Biology_of_Mustelids_Vol_1.pdf

221.
was observed in 2.3% of the martens (in December and January).
The
average per infected animal was 2.7 foci.
From December to February the
number of martens with the maximum number of foci in the lungs increased
almost two-fold (from 5.6 to 10.5%), while the number with one focus
increased towards the end of the winter from 15.7 to 31%, and the number
with 3 foci fell by more than half.
The mean intensity and extent of
invasion did not change significantly (Table 3).
Table 3.
Infection of martens by Filaroides through the hunting season,
1957-58-1967-68 in the North-West RSFSR
Infected
Mean no. of foci
Month No. of martens in lungs, per
studied no. % infected animal
November 123 70 56.9 2.8
December 203 96 47.2 2.8
January 160 80 50.0 2.8
February-March 67 32 47.7 2.5
Total. 553 278 50.3 2.7
The intensity and distribution of Filaroides invasion in the
North-West RSFSR is lower than in the adjacent areas of the Archangel
region and the Komi ASSR (Grakov 1962), and the Vologda region (Gribova
1959), but is higher than in the Mari, Tatar and Bashkirian ASSR
(Troitskaya 1962).
In martens in the North-West RSFSR, there is a clear relation
between Filaroides invasion and age (Table 4):
yearlings are much more
infected (61.0%) than adults (47.5%).
The proportion infected gradually
decreases in the older age groups, because immunity of the martens to
helminths increases with age (Shikhobalova 1950, Dogel 1962).