Emerging illnesses of human or veterinary significance pose a significant risk to human society. Comprehensive epidemiological studies and disease surveillance of wild mammal populations will improve our ability to detect and control infectious diseases that may occur in human and domestic animal populations in the future.
A recent North Carolina State University study discovered that a technique that uses dried spots of blood to measure health indicators in elephants is comparable to techniques that use larger blood samples and require immediate cold storage – technology that is not always available when monitoring animals in the wild.
“Our study focused on omega-3 and omega-6 fatty acids, which can be quantified in blood and tell us a lot about an animal’s health,” explains Jordan Wood, who recently defended her Ph.D. dissertation at NC State and was the first author on the publication. “These fatty acids are especially important indicators of cardiovascular and reproductive health in elephants.”
Our study focused on omega-3 and omega-6 fatty acids, which can be quantified in blood and tell us a lot about an animal’s health. These fatty acids are especially important indicators of cardiovascular and reproductive health in elephants.Jordan Wood
Traditional approaches for measuring these fatty acids require the collection of entire blood samples, which many people are familiar with from doctor’s visits. The whole blood, plasma, or serum from the blood can then be used to test the samples. All of these approaches, however, necessitate researchers either immediately freezing or processing blood samples when they are obtained. If frozen, the samples then won’t be thawed until they reach a lab capable of performing the relevant tests.
DBS, or “dry blood spot” sampling, is another option. Only a few drops of entire blood are needed for this procedure, which is dried on specialized filter paper. DBS samples do not need to be immediately frozen, which is a significant advantage, particularly for field researchers. DBS samples also take up far less space than freezer equipment carrying vials of frozen blood, because little pieces of paper take up far less space than freezer equipment containing vials of frozen blood.
Furthermore, DBS requires substantially less blood from the animal. This is less traumatic for the animal and can be beneficial to the health of smaller animals when the volume of blood available for collection is restricted. However, there have been concerns raised about the accuracy of DBS techniques in measuring fatty acids, particularly in non-human species.
“We know DBS is effective for DNA and protein testing,” Wood explains. “However, because fatty acids degrade when exposed to air and ambient temperatures, this was an unresolved subject. That is what we set out to investigate with this study.”
The researchers collected whole blood, plasma, serum, and DBS samples from six adult African elephants (Loxodonta africana) at the North Carolina Zoo to this purpose. The samples were then processed by the researchers to determine how they compared to one another.
The researchers discovered that there were very few differences between whole blood and DBS samples, implying that elephant researchers can use DBS sampling techniques to assess omega-3 and omega-6 fatty acids – as well as related animal health parameters – in both wild and managed elephant populations.
“This also informs us that we can compare data collected from whole blood samples to data collected from DBS samples — we’re comparing apples to apples, not oranges to apples,” Wood says. Furthermore, the researchers discovered that fatty acid data from serum and plasma samples was closer to whole blood and DBS samples than they had anticipated.
“They weren’t quite as near as the DBS samples were to entire blood samples, but they were close,” Wood adds. “This is useful because it allows us to draw meaningful comparisons utilizing historical data collected with plasma and serum samples.” This is especially relevant because much of the historical data is on wild animal populations, allowing us to better understand how animal health may have changed over time and under different situations.
“We hope that our research will allow the scientific and conservation communities to gather more samples from wild populations because it will be easier, less expensive, and less stressful for the animals. This could enable us better understand the health of wild elephant populations and how it compares to controlled elephant populations. Finally, we believe that this will assist us in continuing to improve food and other circumstances for managed elephant populations and other animals.”