The latest Paper of the Month for Parasitology is Differences in clinical aspects of human cystic echinococcosis caused by Echinococcus granulosus sensu stricto and the G6 genotype in Neuquén, Argentina and is freely available. 

In the captivating world of parasitology, the variability observed in certain pathogens holds the potential to significantly influence the course of a disease affecting the severity, duration, and even the response to treatment or vaccines. Understanding the complexities of these variations is key to comprehending disease dynamics and devising effective strategies for prevention and treatment.

The parasite Echinococcus granulosus can form cysts in the lungs, liver, and other organs of humans and animals when they ingest the parasite’s eggs found in the environment, which are excreted in the faeces of an infected dog. In pastoral regions where dogs and goats coexist, there is a risk of a particular variant of the parasite of being transmitted. This variant is known as genotype 6 (commonly referred to as G6) of Echinococcus granulosus, which is the second most common cause of the disease in the world. However, the majority of human CE cases worldwide are caused by E. granulosus sensu stricto. In both cases, the transmission to humans is linked to feeding dogs with the internal organs (viscera) of livestock infected with the parasite. The G6 genotype is particularly important in the Neuquén province in Argentina where the main livestock species is the goat.

Previous studies suggest that cysts attributed to the G6 genotype may exhibit a higher growth rate compared to those caused by E. granulosus s.s. and it also appears that G6 genotype prefer brain tissue.  However, further research is needed to gain a better understanding of how different variants of the parasite can cause variations in the disease. Acquiring data from humans is not easy; it requires collaboration between doctors and researchers and the approval of ethics committees to respect the privacy of patients who were surgically treated to remove cysts from their internal organs. To address this gap, we closely analysed 124 Echinococcus cysts from 90 confirmed cases of cystic echinococcosis (CE) in patients from the Neuquén province. We aimed to compare the genotypes of E. granulosus s.s. and the G6 genotype to understand their impact on the development and severity of the disease in humans.

Our findings revealed that E. granulosus s.s. was found in 56.7% of patients (81 cysts), while G6 genotype was present in 43.3% of patients (43 cysts). E. granulosus s.s. was more common in the liver, while G6 genotype was predominant in the lungs and other organs. Patients infected with E. granulosus s.s. presented up to six cysts, while those with G6 genotype had a maximum of two cysts. Additionally, lung cysts caused by E. granulosus s.s. were significantly larger than those caused by G6 genotype. Interestingly, 55.6% of G6 cysts were inactive, compared to 15.3% of E. granulosus s.s. cysts, suggesting differences in disease progression and severity.

To conclude, this research enhances our understanding of the Echinococcus granulosus complex and its impact on human health. Parasitology continues to unravel the mysteries of these parasites, ultimately contributing to global well-being.

The paper Differences in clinical aspects of human cystic echinococcosis caused by Echinococcus granulosus sensu stricto and the G6 genotype in Neuquén, Argentina by María Florencia Debiaggi, Cristian A. Alvarez Rojas, Lorena Evelina Lazzarini, Daniel Calfunao, Paola Titanti, Liliana Calanni, Marisa Iacono, Silvia Viviana Soriano, Peter Deplazes and Nora Beatriz Pierangeli, published in Parasitology, is freely available.