TUBERCULOSIS TRANSMISSION IN A SOUTH AFRICAN PRISON

Robin WoodDesmond Tutu HIV CentreInstitute of Infectious Disease & Molecular MedicineUniversity of Cape Town

NEW YORK 1903The average prison is no less than a tubercular death trap.. from forty to sixty per cent, of all the deaths in prison are due to tuberculosis and autopsies show that nearly all the prisoners have in some degree been infected!”

Dr. J. B. Ransom, of Clinton Prison, New York

December 2010 | Volume 7 | Issue 12 | e1000381

The median estimated annual incidence rate ratio (IRR) for LTBI and TB were 26.4 (interquartile range [IQR]: 13.0–61.8) and 23.0 (IQR: 11.7–36.1), respectively.

The median estimated fraction (PAF%) of tuberculosis in the general population attributable to the exposure in prisons for TB was 8.5% (IQR: 1.9%–17.9%) and 6.3% (IQR: 2.7%–17.2%) in high- and middle/low-income countries, respectively.

These findings suggest that the risk of LTBI and TB is at least an order of magnitude higher in prisons than in the general population and that the within-prison spread of LTBI and TB is likely to substantially affect the incidence of LTBI and TB in the general population.

CURRENT WHO RECOMMENDATIONS

The priority strategy must be the widespread implementation of the Stop TB Strategy, particularly addressing TB/HIV co-infection and MDR-TB, in the incarcerated population. Every prisoner should have unrestricted access to the correct diagnosis and treatment of TB.

Delays in the detection and treatment of TB cases must be minimized to reduce further transmission of infection and pressures to self-treat TB.

Unregulated, erratic treatment of TB in prisons should cease.

Urgent action is needed to integrate prison and civilian TB services to ensure treatment completion for prisoners released during treatment.

Measures to reduce overcrowding and to improve living conditions for all prisoners should be implemented to reduce transmission of TB

TB TRANSMISSION

A. Quantity of exhaled air rebreathed B. Concentration of TB particles

Infectious TB case Susceptible individual

Prob

abili

ty o

f TB

infe

ction

Concentration of TB organisms Quantity of rebreathed air

TB INFECTION RISK IN PRISONS

No of TB casesInfectivityPeriod of infectivity=Δ

Cell crowdingLock-up timeCell ventilation

Pollsmoor prison has 3,200 awaiting trial prisonersSpace allocation: 1,4 m2 per prisoner Lock-up time 23 hours per day SAMJ 2011;101(11):809-13

Fig. 1. The effect of prison cell overcrowding on TB transmission probabilities is plotted against time periods of infectiousness up to 180 days. They are shown for 3 levels of overcrowding; 250% approximates the current level cell occupancy; 100% represents implementation of current South African statutory minimum occupancy of 3.44 m2 of floor space per inmate,7-10 and 50% corresponds to international space recommendations.

SAMJ 2011;101(11):809-13

CROWDING & TB TRANSMISSIONSpace allocation: 1,4 m2 per prisoner

WHO 5.4m2

RSA 3.4m2

Current 1.4m2

Fig. 2. The effect of length of period of restriction in prison cell per day on TB transmission probabilities is plotted against time periods of infectiousness up to 180 days, shown for 3 time periods of cell occupancy during a 24-hour period; 23 hours per day, 12 hours per day and 8 hours per day. NB: 23 hours per day is the current period of restriction to cells in Pollsmoor prison.

LOCK-UP TIME & TB TRANSMISSION

SAMJ 2011;101(11):809-13

CELL VENTILATION

CELL VENTILATION & TB TRANSMISSION

Fig. 3. The effect of increasing levels of cell ventilation on TB transmission probabilities is plotted against time periods of infectiousness up to 180 days. They are shown for 4 values of ventilation air change per hour (ACH): 1 ACH (current estimated cell ventilation), 3 ACH (minimal international recommendation), 8 ACH (moderately increased ventilation) and 12 ACH (the optimal level of ventilation recommended by WHO for health care set- tings).

SAMJ 2011;101(11):809-13

COMBINED TB CONTROL MEASURES

Fig. 2. The effect of length of period of restriction in prison cell per day on TB transmission probabilities is plotted against time periods of infectiousness up to 180 days, shown for 3 time periods of cell occupancy during a 24-hour period; 23 hours per day, 12 hours per day and 8 hours per day. NB: 23 hours per day is the current period of restriction to cells in Pollsmoor prison.

SAMJ 2011;101(11):809-13

PRISON CELL CO2 LEVELS > 5000ppm (SABS 1040)

• ASHRAE Standard 62-1989 1000ppm– CO2 concentration in occupied buildings should not exceed 1000ppm

• Building bulletin 101 (BB101) 1500ppm– UK standard for schools, average CO2 during day should not exceed

1500ppm

• EPA Taiwan 1000ppm and 600ppm– Type-1: Stores, theaters, restaurants, & libraries the 8hour

average CO2 should not exceed 1000ppm– Type 2: Special areas e.g. schools, hospital, day care centers

recommend 600ppm

Regulatory CO2 Exposure Limits

The average prison is no less than a tubercular death trap. Dr. J. B. Ransom 1903

TUBERCULOSIS CONTROL IN PRISONS

• Decrease TB disease prevalence– Effective TB case management– Active case finding at entry and subsequently– Rapid diagnostics

• Reduce overcrowding – Communal cells are a disaster!– Lock up times too long!

• Ventilation– Use appropriate building codes– Maintain cross cell air flow– Ventilation monitored by CO2