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Cayman Turtle Farm - Scientific Papers - Coccidiosis in the Green Sea Turtle in Maricult.
Scientific Papers
COCCIDIOSIS IN THE GREEN TURTLE
(Chelonia mydas) IN MARICULTURE
Proceedings of the Fifth Annual Meeting World Mariculture Society, Gerbert Rebell, Arkadi Rywlin, and Glen Ulrich Mount Sinai Medical Center (Skin and Cancer Unit and Division of Pathology) Miami Beach, Florida 33140 University of Miami School of Medicine (Department of Pathology) Miami, Florida 3315 and Mariculture, Ltd. Grand Cayman, British West Indies ABSTRACT
INTRODUCTION
HISTORY OF THE EPIDEMIC
SYMPTOMS AND DIAGNOSIS
PATHOLOGY
IDENTIFICATION OF THE PARASITE
EPIDEMIOLOGY
TREATMENT AND CONTROL
DISCUSSION
ACKNOWLEDGEMENT
LITERATURE CITED

ABSTRACT
An epidemic of disease in recently hatched green turtles (Chelonia mydas) was found to be
associated with a new coccidial intestinal parasite. The disease and associated mortality appeared
in young turtles approximately 30 days after hatching, and ran a 60 day course through the stock
hatchlings at the farm. Symptoms of the disease were emaciation and lethargy. Tube-like casts of
intestinal mucosa and impaction of the gut with caseous masses of oocysts occurred late in the
disease. Active patches of coccidial infection were found in the intestinal tract of surviving and
apparently healthy turtles as late as 1 month after the end of the epidemic.

INTRODUCTION
Protozoa of the subphylum Sporozoa, subclass Coccidia, are a group of intestinal parasites which
cause economically important diseases in poultry, ducks, rabbits, hogs, and other domestic
animals, as well as infections of varying severity in a wide variety of other vertebrates. Coccidios
is, genus Eimerie, occurs in fresh water turtles (Deeds and Jahn, 1939; Lainson, 1968; Sampson
end Ernst, 1969; Ernst et al, 1969).
Typically, coccida are:
1) strictly host-specific,
2) undergo their life cycle in a single host,
3) produce relatively brief infections, consisting of a finite number of cycles of multiplication via
schizogony in the mucosal cells of the intestinal tract terminated by sporogony and the formation
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of oocysts, which remain non-infective until after they are passed from the host and have undergone sporulation in the external environment, 4) produce states of chronic infection only via oronic reinfection from the external environment, and, 5) evoke protective immunity in animals which survive infection. The severity of coccidial infections, therefore, depends ultimately on the number of sporulatad oocysts which are ingested and the state of resistance of the host animal. During the spring of 1973 there occurred an epidemic of coccidial disease envolving the stock hatchlings of green turtles (Chelonia mydas) at Mariculture, Ltd,, Grand Cayman, B .W .1., which appeared to be typical with respect to these characteristics of coccidial infections, HISTORY OF THE EPIDEMIC
Coccidiosis appeared sequentially in two groups of turtles hatched in the spring of 1973. The
turtles were raised in a series of circular fiber glass tanks, 2.4m in diameter, in a constant exchange
of fresh sea water, There were over 1,000 turtles per tank volume of 2841 litres
In the two groups of turtles the onset of an increase in daily mortality, associated with presence of
the coccidial parasite, occurred on 29 May and 17 June, respectively, or approximately 30 days
after the groups were hatched, The disease appeared in the second and larger group of hatchlings
after it had already reached a maximum in 15 days. There followed a gradual and simultaneous
decrease in the daily mortality in both groups to pre-epidemic levels The total course of the
epidemic in the first group of hatchlings was 72 days and in the second group 53 days. Early in
September, 1 month after the epidemic had passed, apparently healthy turtles which had survived
the epidemic still were found to have active areas of coccidial infection in the intestinal tract, By
November most surviving turtles appeared to be free of the parasite.
SYMPTOMS AND DIAGNOSIS
Affected turtles were typically flat, weak, and emaciated. Characteristic ellipsoidal oocysts of the
parasite were abundant in the intestinal tract. Placed on wet paper towelling overnight, diseased
turtles were found to pass cylindrical casts of intestinal mucosa and faeces packed with oocysts.
Late in the epidemic emaciated turtles with lusterless shells were found to have the lower gut filled
with osseous masses of oocysts.
PATHOLOGY
Infection was massive. Plaque-like, opaque lesions of the mucosa, and gelatinous sloughs of
mucosa and oocysts were found essentially throughout the length of the intestinal tract distal to the
opening of the bile duct. Typical life history stages of a coccidial parasite, consisting of
merozoites, schizonts, micro - and macrogametes, and developing oocysts, in intracellular
location, were easily found, both in smears of the intestinal mucosa examined wet in saline under a
coverslip, and in hematoxylin and eosin-stained sections of the gut, which had been fixed in 10%
neutral buffered formalin. Infection appeared to be confined to the intestinal mucosa.
Histoplathological sections of other organs and tissues were found to be free of parasites.
Bacterial cultures revealed an enteric flora essentially typical of turtles at the Grand Cayman Farm,
consisting of Klebsiella, Salmonella, Citrobacter, and Arizona, as well as Clostridium fallax and
enterococci.

IDENTIFICATION OF THE PARASITE
When incubated in 2% sodium dichromate solution for 24 hrs, oocysts sporulated with the
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formation of eight sporozoites. Sporulated oocysts were sent to Dr. Louis Leibovitz, Department of Avian Diseases, New York State Veterinary College, Cornell University, Ithaca, New York, who identified the parasite as a new species of Caryospors. A taxonomic description will be published separately.
EPIDEMIOLOGY
Early in the epidemic it was found that a food and faecal sludge had been permitted to accumulate
in the bottom of the affected tanks in amounts not usually tolerated at the farm. There had
evidently been a temporary laxity in maintenance due to an increased work load imposed by the
large number of turtles being hatched in the second group, later to be affected by the epidemic.
Large numbers of unsporulated cocysts were found in this anaerobic bottom sludge. It was also
observed that when the tanks were cleaned the turtles were transferred sequentially from tank to
tank, a supernumerary tank being hold in the row to permit this shift. Spread of the epidemic in a
row of tanks occurred rapidly, possibly as a result of this practice. For various experimental
purposes several hundred hatchlings from the two groups were being raised separately from the
stock hatchlings under the care of different personnel. These failed to develop symptoms of
coccidiosis and remained free of parasites, further implicating management practice in the
epidemic. Two subsequent groups of hatchlings have been raised at the farm free of any signs of a
return of coccidiosis,
No anticoccidial medication was used in these groups. Examination of the intestinal contents of older turtles at the farm, also under separate maintenance, failed to reveal the coccidial parasitein any turtles, other than those of the two groups envolved in the epidemic. In the intestinal tract of turtles oocysts have invariably been in am unsporulated state.
TREATMENT AND CONTROL
Controlled experiments were set up with small groups of 25 to 100 turtles from affected tanks to
test the effect of tetracycline and the anticoccidial sulfonamide, sulfamethazine, administered by
ingestion, intraperitoneal injection, and overnight soaks. No positive effects were obtained from
these experiments. Since medicated feed was not available treatment in the stock tanks was not
attempted until late in the epidemic. Increased care in cleaning and disinfecting tanks did not
appear to alter the course of the epidemic.
DISCUSSION
The occurrence of an epidemic of coccidiosis at Mariculture, Ltd. appeared to be unprecedented in
the history of the farm. The parasite may have been introduced as a new agent of disease in the
spring of 1973, either in eggs or sand brought from Ascension Island or Surinam or from some
other source, or it may have been endemic and undetected at the farm until circumstances
permitted it to increase to epidemic numbers. It seems probable that once a large number of turtles
were infected, and large numbers of oocysts were being constantly released into the well-aerated
water, which probably favoured rapid sporulation, vigorous hygienic measures were not sufficient
to control the epidemic. However, hatchlings placed in the same stock tanks as early as September,
one month after the end of the epidemic did not contract coccidiosis.
Experimental trials of medication were hampered by the fact that medicated feed was not available
to treat large numbers of turtles in the stock tanks. It was probably impossible to select and remove
sample groups of turtles from stock tanks for experiments without altering the epidemic
composition and conditions present in the stock tanks. In sick animals no significant differences
were obtained between the mortality of treated and untreated groups. In randomly selected animals
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the mortality in untreated groups was too low to permit comparison. Under the circumstances the drugs were probably being tested for marginal therapeutic effect in advanced disease rather than prophylaxis. It seems probable that after ingestion of sporulated oocysts coccidial disease runs its course in the turtle in a few days, although the resulting oocysts may be retained in the intestinal tract for longer periods. It is postulated that the coccidial parasite caused the morbidity and mortality associated with the epidemic. To investigate this and other questions rigorously, however, it will be necessary to establish experimental infections. ACKNOWLEDGEMENT
The authors wish to acknowledge help received from J. W. Beck, Department of Epidemiology
and Public Health, University of Miami School of Medicine Miami, Florida. Principal support for
the research was provided by Mariculture, Ltd., Grand Cayman, British West Indies.
LITERATURE CITED
Deeds, 0. J., and R. L. Jahn. 1929. Coccidial infections of Western Painted Turtles of the Okaboji region. Transactions
American Microscopical Society
58: 249-253.
Ernst, J. V., T. B. Steward, J. R. Sampson, and J. W. Fincher. Eimeria serpentia from Snapping Turtle Chelydra
serpentia. Bulletin Wildlife Diseases
5: 410-411.
Lainson, R. 1968. Parasitological studies from British Honduras IV - some coccidial parasites of reptiles. Annals of
Tropical Medicine and Parasitology
62: 260-266.
Sampson, J. R., and J. V Ernst. 1969. Emeria scripts n. sp.(Sporozoa: Eimeridae) from the Red-Eared Turtle
Pseudemys scripta elegans. Journal of Protozoology 16: 444-445.
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