ISRAEL JOURNAL OF
VETERINARY MEDICINE
VOLUME
54 (3) 1999
AN OUTBREAK OF A LYMPHOPROLIFERATIVE DISEASE
SYNDROME IN IMPORTED TURKEYS IN NIGERIA
O.O. Alaka, M.O. Olaniyi, and G.A. Adeniran
Department of Veterinary Pathology, Faculty of Veterinary Medicine, University of Ibadan, Nigeria
Summary
Progressive mortality was observed in fourteen weeks old male turkeys raised on
deep litter system on a farm in Ibadan, Nigeria. A lymphoproliferative syndrome was
diagnosed histologically at necropsy of some of the affected turkeys. Affected organs
included liver, spleen, kidneys and proventriculus. It is suggested that the condition
may be more common in imported turkeys than the paucity of reports on incidence
indicated. It is concluded that rearing turkeys in houses recently occupied by chickens
without thorough disinfection could predispose them to avian tumour virus infections.
Introduction
Lymphoproliferative disease is a term used to describe a lymphoid tumor of
turkeys. Similar conditions in the past have been called Marek’s (MD) - like disease
(1), visceral lymphomatosis (2) and turkey leukosis (3). The condition was first
recognized as a disease entity in 1972 in the U.K. (4), subsequently reported in Israel
(5) and recently found to occur in a number of turkey flocks in several European
countries (6).
The natural disease in growing turkeys occurs mainly between 7 and 18 weeks of
age, although it can occur sporadically in adults (4, 7, 8, 9). The condition is also
more common in males than females, with a mortality rate of about 25% (6).
Although LPD has long been reported in the U.K. and elsewhere, there is presently
no previous report of this disease in Nigeria. Therefore, this paper reports for the first
time an outbreak of LPD of turkey in Ibadan Oyo State, Nigeria.
Materials and Methods
The case was presented from a flock of two hundred turkeys obtained at 6 weeks
of age and raised in a turkey farm in Ibadan. These were part of a batch of 2,500 day-
old poults imported from British United Turkeys (BUT) which were raised together
before being distributed to other farms.
The clinical picture was that of weakness, anorexia, ruffled feathers, reduced
weight gain and about 10% mortality within two weeks of the onset of disease. The
turkeys were fed commercial turkey grower ration.
At necropsy, the birds were found to have consistently markedly enlarged liver,
spleen and proventriculus. In one bird, the kidneys were also enlarged. The livers in
all the birds had milliary grey-white foci with diffuse yellowish mottling. There was a
firm mass of about 2 cm in diameter located towards the tip of one of the lobes in one
liver. Sections from the liver, kidney, spleen and proventriculus were fixed in 10%
buffered formalin solution, processed routinely for histopathological examination and
stained with Haematoxilin and Eosin (H&E).
A tentative diagnosis of a lymphoid tumour was made based on the post-mortem
lesions with differential diagnoses of reticuloendotheliosis LPD and Marek’s disease.
Results
Histopathological findings
Aggregates of pleomorphic lymphoid cells (mature lymphocytes, lymphoblasts,
plasma cells and reticular cells) were observed diffusely infiltrating the liver with
marked dissociation of hepatic cords and necrosis of the adjacent hepatocytes (Fig. 1).
Fig.1. Histological section of the liver showing aggregates of pleomorphic limphoid cells, necrosis and
dissociation of hepatic cords. Arrow - mitotic figures.
Similar infiltrating cells were observed in the lamina propria of the proventricular
mucosa and the interstitium of the proventricular glands with severe coagulative
necrosis of the glandular epithelial cells (Fig. 2).
Fig. 2(a). Histological section of proventriculus showing coagulative necrosis of glandular epithelial
cells and infiltration of the lumina propria by pleomorphic lymphoid cells.
Fig. 2(b). Histological section of proventriculus at higher magnification showing severe infiltration of
the lamina propria by cells of the lymphoid series. Arrow - mitotic figures.
In addition, the interstitium of affected kidneys showed thick infiltrations by
similar cells. Numerous mitotic figures were also seen in the liver, spleen and
proventricular sections (Figs. 1 & 2, arrow).
The observed lesions in the various organs are consistent with those of LPD or
Marek’s disease of turkeys as described previously (4, 6, 8).
Discussion
LPD of turkey was first recognized as a disease entity in 1972 in the U.K. (4,7).
Since that time it has been reported in Israel (5) and several other countries in Europe
(6).
There have been no previous reports of LPD cases in the indigenous breeds of
turkeys. This rarity of documented cases in Nigeria may be attributed to lack of
clinical information on the disease or misdiagnosis.
The alternate rearing of chickens and turkeys on the same contaminated litter has
been considered an epidemiological hypothesis of transmission by the litter of an
oncogenic agent for turkeys (10). The situation in this case is similar though the birds
were not raised on litter previously occupied by chickens, but the pen was recently
used for laying birds on deep litter. It is also worthy of note that other birds of the
same batch reared from 6 weeks of age at various locations in the country did not
suffer similar outbreaks.
At present, there is little or no information on the prevention and control of LPD.
However, in addition to avoidance of rearing turkeys in houses recently occupied by
chickens, commercial turkey breeders should selectively breed LPD - resistant turkey
strains.
Above all, utmost attention should be paid to excellent management and hygiene
procedures.
Acknowledgments:
The authors are grateful to the technical and secretarial staff of the department of
Veterinary Pathology, University of Ibadan, for photomicrography and typing of the
manuscript.
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