Documentation Parasites
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Occurence of Ascaris suum eggs in the
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85 % |
phosphate complex |
In a 32 % solution pH 2.51 [Mehtling et al. 1996] and in a 0.5 % solution pH 3.45. After making a very detailed protocol and trial report, the final conclusion describes Stalosan F as a 'most valuable hygiene product'.
HANDLING THE DISINFECTANT MATERIALS
Samples taken before and after treatment with lime and Stalosan F.
Location: Farm 1 - dunging area, pen 12, finishing house. See Fig 3.
Method:
Underneath the slats in this slatted floor, in the dunging area, at the edges at each end, slats
rest upon. In this area deposits build up with dung and A.suum eggs. These cavities measured 10 cm x
2 cm x 4 cm. Before treatment the upper half of each of 20 cavities was removed and kept in sealed
and numbered plastic containers. Stalosan F was placed into cavity no. 7-13 [no. 1-6 control] for
24 hours as recommended by the producer. Slaked lime in no. 14-20 the next day. 150 ml of cold
tap water [13.5 °C] was added and stirred into each cavity - the temperature being recorded. After
30 minutes all 7 cavities were completed. Then the 20 post samples were taken.
Fig.3 Dunging area in finishing pen. Farm 1.Exact location of samples taken (small rectangles at the top).
MORPHOLOGY OF Ascaris EGG
In all floor samples the stage of development and morphology of Ascaris eggs was evaluated. These following diagrams produced after Roepstorff [1996].
Diagrams of Ascaris eggs classification
A |
The newly excreted or resting egg. Shell is totally filled with a heterogeneous mass. |
AB |
Egg contents have started to contract within the shell. |
B |
Egg centre is one homogeneous global cell, not completely filling the shell |
BC |
The last stage has begun to divide internally |
C |
Egg centre clearly divided into two cells joined together |
CD |
Start to divide again into 4 |
D |
Clearly 4 cells |
DE |
Four cells have begun to divide further |
E |
8 or more cells visible with distinct borders |
EF |
Border lines are no longer distinct |
F |
Centre of egg is an uneven mass without visible cell borders |
FG |
Cell mass is undergoing change perhaps visible larvae ends evolving |
G |
Short thick larva almost filling shell |
GH |
Little longer larva lying in a loose spiral |
H |
Infectius larva long, slim in tight spiral |
S |
Normal eggs with black spots clearly defined |
0 |
Degenerated egg - sometimes cracked shell |
TOM |
Eggshell [empty] |
Furthermore I decided to work with the following simplified groups:
A |
not started development |
G-H |
almost/completely developed/infective |
AB-FG |
developing |
S-TOM |
presumed dead |
RESULTS
FARM 1
On 24/6/98 rectal faeces samples for all 12 sows [lactating]. All sows had O EPG [eggs per gram]. There is reason to believe that all the sows on Farm 1 had been continually infected throughout their life.
Table 1 - location of A.suum eggs. Farm 1.
Floor samples from farrowing pens 24/6/98.
All samples 5 gm.
Pen:sample |
Exact location of sample (see also fig.1) physical appearance of sample. |
E.P.G. |
1:1 |
Corner (feeder trough/wall); composted (food, faeces, straw); slightly moist |
0 |
1:2 |
Corner (resting area/dunging area/wall) slightly composted (food, faeces, straw), wet |
0 |
1:3 |
Corner (dunging area/wall); (faces, straw) dry |
0 |
1:4 |
Corner (dunging area/resting area); faeces, straw), wet |
0,2 |
1:5 |
Piglets resting area (beneath a hanging bale of straw); (dust, straw), dry |
0 |
1:6 |
Corner (feeder trough(neighbour pen divider) piglets resting area; composted (straw, food, maggots); wet |
0 |
1:7 |
Beneath watersupply dispenser in sow's area (straw, food); rotten |
0 |
1:8 |
Center of piglets resting area; (straw, dust, faeces in "flakes"), dry |
0 |
2:1 |
Corner (feeder trough/neighbour pen divider) composted (faeces, straw, food) moist (like fertile soil) |
0 |
2:2 |
Corner (resting area/dunging area); (faeces, straw, crumbling wood, urine smelling); moist |
0 |
2:3 |
Corner (dunging area/wall/neighbour pen divider) (faeces, straw); moist |
0,6 |
2:4 |
Corner (dunging area(resting area/neighbour pen divider); (faeces, crumbling wood, maggots); wet |
0 |
2:5 |
Piglets resting area (beneath a hanging bale of straw); (dust, straw) dry |
0 |
2:6 |
Corner, piglets resting area (feed trough/neighbour pen divider); (straw, food, maggots); composted, slightly moist |
0 |
2:7 |
Beneath watersupply (dispenser) in sow's area (straw, food); rotten |
0,6 |
2:8 |
Center of piglets resting area (straw, dust, faeces in "flakes"); dry |
0 |
3:1 |
Corner (feeder trough/neighbour pen divider); composted (faeces, straw, food) slightly moist |
0 |
3:2 |
Corner (resting area/dunging area); (faeces, straw, dust); dry |
0 |
3:3 |
Corner (dunging area/wall/neighbour pen divider) (faeces, straw, urine smelling), slightly moist |
0 |
3:4 |
Corner (dunging area/resting area/neighbour pen divider); (faeces, crumbling wood); moist |
1,8 |
3:5 |
Piglets resting area (beneath a hanging bale of straw); (dust, straw); dry |
0 |
3:6 |
Corner, piglets resting area (feeder trough/neighbour pen divider); (faeces, straw, food, dust); slightly composted, slightly moist |
0,2 |
3:7 |
Beneath watersupply dispenser in sow's area (straw, food); rotten, wet |
3,0 |
3:8 |
Center of piglets resting area; (faeces, dust); dry |
0 |
From table 1 one can see there was an excretion of Ascaris-eggs in the farrowing pens, but the amount of eggs is very low. This can be dued to at low amount in the floor-material, but it can also be caused by taking the samples just beside the actual position of the eggs.
Samples taken from locations 1,2,5 and 8 [see fig. 1] in farrowing were negative. It was noted that no sows in the farrowing house excreted eggs on that day. Therefore, when sampling in the finishing house, the sampling technique focused on the most likely areas for infection. In table 1 this rather simplistic table details are fully described: In all the following tables a uniformity will be used which raises the level of comprehension. When using the Aug 98 finishing pen results - the most descriptive results were selected [due to inbalance in numbers] . In all other tables all results are recorded.
Table 2
Egg stages expressed in percentage terms as defined in fig. 4. Farrowing house, floor samples,
farm 1 [see also table 1 June 98]
|
Total number found |
% of total number |
Eggstadium A |
24 |
80 |
From table 2 it can be seen that a large majority of eggs in Farm 1 had not developed.
In the finishing house similar samples were taken. The pigs were 12-16 weeks old in Aug 98. The results from Aug 98 can be seen in table 3. Standard deviations are very large due to the wide variation in the sample results. The results point out the status of the house i.e. Ascaris eggs are widely and consistently found. I therefore chose not to exclude the extreme results in order to reflect the true situation.
Table 3. Average and distribution in percentage in groups of egg stadium. Floor samples from finishing house farm 1 were taken 12&13/8/98. The exact position of sample location can be seen in figure 2. Definition of egg stadia see figure 4. Values express average EPG [eggs per gramme]. Percentages are estimated on the basis of the total of the individual samples. See as well tables 4; 7 & 8.
Sample location number |
1 |
2 |
3 |
4 |
Standard deviation |
|||
Number of samples |
12 |
12 |
12 |
12 |
Loc. 1 |
Loc. 2 |
Loc. 3 |
Loc. 4 |
Group A |
2,7 |
11,6 |
23,4 |
3,4 |
3,7 |
17,1 |
36,2 |
2,5 |
AB-FG |
25,1 |
120,0 |
384,0 |
16,1 |
41,9 |
165,4 |
889,8 |
17,3 |
G-H |
7,0 |
27,5 |
144,4 |
4,8 |
10,4 |
41,3 |
371,5 |
6,3 |
S-Empty |
0,4 |
3,0 |
4,2 |
2,0 |
0,7 |
4,3 |
7,3 |
6,3 |
(Average in total is 194.9 E.P.G.)
Table 3 shows that Ascaris eggs in location 3 [555.9 ± 1 290.7 EPG. Minimum 13.6 EPG, maximum 4 756 EPG] which is from the corner between the dunging area, wooden divider and the neighbouring pen. The majority of eggs [69.1 %] were under development [group AB-FG] toward infective stadium. 26 % of the eggs had reached infective stadium [group G-H]. Only 4.2 % were still in group A [newly excreted or resting]. This may be due to excretion of the eggs within a few days or inhibition perhaps because of temperatures below 15 °C or relative humidity below 78 % [Nilsson 1987].
Unfortunately it was not possible to measure these quantities on the day of sampling but, in any case, the temperature was certainly well above 15 °C. Relative humidity in the sample material was evaluated at the time of sampling as 'moist' in 7 out of 12 and 'slightly moist' in 5 of 12 samples from location 3.
Table 4. Absolute and distribution percentages in groups of egg development [ EPGs of all pens summed up]. Finishing house, farm 1; Aug 1998. Samples taken from all 12 pens, 4 samples from each. Definition of egg stadia and groups: see figure 4 and also tables 3;7&8.
|
Eggs found |
% of eggs found |
Group A |
465,1 |
5,0 |
TOTAL |
9.353,0 |
100,0 |
One can see a large majority of developing eggs [AB-FG] in the finishing house taken as a whole. The average is 194.9 EPG.
Figure 5. Diagram showing egg excretion in rectal samples. Columns 1 & 3 represent the average
EPG in the finishing house pens on farm 1. Columns 2 & 4 represent the matching standard
deviations. Pen no. 2 is at the back. In front of it are pens 3,4,5,6,7,8,9,10 & 11. Foremost
is pen 12.
In figure 5 one can see that the average egg excretion in most pens was slightly larger
in the second sample sequence. Pens 2 & 6 had much bigger excretion levels [11 716 and
12 387 EPG on 2/10 as against 2 120 and 5 137 EPG on 12/9]. The average for all pens on 12/9 was
3 569 EPG [minimum 20 EPG and maximum 19 040 EPG]. The average on 2/10 was 4 827 EPG for all
pens [minimum 60 EPG and maximum 35 760 EPG.] Rise in the average is therefore [4 827 - 3 569 / 3
569] i.e. 35 %.
The most likely explanation is that the pigs entered the finishing house in the first week of
August and the shortest time from infection to excretion [prepatens time] is 6-8 weeks [Monrad
& Nansen 1994]. The eggs excreted on 12/9 can only come from infective eggs ingested in the
farrowing house.
The second rectal sample sequence was taken approximately 8 weeks after removal of the pigs to the
finishing house. These samples contain A.suum eggs ingested both in the farrowing house and the
finishing house.
Table 5 EPG before and after treatment of the cavities as well as the reduction in EPG as a percentage. Please notice sign of reduction! For each group of treatment average, standard deviation and parameters for determining if results are Gauss-distributed (Bell-distribution). All 20 samples were taken in the dunging area in pen no. 12, farm 1. See fig. 3 for exact locations of samples taken. Samples before treatment were taken 17. Nov. and after treatment 18. Nov. 1998.
|
Sample number |
Before |
After |
Before-After |
Reduction in % |
Calculations |
Control |
1 |
441,1 |
280,4 |
160,7 |
36,4 |
Average (before-after)= 1,6 |
|
2 |
62,3 |
74,8 |
-12,5 |
-20,1 |
Standard deviation(before)=144,9 |
|
3 |
158,4 |
71,3 |
87,1 |
55,0 |
Standard deviation(after)=94,5 |
|
4 |
101,4 |
72,0 |
29,4 |
29,0 |
KS-distance(before;after)=0,33;0,31 |
|
5 |
126,3 |
227,6 |
-101,4 |
-80,3 |
P(before) > 0,10 P(after) > 0,10 |
|
6 |
51,2 |
212,7 |
-161,5 |
-315,4 |
Gauss' distributed (5%-level) YES |
Slaked lime |
7 |
169,5 |
109,9 |
59,6 |
35,2 |
Average (before-after)= 93,4 |
|
8 |
177,4 |
91,4 |
86,0 |
48,5 |
Standard deviation(before)=78,2 |
|
9 |
119,1 |
73,9 |
45,3 |
38,0 |
Standard deviation(after)=40,0 |
|
10 |
65,2 |
44,6 |
20,6 |
37,3 |
|
|
11 |
228,0 |
48,1 |
179,9 |
78,9 |
KS-distance(before;after)=0,18;0,13 |
|
12 |
240,4 |
13,3 |
227,1 |
94,5 |
P(before) > 0,10 P(after) > 0,10 |
|
13 |
35,1 |
0,0 |
35,1 |
100,0 |
Gauss' distributed (5%-level) YES |
Stalosan |
14 |
98,5 |
21,1 |
77,4 |
78,6 |
Average (before-after)=109,6 |
|
15 |
63,3 |
33,2 |
30,1 |
47,6 |
Standard deviation(before)=84,9 |
|
16 |
25,7 |
4,6 |
21,1 |
82,1 |
Standard deviation(after)=9,5 |
|
17 |
116,3 |
8,8 |
107,5 |
92,4 |
|
|
18 |
280,4 |
10,3 |
270,1 |
96,3 |
KS-distance(before;after)=0,26;0,14 |
|
19 |
189,5 |
17,9 |
171,7 |
90,6 |
P(before) > 0,10 P(after) > 0,10 |
|
20 |
103,4 |
14,0 |
89,4 |
86,5 |
Gauss' distributed (5%-level)YES |
Relative humidity in all samples was 81.5-85.0 %. The temperature range was 13.5-15.3°C in the samples taken before treatment and 71.9 ± 10.5 °C after treatment with slaked lime. Temperature did not change after treatment with Stalosan F.
In table 5 one can see equal numbers of Ascaris eggs in the cavities for control both
before and after treatment. In other words it made no difference that the samples were taken
profoundly or superficially. After lime treatment the situation was different: egg numbers were
reduced by, on average, 93.4 EPG. The difference was even more marked after Stalosan F treatment: 1
09.6 EPG on average.
Control [before treatment], control [after treatment], lime [before], lime [after], Stalosan F
[before], Stalosan F [after], control [reduction], lime [reduction] and Stalosan F [reduction]
were all shown to have Gauss's distributed EPGs.
Another result worth noting is the extreme morphological changes to the Ascaris eggs after
treatment. More about this later.
To test whether the differences between the 3 treatments [control, slaked lime and Stalosan F]
were significant, a paired two-tailed T test was carried out. The result was that there was no
significant difference between control [before] and control [after]. P = 0.995 t = 0.0006, df=5
95% confidence interval = {-12.46 to 125.2} r = 0.6.
There was significant differences between slaked lime [before] and slaked lime [after].
P=0.0205 t = 3.122 df=6 95% confidence interval = {20.2 to 166.5} r = 0.2. There was also a
significant difference between Stalosan F [before] and Stalosan F [after]. P=0.0156 t = 3.340
df=6 95% confidence interval {29.3 to 189.9} r = -0.1
Table 6. ANOVA parameters to test differences between treatments [control, slaked lime and Stalosan F] before and after in farm 1, finishing house, pen 12, dunging area;Nov1998.
ANOVA (before) |
SS |
df |
MS |
|
Signifikans ? |
Treatments (between columns) |
3487 |
2 |
1.744 |
|
|
Residual (in columns) |
184.800 |
17 |
10.870 |
|
|
Total |
188.300 |
19 |
|
|
|
Tukeyøs multiple comparison test |
Differens in average |
q |
P-value |
95% confidence interval |
|
Control versus slaked lime |
8,963 |
0,2185 |
P>0,05 |
139,9 to 157,8 |
NO |
Control versus Stalosan F |
31,46 |
0,7669 |
P>0,05 |
-117,4 to 180,3 |
NO |
Slaked lime versus Stalosan F |
22,50 |
0,5709 |
P>0,05 |
-120,5 to 165,5 |
NO |
ANOVA (after) |
SS |
df |
MS |
|
|
Treatments (between columns) |
67.150 |
2 |
33.580 |
|
|
Residual (in columns) |
54.800 |
17 |
3.223 |
|
|
Total |
121.900 |
19 |
|
|
|
After treatment |
Differens in average |
q |
P-value |
95% confidence interval |
|
Controle versus slaked lime |
102,0 |
4,568 |
P<0,05 |
21,00 to 183,1 |
YES |
Control versus Stalosan F |
140,8 |
6,303 |
P<0,05 |
59,74 to 221,8 |
YES |
Slaked lime versus Stalosan F |
38,74 |
1,805 |
P>0,05 |
-39,11 to 116,6 |
NO |
From table 6 one can see that there is no significant difference between samples taken before treatment. After treatment there is still no significant difference between slaked lime [after] versus Stalosan F [after] but there is a significant difference between control [after] v slaked lime [after] and control [after] v Stalosan F [after].
Table 7. Absolute counts and distribution in percentages differentiating Ascaris eggs by groups related to their development status before and after treatment [control, slaked lime and Stalosan F all together.] Finishing house, pen 12, farm 1; November 1998 [see also tables 3; 4 & 8]
|
Before treatment |
After treatment |
||
|
Egg amount |
% of egg amount |
Egg amount |
% of egg amount |
Group A |
66,8 |
2,3 |
45,9 |
3,2 |
After treatment, approximately 50% less eggs were found than before treatment. In group A and group S-empty [presumed dead eggs] a few more eggs were found after treatment than before. The average number of eggs before treatment was 144.1 EPG and after treatment 71.5 EPG.
Table 8. Relativ distribution of the Ascaris eggs in development groups related to treatments. Farm 1, finishing house, pen 12, Nov. 1998. (see also table 3; 4 & 7)
|
CONTROLE |
SLAKED LIME |
STALOSAN F |
|||
|
Before |
After |
Before |
After |
Before |
After |
Group A |
1,3 |
3,6 |
2,0 |
3,3 |
3,3 |
0,0 |
In table 8 one can see relatively more eggs in group S-empty [presumed dead eggs] after treatment, both with slaked lime and with Stalosan F. This indicates that both slaked lime and Stalosan F have a destructive effect on Ascaris eggs. By way of contrast, the percentage of group S-empty in the control samples [after] almost halved. The difference factor between control and slaked lime is [43.4 / 22.7 : 46.2 / 85.5 =] 3.5 and between control and Stalosan F the difference factor is [43.4 / 22.7 : 14.1 / 57.6 =] 7.8
Table 9. Percentage reduction in Ascaris eggs related to treatment. Farm 1, finishing house, pen 12, November 1998
E.P.G. per sample. |
CONTROLE |
SLAKED LIME |
STALOSAN F |
|||
|
Before |
After |
Before |
After |
Before |
After |
Number of samples |
6 |
6 |
7 |
7 |
7 |
7 |
Table 9 shows that slaked lime reduces the total number of eggs by 63.2 % and Stalosan F by 87.5 %
FARM 2
Table 10. The average EPG in each of the 6 houses. Floor samples taken in finishing houses, farm 2; 14/10/98
House |
Cleaning status |
E.P.G. |
Positive |
Total number |
1 |
Soaking |
0,4 |
1 |
2 |
In table 10 it can be seen that there were more eggs per gramme from the floor samples in houses 4 and 5 than in the other houses. House 6 should be noted because of the relatively low EPG results combined with a concrete floor and daily cleaning. The reason for the low number of samples taken from farm 2 is pressure of business from the farm owner combined with owners' desire to participate in and supervise the sampling process.
Table 11. Percentage of development groups of Ascaris eggs. Farm 2, finishing pens [all together] 14/10/98. See definition of development groups in figure 4.
|
Amount of eggs |
% of amount |
Group A |
3,4 |
2,8 |
It can be seen from table 11 that the majority of Ascaris eggs are in the developing stadia [group AB-FG] and, after that, most eggs are in group G-H [quite or almost infected eggs]. This is exactly the same result as in farm 1 [see tables 3; 4; 7 & 8].
Table 12. Average of EPG and distribution in developing groups in finishing houses, farm 2; 14/10/98. {Values are average EPG in each house individually.] See definition of developing groups in figure 4.
Cleaning status |
No. |
Total E.P.G |
|
|
|
|
||||||||||||||||||||
Soaking |
2 |
0,4 |
0,2 |
50 |
0,2 |
50 |
0 |
0 |
0 |
0 |
||||||||||||||||
Table 12 shows that, despite the very small number of samples and the very small number of eggs in each sample, there was a clear tendency toward an increasing percentage of more developed Ascaris eggs with increasing time between cleaning and sampling. It may appear serious but the numbers represent 2 black eggs found in 4 samples all together, in other words only 2 eggs were found in house 3.
BLACK Ascaris EGGS
In the following microphotos damaged Ascaris eggs are shown. Black Ascaris eggs were found on both farms. Magnification is 100x and 200x
These 23 photographs show Ascaris eggs initially with small alterations [photo 1] but eventually with drastic alterations [photos 21;22 & 23] making the egg interior totally black. No visible difference was observed regardless of whether the samples had been treated with slaked lime or Stalosan F. Some black Ascaris eggs were also found in samples taken before any treatment. These samples did contain fewer black eggs.
MILKSPOTS IN THE LIVERS
Unfortunately only partial results were obtained for the finishers on farm 1. At the last moment [when I telephoned the slaughterhouse for the results] 8 finishers from farm 1 were dissected and 2-10 milkspots were found in each of their livers. Farm 2 did not wish to participate in this aspect of the investigation.
DISCUSSION
The negative results from the lactating sow rectal samples in Farm 1 harmonise with investigations
done by Urban et al. [1984] who found that natural infection of A.suum induced > 99 % resistance to
new infection. At the same time it must be remembered that the sows on this farm are treated with
anthelmintics one month before farrowing, in this case, early April 98. Nilsson [1982] describes
that, from 72 lactating sows, none of them was excreting A.suum eggs. Regular faecal samples show
that excretion from sows of A.suum is of short duration. His comment is that the life span of A.suum
can be short in adult pigs or that the worms' fertile period is extremely short. After this he notes
that many scientists have observed that the natural immune system of the adult pig appears to
suppress larval migration and the fertility of the adult worm.
Roepstorff et al. [1997] write that there is no indication that different levels of infection relate
to the number of established patent worms. On the contrary, in 1991 Roepstorff found that 46 % of
sows on Farm 1 were excreting A.suum eggs. In total 8 farms were investigated at that time and
between 0-46 % of sows were found to be excreting eggs over 2 breeding cycles including lactation.
In that investigation, no anthelmintics were used. In the present investigation the sows were
treated one month before farrowing with Panacur® [Fenbendazole]. Rectal samples were taken 24/6/98.
An investigation by Ryundiger [1996] demonstrated that sows treated with Panacur® produced piglets
3.2 % heavier than untreated sows. Roepstorff [1997] found that after treating sows with a range
of anthelmintics, a lasting effect was variable and not specific to the anthelmintics. Eriksen
et al. [1992] found that both experimental and natural infection A.suum results in 'earned' immunity.
The most significant immunity is gained by repeated ingestion of infective eggs. Immunity is effected
as the parasite is eliminated on its migratory route through the body also from the gut. She also
writes that this earned immunity may be giving effect in the intestinal loci before the larval
migration begins. Eriksen et al. [1992] found that the naturally exposed sows had a strong immunity
which showed no or just a few milk spots in their livers when slaughtered.
Muff et al. [1984] investigated the presence of A.suum eggs in the pig housing and in that article
a sample was considered positive if just one single egg in one of the group samples [up to 25 samples
in each group] was found. Unfortunately this fact is not discussed. It is reported that only 3 % of
animals more than 12 months old have positive egg counts in faecal samples. This is in harmony
with my own investigations [table 1].
Whether the anthelmintic treatment or the earned and retained immunity [which the small number of
identified eggs from floor samples in the farrowing pens indicate] is the reason for the negative
faecal samples, it cannot be hypothesised from this investigation.
As shown in table 1 only a few eggs were found in the farrowing pen at Farm 1. Only the sample areas in corners between resting and dung areas and close to the feed troughs and water supply were positive. These samples were all damp to wet. None of the dry samples contained eggs. Unfortunately the equipment for measuring relative humidity was not available until November therefore descriptions are subjective.
Table 2 shows that in floor samples from the farrowing house [Farm 1] 80 % of A.suum eggs were in Group A and this differs from all other samples [see tables 3;4;7;8;11 & 12] both on Farms 1 and 2 and taken before treatment. These others only had 1.3-5.0 % in Group A. The samples taken after treatment had 0-3.6 % in Group A. This indicates that the sample from the farrowing house either mainly contained newly excreted eggs or that the development of eggs was suppressed, probably because of low relative humidity.
The same tables [3;4;7;8;11& 12] show that between 39.3-69.9 % of the eggs were in Group AB-FG with the exception of the farrowing house where 16.3 % were in this group.
In the farrowing house 3.3 % of eggs and in all other houses [both Farms 1 & 2] 9.1-25.3% were in Group G-H [developed larva in eggs].
This indicates that, despite the limited number of samples taken, the Ascaris eggs were probably effectively removed by cleaning the farrowing house before the sows were introduced [in Farm 1]. It also indicates that there was a new excretion of eggs from the sows [despite anthelmintic treatment which the farmer wasn't sure he had administered].
From table 3 one can see there is a big difference in the mean EPG between the different sample locations but the percentage of the egg groups is approximately the same size in every location. In the floor samples [finishing pen Farm 1] from August the majority most significant in location 3 which had 69 % developing Ascaris eggs [group AB-FG] and 26.0% in Group G-H. Only 4.2 % in this location was newly excreted or resting [Group A] which happens when the temperature is beyond 15°C or the relative humidity in the substance that surrounds the eggs is beyond 78 % [Nilsson 1982]. Unfortunately it was not possible to measure these details because of problems with delivery of equipment for this purpose. My subjective impression was that air temperature in this house exceeded 15 °C pretty much. This makes me believe that the samples on locations exceeded 15 ºC as well. The relative humidity in 7 of 12 samples was evaluated to be 'moist' 5 of 12 samples from location 3 were evaluated to be 'slightly moist'. This goes as well for the 3 x 12 samples from the other sample locations [locations 1;2 &4].
As early as 1935 Allocate [1935] was able to show/monitor that Ascaris eggs need some time after excretion until/before they can become infective. He investigated it in the following range of temperatures: 22-24 °C and 32-34 °C and concluded that the development is 16 days at 32-34 °C and 28 days at 22-24 °C.
Nilsson [1982] describes that eggs do not develop in relative humidities beyond 78.5 % and beyond 15 °C. He found that the shortest time from excretion until infectivity is 56 days in housing environment in Sweden.
In conclusion I would say that the finishing house, Farm 1, had a favourable environment for developing eggs in August 1998.
From fig. 5 one can see in the majority of pens in finishing house, Farm 1, the mean average excretion in the second rectal [faecal] samples exceeded the first excretion. Pens 2 & 6 showed much higher EPG counts at the two samples [2/10/98] The average for all 12 pens 12/9/98 was 3 569 EPG with minimum 20 EPG and maximum 19 040 EPG. The 2/10/98 average was 4 827 EPG minimum 60 EPG and maximum 35 760 EPG. The pigs entered the finishing pens during the first week of August 1998 and when [as mentioned before] the shortest time from excretion until infective state can be reached is 6-8 weeks [Monrad and Nansen 1994}. First rectal [faecal] samples were taken 5 weeks after the pigs were put into the finishing pens. This makes me sure that the egg excretion could only come from infection sources in the farrowing house. The 35 % rise from September to October could only depend on the fact that the infection picked up in the finishing pens had become patent.
Table 4 shows 1.2 % of all eggs found in floor samples [finishing house; Farm 1; August 1998] belong to Group S-Empty which are, presumably, dead eggs. Further discussion of this point later [ table 8].
Table 5. There is no difference whether the samples from the slats
are taken superficially or profound in the cavities. The samples of controls had same size of E.P.G.
on average before and after 'treatment' [which was to do nothing] After lime treatment E.P.G. was,
on average, 93.4 EPG lower thanbefore lime treatment of the dung in the cavities. Even more marked
was the effect of Stalosan F. After Stalosan F treatment 109.6 EPG less than average was found than
before the treatment. THESE RESULTS ARE ASTONISHING. I especially did not expect to find a reduction
of EPG after treatment with Stalosan F which I actually chose because I had not thought it could
harm Ascaris eggs. This opinion was based on a lot of published articles which described the chemicals
as having no effect on Ascaris eggs.
In addition it was noted that Stalosan F contained no aggressive substances [see Stalosan F contents
pages 15]. For instance an investigation by van den Burg et al. [1987] showed that none of the 11
disinfectants containing the following active chemicals: aggressive chlorine, phenol, cresol, sodium
hydroxide, potassium hydroxide, quarternary ammonium compounds, glutaraldehyde and para-glutar
aldehyde was found to be effective toward/against Ascaris eggs. This investigation administered both
the recommended and double the recommended doses of those disinfectants. Volkov [1993] found no effect
on Ascaris eggs after treatment with ammonium-chloride and ammonium-poly-sulphide.
Juris and Breza [1988] showed that Orsanol BF12, potassium hydrochloride, sodium hydrochloride, Jodonal
B and liquid Jodisol only affected Ascaris eggs slightly.
Hurley and Sommerville [1982] monitored reversible inhibition of developed Ascaris eggs hatching.
Hydrogen sulphide is able to reconstruct the ability of hatching.
Of course Ascaris eggs can be killed by chemicals but very strong and concentrated poisons are
needed. This is NOT ACCEPTABLE for the environment nor farmers/animals. DDT and Carbathio kill more
than 60 % of A.suum eggs in soil samples treated with 3 % solutions for 24 hours according to Volkov
[1973].
A better way of Ascaris control is heat treatment. Persson [1973] says that after aerobic decomposition
in liquid dung, all Ascaris eggs died after 6 days at 56 °C or 8 days at 50°C.
Birbaum and Eckert [1985] write that all A.suum eggs were destroyed after 10-110 minutes
at 50-56°C or [if the eggs were in sludge] 30 minutes at 65-70°C and only 10 minutes at 80°C.
According to Grebenkin [1982] relative humidities beyond 60 % are lethal for A.suum eggs [they died
within 7 days] which makes drying out another possibility in Ascaris control.
Ultrasound [50 w/cm2, 24 kHz] for 10 minutes kills 98.7 % of Ascaris eggs kept in ferro-magnetic
powder which is at waste after manufacturing engine tools according to Sokhrokov [1979].
Other existing methods for controlling Ascaris are for instance growing spores of fungi [mycelium]
in samples with Ascaris eggs. Sobenina [1975] found reducing effect of survival of Ascaris eggs
after growing Aspergillus nidulans some Penicilium-species and Catenaria angillulae the reduction
is respectively 72 %, 61 % and 20 %. Lysec [1979] investigated Verticillium clamydosporum and concluded
that it is a strong natural regulator towards Ascaris lumbricoides.
Certain plantroots [rhizosphers] also can be ovicide. Volkov [1976] found that Tagetes, Calendula
and barley but not oat and wheat can destroy Ascaris eggs. Oats and wheat however inhibit the
development of Ascaris eggs.
Simon and Volkov [1973] described ovicide effect [50-80 % killed eggs] after growing Pisum, Vicia,
Panicum miliaceum and Calendula in samples with A.suum eggs. This should be compared to DDT which
kills 60 % after 24 hours [Volkov 1973].
On the other hand it has no ovicide effect when earth worms eat Ascaris eggs [Smirnov 1975]
[Schumakovitch 1976] or when adult flies [musca domestica] or larvae from these eat Ascaris eggs
[Dipecoln, 1982 & Koltypin, et al. 1975].
In short it was ASTONISHING to find this large ovicide effect from lime and especially
from Stalosan F.
Table 7. After treatment was found approximately half as many eggs as before treatment when all treatments [controls, lime, Stalosan F] are put together. This goes as well in total and for the four groups [A, AB-FG, G-H and S-Empty].
Table 8 is itemised account, specifying this, and shows that the
proportions between group S-Empty is markedly different after the treatments [controls, lime and
Stalosan F] in control samples the reduction of presumed dead eggs [S-Empty] goes from 43.4 % before
treatment to 22.7 % after treatment . In lime samples this proportion is 46.2 % before treatment
and 85.5 % after treatment. In Stalosan F samples before treatment 14.1 % presumed dead eggs were
found and 57.6 % after treatment. Comparing these findings one finds a difference from control
[after] to lime [after] on factor 3.5. The difference from control [after] to Stalosan F [after] is
found to be factor 7.8.
It must be pointed out that one half of the presumed dead eggs in the control samples [after] can be
due to the deeper and more protected [more profound] location in the cavities. This goes naturally
also for the treatment with lime and Stalosan F. Therefore the destructive effect on A.suum eggs of
these treatments is even stronger.
The reason for the rather big proportion of presumed dead eggs before the treatment is probably found
in the fact that the environment influences the Ascaris eggs over time. Table 4 showed 1.2 % presumed
dead eggs. The rise of presumed dead eggs has risen markedly.
In autumn temperatures fall to suboptimal values [A.suum eggs: temperature optimum 30-33 °C, Seamster
1950. Arene [1986] monitored egg development between 16 ± 1 °C and 31 ± 1 °C and concluded that
temperature optimum to be 22 ± 1 °C for development of infective larvae.
As to whether or not suboptimal temperature can damage the Ascaris eggs, I did not find support for
anywhere but keeping A.suum eggs in a refrigerator did not seem to change the morphology of A.suum
eggs [personal observation].
Before lime and Stalosan F treatments the temperature in the present investigation was measured to
13.5-15.3 °C. Urine from the pigs can damage the eggs [Nilsson 1982]. Despite the slat floor, the
dung area the substances deposited/collected in the cavities [see fig.3] can absorb humidity from
air and from pig urine. Relative humidity before treatments was 81.5-85.0 %. Unfortunately I do not
know how much of this was urine.
The morphological changes of the A.suum eggs also could be due to drying out. Relative humidity below
60 % for more than 7 days is, according to Grebenkin [1982], lethal to Ascaris eggs.
After treatment with lime, especially eggs from group G-H were damaged [9.1 to 0.8 %] also the
proportion of eggs in development [group AB-FG] was strongly reduced [42.8 % to 10.4 %]. The number of
eggs from group A [no development started yet] on the other hand rose from 2.0 % to 3.3 %. A predictable
consequence of at least the lime treatment which produced a lot of heat in the samples themselves
[the maximal temperature in these samples were, on average, 71.9 ± 10.5 °C] was changes in the centre
of the eggs. According to Wharton [1980] temperatures beyond 30 °C cause a loss of water. This loss
follows the rising temperature in an exponential way. At the same time a graduated melting or transition
of the complexes of the components which form the lipid layer of the A.suum shell. Wharton [1979]
concluded that the permeability barrier of the eggs to be totally destroyed at 63-65 °C.
The reason for the 14.5 % morphologically undamaged eggs after the temperatures achieved during the
lime treatment is not known. Unequal heat distribution is one possible reason. Another could be not
all damage could be seen for sure in a microscope [magnification 100 x ].
After Stalosan F treatment the situation was different; all the eggs in group A [not yet developing]
were gone [27 observed in group A before Stalosan F treatment. Total observed eggs before treatment
691]. The proportion of group AB-FG was reduced from 69.7 % to 31.8 %. The number of almost / quite
infective eggs [group G-H] was only reduced from 13.0 % to 10.6 %. This indicates Stalosan F can
particularly effect eggs in the early stages of development. No explanation was found for the effect
of Stalosan F.
The qualitative changes after these treatments [lime and Stalosan F] seem to be equal. No references
on this issue were found. Further investigations must be undertaken to evaluate if lime and
Stalosan F treatments one after the other could produce better disinfection.
Egg survival changes after lime and Stalosan F treatments respectively and investigating if the black
eggs are dead eggs seem to be interesting questions.
Table 9 describes absolute egg counts estimates from EPG in the group controls, lime and Stalosan F treatment. Lime treatment reduced the absolute egg count by 63.2 % and Stalosan F treatment by 87.5 %. These results are surprising especially when one considers that these treatments were disinfections directly in organic substances [partly composted faeces].
Table 10 is monitoring EPG according to cleaning status. As
expected, the egg counts are lower in houses 1; 2 and 3 which are cleaned on the day of sampling, 1 week
and 6 weeks before respectively, that is 0.4 EPG; 1.1.EPG and 0.1 EPG. This agrees with A.suum eggs
taking on average 6-8 weeks to become patent [Monrad & Nansen 1994]. In houses 4 and 5 [cleaned 7-8
weeks and more than 16 weeks before sampling] 22.0 EPG and 10.3 EPG were found on average.
It was surprising to find only 2.4 EPG on average in the 'old fashioned' house. This indicates effective
cleaning.
By comparison with farm 1, all the EPG's were low in farm 2. The average in farm 1 was 125.3 - 194.9
EPG [table 6: Nov 1998 before treatment and table 3: Aug 1998] in the finishing house. The highest egg
count in farm 2 was 22.0 EPG. This difference may be due to differences in management.
In the farrowing house in farm 1 [concrete floor like the old fashioned house in farm 2] the highest
egg count found was 3.0 EPG but, as mentioned in the discussion of rectal [faecal] samples of lactating
sows, adult swine only excrete a few eggs because of the earned and retained immunity.
Taken together, the results in table 10 indicate careful and effective cleaning in farm 2. Anthelmintic
treatment of bought pigs before transportation to farm 2 could reduce the problems with milkspots in
the livers of the finishers [which was the criterion for choosing farm 2].
Table 11. One can see that a majority of eggs are under development [group AB-FG] in farm 2. Despite extensive efforts to limit A.suum [among other microbes] there is a favourable environment which makes it possible for the small number of A.suum eggs left to develop to the infective state [group G-H].
Table 12 shows a fast development after end of prepatent periode
[6-8 weeks after ingestion of infective A.suum eggs; Monrad & Nansen 1994]. It should be noted
that October temperatures can be low and therefore inhibit egg development. Unfortunately no
temperature measurements were available but the impression gained was of 18-20 °C in all houses
in farm 2.
In house 2, 1 week after cleaning, 88 % of eggs found belonged to group AB-FG [developing] but none
in group G-H [infective]. In houses 4 and 5 [7-8 weeks and more than 16 weeks after cleaning] 30 %
and 14 % respectively in group G-H were found. In house 6 [daily cleaning] the distribution of A.suum
eggs corresponds to the distribution in farm 1 [see tables 2; 3; 4; 7 & 8 - before treatment]. Apparently
the thoroughness of cleaning is different as between farms 1 and 2 accounting for the
difference in EPG.
Black A.suum eggs were found both in farms 1 and 2. The black eggs appear damaged but in several instances the inside structure of black eggs could be seen clearly. For example microphoto no. 16 shows an egg containing a larva almost developed to infective stadium [G-H]. I wonder whether the blackening could be due to previous cleanings using a high pressure hose and hot water or to the use of certain disinfectants but could find no answer. Neither extensive research in written material no enquiry of scientists and laboratory technicians revealed any information about the black A.suum eggs. In fact no-one at C.E.P. had ever observed similar black eggs. [A colour photo can be ordered from Stormollen A/S, Ringsbjergvej 16, 4682 Tureby, Denmark.]
Unfortunately only partial results were obtained concerning milk spots in the liver of finishers on farm 1. The slaughterhouse found 2-10 milkspots in livers from 8 finishers. It can be presumed that pigs on farm 1 had been exposed to Ascaris infection throughout their lives. This would explain the small number of milkspots in their livers.
Eriksen et al. [1992] concluded that the highest number of milk spots were found in growers
(average 86 in 1 liver) decreasing to 71 in finishers [due to earned immunity] and the lowest number
in adult sows/boars (average 3 in 1 liver). This also applies to naturally exposed animals which in
an experiment were exposed to controlled A.suum infection.
The finishers in this present investigation were not exposed to experimental controlled A.suum
infection. The earned and retained immunity theory [supported by the finding of infective eggs
in the farrowing pens as well as in the finishing pens] must be considered the explanation for
the low number of milkspots in the livers of the finishers from farm 1.
Milkspots [interstitial hepatitis] develop in the liver 8 days after ingestion of infective
A.suum eggs in unimmunised pigs and disappear again approximately 85 days later [Mehl et al. 1983]
Eriksen et al. [1981] found milkspots in 43.6 % of 119 038 livers in finishers. Among these 43.6 %,
73.2 % were approved fit for human consumption after local cleansing. Wismer- Pedersen et al.
[1990] describe problems with the quality of fried liver because of excess connective tissue in the
livers after recovery from A.suum larva migration. At the same time they argued for better
anthelmintic control and, with that, better quality livers for consumption.
Frank [1995] showed that in pigs Ascaris can reduce levels of nutrition, cause vomiting and anorexis,
increase intake of food, reduce body weight and number of piglets born together with decreased
immunity to other pathogens. Andersen [1976] found that the growth rate in finishers was 20 % lower
in finishers not previously exposed to Ascaris. Among slightly immunised finishers the growth rate
was reduced by 8 %.
How much farm 2 could gain from better anthelmintic control is not known because regular E-control reports [economic control reports] or similar information was not available. Considering the very low price of pork at present, even a slight improvement in growth rate, feed utilisation and immunity would make better anthelmintic control a good bargain.
CONCLUSION
A.suum eggs develop in the floor material mixed with condensed water and/or swine urine. The
cavities within the dung area provide the/an ideal environment for egg development. Light slaked
lime and Stalosan F reduce numbers very much and, significantly, A.suum eggs in the house. Lime
especially attacks eggs in groups AB-FG and G-H [the more significant]. Stalosan F especially reduces
egg numbers in group A and less significantly in group AB-GH. That is to say both light slaked lime
and Stalosan F are suitable in conventional systems. From a health and safety point of view
Stalosan F is preferable.
In addition it can be said that the Organic-Soil Association [LØJ] in Denmark does not accept either
lime or Stalosan F in organic systems.
SUMMARY
Traditional farm [Farm 1] is known as 'a good place to find Ascaris' with 12 sows producing
approximately 225 finishes per annum. This farm was investigated for occurrence of A.suum in the housing
environment. The sows were treated with anthelmintics. Faecal samples were taken after 2.5 months and
all 12 were negative. In the farrowing pens where the sows and piglets were housed floor samples
contained a mean of 2.1 EPG [eggs per gram] mainly type group A [newly excreted].
Earned immunity seems to be present in the finishers; amongst 8 randomly selected finishers all were
found to have 2-10 milk spots of the liver when slaughtered. Developing eggs were found in the floor
samples which indicate immunity is sustained through repeated ingestion of infected eggs from the
environment.
Floor samples were collected from the floor of the finishing house mid Aug 98. Most of these eggs fell
into group AB-FG [developing eggs] which indicates a favourable environment for A.suum [relative
humidity >78 % and temperature 15 ºC in the floor substances]. Not every part of the floor is
suitable for egg development but especially damp areas with fissures or cavities which could harbour
very small amounts of dung contained eggs at all stages of the cycle [A-H]. Dung that had fully
composted [musty] and smelled like forest contained up to 4 856.4 eggs/gm of which 4 829.1 E.P.G.
was recognised as living under the microscope [ x 100]. The mean value in 4 locations was 26.3; 35.1;
162.1 and 555.9 EPG.
Faecal samples from the finishers 12/10 1998 and 2/11 1998 showed that the egg excretion had increased by 35 % between those dates. One may conclude that the rise in egg excretion was due to ingestion of eggs in the finishing pen completing a full cycle. This infection had become patent.
After lime treatment in 7 cavities in the dung area between the slats and supports at each end the
temperature rose to 71.9 ± 10.5 °C. The number of developing eggs was reduced to a level 63.2 %
lower than the control.
After Stalosan F treatment in 7 other cavities the level was reduced to 87.5 % below the control.
After these two treatments, the percentage of 'black' [presumed dead] eggs was significantly increased: Lime from 46.2-85.5 % of the total EPG and Stalosan F 14.1-57.6 % of total EPG.
Light slaked lime and Stalosan F strongly reduce in number and have a significant effect on A.suum eggs in the houses.
Classification of the stage of development of Ascaris is shown using figures and diagrams. Furthermore 23 microphotos of 'black' eggs are shown.
Farm 2 was described by the slaughterhouse as a 'well managed farm but with a high incidence of
milk spots in the liver's. 6 houses were investigated [1: cleaning in progress, 2: 1 week after
cleaning, 3: 6 weeks after cleaning, 4: 7-8 weeks after cleaning, 5: more than 16 weeks after
cleaning, 6: daily cleaning]. The proportion of different egg stages was as found like in the
finishing house on Farm 1 but the egg counts were much lower [0.1-22.0 EPG]. 'Black' eggs were also
found here.
Neither light slaked lime nor Stalosan F can be accepted in organic systems at the present time.
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