The global diabetes epidemic: what does it mean for infectious diseases in tropical countries?

Tropical countries are experiencing a substantial rise in type 2 diabetes, which is often undiagnosed or poorly controlled. Since diabetes is a risk factor for many infectious diseases, this increase probably adds to the large infectious disease burden in tropical countries. We reviewed the literature to investigate the interface between diabetes and infections in tropical countries, including the WHO-defined neglected tropical diseases. Although solid data are sparse, patients with diabetes living in tropical countries most likely face increased risks of common and health-care-associated infections, as well as infected foot ulcers, which often lead to amputation. There is strong evidence that diabetes increases the severity of some endemic infections such as tuberculosis, melioidosis, and dengue virus infection. Some HIV and antiparasitic drugs might induce diabetes, whereas helminth infections appear to afford some protection against future diabetes. But there are no or very scarce data for most tropical infections and for possible biological mechanisms underlying associations with diabetes. The rise in diabetes and other non-communicable diseases puts a heavy toll on health systems in tropical countries. On the other hand, complications common to both diabetes and some tropical infections might provide an opportunity for shared services-for example, for eye health (trachoma and onchocerciasis), ulcer care (leprosy), or renal support (schistosomiasis). More research about the interaction of diabetes and infections in tropical countries is needed, and the infectious disease burden in these countries is another reason to step up global efforts to improve prevention and care for diabetes.

Dynamics of Cough Frequency in Adults Undergoing Treatment for Pulmonary Tuberculosis

Background

Cough is the major determinant of tuberculosis transmission. Despite this, there is a paucity of information regarding characteristics of cough frequency throughout the day and in response to tuberculosis therapy. Here we evaluate the circadian cycle of cough, cough frequency risk factors, and the impact of appropriate treatment on cough and bacillary load.

Methods

We prospectively evaluated human immunodeficiency virus-negative adults (n = 64) with a new diagnosis of culture-proven, drug-susceptible pulmonary tuberculosis immediately prior to treatment and repeatedly until treatment day 62. At each time point, participant cough was recorded (n = 670) and analyzed using the Cayetano Cough Monitor. Consecutive coughs at least 2 seconds apart were counted as separate cough episodes. Sputum samples (n = 426) were tested with microscopic-observation drug susceptibility broth culture, and in culture-positive samples (n = 252), the time to culture positivity was used to estimate bacillary load.

Results

The highest cough frequency occurred from 1 pm to 2 pm, and the lowest from 1 am to 2 am (2.4 vs 1.1 cough episodes/hour, respectively). Cough frequency was higher among participants who had higher sputum bacillary load (P < .01). Pretreatment median cough episodes/hour was 2.3 (interquartile range [IQR], 1.2-4.1), which at 14 treatment days decreased to 0.48 (IQR, 0.0-1.4) and at the end of the study decreased to 0.18 (IQR, 0.0-0.59) (both reductions P < .001). By 14 treatment days, the probability of culture conversion was 29% (95% confidence interval, 19%-41%).

Conclusions

Coughs were most frequent during daytime. Two weeks of appropriate treatment significantly reduced cough frequency and resulted in one-third of participants achieving culture conversion. Thus, treatment by 2 weeks considerably diminishes, but does not eliminate, the potential for airborne tuberculosis transmission.

Ebola exposure, illness experience, and Ebola antibody prevalence in international responders to the West African Ebola epidemic 2014-2016: A cross-sectional study

BACKGROUND

Healthcare and other front-line workers are at particular risk of infection with Ebola virus (EBOV). Despite the large-scale deployment of international responders, few cases of Ebola virus disease have been diagnosed in this group. Since asymptomatic or pauci-symptomatic infection has been described, it is plausible that infections have occurred in healthcare workers but have escaped being diagnosed. We aimed to assess the prevalence of asymptomatic or pauci-symptomatic infection, and of exposure events, among returned responders to the West African Ebola epidemic 2014-2016.

METHODS AND FINDINGS

We used snowball sampling to identify responders who had returned to the UK or Ireland, and used an online consent and questionnaire to determine their exposure to EBOV and their experience of illness. Oral fluid collection devices were sent and returned by post, and samples were tested using an EBOV IgG capture assay that detects IgG to Ebola glycoprotein. Blood was collected from returnees with reactive samples for further testing. Unexposed UK controls were also recruited. In all, 300 individuals consented, of whom 268 (89.3%) returned an oral fluid sample (OFS). The majority had worked in Sierra Leone in clinical, laboratory, research, and other roles. Fifty-three UK controls consented and provided samples using the same method. Of the returnees, 47 (17.5%) reported that they had had a possible EBOV exposure. Based on their free-text descriptions, using a published risk assessment method, we classified 43 (16%) as having had incidents with risk of Ebola transmission, including five intermediate-risk and one high-risk exposure. Of the returnees, 57 (21%) reported a febrile or diarrhoeal illness in West Africa or within 1 mo of return, of whom 40 (70%) were not tested at the time for EBOV infection. Of the 268 OFSs, 266 were unreactive. Two returnees, who did not experience an illness in West Africa or on return, had OFSs that were reactive on the EBOV IgG capture assay, with similar results on plasma. One individual had no further positive test results; the other had a positive result on a double-antigen bridging assay but not on a competitive assay or on an indirect EBOV IgG ELISA. All 53 controls had non-reactive OFSs. While the participants were not a random sample of returnees, the number participating was high.

CONCLUSIONS

This is the first study, to our knowledge, of the prevalence of EBOV infection in international responders. More than 99% had clear negative results. Sera from two individuals had discordant results on the different assays; both were negative on the competitive assay, suggesting that prior infection was unlikely. The finding that a significant proportion experienced "near miss" exposure events, and that most of those who experienced symptoms did not get tested for EBOV at the time, suggests a need to review and standardise protocols for the management of possible exposure to EBOV, and for the management of illness, across organisations that deploy staff to outbreaks.

Detecting Mutations in the Mycobacterium tuberculosis Pyrazinamidase Gene pncA to Improve Infection Control and Decrease Drug Resistance Rates in Human Immunodeficiency Virus Coinfection

Hospital infection control measures are crucial to tuberculosis (TB) control strategies within settings caring for human immunodeficiency virus (HIV)-positive patients, as these patients are at heightened risk of developing TB. Pyrazinamide (PZA) is a potent drug that effectively sterilizes persistent Mycobacterium tuberculosis bacilli. However, PZA resistance associated with mutations in the nicotinamidase/pyrazinamidase coding gene, pncA, is increasing. A total of 794 patient isolates obtained from four sites in Lima, Peru, underwent spoligotyping and drug resistance testing. In one of these sites, the HIV unit of Hospital Dos de Mayo (HDM), an isolation ward for HIV/TB coinfected patients opened during the study as an infection control intervention: circulating genotypes and drug resistance pre- and postintervention were compared. All other sites cared for HIV-negative outpatients: genotypes and drug resistance rates from these sites were compared with those from HDM. HDM patients showed high concordance between multidrug resistance, PZA resistance according to the Wayne method, the two most common genotypes (spoligotype international type [SIT] 42 of the Latino American-Mediterranean (LAM)-9 clade and SIT 53 of the T1 clade), and the two most common pncA mutations (G145A and A403C). These associations were absent among community isolates. The infection control intervention was associated with 58-92% reductions in TB caused by SIT 42 or SIT 53 genotypes (odds ratio [OR] = 0.420, P = 0.003); multidrug-resistant TB (OR = 0.349, P < 0.001); and PZA-resistant TB (OR = 0.076, P < 0.001). In conclusion, pncA mutation typing, with resistance testing and spoligotyping, was useful in identifying a nosocomial TB outbreak and demonstrating its resolution after implementation of infection control measures.

The effect of surgery on the outcome of treatment for multidrug-resistant tuberculosis: a systematic review and meta-analysis

BACKGROUND

In 2014 only 50 % of multidrug-resistant tuberculosis (MDR-TB) patients achieved a successful treatment outcome. With limited options for medical treatment, surgery has re-emerged as an adjuvant therapeutic strategy. We conducted a systematic review and meta-analysis to assess the evidence for the effect of surgery as an adjunct to chemotherapy on outcomes of adults treated for MDR-TB.

METHODS

Databases and grey literature sources were searched using terms incorporating surgery and MDR-TB. No language or publication type limits were applied. Articles published pre-1990, without a comparator group, or reporting <10 surgical participants were excluded. Two-stage sifting in duplicate was employed. Data on WHO-defined treatment outcomes were abstracted into a standardised database. Study-level risk of bias was evaluated using standardised tools. Outcome-level evidence quality was assessed using GRADE. Forest plots were generated, random effects meta-analysis conducted, and heterogeneity assessed using the I(2) statistic.

RESULTS

Of 1024 unique citations identified, 62 were selected for full-text review and 15 retained for inclusion. A further four articles were included after bibliography/citation searching, and one additional unpublished manuscript was identified, giving 20 articles for final inclusion. Six were meta-analyses/systematic reviews and 14 were primary research articles (observational studies). From the 14 primary research articles, a successful outcome (cured/treatment completed) was reported for 81.9 % (371/453) and 59.7 % (1197/2006) in the surgical and non-surgical group respectively, giving a summary odds ratio of 2.62 (95 % confidence interval 1.94-3.54). Loss to follow-up and treatment failure were lower in the surgery group (both p = 0.01). Overall GRADE quality of evidence for all outcomes considered was "very low".

CONCLUSIONS

This meta-analysis suggests that surgery as an adjunct to chemotherapy is associated with improved treatment outcomes in MDR-TB patients. However, inherent limitations in observational study design, insufficient reporting, and lack of adjustment for confounders, led to grading of the evidence as very low quality. Data on rationale for surgical referral, subsequent outcomes and resource-limited settings are scarce, precluding evidence-based recommendations on the suitability of surgery by patient characteristics or setting. It is hoped that highlighted methodological and reporting gaps will encourage improved design and reporting of future surgical studies for MDR-TB.

The effect of early versus late treatment initiation after diagnosis on the outcomes of patients treated for multidrug-resistant tuberculosis: a systematic review

BACKGROUND

Globally it is estimated that 480 000 people developed multidrug-resistant tuberculosis (MDR-TB) in 2014 and 190 000 people died from the disease. Successful treatment outcomes are achieved in only 50 % of patients with MDR-TB, compared to 86 % for drug susceptible disease. It is widely held that delay in time to initiation of treatment for MDR-TB is an important predictor of treatment outcome. The objective of this review was to assess the existing evidence on the outcomes of multidrug- and extensively drug-resistant tuberculosis patients treated early (≤4 weeks) versus late (>4 weeks) after diagnosis of drug resistance.

METHODS

Eight sources providing access to 17 globally representative electronic health care databases, indexes, sources of evidence-based reviews and grey literature were searched using terms incorporating time to treatment and MDR-TB. Two-stage sifting in duplicate was employed to assess studies against pre-specified inclusion and exclusion criteria. Only those articles reporting WHO-defined treatment outcomes were considered for inclusion. Articles reporting on fewer than 10 patients, published before 1990, or without a comparison of outcomes in patient groups experiencing different delays to treatment initiation were excluded.

RESULTS

The initial search yielded 1978 references, of which 1475 unique references remained after removal of duplicates and 28 articles published pre-1990. After title and abstract sifting, 64 papers underwent full text review. None of these articles fulfilled the criteria for inclusion in the review.

CONCLUSIONS

Whilst there is an inherent logic in the theory that treatment delay will lead to poorer treatment outcomes, no published evidence was identified in this systematic review to support this hypothesis. Reports of programmatic changes leading to reductions in treatment delay exist in the literature, but attribution of differences in outcomes specifically to treatment delay is confounded by other contemporaneous changes. Further primary research on this question is not considered a high priority use of limited resources, though where data are available, improved reporting of outcomes by time to treatment should be encouraged.

What can we offer to 3 million MDRTB household contacts in 2016?

The diagnosis of multidrug resistant tuberculosis (MDR-TB) in any individual is the beginning of a prolonged and difficult therapeutic journey. It also marks the moment from which to begin consideration of how to manage close contacts. Preventive therapy for drug-susceptible latent tuberculosis infection has been demonstrated to be effective at reducing the risk of future disease; the stakes are higher when considering prevention of MDR-TB because treatment of active disease is more prolonged and toxic and much less effective. This has encouraged exploration of the potential utility of preventive therapy, with second-line agents, in reducing future incident drug-resistant TB.Three clinical trials of preventive therapy for contacts of patients with MDR-TB are starting in 2015/16; results will not be available until at least 2020, so what should be offered to exposed contacts in the interim?A recent policy brief, arising from a global consultation meeting of international experts, recommended preventive therapy based upon very limited available observational data. However the many known unknowns associated with this approach, include the high proportion of index-contact pairs with discordant drug susceptibility profiles and (even if susceptibilities are shared) the lack of data supporting the use of the selected agents in the treatment of latent infection (rather than active disease).It is important to acknowledge that the alternative to offering preventive therapy is not doing nothing. On the contrary, identified contacts should be maintained under close, active surveillance for 24 months, enabling early detection of active disease in the small proportion amongst whom this may occur. Such patients should benefit from less extensive disease at diagnosis and early access to individualized therapeutic regimens with improved treatment outcomes. Moreover the vast majority of contacts that do not develop disease will benefit from avoidance of potentially toxic, unnecessary therapy.Whether preventive therapy or close observation are implemented, national programmes should maintain a register of all contacts, interventions and 24 month outcomes; these will provide important performance metrics for programmatic management of MDRTB. If harmonized and standardized internationally, such a register could rapidly yield a wealth of observational data, to complement the trial results of the future.

Rationing tests for drug-resistant tuberculosis - who are we prepared to miss?

BACKGROUND

Early identification of patients with drug-resistant tuberculosis (DR-TB) increases the likelihood of treatment success and interrupts transmission. Resource-constrained settings use risk profiling to ration the use of drug susceptibility testing (DST). Nevertheless, no studies have yet quantified how many patients with DR-TB this strategy will miss.

METHODS

A total of 1,545 subjects, who presented to Lima health centres with possible TB symptoms, completed a clinic-epidemiological questionnaire and provided sputum samples for TB culture and DST. The proportion of drug resistance in this population was calculated and the data was analysed to demonstrate the effect of rationing tests to patients with multidrug-resistant TB (MDR-TB) risk factors on the number of tests needed and corresponding proportion of missed patients with DR-TB.

RESULTS

Overall, 147/1,545 (9.5%) subjects had culture-positive TB, of which 32 (21.8%) had DR-TB (MDR, 13.6%; isoniazid mono-resistant, 7.5%; rifampicin mono-resistant, 0.7%). A total of 553 subjects (35.8%) reported one or more MDR-TB risk factors; of these, 506 (91.5%; 95% CI, 88.9-93.7%) did not have TB, 32/553 (5.8%; 95% CI, 3.4-8.1%) had drug-susceptible TB, and only 15/553 (2.7%; 95% CI, 1.5-4.4%) had DR-TB. Rationing DST to those with an MDR-TB risk factor would have missed more than half of the DR-TB population (17/32, 53.2%; 95% CI, 34.7-70.9).

CONCLUSIONS

Rationing DST based on known MDR-TB risk factors misses an unacceptable proportion of patients with drug-resistance in settings with ongoing DR-TB transmission. Investment in diagnostic services to allow universal DST for people with presumptive TB should be a high priority.

The transmission of Mycobacterium tuberculosis in high burden settings

Unacceptable levels of Mycobacterium tuberculosis transmission are noted in high burden settings and a renewed focus on reducing person-to-person transmission in these communities is needed. We review recent developments in the understanding of airborne transmission. We outline approaches to measure transmission in populations and trials and describe the Wells-Riley equation, which is used to estimate transmission risk in indoor spaces. Present research priorities include the identification of effective strategies for tuberculosis infection control, improved understanding of where transmission occurs and the transmissibility of drug-resistant strains, and estimates of the effect of HIV and antiretroviral therapy on transmission dynamics. When research is planned and interventions are designed to interrupt transmission, resource constraints that are common in high burden settings-including shortages of health-care workers-must be considered.

Microscopic Observation Drug Susceptibility Assay for Rapid Diagnosis of Lymph Node Tuberculosis and Detection of Drug Resistance

In this study, 132 patients with lymphadenopathy were investigated. Fifty-two (39.4%) were diagnosed with tuberculosis (TB). The microscopic observation drug susceptibility (MODS) assay provided rapid (13 days), accurate diagnosis (sensitivity, 65.4%) and reliable drug susceptibility testing (DST). Despite its lower sensitivity than that of other methods, its faster results and simultaneous DST are advantageous in resource-poor settings, supporting the incorporation of MODS into diagnostic algorithms for extrapulmonary TB.

Risk of tuberculosis in patients with diabetes: population based cohort study using the UK Clinical Practice Research Datalink

BACKGROUND

Previous cohort studies demonstrate diabetes as a risk factor for tuberculosis (TB) disease. Public Health England has identified improved TB control as a priority area and has proposed a primary care-based screening program for latent TB. We investigated the association between diabetes and risk of tuberculosis in a UK General Practice cohort in order to identify potential high-risk groups appropriate for latent TB screening.

METHODS

Using data from the UK Clinical Practice Research Datalink we constructed a cohort of patients with incident diabetes. We included 222,731 patients with diabetes diagnosed from 1990-2013 and 1,218,616 controls without diabetes at index date who were matched for age, sex and general practice. The effect of diabetes was explored using a Poisson analysis adjusted for age, ethnicity, body mass index, socioeconomic status, alcohol intake and smoking. We explored the effects of age, diabetes duration and severity. The effects of diabetes on risk of incident TB were explored across strata of chronic disease care defined by cholesterol and blood pressure measurement and influenza vaccination rates.

RESULTS

During just under 7 million person-years of follow-up, 969 cases of TB were identified. The incidence of TB was higher amongst patients with diabetes compared with the unexposed group: 16.2 and 13.5 cases per 100,000 person-years, respectively. After adjustment for potential confounders the association between diabetes and TB remained (adjusted RR 1.30, 95 % CI 1.01 to 1.67, P = 0.04). There was no evidence that age, time since diagnosis and severity of diabetes affected the association between diabetes and TB. Diabetes patients with the lowest and highest rates of chronic disease management had a higher risk of TB (P <0.001 for all comparisons).

CONCLUSIONS

Diabetes as an independent risk factor is associated with only a modest overall increased risk of TB in our UK General Practice cohort and is unlikely to be sufficient cause to screen for latent TB. Across different consulting patterns, diabetes patients accessing the least amount of chronic disease care are at highest risk for TB.

Transmission of Multidrug-Resistant and Drug-Susceptible Tuberculosis within Households: A Prospective Cohort Study

BACKGROUND

The "fitness" of an infectious pathogen is defined as the ability of the pathogen to survive, reproduce, be transmitted, and cause disease. The fitness of multidrug-resistant tuberculosis (MDRTB) relative to drug-susceptible tuberculosis is cited as one of the most important determinants of MDRTB spread and epidemic size. To estimate the relative fitness of drug-resistant tuberculosis cases, we compared the incidence of tuberculosis disease among the household contacts of MDRTB index patients to that among the contacts of drug-susceptible index patients.

METHODS AND FINDINGS

This 3-y (2010-2013) prospective cohort household follow-up study in South Lima and Callao, Peru, measured the incidence of tuberculosis disease among 1,055 household contacts of 213 MDRTB index cases and 2,362 household contacts of 487 drug-susceptible index cases. A total of 35/1,055 (3.3%) household contacts of 213 MDRTB index cases developed tuberculosis disease, while 114/2,362 (4.8%) household contacts of 487 drug-susceptible index patients developed tuberculosis disease. The total follow-up time for drug-susceptible tuberculosis contacts was 2,620 person-years, while the total follow-up time for MDRTB contacts was 1,425 person-years. Using multivariate Cox regression to adjust for confounding variables including contact HIV status, contact age, socio-economic status, and index case sputum smear grade, the hazard ratio for tuberculosis disease among MDRTB household contacts was found to be half that for drug-susceptible contacts (hazard ratio 0.56, 95% CI 0.34-0.90, p = 0.017). The inference of transmission in this study was limited by the lack of genotyping data for household contacts. Capturing incident disease only among household contacts may also limit the extrapolation of these findings to the community setting.

CONCLUSIONS

The low relative fitness of MDRTB estimated by this study improves the chances of controlling drug-resistant tuberculosis. However, fitter multidrug-resistant strains that emerge over time may make this increasingly difficult.

Robust and Reproducible Quantification of the Extent of Chest Radiographic Abnormalities (And It's Free!)

Rationale

Objective, reproducible quantification of the extent of abnormalities seen on a chest radiograph would improve the user-friendliness of a previously proposed severity scoring system for pulmonary tuberculosis and could be helpful in monitoring response to therapy, including in clinical trials.

Methods

In this study we report the development and evaluation of a simple tool using free image editing software (GIMP) to accurately and reproducibly quantify the area of affected lung on the chest radiograph of tuberculosis patients. As part of a pharmacokinetic study in Lima, Peru, a chest radiograph was performed on patients with pulmonary tuberculosis and this was subsequently photographed using a digital camera. The GIMP software was used by two independent and trained readers to estimate the extent of affected lung (expressed as a percentage of total lung area) in each radiograph and the resulting radiographic SCORE.

Results

56 chest radiographs were included in the reading analysis. The Intraclass correlation coefficient (ICC) between the 2 observers was 0.977 (p<0.001) for the area of lung affected and was 0.955 (p<0.001) for the final score; and the kappa coefficient of Interobserver agreement for both the area of lung affected and the score were 0.9 (p<0.001) and 0.86 (p<0.001) respectively.

Conclusions

This high level of between-observer agreement suggests that this freely available software could constitute a simple and useful tool for robust evaluation of individual and serial chest radiographs.

Induced sputum is safe and well-tolerated for TB diagnosis in a resource-poor primary healthcare setting

Improved tuberculosis (TB) diagnostics are required. Induced sputum sampling is superior to spontaneous sputum analysis for diagnosis of pulmonary TB. Therefore, we examined the applicability of induced sputum in primary health centers of the Peruvian TB program and studied the safety and tolerability of this procedure. We show that induced sputum is safe, inexpensive, and well-tolerated in a resource-limited environment. Widespread use of induced sputum at primary health centers can be implemented and may improve TB diagnosis.

A field evaluation of the Hardy TB MODS Kit™ for the rapid phenotypic diagnosis of tuberculosis and multi-drug resistant tuberculosis

Background

Even though the WHO-endorsed, non-commercial MODS assay offers rapid, reliable TB liquid culture and phenotypic drug susceptibility testing (DST) at lower cost than any other diagnostic, uptake has been patchy. In part this reflects misperceptions about in-house assay quality assurance, but user convenience of one-stop procurement is also important. A commercial MODS kit was developed by Hardy Diagnostics (Santa Maria, CA, USA) with PATH (Seattle, WA, USA) to facilitate procurement, simplify procedures through readymade media, and enhance safety with a sealing silicone plate lid. Here we report the results from a large-scale field evaluation of the MODS kit in a government service laboratory.

Methods & Findings

2446 sputum samples were cultured in parallel in Lowenstein-Jensen (LJ), conventional MODS and in the MODS kit. MODS kit DST was compared with conventional MODS (direct) DST and proportion method (indirect) DST. 778 samples (31.8%) were Mycobacterium tuberculosis culture-positive. Compared to conventional MODS the sensitivity, specificity, positive, and negative predictive values (95% confidence intervals) of the MODS Kit were 99.3% (98.3–99.8%), 98.3% (97.5–98.8%), 95.8% (94.0–97.1%), and 99.7% (99.3–99.9%). Median (interquartile ranges) time to culture-positivity (and rifampicin and isoniazid DST) was 10 (9–13) days for conventional MODS and 8.5 (7–11) for MODS Kit (p<0.01). Direct rifampicin and isoniazid DST in MODS kit was almost universally concordant with conventional MODS (97.9% agreement, 665/679 evaluable samples) and reference indirect DST (97.9% agreement, 687/702 evaluable samples).

Conclusions

MODS kit delivers performance indistinguishable from conventional MODS and offers a convenient, affordable alternative with enhanced safety from the sealing silicone lid. The availability in the marketplace of this platform, which conforms to European standards (CE-marked), readily repurposed for second-line DST in the near future, provides a fresh opportunity for improving equity of access to TB diagnosis and first and second-line DST in settings where the need is greatest.

[Tuberculosis and diabetes co-morbidity: an unresolved problem]

Co-morbidity between tuberculosis and diabetes has been described since the early 20th century. In developed countries, where there has been a decrease of infectious diseases with an increase of non-communicable diseases, as well as those countries who still have a high prevalence of infectious diseases but an increase of non-communicable diseases, it is observed that the prevalence of co-morbidity between tuberculosis and diabetes is increasing, making clinical management and control at the public health level a new challenge for health systems. This review aims to show the current available evidence that can inform research lines being developed to understand the problem. In countries like Peru, where there is an epidemiological transition, further research could allow us to understand and describe in a better way the characteristics and impact of this co-morbidity.

Factors associated with parasitic infection amongst street children in orphanages across Lima, Peru

Infection caused by intestinal parasites has significant public health consequences amongst children in the developing world. Street children are an under-studied group of society subjected to increased health risks when compared to their peers. To estimate the prevalence of intestinal parasitic infection and ascertain risk factors for parasitosis amongst this population, stool samples were collected from 258 children across four orphanages in three districts of Lima, Peru. Surveys were used to determine associations between risk factors and infection status. The prevalence of parasitic infection within the study sample was 66·3%, with 30·6% testing positive for pathogenic species. Entamoeba coli was the most commonly detected parasite (41·9%) and Giardia lamblia was the most commonly detected pathogenic parasite (17·1%). Of the group 15·1% had helminth infection. When testing for association, age and BMI were risk factors for infection. A notable difference in prevalence (P < 0·00001) based on orphanage was observed, but the duration of residence in an orphanage was not a predictor for infection. A sub-analysis conducted amongst children who were given anti-parasitic treatment 5 months beforehand found no significant difference in parasitosis between those who had been given treatment and those who had not (P = 0·218). It is suggested that a single dose of albendazole alone may not be effective in combating long-term infection rates.

Morphological characterization of Mycobacterium tuberculosis in a MODS culture for an automatic diagnostics through pattern recognition

Tuberculosis control efforts are hampered by a mismatch in diagnostic technology: modern optimal diagnostic tests are least available in poor areas where they are needed most. Lack of adequate early diagnostics and MDR detection is a critical problem in control efforts.

The Microscopic Observation Drug Susceptibility (MODS) assay uses visual recognition of cording patterns from Mycobacterium tuberculosis (MTB) to diagnose tuberculosis infection and drug susceptibility directly from a sputum sample in 7–10 days with a low cost.

An important limitation that laboratories in the developing world face in MODS implementation is the presence of permanent technical staff with expertise in reading MODS.

We developed a pattern recognition algorithm to automatically interpret MODS results from digital images. The algorithm using image processing, feature extraction and pattern recognition determined geometrical and illumination features used in an object-model and a photo-model to classify TB-positive images. 765 MODS digital photos were processed. The single-object model identified MTB (96.9% sensitivity and 96.3% specificity) and was able to discriminate non-tuberculous mycobacteria with a high specificity (97.1% M. avium, 99.1% M. chelonae, and 93.8% M. kansasii). The photo model identified TB-positive samples with 99.1% sensitivity and 99.7% specificity.

This algorithm is a valuable tool that will enable automatic remote diagnosis using Internet or cellphone telephony. The use of this algorithm and its further implementation in a telediagnostics platform will contribute to both faster TB detection and MDR TB determination leading to an earlier initiation of appropriate treatment.

Reaching out to take on TB in Somalia

Among the many challenges facing populations disrupted by complex emergencies, personal security and food security rank much higher than access to healthcare. However, over time health needs assume increasing importance. Many complex crises occur in settings where the background incidence of TB is already high; social and economic conditions in crises are then highly conducive to amplification of the existing TB problem. Innovative approaches to delivery of diagnostic and treatment services, transition planning and integration with other healthcare providers and services are vital. In the extremely challenging environment of Somalia, multiple partners are making headway though collaboration and innovation.

Validation of microscopic observation drug susceptibility testing for rapid, direct rifampicin and isoniazid drug susceptibility testing in patients receiving tuberculosis treatment

Drug susceptibility testing (DST) is often needed in patients clinically failing tuberculosis (TB) therapy. Most studies of phenotypic direct drug susceptibility tests, such as microscopic observation drug susceptibility (MODS) tests, have been performed in patients not receiving TB treatment. The effect of ongoing TB treatment on the performance of MODS direct DST has not been previously explored, but patients failing such therapy constitute an important target group. The aim of this study was to determine the performance of MODS direct rifampicin and isoniazid DST in patients clinically failing first-line TB treatment, and to compare MODS direct DST with indirect proportion method DST. Sputa from 264 TB patients were cultured in parallel in Lowenstein–Jensen (LJ) and MODS assays; strains were tested for rifampicin and isoniazid susceptibility by the proportion method at the national reference laboratory. Ninety-three samples were culture-positive by LJ and MODS (concordance of 96%; kappa 0.92). With conventional MODS plate DST reading (performed on the same day as the sample is classified as culture-positive), the isoniazid DST concordance was 96.8% (kappa 0.89), and the concordance for rifampicin susceptibility testing was 92.6% (kappa 0.80). Reading of MODS DST plates 1 week after cultures had been determined to be culture-positive improved overall performance marginally—the isoniazid DST concordance was 95.7% (kappa 0.85); and the rifampicin DST concordance was 96.8% (kappa 0.91). Sensitivity for detection of multidrug-resistant TB was 95.8%. MODS testing provided reliable rifampicin and isoniazid DST results for samples obtained from patients receiving TB therapy. A modified DST reading schedule for such samples, with a final reading 1 week after a MODS culture turns positive, marginally improves the concordance with reference DST.

A rapid and low-cost microscopic observation drug susceptibility assay for detecting TB and MDR-TB among individuals infected by HIV in South India

BACKGROUND

The converging epidemics of HIV and tuberculosis (TB) pose one of the greatest public health challenges of our time. Rapid diagnosis of TB is essential in view of its infectious nature, high burden of cases, and emergence of drug resistance.

OBJECTIVE

The purpose of this present study was to evaluate the feasibility of implementing the microscopic observation drug susceptibility (MODS) assay, a novel assay for the diagnosis of TB and multi-drug-resistant tuberculosis (MDR-TB) directly from sputum specimens, in the Indian setting.

MATERIALS AND METHODS

This study involved a cross-sectional, blinded assessment of the MODS assay on 1036 suspected cases of pulmonary TB in HIV-positive and HIV-negative patients against the radiometric method, BD-BACTEC TB 460 system.

RESULTS

Overall, the sensitivity, specificity, positive predictive value, and negative predictive value of the MODS assay in detecting MTB among TB suspected patients were 89.1%, 99.1%, 94.2%, 95.8%, respectively. In addition, in the diagnosis of drug-resistant TB, the MODS assay was 84.2% sensitive for those specimens reporting MDR, 87% sensitivity for those specimens reporting INH mono-resistance, and 100% sensitive for specimens reporting RIF mono-resistance. The median time to detection of TB in the MODS assay versus BACTEC was 9 versus 21 days (P<0.001).

CONCLUSION

Costing 5 to 10 times lesser than the automated culture methods, the MODS assay has the potential clinical utility as a simple and rapid method. It could be effectively used as an alternative method for diagnosing TB and detection of MDR-TB in a timely and affordable way in resource-limited settings.