Δευτέρα, 17 Ιουνίου 2013

PUBLIC HEALTH SIGNIFICANCE OF MARINE MAMMAL DISEASES, BY C.D.BUCK & J.P.SCHRODER


TAKEN FROM THE CRC HANDBOOK OF MARINE MAMMAL MEDICINE; HEALTH, DISEASE, AND REHABILITATION.

The above publication lists numerous infections known to be transmittable to humans from cetaceans.



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To minimise the risk of acquiring serious infections and to facilitate the proper management of those which do occur, it is important that persons dealing with the animals, and their physicians, be aware of the microbiological hazards associated with handling marine mammals. Persons handling marine mammals are at risk from infection by the numerous microorganisms normally present in the aquarium or marine environment, by the microorganisms that constitute the normal flora of the animal, as well as by the pathogenic microorganisms that cause disease in various marine mammals.

Infectious zoonotic agents can also gain access to humans by indirect methods of transmission. Respiratory aerosols, water contaminated with urine and feces, and hardware such as feed containers can facilitate the entry of the micro-organism into a human host.


BACTERIAL INFECTIONS: Streptococci, staphylococci, pseudomonas, proteus, aeromonas, erysipelothrix, vibrio, clostridium and mycobacteria are all known to infect skin wounds of marine mammals. It also states some marine organisms require special diagnostic techniques. It also lists 15 Vibrio spp. isolated in Hawaiian captive dolphins.

In another instance, a bite from a dolphin resulted in a long term infection with the agent (mycobacterium marinum).

A more insidious pathogen is Pseudomonas pseudomallei. It is know to cause respiratory disease in man and marine mammals. The organism also causes serious wound infections which can result in fatal septicaemia. Antibody levels were highest in those animal handlers who had more intimate contact with dolphins and handled the front end of the animal.


VIRAL INFECTIONS.
Marine mammals are also subject to viral and presumed viral diseases. Many of these have the potential of infecting man. Although many of these viral agents have only recently been recognised, the diseases they cause are not new.

A pox like virus has been isolated in a dolphin kidney cell line.

Members of the herpes family have been isolated.

With some diseases, such as rabies, one might be tempted to dismiss the risk of contracting the disease from marine mammals as non existent; however, rabies has been documented in a wild seal. All marine mammals are capable of contracting rabies, and workers who deal with wild marine mammals must consider the risk when planning their vaccinations or seeking treatment for bite wounds.

A rotavirus-like agent has been isolated from sea lions. In humans, members of this group are responsible for viral gastro-enteritis, which may cause serious diarrhoea in young children.


FUNGAL DISEASES
Many microorganisms have been isolated from dolphins that would not ordinarily be expected to be found in the marine environment. Blastomycosis and other mycotic diseases of marine mammals pose a health risk for their handlers. Several cetaceans are known to have died from disseminated yeast infections, and the transmission of blastomycosis from dolphin to a veterinarian has been documented.

Several Candida species are commonly found in aquarium waters. Candida albicans can cause localised inflammations in humans.

Several cetacean deaths have been reported due to asperillosis. Infections of cetaceans as well as other species have been reported.


According to Dr. Sweeney, the situation in captivity creates an alteration in the normal social structure found in the wild, where males intermittently join and withdraw from the female centered groups, to captivity where adult males permanently interact within the social group. The frequent result, establishment of male dominance (especially related to juveniles), is often the source of many social and behavioural problems. Hierarchies where dominance plays a part, are known to exist in wild dolphin groups. However, as Dr. Sweeney explains, behaviours which are perhaps normal for aquatic mammals in the wild can become excessive or exaggerated under conditions of captivity. In situations where the social and behavioural environment is less than ideal, animals may respond by exhibiting excessive manifestions of behaviour. One such category of exaggerated behaviour is aggression, appearing most commonly in the form of intimidation, with infliction of rake-bite lacerations. Dr. Sweeney notes that at times the rake lacerations can be quite severe and not only represent cutaneous pathology, but also signal the presence of probable psychological intimidation in the secondary animal. Such aggression has also been aimed at swimmers and staff at captive facilities.

It is already known that the exaggerated aggression found in some captive dolphins can have dire consequences for the dolphins being intimidated. It is this intimidation which is the likely cause of the onset of many medical problems including gastric ulcerations, loss of immunity, and consequently, an increased incidence of incidental and potentially life-threatening infections. (Sweeney, 1990).

Disease transmission wild dolphin to captive dolphin & captive to wild.
Hundreds of striped dolphins died along the Spanish Mediterranean coasts from a morbillivirus, a highly infectious virus. Any cetaceans held in sea-pens, having access to open water or water drawn from the sea, must be a major cause of concern for disease transmission. Waste water from closed dolphinariums located on the coast also pose a potential threat of contamination to wild populations. The virus causes flu/pneumonia symptoms at death. (More details can be obtained from the Department of Pathology, Faculty of Veterinary Science, University of Barcelona, title; PATHOLOGIC AND IMMUNOCYTOCHEMICAL STUDIES OF MORBILLIVIRUS INFECTION IN STRIPED DOLPHINS, BY M. DOMINGO, J. VISA).


For those who are also concerned over the captivity industries latest way of exploiting both dolphins and humans with Dolphin Assisted Therapy, I would suggest you obtain a paper by Dr Lori Marino & Scott O.Lilienfeld, Department of Psychology, Emory University, USA. Entitled, Dolphin-Assisted Therapy: Flawed data, flawed conclusions.

Some quotes from this very enlightening paper:

1. Furthermore, despite their claim that attention deficits underline both their subjects disabilities and effectiveness of DAT, Nathenson et al. (1997) never assessed attention in their subjects either before of after DAT.

2. Nathenson et al. (1997) and Nathenson (1998) violated several important criteria for validity.

3. The source of most of the major flaws in Nathenson et al. (1997) is the absence of experimental control, making it impossible to determine whether their results were due to the specific effects of DAT or to a host of potentially confounding factors.

4. When comparing subjects responses with dolphins versus favourite toys the two conditions took place at entirely different facilities, viz, The Dolphin Research Centre versus a local motel, resulting in a complete confounding of treatment condition with setting.

5. Remarkably, behaviours that might have worsened were never systematically assessed or analysed.

6. Of 137 questionnaires sent out to parents only 52% were returned. This relatively low rate of return raises the possibility that parents who responded were unrepresentative of the entire sample of parents whose children were given DAT.

7. In summary, a plethora of serious threats to validity and flawed data analytic procedures render the findings of Nathenson and colleagues uninterpetable and their conclusions unwarranted and premature.

8. Both practitioners of DAT and parents considering DAT for their children should be made aware that this treatment has yet to be subjected to an adequate empirical test, and Nathenson and colleagues attention deficit hypothesis remains an explanation in search of a phenomenon. (Dr L. Marino, Neurosciences and Behavioural Biology Program, Department of Psychology, Emory University, Atlanta, Georgia 30322, USA).

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