Environmental and biological interactions of Hepatitis B virus in leeches - a molecular investigation

The aim of the study is to investigate whether transovarial transmission of the Hepatitis B virus occurs in leeches, and whether the virus is released into the external environment through their secretions.

52 reproductive leeches (Hirudo verbana) were experimentally fed with hepatitis B infected human blood. From these reproductive leeches, juveniles were produced. Additionally, diverse leech-associated samples were collected, encompassing water and soil from the habitats of the reproductive leeches, faeces, body surface secretions, and cocoon shells. Each sample was analyzed for the presence of the hepatitis B virus using advanced molecular methods, specifically, real-time quantitative polymerase chain reaction.

90 juveniles, 15 leech-associated samples, and 13 cocoon shells were analyzed. Analyses did not reveal the presence of HBV in any of the 90 juveniles, or in the leech-associated samples. The results suggest that HBV is neither vertically transmitted to the juveniles through transovarial transmission, nor disseminated into the external environment through secretions or other biological materials linked to leeches.

The study concludes that leeches (Hirudo verbana) do not facilitate the transovarial transmission of HBV. Moreover, the absence of HBV in the environmental samples highlights the minimal risk of viral spread via leech secretions, or associated materials. These findings provide critical insights for the ecological management of leech populations, especially in minimizing viral transmission risks. In the literature, studies on transovarial transmission in leeches are quite limited, and it has been concluded that while the data from the presented study are valuable, they are insufficient and highlight the need for further research in this field.