Table 2.
Detection of influenza virus in respiratory and non-respiratory sites
| H5N1 | |||||||
|---|---|---|---|---|---|---|---|
| H5N1 | H3/H1 | P | Fatal | Not fatal | P | ||
| Nasopharynx | |||||||
| Virus isolation rate (positive/tested; %) | 12/16a (75) | NA | 8/12 (67) | 4/4 (100) | |||
| Detectable RNA (positive/tested; %) | Nose | 13/17 (76) | 6/8 (75) | 10/12 (83) | 3/5 (60) | ||
| Throat | 18/18 (100) | 8/8 (100) | 13/13 (100) | 5/5 (100) | |||
| Viral load (median; range) | Nose | 5.5 (und.–8.1) | 4.5 (und.–7.7) | 0.59 | 5.8 (und.–8.1) | 4.5 (und.–6.4) | 0.20 |
| Throat | 7.0 (4.3–8.2) | 4.8 (4.2–5.8) | 0.003 | 7.5 (4.7–8.2) | 5.9 (4.3–7.0) | 0.058 | |
| P | 0.001 | 0.87 | |||||
| Rectum b | |||||||
| Virus isolation rate (positive/tested; %) | 1/7 (14) | NA | 1/7 (14) | NA | |||
| Detectable RNA (positive/tested; %) | 5/7 (71) | NA | 5/7 (71) | NA | |||
| Viral load (median; range) | 4.8 (3.6–5.8) | NA | 4.8 (3.6–5.8) | NA | |||
| Blood c | |||||||
| Virus isolation rate (positive/tested; %) | 1/6 (17) | NA | 1/6 (17) | NA | |||
| Detectable RNA (positive/tested; %) | 9/16 (56) | 0/6 (0) | 0.046 | 9/11 (82) | 0/5 (0) | 0.005 | |
| Viral load (median; range) | 4.5 (3.2–-5.7) | Und. | 4.5 (3.2–5.7) | Und. | |||
Rates of virus isolation, detection of viral RNA and viral loads in nasopharyngeal, rectal and blood specimens of patients with influenza H5N1 and H3N2 or H1N1. Viral loads are given as log10 cDNA copies per ml of viral transport medium. Und., below detection limit; NA, not assessed.
aVirus isolation was not performed in two cases due to insufficient specimens.
bRectal swabs were obtained after 6–11 d (median 8) of illness.
cBlood specimens were obtained after 5–9 d (median 7) of illness.