Epidemiology of Anaplasma marginale and Anaplasma centrale infections in African buffalo (Syncerus caffer) from Kruger National Park, South Africa.

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EXPLORING THE USE OF THE ERYTHROCYTE SEDIMENTATION RATE AS AN INFLAMMATORY MARKER FOR FREE-RANGING WILDLIFE: A CASE STUDY IN AFRICAN BUFFALO (SYNCERUS CAFFER).

Measuring inflammatory markers is critical to evaluating both recent infection status and overall human and animal health; however, there are relatively few techniques that do not require specialized equipment or personnel for detecting inflammation among wildlife. Such techniques are useful in that they help determine individual and population-level inflammatory status without the infrastructure and reagents that many more-specific assays require. One such technique, known as the erythrocyte sedimentation rate (ESR), is a measure of how quickly erythrocytes (red blood cells) settle in serum, with a faster rate indicating a general, underlying inflammatory process is occurring. The technique is simple, inexpensive, and can be performed in the field without specialized equipment. We took advantage of a population of African buffalo (Syncerus caffer), well studied from June 2014 to May 2017, to understand the utility of ESR in an important wildlife species. When ESR was compared with other markers of immunity in African buffalo, it correlated to known measures of inflammation. We found that a faster ESR was significantly positively correlated with increased total globulin levels and significantly negatively correlated with increased red blood cell count and albumin levels. We then evaluated if ESR correlated to the incidence of five respiratory pathogens and infection with two tick-borne pathogens in African buffalo. Our results suggest that elevated ESR is associated with the incidence of bovine viral diarrhea virus infection, parainfluenza virus, and Mannheimia haemolytica infections as well as concurrent Anaplasma marginale and Anaplasma centrale coinfection. These findings suggest that ESR is a useful field test as an inflammatory marker in individuals and herds, helping us better monitor overall health status in wild populations.

Age of first infection across a range of parasite taxa in a wild mammalian population.

Newborn mammals have an immature immune system that cannot sufficiently protect them against infectious diseases. However, variation in the effectiveness of maternal immunity against different parasites may couple with temporal trends in parasite exposure to influence disparities in the timing of infection risk. Determining the relationship between age and infection risk is critical in identifying the portion of a host population that contributes to parasite dynamics, as well as the parasites that regulate host recruitment. However, there are no data directly identifying timing of first infection among parasites in wildlife. Here, we took advantage of a longitudinal dataset, tracking infection status by viruses, bacteria, protists and gastro-intestinal worms in a herd of African buffalo (Syncerus caffer) to ask: how does age of first infection differ among parasite taxa? We found distinct differences in the age of first infection among parasites that aligned with the mode of transmission and parasite taxonomy. Specifically, we found that tick-borne and environmentally transmitted protists were acquired earlier than directly transmitted bacteria and viruses. These results emphasize the importance of understanding infection risk in juveniles, especially in host species where juveniles are purported to sustain parasite persistence and/or where mortality rates of juveniles influence population dynamics.

Molecular characterisation of Anaplasma species from African buffalo (Syncerus caffer) in Kruger National Park, South Africa.

Bovine anaplasmosis is a tick-borne disease, mainly caused by Anaplasma marginale and A. centrale and is distributed in tropical and sub-tropical areas. This study aimed to characterise A. marginale and A. centrale from African buffaloes in Kruger National Park (KNP), South Africa, using the DNA sequences of the genes coding for major surface protein (msp1ß) and heat shock protein (groEL), respectively. A total of 747 blood samples were collected from February 2014 to August 2016 from African buffaloes kept in KNP, and DNAs were tested using a molecular-phylogenetic approach. Out of 747 samples tested, 129 (17.3%) and 98 (13.1%) were positive for single infection with A. marginale and A. centrale, respectively; whereas 113 (15.1%) were positive for both Anaplasma spp. Pairwise difference of 1.6-8.5% was observed in msp1ß sequences of A. marginale whereas that was only 0.3-2.4% for groEL sequences of A. centrale. Separate phylogenetic analyses of msp1ß and groEL sequences of A. marginale and A. centrale, respectively, revealed that sequences of Anaplasma spp. from African buffaloes were unique and they grouped separately when compared with previously published sequences of both species. This is the first study to characterise A. marginale and A. centrale from African buffalo using species specific molecular markers. This study will pave the way for future studies to assess genetic variation among Anaplasma spp. from wild ruminants using molecular markers that are better at differentiating between species and strains than the more commonly used 16S rRNA gene, and help to undertake health and fitness studies and host-parasite dynamics using quantitative molecular tools.