanus - Asiatic black bear
shot in Ogata, Oita Prefecture, Kyushu, Japan in September 1987. (J1.26.w11)
- Ursus thibetanus japonicus (Ursus thibetanus - Asiatic black bear)
in Japan. (J345.3.w2)
- Ursus arctos beringianus (Ursus arctos - Brown bear)
from Sakhalin Island, Siberia. (J345.3.w2)
- Ursus arctos - Brown bear
from south-eastern USSR. (J345.3.w2)
- Dirofilaria ursi were found in the perirenal fascia of three
bears from the Yukon and British Columbia; in one bear it was found
also in the superficial fascia of the inguinal region, during a survey
of grizzly bears (Ursus arctos - Brown bear)
from northern Canada, 1965-1967. (J30.47.w1)
- Dirofilaria ursi microfilaria were found in the blood of 57
live bears and Dirofilaria ursi adults in 91 bears necropsied
(total 140/148 bears) to give a total prevalence of infection of 94.6%
during a survey of Ursus
americanus - American black bears in central Ontario, Canada,
1975-1977. (J30.56.w4)
- Dirofilaria ursi were found in perirenal and other connective
tissues of 37/110 bear carcasses examined (33.7%) during a survey of Ursus americanus - American black bear
from New Brunswick, eastern Canada, 1989-1991. (J11.80.w1)
- Wild Ursus americanus - American black bear
from Ontario and Quebec in Canada, and from New York, Michigan,
Minnesota and Montana in the USA. (J345.3.w2)
- Wild Ursus arctos - Brown bear
in Alaska (found commonly), Montana and north-western Canada. (J345.3.w2)
- Microfilaria were found in the blood of 34/36 Ursus americanus - American black
bears examined live in New York (Adirondacks, plus five from Allegany State Park),
1956-1958. Microfilaria were found in the blood of all of 10 adult
bears from a further group of bears live-trapped in the Adirondacks.
However, no microfilaria were found in the blood of 17 Ursus americanus - American black
bears from zoos in New York State. (J413.7.w1)
- Dirofilaria ursi were present in the subcutaneous tissues and
peri-oesophageal connective tissue of a wild 14-year-old female Ursus americanus - American black bear
in northeastern Minnesota. (J1.16.w11)
- A study of 177 wild Ursus americanus - American black bear
in spruce-fir forest found Dirofilaria ursi in two bears
killed on the Big Creek study area. (D274)
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| Associated Techniques |
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| Host taxa groups /species |
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