VN May 2017

20 / 52

18 Mei/May 2017
Regulars I From the Journal of the SAVA
Validity of somatic cell count as
indicator of pathogen-specific
intramammary infections
Inge-Marié Petzer, Joanne Karzis,
Edward F. Donkin, Edward C. Webb,
Eric M.C. Etter
Journal of the South African Veterinary Association;
Vol 88 (2017), 10 pages. doi: 10.4102/jsava.v88i0.1465
Abstract
The objective of this study was to determine whether
somatic cell count (SCC) was an effective test, with
a sensitivity exceeding 85%, to determine species-
specific bacterial infections. In addition, the relation
between the SCC and various udder pathogen groups
was investigated. SCC thresholds of greater than
200 000 cells/mL were used in quarter and greater
than 150 000 cells/mL in composite milk samples. A
retrospective study was conducted on a data set for
89 635 quarter and 345 467 composite cow milk
samples. Eleven SCC threshold values were used to
evaluate the diagnostic efficacy for the following bac­
teria: Gram-positive major pathogens: Staphylococcus
aureus, Streptococcus agalactiae, Streptococcus
dysgalactiae and Streptococcus uberis; Gram-
negative major pathogens: Escherichia coli, Klebsiella
pneumonia and Serratia spp.; minor pathogens:
coagulase-negative staphylococci, Micrococcus spp.,
Staphylococcus pseudintermedius, Streptococcus
pyogenes, Enterococcus faecalis, Enterococcus canis,
Trueperella pyogenes and other Enterobacteriaceae.
Sensitivity and specificity were calculated taking the
effect of clustering into account with quarter milk
samples. Most samples yielding major Gram-positive
pathogens (88.9% in quarter and 79.9% in composite
samples) and minor pathogens (61.4% in quarter and
51.7% in composite samples) had SCC greater than
200 000 cells/mL. Sensitivity of the SCC test to detect
major pathogens at an SCC threshold of greater than
200 000 cells/mL in quarter samples and greater than
150 000 cells/mL in composite milk samples was 88.2%
and 84.2%, respectively, but specificity was low (57.7%
and 52.8%, respectively). v
From the Journal of the SAVA
Enhanced diagnosis of
rabies and molecular evidence
for the transboundary
spread of the disease in
Mozambique
Andre Coetzer, Iolanda Anahory,
Paula T. Dias, Claude T. Sabeta,
Terence P. Scott, Wanda Markotter,
Louis H. Nel
Journal of the South African Veterinary Association;
Vol 88 (2017), 9 pages. doi: 10.4102/jsava.v88i0.1397
Abstract
Rabies is a neglected zoonotic disease with veterinary and
public health significance, particularly in Africa and Asia.
The current knowledge of the epidemiology of rabies in
Mozambique is limited because of inadequate sample sub­
mission, constrained diagnostic capabilities and a lack of
molecular epidemiological research. We wanted to con-
sider the direct, rapid immunohistochemical test (DRIT) as
an alternative to the direct fluorescent antibody (DFA) for
rabies diagnosis at the diagnostic laboratory of the Central
Veterinary Laboratory (CVL), Directorate of Animal Science,
Maputo, Mozambique. Towards this aim, as a training
exercise at the World Organisation for Animal Health (OIE)
Rabies Reference Laboratory in South Africa, we performed
the DRIT on 29 rabies samples from across Mozambique.
With the use of the DRIT, we found 15 of the 29 samples
(52%) to be negative. The DRIT-negative samples were
retested by DFA at the OIE Rabies Reference Laboratory,
as well as with an established real-time Polymerase
chain reaction, confirming the DRIT-negative results. The
DRIT-positive results (14/29) were retested with the DFA
and subsequently amplified, sequenced and subjected to
phylogenetic analyses, confirming the presence of rabies
RNA. Molecular epidemiological analyses that included
viruses from neighbouring countries suggested that rabies
cycles within Mozambique might be implicated in multiple
instances of cross-border transmission. In this regard, our
study has provided new insights that should be helpful
in informing the next steps required to better diagnose,
control and hopefully eliminate rabies in Mozambique. v
FOR MORE ARTICLES, VISIT