Natural ventilation reduces high TB transmission risk in traditional homes in rural KwaZulu-Natal, South Africa

Background: Transmission of drug susceptible and drug resistant TB occurs in health care facilities, and community and households settings, particularly in highly prevalent TB and HIV areas. There is a paucity of data regarding factors that may affect TB transmission risk in household settings. We evaluated air exchange and the impact of natural ventilation on estimated TB transmission risk in traditional Zulu homes in rural South Africa. Methods: We utilized a carbon dioxide decay technique to measure ventilation in air changes per hour (ACH). We evaluated predominant home types to determine factors affecting ACH and used the Wells-Riley equation to estimate TB transmission risk. Results: Two hundred eighteen ventilation measurements were taken in 24 traditional homes. All had low ventilation at baseline when windows were closed (mean ACH = 3, SD = 3.0), with estimated TB transmission risk of 55.4% over a ten hour period of exposure to an infectious TB patient. There was significant improvement with opening windows and door, reaching a mean ACH of 20 (SD = 13.1, p < 0.0001) resulting in significant decrease in estimated TB transmission risk to 9.6% (p < 0.0001). Multivariate analysis identified factors predicting ACH, including ventilation conditions (windows/doors open) and window to volume ratio. Expanding ventilation increased the odds of achieving ≥12 ACH by 60-fold. Conclusions: There is high estimated risk of TB transmission in traditional homes of infectious TB patients in rural South Africa. Improving natural ventilation may decrease household TB transmission risk and, combined with other strategies, may enhance TB control efforts

ERP correlates of remember/know decisions: association with the late posterior negativity

Abstract A number of studies have utilized the Remember/Know paradigm to determine event-related potential (ERP) correlates of recollection and familiarity. However, no prior work has been specifically directed at examining the processing involved in making the Remember/Know distinction. The following study employed a two-step recognition memory test in which participants first decided whether they recognized a word from a prior study list (Old/New decision); if they did, they then determined whether it was recognized on the basis of recollection (&apos;Remember&apos; responses) or familiarity (&apos;Know&apos; responses). By time-locking ERPs to the initial Old/New decision, processing related to making the introspective Remember/Know judgment was isolated. This methodology revealed a posterior negativity that was largest for &apos;Remember&apos; responses. Previous work has described a late posterior negativity which appears to be related to the search for and recapitulation of study details. Such processing may be critical in making Remember/Know determinations.

Culture Conversion Among HIV Co-Infected Multidrug-Resistant Tuberculosis Patients in Tugela Ferry, South Africa

Little is known about the time to sputum culture conversion in MDR-TB patients co-infected with HIV, although such patients have, historically, had poor outcomes. We describe culture conversion rates among MDR-TB patients with and without HIV-co-infection in a TB-endemic, high-HIV prevalent, resource-limited setting.Patients with culture-proven MDR-TB were treated with a standardized second-line regimen. Sputum cultures were taken monthly and conversion was defined as two negative cultures taken at least one month apart. Time-to-conversion was measured from the day of initiation of MDR-TB therapy. Subjects with HIV received antiretroviral therapy (ART) regardless of CD4 count.Among 45 MDR-TB patients, 36 (80%) were HIV-co-infected. Overall, 40 (89%) of the 45 patients culture-converted within the first six months and there was no difference in the proportion who converted based on HIV status. Median time-to-conversion was 62 days (IQR 48-111). Among the five patients who did not culture convert, three died, one was transferred to another facility, and one refused further treatment before completing 6 months of therapy. Thus, no patients remained persistently culture-positive at 6 months of therapy.With concurrent second-line TB and ART medications, MDR-TB/HIV co-infected patients can achieve culture conversion rates and times similar to those reported from HIV-negative patients worldwide. Future studies are needed to examine whether similar cure rates are achieved at the end of MDR-TB treatment and to determine the optimal use and timing of ART in the setting of MDR-TB treatment

Kaplan-Meier plot of time to sputum culture conversion, by HIV-status.

<p>Kaplan-Meier plot of time to sputum culture conversion, by HIV-status.</p

Baseline characteristics by HIV status.

<p>IQR: interquartile range; MDR-TB: multidrug-resistant tuberculosis; ART: antiretroviral therapy;</p><p>BMI: body mass index.</p