Please read the abstract in the section 00front of this document
Canine babesiosis, caused by the tick-borne protozoan Babesia canis rossi, is an
economically important and potentially fatal disease of dogs in South Africa. The host's
response to many infectious diseases is mediated (at least in part) by intercellular
messengers called cytokines. One of the most important cytokines released is tumour
necrosis factor (TNF).
A study was designed to measure serum concentrations of TNF in dogs naturally
infected with canine babesiosis and to relate TNF concentrations to clinical severity,
mortality, rectal temperature and parasitaemia.
There was a statistically significant difference in TNF concentrations between groups
of differing disease severity, with a general trend of increasing mean 10g(TNF) with
increasing severity of disease. A noteworthy finding was that dogs with hypoglycaemia
had very high TNF (mean 15.03 nglml compared to a mean of 2.32 nglml for other sick
dogs without hypoglycaemia). When TNF values were compared between survival and
non-survival groups, there was no significant difference. The rectal temperature of the
dogs in this study did not show any statistically significant association with TNF
concentrations. When parasitaemia and TNF were examined within groups of infected
dogs, there was no significant relationship. However, when the sample size was
increased by pooling all infected dogs and treating them as a single group, there was a
highly significant positive correlation (p = 0.003) between parasitaemia and serum TNF
concentrations.
The results ofthis study were encouraging and indicate that canine babesiosis may
share a similar pathophysiology with human malaria in terms ofTNF being associated
with disease severity. One ofthe most significant findings in this study was the
presence ofvery high TNF values in two ofthree dogs with hypoglycaemia.
Hypoglycaemia has not been previously recorded in dogs with babesiosis and is a
potentially important finding particularly in view ofthe hypoglycaemia associated with
malaria in humans. Malarial hypoglycaemia is correlated with a higher mortality in
humans, especially in pregnant women and children. If the findings ofthis study can be
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confinned and expanded, they may lend further support to the use of canine babesiosis
as a model for some ofthe problems encountered in human malaria research.
