Influence of environmental factors on the infectivity ofEchinococcus multiloculariseggs

Abstract

The sensitivity of eggs of Echinococcus multilocularis to environmental and controlled laboratory conditions was tested. Egg material was exposed and the infectivity was subsequently monitored by in vitro activation and by oral infection of the natural host, Microtus arvalis. To study the impact of environmental conditions in an endemic area of south-western Germany, eggs were sealed into bags of nylon mesh and exposed to the natural climate during various seasons. The maximal survival time of eggs was 240 days in an experiment performed in autumn and winter and 78 days in summer. A study of the tenacity of eggs under laboratory conditions revealed a high sensitivity to elevated temperatures and to desiccation. At 45 degrees C and 85-95% relative humidity the infectivity was lost after 3 h as well as after 4 h exposure to 43 degrees C suspended in water. Exposure to 27% relative humidity at 25 degrees C as well as exposure to 15% relative humidity at 43 degrees C resulted in a total loss of infectivity within 48 and 2 h, respectively. Temperatures of 4 degrees C and of -18 degrees C were well tolerated (478 days and 240 days survival, respectively), whereas exposure to -83 degrees C and to -196 degrees C quickly killed off the eggs (within 48 h and 20 h, respectively). Eggs of E. multilocularis were not killed off by exposure to various commercially available disinfectants applied according to the manufacturers' instructions and by exposure for 24 h to low concentrations of ethanol. Irradiation with 40 krad. from a 137Caesium source prevented the development of metacestodes but allowed seroconversion of infected rodents.

The Carriage of Larval Echinococcus Multilocularis and Other Cestodes by the Musk Rat (Ondatra Zibethicus) Along the Ourthe River and Its Tributaries (Belgium)

“…In the present work, only one of 58 tissue samples was unfertile. This lesion was probably too young (from 1.5 mo to 3 mo are necessary for the appearance of protoscoleces; Marchiondo and Andersen, 1984;Veit et al, 1995). This would suggest that O. zibethicus is a very effective intermediate host for E. multilocularis.…”

“…One of the key factors is probably the altitude: E. multilocularis is a parasite that originates from cold regions (Hanosset et al, 2004). Indeed, the eggs of E. multilocularis have a survival time higher in cold temperatures (Veit et al, 1995). Delattre et al (1991) showed that alveolar echinococcosis is more prevalent in regions with cold temperatures and a relative humidity.…”

Biology and Systematics of Echinococcus

“…Echinococcus eggs are extremely resistant enabling them to withstand a wide range of environmental temperatures for many months (Gemmell et al, 1986 ½Q11 ; Schantz et al, 1995;Thevenet et al, 2005;Veit et al, 1995). Dessication is lethal and the end points for temperature are approximately þ40 C to À70 C (Gemmell and Roberts, 1995).…”

Urban park-related risks forGiardiaspp. infection in dogs

“…The samples were stored at −80°C for 72 h to kill Echinococcus spp. eggs [30] and promote the safety of the researchers. This parasite has recently been found in coyotes in Calgary [31][32][33][34], and therefore this precaution was determined to be necessary.…”