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107
Disease Trend$ on Crocodite Farms in Zimbabwe
C M Foggin, Veterinary Research Laboratory,
P O Box 8101,
Causeway, Zimbabwe
Intaoduction
The crocodile farming industry in Zjmbabwe, reacting to market forces, showed rapld growth
from.1986 to 1990. In the last two years however, this trend has ceased. Most faimers nave
now tlad some o-pportunity to gain expetience in the techniques of raising crocodiles and a
certain
_degree
of standardization prevails in the inclustry. For example al'i farms, including
those situated in hot areas, now hold hatchlings in heaied ponds, generally at #C. n*."
ponds are either indoors, often with iittle ventilation or natu;al light, or are covered at night.
In addirion,^almost all farms keep rearing srock in similar heatJfa;ilites. Stocking densities
arc.usually from 6 ro 12 hatchlings per m: and about one-third of this for rearing stock. There
still exists some variation in dier, which can include f.esh fish, poulrry and fu meat from
abaftoir waste, hunting operations or from natural mortality of tlvestoct. ell farmers now
realise the importance of hygiene and the effect of stress onthe health of crocodiles, though
opinions differ on how to control these facrors.
With such developme s in the industry ir would be expected that mortality from disease should
decrease, and indeed lhis has becn the case. In the yeaft 19g0 ro l9g3 mian annual, hatchling
mortal ity throughout the industry in Zimbabw e vtas 3l,2Vo .In l99l it was llJ% . Howevei,
the importance ofdisease has nor disappeared altogether. previously_known dlseases are still
present and some have altered in their manif'estation
the farm, while new conditions have
been recognised and assumed some importance.
Pr€sent status of specified diseas€s and recent findings
specified diseases incrude the major, communicable diseascs of farmed crocodiles: that is
adeno- and pox,virus infection, chlamydiosis, salmonellosis (Salmonella tvDhimurium
infection), and coccidiosis. A list of farms infected with these diseases
mainta'i'nea ano in
future, once the epizootiological factors have been fxrther elucidated, it is possilie that sales
of live harchlintss trom rh-esc farms may be restricted. Other diseases may ha;e to be controlled
oy tne osc ot vaccines. Some nukilional and other non_specified infectious diseases are also
considered potentially important, because their aetiology i; not fully understood; these will be
also elaborated below.
Adeno-irus infec,ion - the manifestation ofacntc adeno_virus hepatitis, enteritis and pancreatitis
has been described previously (Foggin, 1997; Foggin, l99l). it has now been i""o'rO""r on z+
out of42 farms in production in zimbabwe (572o). The disease
unco.n'on in ou".
five months of age and usually affects slower-growing individuals. More ."cenily. ".oaodil"" it oecame
obvious that the virus could cause chronic inflammation of the liver un,t tt ut tf,ii i., in pu.t,
responsible for the development of runts. These chronic pathological changes include tibrosis
9f ,1h9.p"1{ tracts, bite duc hyperplasi and reduction of pa.eri.t yrna tisiue. iome atecteA
individuals have shown icterus. On some farms a high proportion oi runt. hau" been sno*n
have
to
been all'licted with rhis condition.