Volume 26, Number 3—March 2020
Dispatch
Avian Influenza Virus Detection Rates in Poultry and Environment at Live Poultry Markets, Guangdong, China
, and Eric H.Y. Lau2
Table 1
Sensitivity and specificity of applying environmental samples to assess AIV activity in poultry, based on monthly AIV detection, Guangdong, China, December 2015–July 2018*
| Market type | Subtype | Sensitivity, % (95% CI)† | Specificity, % (95% CI) † | Positive predictive value, % (95% CI)† | Negative predictive value, % (95% CI)† | Accuracy, % (95% CI)† |
|---|---|---|---|---|---|---|
| Wholesale |
H5 | 45.5 (16.8–76.6) | 95.2 (76.2–99.9) | 83.3 (39.9–97.4) | 76.9 (65.8–85.2) | 78.1 (60.0–90.7) |
| H7 | 68.4 (43.5–87.4) | 69.2 (38.6–90.9) | 76.5 (57.6–88.6) | 60.0 (41.4–76.1) | 68.8 (50.0–83.9) | |
| H9‡ |
100 (88.4–100) |
0 (0–84.2) |
93.8 |
NA |
93.8 (79.2–99.2) |
|
| Retail | H5 | 90.0 (55.5–99.8) | 45.5 (24.4–67.8) | 42.9 (32.7–53.7) | 90.9 (59.6–98.6) | 59.4 (40.6–76.3) |
| H7 | 87.0 (66.4–97.2) | 66.7 (29.9–92.5) | 87.0 (72.3–94.5) | 66.7 (38.7–86.4) | 81.3 (63.6–92.8) | |
| H9§ | 100 (89.1–100) | NA | 100 (89.1–100) | NA | 100 (89.1–100) |
*Test results from reverse transcription PCR on bird samples were assumed to be the standard in the analysis. The results may not be applicable to other surveillance systems with more intensive sampling or accurate laboratory testing. AIV, avian influenza virus; NA, not applicable.
†Sensitivity: probability that the environmental samples will test positive when the subtype of AIV is present in chickens on site (true positive rate). Specificity: probability that the environmental samples will test negative when the subtype of AIV is not present (true negative rate). Positive predictive value: probability that the subtype of AIV is present in poultry when environmental samples are tested positive. Negative predictive value: probability that the subtype of AIV is not present in poultry when the environmental samples are tested negative. Accuracy: probability that the presence or absence of AIV in poultry will be correctly determined based on the test results of environmental samples.
‡H9 was detected during every month during the study period in the environmental samples (monthly data can be found in Appendix Table 1).
§H9 was detected during every month during the study period in both the poultry and the environmental samples (monthly data can be found in Appendix Table 2).
1These authors contributed equally to this article.
2These senior authors contributed equally to this article.