The Infectiousness of Tuberculosis Patients Coinfected with HIV

Department of Infectious Diseases and Immunity, Imperial College London, United Kingdom.
PLoS Medicine (Impact Factor: 14). 10/2008; 5(9):e188. DOI: 10.1371/journal.pmed.0050188
Source: PubMed

ABSTRACT The current understanding of airborne tuberculosis (TB) transmission is based on classic 1950s studies in which guinea pigs were exposed to air from a tuberculosis ward. Recently we recreated this model in Lima, Perú, and in this paper we report the use of molecular fingerprinting to investigate patient infectiousness in the current era of HIV infection and multidrug-resistant (MDR) TB.
All air from a mechanically ventilated negative-pressure HIV-TB ward was exhausted over guinea pigs housed in an airborne transmission study facility on the roof. Animals had monthly tuberculin skin tests, and positive reactors were removed for autopsy and organ culture for M. tuberculosis. Temporal exposure patterns, drug susceptibility testing, and DNA fingerprinting of patient and animal TB strains defined infectious TB patients. Relative patient infectiousness was calculated using the Wells-Riley model of airborne infection. Over 505 study days there were 118 ward admissions of 97 HIV-positive pulmonary TB patients. Of 292 exposed guinea pigs, 144 had evidence of TB disease; a further 30 were tuberculin skin test positive only. There was marked variability in patient infectiousness; only 8.5% of 118 ward admissions by TB patients were shown by DNA fingerprinting to have caused 98% of the 125 characterised cases of secondary animal TB. 90% of TB transmission occurred from inadequately treated MDR TB patients. Three highly infectious MDR TB patients produced 226, 52, and 40 airborne infectious units (quanta) per hour.
A small number of inadequately treated MDR TB patients coinfected with HIV were responsible for almost all TB transmission, and some patients were highly infectious. This result highlights the importance of rapid TB drug-susceptibility testing to allow prompt initiation of effective treatment, and environmental control measures to reduce ongoing TB transmission in crowded health care settings. TB infection control must be prioritized in order to prevent health care facilities from disseminating the drug-resistant TB that they are attempting to treat.

Download full-text


Available from: William K Y Pan, Aug 10, 2015
  • Source
    • "The latter could give rise to 'super-spreaders' (Lloyd-Smith et al., 2005), which might be more difficult to control from a public health perspective. Some support to this idea comes from an animal study in which, 98% of infected guinea pigs exposed to ventilated air coming from a ward with HIV/TB coinfected patients, were found to be infected by only 8.5 % of the patients (Escombe et al., 2008). In this study however, transmission of MTBC by HIV-infected and -uninfected individuals were not directly compared. "
    [Show abstract] [Hide abstract]
    ABSTRACT: Tuberculosis (TB) has been affecting humans for millennia. There is increasing indication that human-adapted Mycobacterium tuberculosis complex (MTBC) has been co-evolving with different human populations. Some of the most important drivers of MTBC evolution have been the host immune response and human demography. These old selective forces have shaped many of the features of human TB we see today. Two new selective pressures have emerged only a few decades ago, namely HIV co-infection and the use of anti-TB drugs. Here we discuss how the emergence of HIV/TB and drug resistance could impact the long-term balance between MTBC and its human host, and how these changes might influence the future evolutionary trajectory of MTBC.
    Infection, genetics and evolution: journal of molecular epidemiology and evolutionary genetics in infectious diseases 08/2011; 12(4):678-85. DOI:10.1016/j.meegid.2011.08.010 · 3.26 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Tuberculosis represents one of the top clinical complications in immunocompromised HIV-infected people. When diagnostic and therapeutic interventions are delayed, outcomes could be fatal due to imminent progress of this deadly combination.MethodologyWe carried out a descriptive retrospective study from registered TB/HIV cases from 2000 to 2010 in the municipality of Armenia. Notification forms from both diseases TB and HIV (SIVIGILA), record of home visits, individual treatment cards and death certificates were used as data sources.Results113 patients were included with TB/HIV confirmed tests, which represents a global preva-lence of 6.8% during 10 years in Armenia. The mean age among patients was 34.3 years (ranging from 11 to 68 years), and the group between 14 and 34 years and male (91% extrapulmonary and 75% pulmonary forms) was the most commonly involved. According to the disease presentation, extrapulmonary TB form (50.4%, n = 57) was more frequent than the pulmonary form. The frequency of extrapulmonary forms was: ganglionar, 50% (n = 32); meningeal, 19.3% (n = 11); miliar, 8.8% (n = 5); pleural, 7% (n = 4); peritoneal, 7% (n = 4), and Pott's disease, 1.8% (n = 1). In eight cases both forms presented simultaneously (pulmonary and extrapulmonary). Lethality was 100% among VIH positive patients infected with resistant strains.Conclusions Our results highlight the importance of implementing collaborative actions between TB and HIV programs to improve diagnosis and to reduce mortality and resistant strain dissemination.
    01/2012; 16(3):140–147. DOI:10.1016/S0123-9392(12)70003-6
  • Source
Show more