Temporal Association in Hospitalizations for Tuberculosis, Invasive Pneumococcal Disease and Influenza Virus Illness in South African Children

<div><p>Introduction</p><p>The seasonal variability in hospitalization for tuberculosis may in part relate to super-imposed bacterial or predisposing respiratory viral infections. We aimed to study the temporal association between hospitalization for culture-confirmed pulmonary tuberculosis (PTB), invasive pneumococcal disease (IPD) and influenza virus epidemics in South African children.</p><p>Methods</p><p>We undertook a retrospective analysis which examined seasonal trends, from 2005 to 2008, for hospitalization for culture-confirmed PTB and IPD among children in relation to the influenza epidemics in Soweto, South Africa. Original time-series of the influenza virus epidemics and hospitalization rates for PTB and IPD were decomposed into three components: a trend cycle component, a seasonal component and an irregular component using the X-11 seasonal adjustment method. To compare the seasonality amongst the three series, the trend and irregular components were removed and only seasonal components examined.</p><p>Results</p><p>Across the study period, the influenza virus epidemics peaked during May to July (winter) months, which was closely followed by an increase in the incidence of hospitalization for IPD (August to October) and PTB (August to November).</p><p>Discussion</p><p>Within- and between-year temporal changes associated with childhood TB hospitalization may in part be driven by factors which influence temporal changes in pneumococcal disease, including potential variability in the severity of influenza virus epidemics in temperate climates. The dynamics of the interplay between the host and these infectious agents appears to be complex and multifactorial.</p></div

Seasonality of FLU, IPD and PTB in HIV-uninfected children.

<p>Seasonal factors of influenza (FLU) virus overall circulation and association to hospitalization for invasive pneumococcal disease (IPD) and culture-confirmed pulmonary tuberculosis (PTB) in HIV-uninfected children. The axis for seasonal factors for influenza is on the left and for IPD and PTB is on the right.</p

Seasonality of FLU, IPD and PTB in All children.

<p>Seasonal factors of influenza (FLU) virus overall circulation and association to hospitalization for invasive pneumococcal disease (IPD) and culture-confirmed pulmonary tuberculosis (PTB) in children. The axis for seasonal factors for influenza is on the left and for IPD and PTB is on the right.</p

Seasonality of FLU, IPD and PTB in HIV-infected children.

<p>Seasonal factors of influenza (FLU) virus overall circulation and association to hospitalization for invasive pneumococcal disease (IPD) and culture-confirmed pulmonary tuberculosis (PTB) in HIV-infected children. The axis for seasonal factors for influenza is on the left and for IPD and PTB is on the right.</p

Demographic information on children hospitalized with culture-confirmed pulmonary tuberculosis (PTB) and invasive pneumococcal disease (IPD).

<p>Demographic information on children hospitalized with culture-confirmed pulmonary tuberculosis (PTB) and invasive pneumococcal disease (IPD).</p

Vaccination coverage^* and vaccine effectiveness by year, Viral Watch, South Africa: 2005–2009.

<p><b>Statistically significant values in bold.</b></p>*<p>The proportion of individuals who received at least one dose of influenza vaccine in the relevant period.</p><p>Age groups: <50 and ≥50 years.</p

Comparison of vaccine composition to circulating viruses, South Africa, 2005–2009.

<p><b>Predominating circulating strains in bold.</b></p><p><b>Predominating B strains indicated.</b></p

Influenza detections and detection rates for seasonal influenza (N = 2490) and influenza A(H1N1)pdm09 (N = 496) by age group, Viral Watch, South Africa: 2005–2009.

<p>Influenza detections and detection rates for seasonal influenza (N = 2490) and influenza A(H1N1)pdm09 (N = 496) by age group, Viral Watch, South Africa: 2005–2009.</p

Number of specimens testing positive for influenza and detection rates by year, Viral Watch, South Africa, 2005–2009.

<p>Number of specimens testing positive for influenza and detection rates by year, Viral Watch, South Africa, 2005–2009.</p

Percentage of influenza positives by age group and virus type, Viral Watch, South Africa; 2005–2009.

<p>Percentage of influenza positives by age group and virus type, Viral Watch, South Africa; 2005–2009.</p