Greater genetic diversity of tape worm in Australia discovered
The latest Parasitology Paper of the Month is Microdiversity of Echinococcus granulosus sensu stricto in Australia by C. A. Alvarez Rojas et al.
The parasite Echinococcus granulosus remains as an important public health concern worldwide. It causes the disease cystic echinococcosis affecting mainly the liver and lung in animals, as well as humans. In Australia the parasite affects mainly livestock and wildlife.
Understanding the variability of E. granulosus helps us to better understand its distribution worldwide (in this case in Australia). This knowledge can then be used to improve control measures taken against this tapeworm. E. granulosus is well known to have high genetic variability, however, using the methodology presented in this paper we have shown that this variability is even higher than previously thought. We measured the variability of the parasite by analysing the full length of the cox1 gene and comparing the sequences obtained with the ones deposited in GenBank. For this purpose, a single nucleotide difference is considered a new haplotype.
Previous theories speculated that E. granulosus might have been present in Australia prior to British colonization, though this was never proven. The parasite is thought to have arrived with animals brought by the British around 200 years ago. These animals might have been originated in Spain and North Africa. If this was the case we would expect to find a low genetic variability in E. granulosus in Australia. However our results showed a higher diversity in this parasite than expected. A possible explanation is that the parasite arrived from different sources or that the place where the animals originated from contains many variants of E. granulosus.
Most of the samples used in this study were taken from livestock animals and sent directly to the lab of Marshall Lightowlers at The University of Melbourne, Australia. Other samples, especially the ones from dingoes, were taken by David Jenkins from different places in Australia. Some other samples used in this study were collected by Professor Ian Beveridge in remote locations in Queensland in the 80’s, more specifically, six cysts isolated from wild animals which were invaluable for this study. All together, these samples have been collected over the last 25 years and were kept in the freezers of the Faculty of Agriculture and Veterinary Sciences at The University of Melbourne. I was lucky enough to have the chance to use them to uncover a bit more of the hidden history of E. granulosus in Australia and share it with the scientific community. I also thank the Group of Eight Universities in Australia and the DAAD for the grant that allowed me to visit the lab of Prof. Thomas Romig at the University of Hohenheim to undertake this research.
I believe is important to continue studying this parasite, especially aspects that can contribute to the improvement of the measures taken to control it. The disease caused by this parasite is important in rural and poor areas of developing countries. Therefore, in my opinion, all the efforts made by the scientific community must be focused in contributing to the knowledge that can impair the transmission of the parasite decreasing the chances of human and animal infection.