Diseases / List of Parasitic Diseases / Disease description:
Schistosomiasis in Waterfowl and Elephants

INFORMATION AVAILABLE

GENERAL INFORMATION

CLINICAL CHARACTERISTICS & PATHOLOGY

INVESTIGATION & DIAGNOSIS

TREATMENT & CONTROL

SUSCEPTIBILITY & TRANSMISSION

ENVIRONMENT & GEOGRAPHY

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General and References

Disease Summary
WATERFOWL Fluke infection of the blood vessels of diving ducks and geese, usually subclinical but which may cause liver pathology, enteritis, multi-systemic signs and granulomatous encephalitis.

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Alternative Names (Synonyms)
  • Schistosome Infection
  • Trichobilharzia infection
  • Dendritobilharzia infection
  • Bivitellobilharzia infection in elephants

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Disease Type
 Parasitic - Tapeworms and Flukes

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Infectious/Non-Infectious Agent associated with the Disease
In waterfowl:
  • Trichobilharzia physellae (fluke living in veins), Dendritobilharzia pulverulenta (=Dendritobilharzia anatinarum) (fluke living in arteries).

In elephants:

  • Bivitellobilharzia nairi; reported from Elephas maximus - Asian Elephants in India and Sri Lanka. (J378.53.w1)
    • Ornithobilharzia sp. (later renamed Bivitellobilharzia (B24)) was reported causing illness in Elephas maximus - Asian Elephants from India in 1954. (J12.30.w1)
    • Eggs measured 140 - 160 µm x 65-80 µm and were elongated cones with one side flatter than the other; at one end was a short, abrupt spine (J12.30.w1)
    • Bivitellobilharzia nairi reported from in Kanha National Park, Madhya Pradesh, India. Eggs recovered from faeces were oval, with a stout abrupt spine on one end, and measured 122 x 77 to 205 x 90 µm, with spines ranging from 6.2 x 2.35 to 8.3 x 3.2 µm. (J178.97.w1)
      • Freshwater snails found in the park and which have been confirmed as intermediate hosts for Indian schistosomes include Indoplanorbis exustus and Lymnaea luteola. 
  • Bivitellobilharzia sp. were found in the dung of working elephants from Kerala [1992 data]. (P502.1.w5)
  • Bivitellobilharzia loxodontae. (B24)
  • Schistosomiasis has been recorded in African elephants (Loxodonta africana - African Elephant) and Indian elephants (Elephas maximus - Asian Elephant) (Schistosoma nairi). (J350.10.w1)

Infective "Taxa"

 Specifically recorded for waterfowl:

Specifically recorded for elephants:

Specifically recorded for Elephas maximus - Asian Elephant::

Non-infective agents

 --

Physical agents

 -- Indirect / Secondary

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References

Disease Author

 Debra Bourne MA VetMB PhD MRCVS (V.w5); Gracia Vila-Garcia DVM, MSc, MRCVS (V.w67)
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Major References / Reviews

Code and Title List

 Waterfowl:

B10.26.w11, B13.46.w1, B15, B24
J1.18.w4
J4.181.w2

Elephants:

B24
J12.30.w1
J178.97.w1
J378.53.w1
J381.71.w1
P502.1.w5

Other References

Code and Title List

 Waterfowl:

B91
J1.13.w6, J1.13.w7, J1.17.w6

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Clinical Characteristics and Pathology

Detailed Clinical and Pathological Characteristics

General

 WATERFOWL Often subclinical. May be associated with emaciation and ill-thrift, also with nervous signs. Lesions may be found in the liver, kidneys, brain and other tissues, usually associated with schistosome eggs in tissues.
ELEPHANTS May be subclinical or associated with illness.

Clinical Characteristics

 WATERFOWL Usually subclinical. Various multi-systemic clinical signs described including nervous signs (circling, wing-flapping, listing of head to one side), ill-thrift, weight loss, emaciation and lameness (J1.18.w4, J4.181.w2, B10.26.w11, B13.46.w1, B15).
ELEPHANTS
  • May be found in the absence of any clinical signs. (J12.30.w1)
  • Loss of appetite, constipation and suppression of urination, followed by diarrhoea and vomiting, in six cases in India. (J12.30.w1)

Incubation

 WATERFOWL --
ELEPHANTS --

Mortality / Morbidity

 WATERFOWL --
ELEPHANTS
  • Morbidity appears to be variable, since schistosoma infection has been recorded both with and without clinical signs in elephants. (J12.30.w1)

Pathology

 WATERFOWL Lesions usually related to eggs lodged in tissues (B15).

Gross Pathology:

  • Gross lesions are uncommon.
  • Liver lesions have been described: enlarged, pale, friable, with large numbers of viable schistosomes (Trichobilharzia physellae), mainly males, in the portal veins and degenerating schistosomes (females only) in the interlobular bile ducts (J1.18.w4). Also severe enteritis (B15).

Histopathology:

  • Chronic enteritis and chronic uretitis associated with eggs in the walls of the intestines and ureters (J1.18.w4).
  • Focal granulomas associated with eggs in liver, kidneys, lungs (J4.181.w2).
  • Chronic obstructive fibrosis and chronic inflammation of hepatic portal triads, with necrosis of adjacent hepatic parenchyma, associated with female schistosomes in portal bile ducts (J1.18.w4).
  • Disseminated granulomatous encephalitis affecting the cerebrum and cerebellum, with inflammatory cells surrounding schistosome eggs and adult trematodes in cerebral artery (J4.181.w2).
  • Encephalitis associated with adult schistosome in meningeal vessel and eggs (both normal and degenerating) in cerebral capillaries. (B13.46.w1, B15)
ELEPHANTS
  • These flukes may be found in the portal veins of elephants. (B24)

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Human Health Considerations
Waterfowl schistosomes have been implicated as causes of "swimmer's itch" (cercarial dermatitis) (J1.18.w4, B24).

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Susceptibility / Transmission

General information on Susceptibility / Transmission
WATERFOWL Susceptibility:
  • Normal hosts for Dendritobilharzia pulverulenta are diving ducks; dabbling ducks, geese and swans (in which clinical disease and pathology may be seen) are considered aberrant hosts (B15).

Transmission:

  • Intermediate hosts are fresh water snails such as Physa spp. and Lymnaea spp. (J1.18.w4, B24).
  • Infect hosts by free-swimming cercariae penetrating the skin and entering the circulatory system (B15, B24).
ELEPHANTS Susceptibility:
  • Susceptibility to infection may be high, but illness is less common. (J12.30.w1)

Transmission:

  • In Bombay State, India, either Lymnaea acuminata or Indoplanorbis exustus may be the intermediate host, since both were present in an area where infected elephants were found. (J12.30.w1)

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Disease / Agent has been reported in either the wild or in captivity in:
Disease recorded in:
  • Trichobilharzia physellae in green-winged teal Anas crecca, blue-winged teal Anas discors and northern pintail Anas acuta in Texas, USA (J1.18.w4).
  • Dendritobilharzia pulverulenta in Mute swan Cygnus olor (J4.181.w2).
  • Dendritobilharzia pulverulenta in Whooper swan Cygnus cygnus (encephalitis) and in various ducks (severe enteritis) (B15).
  • Trichobilharzia sp. and Dendritobilharzia sp. in captive Atlantic Brant geese Branta bernicla (B15).

Infection also recorded in:

  • Mallard Anas platyrhynchos and northern pintails Anas acuta (incidental findings in kidneys) (B15).
  • Infection with Dendritobilharzia pulverulenta recorded in green-winged teal Anas crecca in southwest Texas, USA (J1.17.w6).
  • Infection with Trichobilharzia physellae recorded in cinnamon teal Anas cyanoptera in southwest Texas, USA (J1.13.w6).
  • Infection with Dendritobilharzia pulverulenta and Trichobilharzia sp. recorded in the Northern shoveler, Anas clypeata in southwest Texas, USA (J1.13.w7)
  • Cygnus olor - Mute swan (Dendritobilharzia pulverulenta), Anas platyrhynchos - Mallard (Trichobilharzia physellae, Dendritobilharzia pulverulenta), Anas platyrhynchos domesticus - Domestic duck (Trichobilharzia physellae, Dendritobilharzia pulverulenta), Anas acuta - Northern pintail (Trichobilharzia physellae, Dendritobilharzia pulverulenta), Anas clypeata - Northern shoveler (Trichobilharzia physellae, Dendritobilharzia pulverulenta), Anas crecca - Common teal (Dendritobilharzia pulverulenta) Anas discors - Blue-winged teal [taken to be synonymous with Anas erythrorhyncha in this reference] (Trichobilharzia physellae), Anas poecilorhyncha - Spot-billed duck (Trichobilharzia physellae), Anas querquedula - Garganey (Dendritobilharzia pulverulenta), Anas rubripes - American black duck (Dendritobilharzia pulverulenta), Anas strepera - Gadwall (Dendritobilharzia pulverulenta), Aythya ferina - Common pochard (Dendritobilharzia pulverulenta), Aythya fuligula - Tufted duck (Dendritobilharzia pulverulenta), Aythya valisineria - Canvasback (Dendritobilharzia pulverulenta), Aix galericulata - Mandarin duck (Dendritobilharzia pulverulenta) (B91)

In Elephants:

Elephas maximus - Asian Elephant:

  • Schistosomiasis, thought to be infection with Ornithobilharzia nairi was reported causing illness in Elephas maximus - Asian Elephants from India in 1954. (J12.30.w1)
  • Bivitellobilharzia was found in the dung of working elephants from Kerala, recently [1992 data]. (P502.1.w5)
  • Adult Bivitellobilharzia nairi were recovered from a dead Elephas maximus - Asian Elephant in Sri Lanka. (J378.53.w1)
  • Bivitellobilharzia nairi eggs were found in the faeces of elephants, including juveniles born in the park, from the Kanha National Park, Madhya Pradesh, India. (J178.97.w1)

Loxodonta africana - African Elephant

  • Schistosomiasis also has been recorded in African elephants. (J350.10.w1)

Loxodonta cyclotis - Forest Elephant:

  • Eggs of a Bivitellobilharzia, probably Bivitellobilharzia loxodontae, were found in two of six elephant faecal samples from elephants from the Republic of Congo and Central African Republic. (J381.71.w1)

Host Species List

 BIRDS:

MAMMALS:

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Disease / Agent has been specifically reported in Free-ranging populations of:
In waterfowl:

Disease recorded in:

  • Trichobilharzia physellae in green-winged teal Anas crecca, blue-winged teal Anas discors and northern pintail Anas acuta in Texas, USA (J1.18.w4).

Infection also recorded in:

  • Mallard Anas platyrhynchos and northern pintails Anas acuta (incidental findings in kidneys) (B15).
  • Infection with Dendritobilharzia pulverulenta recorded in green-winged teal Anas crecca in southwest Texas, USA (J1.17.w6).
  • Infection with Trichobilharzia physellae recorded in cinnamon teal  Anas cyanoptera in southwest Texas, USA (J1.13.w6).
  • Infection with Dendritobilharzia pulverulenta and Trichobilharzia sp. recorded in the Northern shoveler, Anas clypeata in southwest Texas, USA (J1.13.w7)

Loxodonta cyclotis - Forest Elephant:

  • Eggs of a Bivitellobilharzia, probably Bivitellobilharzia loxodontae, were found in two of six elephant faecal samples from elephants from the Republic of Congo and Central African Republic. (J381.71.w1)

Host Species List

 BIRDS:

MAMMALS:

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Environment/Geography

General Information on Environmental Factors/Events and Seasonality
--

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Regions / Countries where the Infectious Agent or Disease has been recorded

  • Trichobilharzia spp. are found in waterfowl in Canada, USA, Japan. Dendritobilharzia spp. are found in waterfowl (Swans, Anas, Fulica spp.) in Europe, Asia and North America. Pseudobilharziella are found in Anas, Nyroca, Cygnus spp.; Austrobilharzia are found in mainland USA and Hawaii, with marine snails as intermediate hosts (B24).
  • Disease recorded in the USA (J1.18.w4, J4.181.w2).

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Regions / Countries where the Infectious Agent or Disease has been recorded in Free-ranging populations

USA (J1.18.w4).

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General Investigation / Diagnosis

General Information on Investigation / Diagnosis
WATERFOWL Diagnosed on findings of flukes in association with lesions. Dendritobilharzia in arteries, others in veins (B13.46.w1).
Related Techniques
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Similar Diseases (Differential Diagnosis)
WATERFOWL --

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Treatment and Control

Specific Medical Treatment
WATERFOWL --
Related Techniques

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General Nursing and Surgical Techniques
WATERFOWL --
Related Techniques

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Preventative Measures
Vaccination WATERFOWL --
Prophylactic Treatment

WATERFOWL

 --
Related Techniques

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Environmental and Population Control Measures
General Environment Changes, Cleaning and Disinfection

WATERFOWL

 Intermediate hosts are usually removed from captive environments by waterfowl themselves, thereby removing the source of infection (B10.26.w11).
Population Control Measures WATERFOWL --

 
Isolation, Quarantine and Screening WATERFOWL --
Related Techniques
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