WildLife Group
of the SAVA
HemorrhagiC
Septaceamia
IN AFRICAN BUFFALO
Dr Rick Last
BVSc; M.Med.Vet (Pathology)Specialist Veterinary Pathologist
Vetdiagnostix –Veterinary Pathology Services
Introduction
Hemorrhagic septicaemia (HS) is an acute,
often peracute, highly fatal form of septicaemic
pasteurellosis associated with certain serotypes of
Pasteurella multocida, namely serotypes B:2 and E:2
(Carter and Heddleston system). Clinical disease is
most commonly reported in cattle, water buffaloes
and American bison with infrequent natural disease
documented in pigs, sheep, goats, camels, elephants,
horses, donkeys, various species of deer and yaks.
The first reported cases of hemorrhagic septicaemia
in African Buffalo in South Africa were in 2011. Since
this time there have been increasing numbers of
cases documented in African buffalo which have
coincided with logarithmic growth of the game
industry. Historically, type B occurred in Asia and
type E in Africa, with Egypt having both types. South
Africa was mostly free of it, and so it is notifiable
when found.
Onderstepoort therefore included type E in the
cattle Pasteurella vaccine, in the early 1980’s, when
there was a spill-over of HS in cattle due to type E
from Botswana 1 . Type B was however later found
in Zimbabwe 4 , and in Namibia 6, but not in SA, until
the current outbreak of type B in wildlife, mostly in
buffaloes in 2008. (Maryke Henton – Vetdiagnostix,
Personal Communication).
4
Epidemiology
Cattle, water buffaloes and bison are known reservoirs
of infection with a small percentage of healthy
animals harbouring small numbers of P. multiocida B:2
or E:2 in their tonsils/nasopharynx 2, 3, 5, 7, 8 . A similar
scenario is suspected in African buffalo, although
one should also consider increased contact between
buffalo and cattle with the growing intensification
in the game industry and therefore, increased
opportunity for transmission between cattle and
buffalo and vice-versa.
Bacteria are shed from carrier animals during
periods of stress. Common stressors include: high
temperatures and humidity, concurrent infections
and poor nutrition. Clinical disease is more common
during rainy seasons in summer rainfall areas
(moisture, temperature and humidity, promoting
bacterial survival in the environment), with bacteria
being maintained in intervening periods in the
nasopharyngeal areas of carrier animals. Stress
induced recrudescent infections in carrier animals
with extensive proliferation and spread of the bacteria
to susceptible in-contact animals is the most common
trigger for outbreaks 2, 3, 5, 7, 8 .
Transmission occurs by direct contact or through
fomites, with buffalo becoming i