Even when tuberculosis (TB) treatment is free, hidden costs incurred by patients and their households (TB-affected households) may worsen poverty and health. Extreme TB-associated costs have been termed “catastrophic” but are poorly defined. We studied TB-affected households' hidden costs and their association with adverse TB outcome to create a clinically relevant definition of catastrophic costs. From 26 October 2002 to 30 November 2009, TB patients (n = 876, 11% with multi-drug-resistant [MDR] TB) and healthy controls (n = 487) were recruited to a prospective cohort study in shantytowns in Lima, Peru. Patients were interviewed prior to and every 2–4 wk throughout treatment, recording direct (household expenses) and indirect (lost income) TB-related costs. Costs were expressed as a proportion of the household's annual income. In poorer households, costs were lower but constituted a higher proportion of the household's annual income: 27% (95% CI = 20%–43%) in the least-poor houses versus 48% (95% CI = 36%–50%) in the poorest. Adverse TB outcome was defined as death, treatment abandonment or treatment failure during therapy, or recurrence within 2 y. 23% (166/725) of patients with a defined treatment outcome had an adverse outcome. Total costs ≥20% of household annual income was defined as catastrophic because this threshold was most strongly associated with adverse TB outcome. Catastrophic costs were incurred by 345 households (39%). Having MDR TB was associated with a higher likelihood of incurring catastrophic costs (54% [95% CI = 43%–61%] versus 38% [95% CI = 34%–41%], p<0.003). Adverse outcome was independently associated with MDR TB (odds ratio [OR] = 8.4 [95% CI = 4.7–15], p<0.001), previous TB (OR = 2.1 [95% CI = 1.3–3.5], p = 0.005), days too unwell to work pre-treatment (OR = 1.01 [95% CI = 1.00–1.01], p = 0.02), and catastrophic costs (OR = 1.7 [95% CI = 1.1–2.6], p = 0.01). The adjusted population attributable fraction of adverse outcomes explained by catastrophic costs was 18% (95% CI = 6.9%–28%), similar to that of MDR TB (20% [95% CI = 14%–25%]). Sensitivity analyses demonstrated that existing catastrophic costs thresholds (≥10% or ≥15% of household annual income) were not associated with adverse outcome in our setting. Study limitations included not measuring certain “dis-saving” variables (including selling household items) and gathering only 6 mo of costs-specific follow-up data for MDR TB patients. Despite free TB care, having TB disease was expensive for impoverished TB patients in Peru. Incurring higher relative costs was associated with adverse TB outcome. The population attributable fraction indicated that catastrophic costs and MDR TB were associated with similar proportions of adverse outcomes. Thus TB is a socioeconomic as well as infectious problem, and TB control interventions should address both the economic and clinical aspects of this disease. Please see later in the article for the Editors' Summary Caused by the infectious microbe Mycobacterium tuberculosis, tuberculosis (or TB) is a global health problem. In 2012, an estimated 8.6 million people fell ill with TB, and 1.3 million were estimated to have died because of the disease. Poverty is widely recognized as an important risk factor for TB, and developing nations shoulder a disproportionate burden of both poverty and TB disease. For example, in Lima (the capital of Peru), the incidence of TB follows the poverty map, sparing residents living in rich areas of the city while spreading among poorer residents that live in overcrowded households. The Peruvian government, non-profit organizations, and the World Health Organization (WHO) have extended healthcare programs to provide free diagnosis and treatment for TB and drug-resistant strains of TB in Peru, but rates of new TB cases remain high. For example, in Ventanilla (an area of 16 shantytowns located in northern Lima), the rate of infection was higher during the study period, at 162 new cases per 100,000 people per year, than the national average. About one-third of the 277,895 residents of Ventanilla live on under US$1 per day. Poverty increases the risks associated with contracting TB infection, but the disease also affects the most economically productive age group, and the income of TB-affected households often decreases post-diagnosis, exacerbating poverty. A recent WHO consultation report proposed a target of eradicating catastrophic costs for TB-affected families by 2035, but hidden TB-related costs remain understudied, and there is no international consensus defining catastrophic costs incurred by patients and households affected by TB. Lost income and the cost of transport are among hidden costs associated with free treatment programs; these costs and their potential impact on patients and their households are not well defined. Here the researchers sought to clarify and characterize TB-related costs and explore whether there is a relationship between the hidden costs associated with free TB treatment programs and the likelihood of completing treatment and becoming cured of TB. Over a seven-year period (2002–2009), the researchers recruited 876 study participants with TB diagnosed at health posts located in Ventanilla. To provide a comparative control group, a sample of 487 healthy individuals was also recruited to participate. Participants were interviewed prior to treatment, and households' TB-related direct expenses and indirect expenses (lost income attributed to TB) were recorded every 2–4 wk. Data were collected during scheduled household visits. TB patients were poorer than controls, and analysis of the data showed that accessing free TB care was expensive for TB patients, especially those with multi-drug-resistant (MDR) TB. Total expenses were similar pre-treatment compared to during treatment for TB patients, despite receiving free care (1.1 versus 1.2 times the same household's monthly income). Even though direct expenses (for example, costs of medical examinations and medicines other than anti-TB therapy) were lower in the poorest households, their total expenses (direct and indirect) made up a greater proportion of their household annual income: 48% for the poorest households compared to 27% in the least-poor households. The researchers defined costs that were equal to or above one-fifth (20%) of household annual income as catastrophic because this threshold marked the greatest association with adverse treatment outcomes such as death, abandoning treatment, failing to respond to treatment, or TB recurrence. By calculating the population attributable fraction—the proportional reduction in population adverse treatment outcomes that could occur if a risk factor was reduced to zero—the authors estimate that adverse TB outcomes explained by catastrophic costs and MDR TB were similar: 18% for catastrophic costs and 20% for MDR TB. The findings of this study indicate a potential role for social protection as a means to improve TB disease control and health, as well as defining a novel, evidence-based threshold for catastrophic costs for TB-affected households of 20% or more of annual income. Addressing the economic impact of diagnosis and treatment in impoverished communities may increase the odds of curing TB. Study limitations included only six months of follow-up data being gathered on costs for each participant and not recording “dissavings,” such as selling of household items in response to financial shock. Because the study was observational, the authors aren't able to determine the direction of the association between catastrophic costs and TB outcome. Even so, the study indicates that TB is a socioeconomic as well as infectious problem, and that TB control interventions should address both the economic and clinical aspects of the disease. Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001675.

Background. Unlike other respiratory infections, tuberculosis diagnoses increase in summer. We performed an ecological analysis of this paradoxical seasonality in a Peruvian shantytown over 4 years. Methods. Tuberculosis symptom-onset and diagnosis dates were recorded for 852 patients. Their tuberculosis-exposed cohabitants were tested for tuberculosis infection with the tuberculin skin test (n = 1389) and QuantiFERON assay (n = 576) and vitamin D concentrations (n = 195) quantified from randomly selected cohabitants. Crowding was calculated for all tuberculosis-affected households and daily sunlight records obtained. Results. Fifty-seven percent of vitamin D measurements revealed deficiency (<50 nmol/L). Risk of deficiency was increased 2.0-fold by female sex (P < .001) and 1.4-fold by winter (P < .05). During the weeks following peak crowding and trough sunlight, there was a midwinter peak in vitamin D deficiency (P < .02). Peak vitamin D deficiency was followed 6 weeks later by a late-winter peak in tuberculin skin test positivity and 12 weeks after that by an early-summer peak in QuantiFERON positivity (both P < .04). Twelve weeks after peak QuantiFERON positivity, there was a midsummer peak in tuberculosis symptom onset (P < .05) followed after 3 weeks by a late-summer peak in tuberculosis diagnoses (P < .001). Conclusions. The intervals from midwinter peak crowding and trough sunlight to sequential peaks in vitamin D deficiency, tuberculosis infection, symptom onset, and diagnosis may explain the enigmatic late-summer peak in tuberculosis.

SETTING: Tuberculosis (TB) affected households in impoverished shantytowns, Lima, Peru. OBJECTIVE: To evaluate socio-economic interventions for strengthening TB control by improving uptake of TB care and prevention services. DESIGN: Barriers to TB control were characterised by interviews with TB-affected families. To reduce these barriers, a multidisciplinary team offered integrated community and household socio-economic interventions aiming to: 1) enhance uptake of TB care by education, community mobilisation and psychosocial support; and 2) reduce poverty through food and cash transfers, microcredit, microenterprise and vocational training. An interim analysis was performed after the socio-economic interventions had been provided for 2078 people in 311 households of newly diagnosed TB patients for up to 34 months. RESULTS: Poverty (46% earned <US$1 per day), depression (40%), stigmatisation (77%), and perceived isolation (39%) were common among TB patients (all P < 0.05 vs. non-patients). The project had 100% recruitment, and involved 97% of TB-affected households in regular visits, 71% in community groups, 78% in psychosocial support and 77% in poverty-reduction interventions. The socio-economic interventions were associated with increases in household contact TB screening (from 82% to 96%); successful TB treatment completion (from 91% to 97%); patient human immunodeficiency virus testing (from 31% to 97%); and completion of preventive therapy (from 27% to 87%; all P < 0.0001). CONCLUSIONS: Socio-economic interventions can strengthen TB control activities.

Contacts of tuberculosis index cases are at increased risk of developing tuberculosis. Screening, preventive therapy, and surveillance for tuberculosis are underused interventions in contacts, particularly adults. We developed a score to predict risk of tuberculosis in adult contacts of tuberculosis index cases. In 2002-06, we recruited contacts aged 15 years or older of index cases with pulmonary tuberculosis who lived in desert shanty towns in Ventanilla, Peru. We followed up contacts for tuberculosis until February, 2016. We used a Cox proportional hazards model to identify index case, contact, and household risk factors for tuberculosis from which to derive a score and classify contacts as low, medium, or high risk. We validated the score in an urban community recruited in Callao, Peru, in 2014-15. In the derivation cohort, we identified 2017 contacts of 715 index cases, and median follow-up was 10·7 years (IQR 9·5-11·8). 178 (9%) of 2017 contacts developed tuberculosis during 19 147 person-years of follow-up (incidence 0·93 per 100 person-years, 95% CI 0·80-1·08). Risk factors for tuberculosis were body-mass index, previous tuberculosis, age, sustained exposure to the index case, the index case being in a male patient, lower community household socioeconomic position, indoor air pollution, previous tuberculosis among household members, and living in a household with a low number of windows per room. The 10-year risks of tuberculosis in the low-risk, medium-risk, and high-risk groups were, respectively, 2·8% (95% CI 1·7-4·4), 6·2% (4·8-8·1), and 20·6% (17·3-24·4). The 535 (27%) contacts classified as high risk accounted for 60% of the tuberculosis identified during follow-up. The score predicted tuberculosis independently of tuberculin skin test and index-case drug sensitivity results. In the external validation cohort, 65 (3%) of 1910 contacts developed tuberculosis during 3771 person-years of follow-up (incidence 1·7 per 100 person-years, 95% CI 1·4-2·2). The 2·5-year risks of tuberculosis in the low-risk, medium-risk, and high-risk groups were, respectively, 1·4% (95% CI 0·7-2·8), 3·9% (2·5-5·9), and 8·6%· (5·9-12·6). Our externally validated risk score could predict and stratify 10-year risk of developing tuberculosis in adult contacts, and could be used to prioritise tuberculosis control interventions for people most likely to benefit. Wellcome Trust, Department for International Development Civil Society Challenge Fund, Joint Global Health Trials consortium, Bill & Melinda Gates Foundation, Imperial College National Institutes of Health Research Biomedical Research Centre, Foundation for Innovative New Diagnostics, Sir Halley Stewart Trust, WHO, TB REACH, and Innovation for Health and Development.

Using a large, passive, clinic-based surveillance program in Iquitos, Peru, we characterized the prevalence of rickettsial infections among undifferentiated febrile cases and obtained evidence of pathogen transmission in potential domestic reservoir contacts and their ectoparasites. Blood specimens from humans and animals were assayed for spotted fever group rickettsiae (SFGR) and typhus group rickettsiae (TGR) by ELISA and/or PCR; ectoparasites were screened by PCR. Logistic regression was used to determine associations between patient history, demographic characteristics of participants and symptoms, clinical findings and outcome of rickettsial infection. Of the 2,054 enrolled participants, almost 2% showed evidence of seroconversion or a 4-fold rise in antibody titers specific for rickettsiae between acute and convalescent blood samples. Of 190 fleas (Ctenocephalides felis) and 60 ticks (Rhipicephalus sanguineus) tested, 185 (97.4%) and 3 (5%), respectively, were positive for Rickettsia spp. Candidatus Rickettsia asemboensis was identified in 100% and 33% of the fleas and ticks tested, respectively. Collectively, our serologic data indicates that human pathogenic SFGR are present in the Peruvian Amazon and pose a significant risk of infection to individuals exposed to wild, domestic and peri-domestic animals and their ectoparasites. Rickettsial infection remains relatively unexplored in South America compared to other regions of the world. For most regions of Peru (including the Amazon Basin), nothing more than broad serological characterization is available about circulating rickettsiae. Even less is known about the animal reservoirs and insect vectors involved in disease transmission. With this study we aimed to better characterize the circulating species of Rickettsia in humans in the Amazon Basin, as well as investigate their domestic animal reservoir and arthropod vectors. Out of 2054 fever patients enrolled we identified 38 individuals with serologic evidence for acute rickettsial infection. Their homes were visited in order to draw blood samples and collect ectoparasites from their domestic animals. Serology and molecular methods were used to test the animal blood samples as well as the ectoparasites. The information collected contributes to the understanding of the transmission dynamics of rickettsial diseases in Iquitos and leads to a better understanding of the exposure risk to rickettsial infection and it will guide approaches for prevention.

The tuberculin skin test (TST) quantifies cell-mediated immunity to tuberculosis antigens. Helminths suppress cell-mediated immunity, so we studied the effect of helminth infection and deworming on the TST in a randomized, double-blind, placebo-controlled study in an indigenous Amazon community (N = 195). Stool microscopy diagnosed helminths in 98% and co-infection with multiple species in 24% of study subjects. The TST was positive (≥ 10 mm) for 49%, and responses increased with age (P < 0.001), Bacille Calmette Guerin (BCG) vaccination (P = 0.01), and tuberculosis contact (P = 0.05). TST results had no association with helminth-egg concentrations, species, or co-infections (all P > 0.1). One month after deworming with albendazole (three daily 400-mg doses), helminths were reduced, but 63% remained infected with helminths. Albendazole did not cause a change in TST size (P = 0.8) or positivity (P = 0.9) relative to placebo. Thus, TST reactions were unaffected by albendazole therapy that partially cured intestinal helminth infections, and TST interpretation was unaffected by high-burden helminth infections and co-infection with multiple helminth species.