ISSN 1063-0740, Russian Journal of Marine Biology, 2009, Vol. 35, No. 6, pp. 494–497. © Pleiades Publishing, Ltd., 2009.Original Russian Text © A.Yu. Alekseev, A.Yu. Reguzova, E.I. Rozanovab, A.V. Abramov, Yu.V. Tumanov, I.N. Kuvshinova, A.M. Shestopalov, 2009, published in Biologiya Morya.
494
The Black Sea bottlenose dolphin
Tursiops trunca-tus ponticus
Barabasch–Nikiforov, 1940 (Russ.“afalina”) is common in the temperate and warm watersof the World Ocean. This species leads a settled modeof life or roves in pods, mainly in the near-shore zone,which is explained by its near-bottom feeding. The pro-tection status of the bottlenose dolphin in Russia andthe Ukraine is Category III, which is defined as “a rareendemic subspecies.” The Black Sea population of thedolphin
T. truncatus ponticus
was put in the Classifica-tion of “Endangered” within The Global Plan of Actionfor the Conservation, Management, and Utilization ofMarine Mammals, which is a UNEP’s leading docu-ment.
The beluga whale
Delphinapterus leucas
Pallas,1776 or a white polar dolphin is circumpolar and livesamong the icebergs and floating ice-floes of the Arctic.Unlike the bottlenose dolphin that occurs in inshoremarine waters, the beluga whale is common in openwaters of the northern seas. This species is highly socialand lives in pods of 70–90 individuals.
In recent years, cases of new infectious diseases inmarine mammals have increased. Sometimes, largeoutbreaks of these diseases—epizootics—lead to the
death of animal populations. However, the carrying ofinfections by the Black Sea bottlenose dolphin and bel-uga whale and the background of antibodies to specificpathogens have been studied little if at all. At the sametime, an increasing body of evidence suggests that out-breaks of infectious diseases in wild-animal popula-tions are associated with human activities [5]. Theanthropogenic effect on the environment can manifestitself as the transmission or introduction of infectiousagents and their hosts into new ecological niches and asthe general influence of radiation, chemical and otherkinds of environmental contamination on the hostorganism. An increasing number of reports on reducednatural resistance to bacterial and viral infections inmarine mammals experiencing the effects of high con-centrations of anthropogenic pollutants, e.g., organichalogens, have been published [6, 19, 23].
The area of geographical distribution of the BlackSea bottlenose dolphin is the Black Sea and the AzovSea. These seas are surrounded by densely populatedterritories, which have long been utilized by humansand are now a zone of vigorous human activities. Theindices that characterize the state of the socio–ecologi-cal–economic system in this region are as follows: the
ECOLOGY
Detection of Specific Antibodies to Morbilliviruses,
Brucella
and
Toxoplasma
in the Black Sea Dolphin
Tursiops truncatus ponticus
and the Beluga Whale
Delphinapterus leucas
from the Sea of Okhotsk in 2002
−
2007
A. Yu. Alekseev
a
, A. Yu. Reguzova
a
, E. I. Rozanova
b
, A. V. Abramov
b
, Yu. V. Tumanov
a
, I. N. Kuvshinova
c
, and A. M. Shestopalov
a
a
Vector State Research Center of Virology and Biotechnology, Rospotrebnadzor, Koltsovo, Novosibirsk oblast, 630559 Russia
b
Utrishskiy Dolphinarium, Moscow, 119071 Russia
c
Vector-Best Koltsovo, Novosibirsk oblast, 630559 Russiae-mail: [email protected]
Received March 26, 2009
Abstract
—The prevalence of antibodies to morbilliviruses,
Brucella
and
Toxoplasma
was studied in the BlackSea bottlenose dolphin
Tursiops truncatus ponticus
and the beluga whale
Delphinapterus leucas
from the Seaof Okhotsk. The blood serum of 74 dolphins and 147 beluga whales was tested in 2002–2007. Antibodies to mor-billiviruses were detected in 15 (20.3%) bottlenose dolphins and 20 (13.6%) beluga whales. Antibodies to
Brucella
were detected in 17 (23.0%) bottlenose dolphins and 10 (6.8%) beluga whales.
Toxoplasma
-specific antibodies weredetected in 39 (52.7%) bottlenose dolphins and 7 (4.8%) beluga whales. Some animals had antibodies to two,or even three, of the pathogens. A high level of incidence of the pathogens in the sea animals was found in thedensely populated coastal areas with high economic development.
Key words
: Bottlenose dolphin, beluga whale, antibodies, morbilliviruses,
Toxoplasma, Brucella.
DOI:
10.1134/S1063074009060078
RUSSIAN JOURNAL OF MARINE BIOLOGY
Vol. 35
No. 6
2009
DETECTION OF SPECIFIC ANTIBODIES TO MORBILLIVIRUSES 495
intensity of anthropogenic effects on the environment is20–40; the intensity of use of total natural resources is20 (www.sci.aha.ru/RUS/mapind.htm); and anthropo-genic load on the Black Sea coastal zone is>100 humans/km
2
(www.biodat.ru/doc/lib/agro04.htm).
The Sea of Okhotsk—one of the areas where thebeluga whale occurs—communicates with the PacificOcean; its neighboring territories have sparse humanpopulation. The intensity of use of total naturalresources is 3–6; the intensity of the anthropogeniceffect on the environment is about 20 (www.sci.aha.ru/RUS/mapind.htm); anthropogenic load onthe territory is 1–3.5 humans/km
2
(www.biodat.ru/doc/lib/agro04.htm).
The literature data on pathogens circulating amongmarine mammals suggest that morbilliviruses,
Brucella
spp., and
Toxoplasma
are the most dangerous patho-gens to humans and agricultural animals.
Outbreaks of morbilliviral infections causing epi-zootics with mass mortalities are very likely to occur inhighly social bottlenose dolphin and beluga whale [12,13]. Apart from the viruses, bacterial and parasitic dis-eases can have a prolonged effect on the numbers ofanimal populations. Brucellosis and toxoplasmosis aresuch infections. The chronic character of the diseasesleads to weakening of immunity and indirectly affectsthe abundance of the animal population. The damage toa fetus inflicted by the disease can cause its abortion orthe birth of nonviable progeny [16]. Brucellas can betransferred to humans. Cases of human brucellosisinfection from marine mammals have been reported(www.cfsph.iastate.edu). The protozoic parasite
Toxo-plasma gondii
and antibodies to it have been found in alarge number of marine mammals [8, 14, 15].
Regular monitoring of the circulation of pathogensin bottlenose dolphin and beluga whale populations isof great importance because of the possibility of trans-fer of the above infections to humans in contact withmarine mammals and because of the need to preservethe abundance of these unique animals. Furthermore, itwould be of interest to compare the infection level in
sea animals living in areas with different anthropogenicloads.
The purpose of this work was to carry out monitor-ing of morbilliviral, brucellosis, and toxoplasmosisinfections in bottlenose dolphins in the Black Sea andbeluga whales in the Sea of Okhostk.
MATERIAL AND METHODS
Material from 74 Black Sea bottlenose dolphins wascollected in 2003–2007 in Taman Bay in the Black Sea.Blood samples from the caudal fin vessels were takeninto vacuum tubes, maintained until a serum layer wasformed, and centrifuged for 15 minutes at 3000–3200 rpm. After separation, plasma or serum wasplaced in polyethylene tubes and frozen at –20
°
C.Material from 147 beluga whales was collected
in 2002–2007 at Chkalov Island (Amur Liman, Sea ofOkhotsk). Blood samples from the caudal fin vesselswere taken as described above.
Antibodies (the sum of IgG and IgM) to brucellas,morbilliviruses, and toxoplasma were detected usingthe immune enzyme assay according to the previouslydescribed procedure [1]. Statistical processing was car-ried out using standard methods [2].
RESULTS AND DISCUSSION
This study revealed the prevalence of antibodies tomorbilliviruses, brucella, and toxoplasma in the BlackSea bottlenose dolphin and beluga whale from the Seaof Okhotsk. Morbillivirus-specific antibodies weredetected in 15 (20.3%) bottlenose dolphins and 20(13.6%) beluga whales. The numbers of bottlenose dol-phins and beluga whales that were serum-positive tobrucellas were 17 (23.0%) and 10 (6.8%), respectively.Toxoplasma-specific antibodies were found in theserum of 39 (52.7%) bottlenose dolphins and 7 (4.7%)beluga whales (Tables 1, 2).
The simultaneous occurrence of antibodies to two orthree pathogens in the blood of one animal was serolog-ically confirmed. Thus, antibodies to brucella occurredtogether with antibodies to morbilliviruses in the blood
Table 1.
The seroprevalence of antibodies to infectious agents in the Black Sea bottlenose dolphins
Year of sampling Number of animalsPathogen Lack of antibodies
to pathogenstoxoplasma brucella morbillivirus
2003 17 0(0%)* 2(11.7
±
7.8%) 1(5.8
±
5.7%) 14(82.3
±
9.2%)
2004 21 18(85.7
±
7.6%) 11(52.3
±
10.9%) 9(42.8
±
10.8%) 1(4.7
±
4.6%)
2005 19 11(91.7
±
6.3%) 3(25.0
±
9.9%) 2(16.7
±
8.5%) 6(50.0
±
11.5%)
2006 9 6(66.6
±
5.7%) 1(11.1
±
0.5%) 2(22.2
±
13.9%) 3(33.3
±
15.7%)
2007 8 4(50.0
±
7.7%) 0(0%) 1(12.5
±
11.7%) 3(37.5
±
17.1%)
Total 74 39(52.7
±
5.8%) 17(23.0
±
4.9%) 15(20.3
±
4.7%) 27(36.5
±
5.6%)
* Number of sea animals (percent
±
error of mean).
496
RUSSIAN JOURNAL OF MARINE BIOLOGY
Vol. 35
No. 6
2009
ALEKSEEV et al.
serum of three beluga whales. Among the bottlenosedolphins, seven specimens in 2004 and two in 2005 hadantibodies to both toxoplasma and brucella. The simul-taneous presence of antibodies to toxoplasma and mor-billiviruses was found in three bottlenose dolphins in2004 and in one in 2006. Antibodies to the three patho-gens were detected in four bottlenose dolphins in 2004and in one bottlenose dolphin in 2006.
Morbillivirus-specific antibodies were found inapproximately the same number of bottlenose dolphinsand beluga whales (P < 0.05). The dynamics of carryingof antibodies to morbilliviruses did not change mark-edly during the period of this study. The morbillivirusesare known to infect many species of mammals, not nec-essarily producing apparent symptoms of the disease[21]. However, the presence of antibodies can be indic-ative of the chronic form of the infection. The chroniccourse of the disease negatively affects the animals,decreasing their immunity indices and leading to abor-tions, still births, and high mortalities in both juvenilesand adults [9].
The data [9, 10, 16] show that the agents of brucel-losis have been isolated from dolphins in variousregions of the world. Our investigations also suggestthe presence of antibodies to brucellas in beluga whalesand bottlenose dolphins living in geographically set-apart regions. In 2002–2007, we found antibodies tobacteria of the genus
Brucella
in 10 out of 147 (6.8%)of the investigated beluga whales from the Sea ofOkhotsk. The Black Sea bottlenose dolphins that wereseropositive to this agent were almost three times asgreat (P < 0.05). Brucellas are widespread amongmarine animals, and they have probably been longendemic to these populations. The transmission of bru-cellas in marine mammals has been studied poorly.Most species of
Brucella
are initially associated with aparticular host; however, other animal species in closecontact can also be infected by them. The situation isaggravated by the fact that several infections maypresent that have a clinical picture similar to that of bru-cellosis. A number of diseases lead to abortions, thedeath of newly born animals, meningoencephalitis, and
inflammations. Brucellosis can proceed without symp-toms and can only be revealed from positive results ofserological tests.
The present study, using the immune enzyme assay,has shown the prevalence of antibodies to
Toxoplasmagondii
in wild beluga whales from the Sea of Okhotskand bottlenose dolphins from the Black Sea. Our resultsare consistent with the data on cetaceans inhabitingother regions [4, 7, 18]. The presence of toxoplasma inbeluga whales was confirmed by the detection of anti-bodies in 7 (4.7%) out of the 147 samples collected in2002–2007. Toxoplasma-specific antibodies werefound in the blood serum of 39 (52.7%) bottlenose dol-phins examined during the period of 2003–2007. Thepresence of toxoplasma in the marine mammals pro-vides an ecological indicator of contamination ofmarine and coastal waters with the oocysts of the givenprotozoan parasite [11, 20]. Some investigators believethat surface water runoff containing feline excrementleads to the contamination of fresh water and themarine environment with
T. gondii
oocysts, thus pro-ducing a risk of infection of sea animals [3, 17]. TheSea of Okhotsk is bordered by sparsely populated landareas and therefore receive runoff that is less contami-nated with the oocysts of this parasite. Accordingly, theaverage incidence of antibodies here was 4.7%. Thisvalue is markedly lower compared to that in the BlackSea, where the antibodies to toxoplasma were presentin 52.7% of bottlenose dolphins (
P
< 0.05). There is arisk of human infection with toxoplasma due to the useof oocyst-contaminated water or the eating of raw orundercooked meat infected with
T. gondii
, which isconsidered to be the main route of the pathogen’s trans-fer to humans [22]. This is particularly the case for theindigenous people of the extreme North, who carry outthe fishery for marine mammals.
Thus, we presented the serological evidence for thecirculation of toxoplasma, brucella, and morbillivirusesin bottlenose dolphins from the Black Sea and in belugawhales from the Sea of Okhotsk. A high incidence ofthe pathogens in these sea animals was found in thedensely populated coastal areas with high economic
Table 2.
The seroprevalence of antibodies to infectious agents in beluga whales from the Sea of Okhotsk
Year of sampling Number of animalsPathogen Lack of antibodies
to pathogenstoxoplasma brucella morbillivirus
2002 2 0(0%)* 2(100%) 0(0%) 0(0%)
2003 33 1(3.0
± 2.9%)
5(15.1
±
6.2%) 5(15.1
±
6.2%) 22(66.6
±
8.2%)
2004 7 1(14.3
±
13.2%) 1(14.3
±
13.2%) 1(14.3
±
13.2%) 4(57.1
±
18.7%)
2005 4 0(0%) 1(25.0
±
21.6%) 1(25.0
± 21.6%)
2(50.0
±
25.0%)
2006 31 2(6.4
±
4.4%) 0(0%) 2(6.4
±
4.4%) 27(87.1
±
6.0%)
2007 70 3(4.2
±
1.7%) 1(1.4
±
1.4%) 11(15.7
±
4.3%) 55(78.6
±
4.9%)
Total 147 7(4.7
± 1.7%)
10(6.8
±
2.1%) 20(13.6
±
2.8%) 110(74.8
±
3.6%)
* Number of sea animals (percent
±
error of mean).
RUSSIAN JOURNAL OF MARINE BIOLOGY
Vol. 35
No. 6
2009
DETECTION OF SPECIFIC ANTIBODIES TO MORBILLIVIRUSES 497
development. The highest occurrence of antibodies tothe tested pathogens and the persistence of theirdynamics was observed in bottlenose dolphins from theBlack Sea. The ecological situation in the remoteregions of the North is better. The results from thisstudy provide further evidence supporting the adverseeffects of anthropogenic environmental changes on theabundance and health of marine animals.
REFERENCES
1. Alekseev, A.Yu., Rozanova, E.I., Ustinova, E.N., et al.,Antibodies to Morbilliviruses, Brucella and Toxoplasmain the Captive Bottlenose Dolphin
Tursiops truncatusponticus
from the Black Sea,
Biol. Morya
, 2007, vol. 33,no. 6, pp. 465–468.
2. Usovich, A.T. and Lebedev, P.T.,
Primenenie matemat-icheskoi statistiki pri obrabotke eksperimental
’
nykhdannykh v veterenarii
(Application of Mathematical Sta-tistics to Experimental Data Treatment in Veterinary),Omsk: Zapadnosibirskoe Knizhn. Izd. (West SiberianBook Publishers). 1970.
3. Bandoli, J.G. and de Oliveira, C.A.B., Toxoplasmose em
Sotalia guianensis
(Van Beneden, 1863) Cetacea-Del-phinidae,
Folha Méd.
, 1977, vol. 75, pp. 459–468.
4. Cabezon O., Resendes A.R., Domingo M. et al. Sero-prevalence of
Toxoplasma gondii Antibodies in WildDolphins from the Spanish Mediterranean Coast,J. Parasitol., 2004, vol. 90, pp. 643–644.
5. Daszak, P., Cunningham, A.A., and Hyatt, A.D., Anthro-pogenic Environmental Change and the Emergence ofInfectious Diseases in Wildlife, Acta Trop., 2001,vol. 78, no. 2, pp. 103–116.
6. De Guise, S., Lagacé, A., Béland, P., et al., Non-neoplas-tic Lesions in Beluga Whales (Delphinapterus leucas)and Other Marine Mammals rom the St. Lawrence Estu-ary, J. Comp. Pathol., 1995, vol. 112, pp. 257–271.
7. Dubey, J.R., Fair, P.A., Bossartt, G.D., et al., A Compar-ison of Several Serologic Tests to Detect Antibodies toToxoplasma gondii in Naturally Exposed BottlenoseDolphins (Tursiops truncatus), J. Parasitol., 2005,vol. 5, no. 91, pp. 1074–1081.
8. Dubey, J.P., Zarnker, R., Thomas, N.J., et al., Toxo-plasma gondii, Neospora caninum, Sarcocystis neurona,and Sarcocystis canis-Like Infections in Marine Mam-mals, Vet. Parasitol., 2003, vol. 116, pp. 275–296.
9. Foster, G., Jahans, K.L., Reid, R.J., and Ross, H.M., Iso-lation of Brucella Species from Cetaceans, Seals and anOtter, Vet. Rec., 1996, vol. 138, pp. 583–586.
10. Jahans, K.L., Foster, G., and Broughton, E.S., The Char-acteristics of Brucella Strains Isolated from MarineMammals, Vet. Microbiol., 1997, vol. 57, pp. 373–382.
11. Jardine, J.E. and Dubey, J.P., Congenital Toxoplasmosisin a Indo-Pacific Bottlenose Dolphin (Tursiops adun-cus), J. Parasitol., 2002, vol. 88, pp. 197–199.
12. Jensen, T., van de Bildt, M., and Dietz, H.H., AnotherPhocine Distemper Outbreak in Europe, Science, 2002,vol. 297, p. 209.
13. Kennedy, S., Kuiken, T., and Jepson, P.D., Mass Die-offof Caspian Seals Caused by Canine Distemper Virus,Emerg. Infect. Dis., 2000, vol. 6, pp. 637–639.
14. Lambourn, D.M., Jeffries, S.J., and Dubey, J.P., Sero-prevalence of Toxoplasma gondii in Harbor Seals (Phocavitulina) in Southern Puget Sound, Washington, J. Para-sitol., 2001,vol. 87, no. 5, pp. 1196–1197.
15. Mikaelian, I., Boisclair, J., Dubey, J.P., et al., Toxoplas-mosis in Beluga Whales (Delphinapterus leucas) fromthe St. Lawrence Estuary: Two Case Reports and a Sero-logical Survey, J. Comp. Pathol., 2000, vol. 122, pp. 73–76.
16. Miller, W.G., Adams, L.G., Ficht, T.A., et al. Brucella-Induced Abortions and Infection in Bottlenose Dolphins(Tursiops truncatus), J. Zoo Wildl. Med., 1999, vol. 30,pp. 100–110.
17. Miller, M.A., Gardner, I.A., Kreuder, C., et al., CoastalFreshwater Runoff Is a Risk Factor for Toxoplasma gon-dii Infection of Southern Sea Otters (Enhydra lutrisnereis), Int. J. Parasitol., 2002, vol. 32, pp. 997–1006.
18. Murata, K., Mizuta, K., Imazu, K., et al., The Prevalenceof Toxoplasma gondii Antibodies in Wild and CaptiveCetaceans from Japan, J. Parasitol., 2004, vol. 4, no. 90,pp. 896–898.
19. Parsons, E.C.M. and Jefferson, T.A., Post-mortem Inves-tigations on Stranded Dolphins and Porpoises fromHong Kong Waters, J. Wildl. Dis., 2000, vol. 36,pp. 342–356.
20. Ratcliffe, H.L. and Worth, C.B., Toxoplasmosis of Cap-tive Wild Birds and Mammals, Am. J. Pathol., 1951,vol. 27, pp. 655–667.
21. Reidarson, T., McBain, J., House, C., et al., Morbillivi-rus Infection in Stranded Common Dolphins from thePacific Ocean, J. Wildl. Dis., 1998, vol. 34, pp. 771–776.
22. Tenter, A.M., Heckeroth, A.R., and Weiss, L.M., Toxo-plasma gondii: From Animals to Humans, Int. J. Parasi-tol., 2000, vol. 30, pp. 1217–1258.
23. Thompson, H.G., Hall, J.G., Lee, W.E., et al., RapidImmunofiltration Assay of Newcastle Disease VirusUsing a Silicon Sensor, J. Immunol. Meth., 1993,vol. 166, no. 1, pp. 123–131.
