Volume 29, Number 2—February 2023
Research
Incidence and Transmission Dynamics of Bordetella pertussis Infection in Rural and Urban Communities, South Africa, 2016‒2018
Table 4
Characteristic | B. pertussis symptomatic, no. positive/no. tested (%) | Univariate analysis |
Multivariable analysis |
|||
---|---|---|---|---|---|---|
Odds ratio (95% CI) | p value | Adjusted odds ratio (95% CI) | p value | |||
Year | ||||||
2016 | 6/33 (18.2) | Referent | NA | NA | ||
2017 | 2/29 (31.0) | 2.03 (0.62–6.62) | 0.24 | NA | NA | |
2018 |
19/56 (33.9) |
2.31 (0.81–6.56) |
0.12 |
NA |
NA |
|
Site | ||||||
Rural | 13/48 (27.1) | Referent | NA | NA | ||
Urban |
21/70 (30.0) |
1.15 (0.51–2.61) |
0.73 |
NA |
NA |
|
Sex | ||||||
M | 10/52 (19.2) | Referent | NA | NA | ||
F |
24/66 (36.4) |
2.40 (1.02–5.63) |
0.04 |
NA |
NA |
|
Age group, y | ||||||
<5 | 4/20 (20.0) | 0.25 (0.05–1.14) | 0.07 | 0.33 (0.06–1.69) | 0.18 | |
5–14 | 15/56 (26.8) | 0.37 (0.11–1.22) | 0.10 | 0.41 (0.11–1.54) | 0.19 | |
15–44 | 8/28 (28.6) | 0.40 (0.11–1.51) | 0.18 | 0.28 (0.06–1.22) | 0.09 | |
>45 |
7/14 (50.0) |
Referent |
Referent |
|||
HIV status | ||||||
Uninfected | 28/104 (26.9) | Referent | Referent | |||
Infected |
6/12 (50.0) |
2.71 (0.81–9.11) |
0.11 |
3.37 (0.77–14.56) |
0.10 |
|
Nutritional status† | ||||||
Underweight | 0/9 (0.0) | 0.15 (0.01–2.65) | 0.19 | NA | NA | |
Normal | 20/77 (25.9) | Referent | NA | NA | ||
Overweight/obese |
13/28 (46.4) |
2.44 (1.00–5.93) |
0.05 |
NA |
NA |
|
Underlying illness‡ | ||||||
No | 31/112 (27.7) | Referent | NA | NA | ||
Yes |
3/6 (50.0) |
2.61 (0.50–13.65) |
0.26 |
NA |
NA |
|
Pertussis vaccination§ | ||||||
Incomplete | 0/2 (0.0) | 0.47 (0.02–11.81) | 0.64 | NA | NA | |
Fully vaccinated | 4/14 (28.6) | Referent | NA | NA | ||
Unknown |
30/102 (29.4) |
0.98 (0.30–3.20) |
0.98 |
NA |
NA |
|
IS481 Ct category¶ | ||||||
<34 | 6/15 (40.0) | 3.05 (0.82–11.38) | 0.09 | NA | NA | |
35–39 | 21/64 (32.8) | 2.23 (0.85–5.89) | 0.11 | NA | NA | |
40–44 |
7/39 (17.9) |
Referent |
NA |
NA |
||
Episode duration, d | ||||||
<7 | 14/75 (18.7) | Referent | Referent | |||
>7 |
20/43 (46.5) |
3.79 (1.64–8.73) |
0.002 |
4.12 (1.70–9.98) |
0.002 |
|
Smoking, >15 y of age | ||||||
No | 14/37 (37.8) | Referent | NA | NA | ||
Yes | 5/16 (31.3) | 0.75 (0.21–2.60) | 0.65 | NA | NA |
*Bold indicates statistical significance. Variables adjusted for in final model: age group, HIV status, and episode duration. Ct, cycle threshold; IS, insertion sequence; NA, not applicable; PHIRST, Prospective Household cohort study of Influenza, Respiratory Syncytial virus, and other respiratory pathogens community burden and Transmission dynamics in South Africa. †Nutritional status is based on a person’s body mass index (BMI). We defined BMI categories as follows: underweight, age <18 y weight for age or BMI <‒2 SDs World Health Organization (WHO) Child Growth Standards; age >18 y BMI <18.5 kg/m2; overweight, age <18 y BMI >+1 and ≤+2 SD of the WHO growth standards, age ≥18 y BMI ≥25 and <30kg/m2; obese, age <18 y BMI >+2 SD of WHO growth standards, age ≥18 y BMI >30 kg/m2. ‡Defined as self-reported history of asthma, lung disease, heart disease, stroke, spinal cord injury, epilepsy, organ transplant, immunosuppressive therapy, organ transplantation, cancer, liver disease, renal disease, or diabetes. §Collected only for children <5 y of age. Vaccine status calculate based on number of doses of vaccine received by age. ¶Used as a proxy for bacterial load.