Volume 20, Number 7—July 2014
CME ACTIVITY - Research
Epidemiology of Influenza Virus Types and Subtypes in South Africa, 2009–20121
, Orienka Hellferscee, Marthi Pretorius, Florette Treurnicht, Sibongile Walaza, Shabir Madhi, Michelle Groome, Halima Dawood, Ebrahim Variava, Kathleen Kahn, Nicole Wolter, Anne von Gottberg, Stefano Tempia, Marietjie Venter, and Cheryl Cohen
Table 1
Characteristics of patients hospitalized with influenza-associated severe acute respiratory illness, by virus type and subtype, 4 sites, South Africa, 2009–2012*
| A(H3N2) (reference) | A(H1N1)pdm09 | B | |||||
|---|---|---|---|---|---|---|---|
| No. pos/no. tested
(% pos) |
No. pos/no. tested (% pos) |
Adjusted RRR (95% CI) |
No. pos/no. tested (% pos) |
Adjusted RRR (95% CI) |
|||
| Age group, y | |||||||
| <5 | 265/463 (57.2) | 167/338 (49.4) | Reference | 171/418 (40.9) | Reference | ||
| 5–24 | 35/463 (7.6) | 49/338 (14.5) | 2.3 (1.4–3.8) | 43/418 (10.3) | 2.0 (1.2–3.4) | ||
| 25–44 | 96/463 (20.7) | 78/338 (23.1) | 1.3 (0.9–2.0) | 128/418 (30.6) | 1.5 (1.0–2.1)† | ||
| 45–64 | 44/463 (9.5) | 35/338 (10.4) | 1.4 (0.9–2.4) | 55/418 (13.2) | 1.4 (0.9–2.2) | ||
| >65 |
23/463 (5.0) |
9/338 (2.7) |
0.6 (0.2–1.3) |
21/418 (5.0) |
1.1 (0.6–2.2) |
||
| Male |
207/461 (44.9) |
149/336 (44.4) |
177/417 (42.5) |
||||
| Black African |
452/460 (98.3) |
327/336 (97.3) |
407/416 (97.8) |
||||
| Year | |||||||
| 2009 | 194/463 (41.9) | 160/338 (47.3) | Reference | 25/418 (6.0) | Reference | ||
| 2010 | 72/463 (15.6) | 37/338 (11.0) | 0.6 (0.4–1.0)† | 164/418 (39.2) | 16.8 (10.1–27.9) | ||
| 2011 | 98/463 (21.2) | 140/338 (41.4) | 1.7 (1.2–2.5) | 124/418 (29.7) | 9.5 (5.7–15.6) | ||
| 2012 |
99/463 (21.4) |
1/338 (0.3) |
0.0 (0.0–0.1) |
105/418 (25.1) |
7.8 (4.7–13.0) |
||
| Co-infections and underlying medical conditions | |||||||
| HIV infection | 112/311 (36.0) | 110/271 (40.6) | 170/352 (48.3) | ||||
| Tuberculosis | 42/458 (9.2) | 34/335 (10.2) | 38/411 (9.3) | ||||
| Underlying medical condition excluding tuberculosis, HIV‡ | 34/460 (7.4) | 31/336 (9.2) | 38/417 (9.1) | ||||
| Pregnancy | 3/251 (1.2) | 2/187 (1.1) | 3/24 (1.3) | ||||
| Pneumococcal co-infection detected by PCR |
23/310 (7.4) |
25/286 (8.7) |
32/325 (9.9) |
||||
| Clinical presentation and course | |||||||
| Temperature >38°C | 181/364 (49.7) | 141/287 (49.1) | 138/407 (33.9) | ||||
| Cough§ | 255/264 (96.6) | 162/167 (97.0) | 163/170 (95.9) | ||||
| Tachypnea§ | 99/250 (39.6) | 73/161 (45.3) | 62/159 (39.0) | ||||
| Difficulty breathing§ | 188/264 (71.2) | 125/167 (74.9) | 111/170 (65.3) | ||||
| Chest wall indrawing§ | 96/264 (36.4) | 77/167 (46.1) | 56/170 (32.9) | ||||
| Stridor§ | 30/264 (11.4) | 20/167 (12.0) | 36/170 (21.2) | ||||
| Symptoms ≥3 d before admission | 206/452 (45.6) | 153/335 (45.7) | 239/415 (57.6) | ||||
| Admitted to ICU | 4/457 (0.9) | 3/336 (0.9) | 4/411 (1.0) | ||||
| Mechanical ventilation needed | 3/457 (0.7) | 1/336 (0.3) | 4/411 (1.0) | ||||
| Supplemental oxygen needed | 138/457 (30.2) | 117/336 (34.8) | 144/411 (35.0) | ||||
| Antimicrobial drugs prescribed on admission | 402/421 (95.7) | 321/335 (95.8) | 384/395 (97.2) | ||||
| Hospitalized for >2 d |
319/451 (70.7) |
255/332 (76.8) |
323/407 (79.4) |
||||
| No. deaths/no. patients (case-fatality ratio) | 13/459 (2.8) | 5/334 (1.5) | 16/412 (3.9) | ||||
*Pos, positive; RRR, relative risk ratio; ICU, intensive care unit. An expanded version of this table is available in the Technical Appendix.
†p<0.05.
‡Asthma, other chronic lung disease, chronic heart disease (valvular heart disease, coronary artery disease, or heart failure excluding hypertension), liver disease (cirrhosis or liver failure), renal disease (nephrotic syndrome, chronic renal failure), diabetes mellitus, immunocompromising conditions excluding HIV infection (organ transplant, immunosuppressive therapy, immunoglobulin deficiency, malignancy), neurologic disease (cerebrovascular accident, spinal cord injury, seizures, neuromuscular conditions), or pregnancy. Concurrent conditions were considered absent for patients for whom the medical records stated that the patient had no underlying medical condition or when there was no direct reference to that condition.
§Patients <5 y of age.
1This information has been presented at Options for the Control of Influenza VIII, Cape Town, South Africa, September 5–9, 2013.