The effects of exposure to a 50 Hz magnetic field on the development of the liver fluke during embryogenesis and during larval development in snails should be investigated.
The snail Galba truncatula is the main intermediate host for the common liver fluke Fasciola hepatica.
Liver fluke eggs were either exposed or not exposed to the magnetic field. Subsequently, snails were either infected with larvae hatched from exposed or from non-exposed eggs and were divided into 4 groups (n=10 snails each): 1) infection with exposed larvae and exposure to the magnetic field, 2) infection with exposed larvae and no exposure to the magnetic field, 3) infection with non-exposed larvae and exposure to the magnetic field, 4) infection with non-exposed larvae and no exposure to the magnetic field (control group).
Cercariae are one type of fluke larvae, which are characterized by a tail for movement. When the tail is thrown off and the larvae encyst inside a host, they are called metacercariae.
| Exposure | Parameters |
|---|---|
|
Exposure 1:
50 Hz
Exposure duration:
for 14 days
|
|
|
Exposure 2:
50 Hz
Exposure duration:
for 36 days
infected snails
|
on day 15 of incubation of fluke eggs, after exposing the eggs from the two cultures to light for 1 h, the resultant miracidia were used for the infection of the snails
| Exposure source | |
|---|---|
| Chamber | petri dishes |
| Setup | eggs were incubated in tap water at 24°C in darkness; dishes were placed in inside solenoid of 24 cm diameter and 16 cm length producing a vertical field; solenoids were mounted on a wooden frame surrounding a cork-jacketed cylinder into which the crystallizers containing eggs or snails were placed |
| Sham exposure | A sham exposure was conducted. |
| Additional info | the control eggs and control snails were placed in a non-active solenoid, in which the wire was spooled in a specific way, i.e. each wire loop had the corresponding loop with current flow in the opposite direction; an additional resistance adjusted the current so that it was the same as in the active solenoid; this setup resulted in the total attenuation of the magnetic field; the thermal effect was the same in both exposure and control conditions |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 2 mT | effective value | measured | - | - |
| Frequency | 50 Hz |
|---|---|
| Type | |
| Waveform | |
| Exposure duration | for 36 days |
| Additional info | infected snails |
| Exposure source |
|
|---|---|
| Chamber | difference to exposure 1: beakers instead of petri dishes for exposure |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| magnetic flux density | 2 mT | effective value | measured | - | - |
The first metacercariae were detected after 35 days of exposure in groups 1-3 (all except control group, no specifications on significance). After 36 days of exposure the only statistically significant difference was found between groups 1 and 2 with significantly more fluke larvae in group 2 (infection with exposed larvae and no exposure of snails) compared to group 1 (infection with exposed larvae and exposure of snails).
The authors conclude that the duration of exposure to a 50 Hz magnetic field (i.e. embryogenesis period vs. the entire larval development) might play a role in the development of liver fluke larvae.
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