Progress towards international adoption of the World Health Organization ultrasound classification of cystic echinococcosis

Abstract

Cystic echinococcosis (CE) is a global parasitic zoonosis for which ultrasound (US) is the gold standard modality for diagnosis. In 2003, the WHO published a standardized US classification of CE, on which WHO treatment guidelines are based. In 2014, global adoption of the classification was questioned by a publication which indicated that, between 2004 and 2014, only half of studies utilizing a classification used the WHO classification. More recent studies have demonstrated that the WHO classification best reflects the natural history of CE, and is used with high reliability by experts in the field; despite these attributes, the classification's impact is ultimately limited by the extent of its adoption. A PubMed search using the terms "Echinococcus granulosus ultrasound," "Echinococcus granulosus classification," "cystic echinococcosis ultrasound," and "cystic echinococcosus classification" revealed publications on human CE utilizing a US classification. Classification(s) used, year of publication, and the country of the first author's institution were recorded. From 2004 to 2010, the WHO classification was used in 50% or fewer of included publications for 6 of the 7 years. After 2011, it appeared in a low of 75% (2013) to a high of 96% (2017) of included publications. Of all included studies published from 2004 to 2017, the WHO classification was referenced in 18% (3 of 17) from Africa, 64% (32 of 50) from Asia, 79% (89 of 113) from Europe, 89% (8 of 9) from North America, and 100% (9 of 9) from South America. Findings suggest that the WHO classification has been progressively taking preference to other classifications, with rate of adoption depending on continent of origin of the research. Residual use of the classification developed by Dr. Hassen Gharbi of Tunisia in 1982, used widely prior to development of the WHO classification (which reversed two stages in Gharbi's classification in order to more closely reflect the natural history of CE) suggests that adoption of a new classification takes time and varies regionally.

Keywords: Classification; Cystic echinococcosis; Ultrasound.