Table 3.
Number and percentage of workers from each abattoir type who had each category of antibody titre changes against Leptospira interrogans serovar Pomona (Pom) and Leptospira borgpetersenii serovar Hardjo (Har) or against either of these two serovars between first and second sampling
| Abattoir type, no. of participants | Antibody titre change | Har, %* (n) | Pom, %* (n) | Har and/or Pom, %* (n) |
|---|---|---|---|---|
| Sheep (N = 384) | Anamnestic | 1·0 (4) | 2·1 (8) | 3·1 (12) |
| Seroconversion | 2·6 (10) | 7·3 (28) | 9·6 (37) | |
| Constant (zero) | 89·3 (343) | 85·7 (329) | 95·3 (366) | |
| Constant (pos.) | 4·2 (16) | 4·7 (18) | 7·8 (30) | |
| Reduction | 2·9 (11) | 0·3 (1) | 3·1 (12) | |
| Deer (N = 50) | Anamnestic | 0·0 (0) | 0·0 (0) | 0·0 (0) |
| Seroconversion | 0·0 (0) | 0·0 (0) | 0·0 (0) | |
| Constant (zero) | 84·0 (42) | 94·0 (47) | 98·0 (49) | |
| Constant (pos.) | 12·0 (6) | 2·0 (1) | 14·0 (7) | |
| Reduction | 4·0 (2) | 4·0 (2) | 8·0 (4) | |
| Beef (N = 158) | Anamnestic | 0·0 (0) | 0·0 (0) | 0·0 (0) |
| Seroconversion | 0·6 (1) | 0·6 (1) | 1·3 (2) | |
| Constant (zero) | 93·7 (148) | 97·5 (154) | 98·7 (156) | |
| Constant (pos.) | 0·6 (1) | 1·3 (2) | 1·9 (3) | |
| Reduction | 5·1 (8) | 0·6 (1) | 5·7 (9) |
Calculated as a proportion of N (species specific).
The ‘Har and/or Pom’ column does not have to sum the ‘Har’ and ‘Pom’ columns. It does sum up in the ‘Har and/or Pom’ column if an event occurs in one or the other group; however, if the event occurs in both groups as with constant zero, it will only be counted once in the ‘Har and/or Pom’ column.
Persons with the same antibody status between sampling are in the category ‘constant (pos.)’, those which remain negative in the ‘constant (zero)’ category and those who had a declining antibody titre are summarized under ‘reduction’.