Untersuchungen zur Epidemiologie der Caninen Babesiose im Bundesstaat Minas Gerais, Brasilien

Studies on the epidemiology of Canine Babesiosis in Minas Gerais,
Brazil. During two stays between April 2004 and February 2005, one
in the dry season and the other during the rainy season, a total of
552 samples from 385 dogs (samples from 167 dogs were collected
twice) from three different regions (Carrancas, Carlos Chagas and
Igarapé) in Minas Gerais, Brazil were collected. While the first
collection only included samples from dogs living in rural areas
the second collection gathered repeat samples from the dogs from
the first collection as well as samples from dogs from the
particular urban areas. Blood was taken from each dog and blood
smears were prepared. The blood smears were microscopically
analysed and the DNA, extracted from the blood, was used for
Real-Time PCR analysis of infections with Babesia canis vogeli or
other piroplasms. A conventional PCR for the detection of Babesia
sp. was carried out. In addition an indirect
immunfluorescent-antibody-test, specific for Babesia canis vogeli,
was performed with all samples. The analysis of samples from the
first collection period resulted in a percentage of prevalence of
10,3 % in the Real-Time PCR and 30,0 % in the indirect
immunfluorescent-antibody-test. The second collection period showed
a prevalence of 8,2 % in the Real-Time PCR and 21,7 % in the
indirect immunfluorescent-antibody-test. No significant difference
has been found in the results from the Real-Time PCR and the origin
(urban-/rural area) of the dogs in Minas Gerais, in general.
However, on examining the three different regions separately, a
significant difference in prevalence emerged in Carlos Chagas. In
Minas Gerais there was a highly significant difference shown in the
results of the indirect immunfluorescent-antibody-test. While
Carrancas showed no significance at all, there was a significant
difference shown in the results of Carlos Chagas and a highly
significant difference shown in Igarapé. Due to the very low
sensitivitiy of the microscopically analysation only two from the
552 samples were positive. With regards to the two different time
periods (dry and rainy season) in which samples where collected, no
significant differences in the results of the Real-Time PCR were
recorded in Minas Gerais in general or in the various regions in
particular. The results of the indirect
immunfluorescent-antibody-test did not show any significance in
Minas Gerais, generally, or the regions of Carrancas and Carlos
Chagas in particular, whereas in Igarapé a significant difference
was visible. Comparing the different age groups, a significant
difference was detected in the Real-Time PCR results and a highly
significant difference in the results from the indirect
immunfluorescent-antibody-test. Concerning the difference in
prevalence’s of infections and antibodies based on sex
(male/female) the results of the PCR showed no significant
difference whereas the difference in seroprevalence was
significant. The results of the hematocrit and a comparison with
the positivity in the different diagnostical methods revealed no
significance for the indirect immunfluorescent-antibody-test and a
high significance for the Real-Time PCR. A reason for the
differences in prevalences across different age groups, as compared
to the results from the Real-Time PCR, could be that puppies are
more prone to infections. In the results of the indirect
immunfluorescent-antibody-test a higher prevalence in the older age
groups points to a certain resistance of those animals after
recovering from infections with B. canis vogeli. A likely cause for
the differences in prevalence in the results of the Real-Time PCR
and the indirect immunfluorescent-antibody-test compared to the
origin (rural or urban area) of the dog samples are differences in
keeping the dogs as well as a lower occurrence of the vector ticks
in the urban areas.