Immunologic changes are detectable in the peripheral blood transcriptome of clinically asymptomatic Chagas cardiomyopathy patients.

Chagas disease, caused by the protozoan parasite Trypanosoma cruzi, is a neglected parasitic disease that affects approximately 6 million individuals worldwide. Of those infected, 20-30% will go on to develop chronic Chagas cardiomyopathy (CCC), and ultimately many of these individuals will progress to advanced heart failure. The mechanism by which this progression occurs is poorly understood, as few studies have focused on early CCC. In this study, we sought to understand the physiologic changes associated with T. cruzi infection and the development of CCC. We analyzed gene expression in the peripheral blood of asymptomatic Chagas patients with early structural heart disease, Chagas patients without any signs or symptoms of disease, and Chagas-negative patients with and without early structural heart disease. Our analysis shows that early CCC was associated with a downregulation of various peripheral immune response genes, with gene expression changes suggestive of reduced antigen presentation and T cell activation. Notably, these genes and processes were distinct from those of early cardiomyopathy in Chagas-negative patients, suggesting that the processes mediating CCC may be unique from those mediating progression to other cardiomyopathies. This work highlights the importance of the immune response in early CCC, providing insight into the early pathogenesis of this disease. The changes we have identified may serve as biomarkers of progression and could inform strategies for the treatment of CCC in its early stages, before significant cardiac damage has occurred.

Bidirectional Transcription at the PPP2R2B Gene Locus in Spinocerebellar Ataxia Type 12.

BACKGROUND: Spinocerebellar ataxia type 12 (SCA12) is a neurodegenerative disease caused by expansion of a CAG repeat in the PPP2R2B gene. OBJECTIVE: In this study, we tested the hypothesis that the PPP2R2B antisense (PPP2R2B-AS1) transcript containing a CUG repeat is expressed and contributes to SCA12 pathogenesis. METHODS: Expression of PPP2R2B-AS1 transcript was detected in SCA12 human induced pluripotent stem cells (iPSCs), iPSC-derived NGN2 neurons, and SCA12 knock-in mouse brains using strand-specific reverse transcription polymerase chain reaction. The tendency of expanded PPP2R2B-AS1 (expPPP2R2B-AS1) RNA to form foci, a marker of toxic processes involving mutant RNAs, was examined in SCA12 cell models by fluorescence in situ hybridization. The apoptotic effect of expPPP2R2B-AS1 transcripts on SK-N-MC neuroblastoma cells was evaluated by caspase 3/7 activity. Western blot was used to examine the expression of repeat associated non-ATG-initiated translation of expPPP2R2B-AS1 transcript in SK-N-MC cells. RESULTS: The repeat region in the PPP2R2B gene locus is bidirectionally transcribed in SCA12 iPSCs, iPSC-derived NGN2 neurons, and SCA12 mouse brains. Transfected expPPP2R2B-AS1 transcripts induce apoptosis in SK-N-MC cells, and the apoptotic effect may be mediated, at least in part, by the RNA secondary structure. The expPPP2R2B-AS1 transcripts form CUG RNA foci in SK-N-MC cells. expPPP2R2B-AS1 transcript is translated in the alanine open reading frame (ORF) via repeat-associated non-ATG translation, which is diminished by single-nucleotide interruptions within the CUG repeat and MBNL1 overexpression. CONCLUSIONS: These findings suggest that PPP2R2B-AS1 contributes to SCA12 pathogenesis and may therefore provide a novel therapeutic target for the disease. © 2023 International Parkinson and Movement Disorder Society.

Epidemiology of animal bite in Iran during a 20-year period (1993-2013): a meta-analysis.

BACKGROUND: Rabies is a fatal disease that still kills 2-6 people a year in Iran. A meta-analysis was conducted in order to generate accurate data on animal bite exposure, and to estimate the incidence of animal bite across the country. MATERIALS AND METHODS: Major national and international electronic databases were searched using the keywords "animal bite," rabies, prevalence, incidence, and Iran. Web of Knowledge, PubMed, Scopus, Ovid, and ScienceDirect were used as international databases, and the national databases included Science Information Database, MagIran, and IranDoc. Descriptive cross-sectional studies addressing the incidence of animal bite were selected and screened by two authors, and pre-specified data were extracted. The population of provinces or cities of studies was extracted from the Statistical Centre of Iran. The overall incidence of animal bite in Iran was estimated using a random-effects model with 95% confidence interval (CI). Study quality was assessed using the STROBE recommended checklist. RESULTS: A total of 34 studies were selected for the meta-analysis out of 1215 retrieved studies. The number of animal bites in the studies during 1993-2013 was 230,019 cases. The overall estimated incidence rate of animal bite in Iran was 13.20/1000 (95%, CI 12.10, 14.30) and the mean age of people was 26.23 (SD = 5.02) year. The incidence rate of animal bite among males (14.90/1000) was much higher than females (4.55/1000), and was higher in rural areas (17.45/1000) compared with urban areas (4.35/1000). The incident rate was highest among students compared with other reported occupations. The incidence rate of dogs was 10.40/1000 followed by cats, cows, wolves, jackals, and foxes. Domestic animals had a higher incidence rate than stray and wild animals. The incidence rate of animal bite during spring was 4.90/1000; however, the incidence rate in other seasons had no significant difference. In the retrieved studies, the highest incidence rate of animal bite was found in the West Azerbaijan Province (146.83/1000). CONCLUSION: The current study is the first comprehensive analysis of the published animal bite studies in Iran. Accurate data on animal bite incidence may lead to more effective policy-decisions towards more efficient resource allocation to primary health care for reducing rabies case. Such information is a primary and major necessity for rabies control program in the country. Animal bite reduction can significantly minimize the risk of rabies infection, thereby reducing public health costs for the expensive post-exposure treatment.

The Frequency of HIV-1 Infection in Iranian Children and Determination of the Transmitted Drug Resistance in Treatment-Naïve Children.

BACKGROUND: The advent of resistance-associated mutations in HIV-1 is a barrier to the success of the ARTs. OBJECTIVE: In this study, the abundance of HIV-1 infection in Iranian children, and also detection of the TDR in naïve HIV-1 infected pediatric (under 12 years old) were evaluated. MATERIALS: From June 2014 to January 2019, a total of 544 consecutive treatment-naïve HIV-1- infected individuals enrolled in this study. After RNA extraction, amplification, and sequencing of the HIV-1 pol gene, the DRM and phylogenetic analysis were successfully performed on the plasma specimens of the ART-naïve HIV-1-infected-children under 12 years old. The DRMs were recognized using the Stanford HIV Drug Resistance Database. RESULTS: Out of the 544 evaluated treatment-naïve HIV-1-infected individuals, 15 (2.8%) cases were children under 12 years old. The phylogenetic analyses of the amplified region of pol gene indicated that all of the 15 HIV-1-infected pediatric patients were infected by CRF35_AD, and a total of 13.3% (2/15) of these children were infected with HIV-1 variants with SDRMs (one child harbored two related SDRMs [D67N, V179F], and another child had three related SDRMs [M184V, T215F, and K103N]), according to the last algorithm of the WHO. No PIs-related SDRMs were observed in HIV-1-infected children. CONCLUSION: The current study demonstrated that a total of 13.3% of treatment-naïve HIV-1-infected Iranian pediatrics (under 12 years old) were infected with HIV-1 variants with SDRMs. Therefore, it seems that screening to recognize resistance-associated mutations before the initiation of ARTs among Iranian children is essential for favorable medication efficacy and dependable prognosis.

Using phylogeographic approaches to analyse the dispersal history, velocity and direction of viral lineages - Application to rabies virus spread in Iran.

Recent years have seen the extensive use of phylogeographic approaches to unveil the dispersal history of virus epidemics. Spatially explicit reconstructions of viral spread represent valuable sources of lineage movement data that can be exploited to investigate the impact of underlying environmental layers on the dispersal of pathogens. Here, we performed phylogeographic inference and applied different post hoc approaches to analyse a new and comprehensive data set of viral genomes to elucidate the dispersal history and dynamics of rabies virus (RABV) in Iran, which have remained largely unknown. We first analysed the association between environmental factors and variations in dispersal velocity among lineages. Second, we present, test and apply a new approach to study the link between environmental conditions and the dispersal direction of lineages. The statistical performance (power of detection, false-positive rate) of this new method was assessed using simulations. We performed phylogeographic analyses of RABV genomes, allowing us to describe the large diversity of RABV in Iran and to confirm the cocirculation of several clades in the country. Overall, we estimate a relatively high lineage dispersal velocity, similar to previous estimates for dog rabies virus spread in northern Africa. Finally, we highlight a tendency for RABV lineages to spread in accessible areas associated with high human population density. Our analytical workflow illustrates how phylogeographic approaches can be used to investigate the impact of environmental factors on several aspects of viral dispersal dynamics.

Fast copolymer network liquid crystals for tunable birefringence colors.

A fast-switching, tunable color filter was found in a copolymer network liquid crystal (LC), which was in situ generated in a conventional LC test cell with parallel aligned glass plates and investigated with polarized light. Polarization filters were used to convert the tunable optical phase retardance of the test cells to birefringence colors as is always possible in a LC test cell with carefully adjusted cell gap and effective birefringence. The cell gap of the samples could be adjusted to a value of 9 µm, which is not easily possible in a polymer LC composite without creating defects. In these samples, the typical pastel colors seen frequently in birefringent samples could be avoided. The transmittance spectra were recorded and converted to CIE 1931 color coordinates, which showed that the colors seen had a reasonable distance to the white point. The electro-optic switching times of the samples were investigated: Fast responses of t on +t off <5 ms were found, which is an impressive speed for tunable birefringence colors in LCs and LC composites. Upon increasing addressing voltages, a blueshift of the peak seen in the transmittance spectra was observed. The samples consisted of copolymer network LC, generated from a reactive mixture with mesogenic monomer and nonmesogenic comonomer. The tunable color was seen selectively in samples with dodecyl acrylate as comonomer. The experiments show how even a straightforward electro-optic experiment still can result in unexpended findings, which may expand the use of LC composites in nondisplay applications. The polymer morphology in samples with a larger cell gap was investigated with scanning electron microscopy, and interdefect distances of ≈40 µm were found. The appearance of defects in test cells with a cell gap of 9 µm could be avoided because the cell gap was much smaller than the measured interdefect distances in test cells with a larger cell gap.

Ante-mortem Diagnosis of Human Rabies Cases Using SYBR Green Real-Time PCR.

BACKGROUND: Rabies, as the most important zoonotic disease, is transmitted through a bite or scratch by an infected domestic or wild carnivores and bats or contact of open wound with infected saliva. The fluorescent antibody test (FAT) is the "gold standard" diagnostic method for suspected brain samples. For close monitoring of unknown encephalitis, rabies surveillance, and also the limitations for post-mortem diagnosis of rabies in human and performing fast prophylactic measures for other individuals in contact with rabid patients, ante-mortem diagnosis based on molecular methods such as real-time polymerase chain reaction (PCR) seems to be more reliable. In this study, we detected 2 positive rabid cases using SYBR Green real-time PCR for the first time in Iran. METHODS: In this study, 3 saliva samples at intervals up to 6 hours were collected from any of the nine suspected patients with nonspecific symptoms between March 2016 and March 2017. Total RNA extraction, cDNA synthesis and real-time PCR were performed along with confirmed negative and positive controls. Then, we tracked the patients for follow-up and understanding of their status. On brain samples of patients who died, FAT and MIT (mouse inoculation test) were performed to obtain definitive results. RESULTS: In this study, the patients were 4 females and 5 males, between 8 and 80 years old from different geographical areas of Iran. The ante-mortem saliva samples of 2 out of nine patients who died were positive by SYBR Green real-time PCR. Positive results of FAT test on these samples confirmed the presence of rabies virus infection in their brains and also the ante-mortem diagnosis results. CONCLUSION: The results of this study suggest that SYBR Green real-time PCR technique on saliva sample can be used as an applicable method for ante-mortem diagnosis of rabies to avoid infection of other people such as the treating medical staff or family members of the patient.

Prevalence of HAV Ab, HEV (IgG), HSV2 IgG, and Syphilis Among Sheltered Homeless Adults in Tehran, 2012.

BACKGROUND: This study investigated the prevalence for hepatitis A virus (HAV), hepatitis E virus (HEV), herpes simplex virus type 2 (HSV2) and syphilis among homeless in the city of Tehran. METHODS: In this cross-sectional study, 596 homeless were recruited in Tehran. A researcher-designed questionnaire was used to study demographic data. Using enzyme-linked immunoassay, and rapid plasma reagin (RPR) test, we evaluated the seroprevalence of HAV anti-body, HEV IgG, herpes, HSV2 IgG, and syphilis among sheltered homeless in Tehran. The associations between the participant's characteristics and infections were evaluated using logistic regression and chi-square. RESULTS: A total of 569 homeless, 78 women (13.7%) and 491 men (86.3%) were enrolled into the study from June to August 2012. Their age mean was 42 years and meantime of being homeless was 24 months. Seroprevalence of syphilis, HEV IgG, HSV2 IgG and HAV Ab was 0.55%, 24.37%, 16.48%, and 94.34%, respectively. History of drug abuse was reported in 77.70%; 46.01% of them were using a drug during the study and 26.87% of them had history of intravenous drug abuse. Among people who had intravenous drug abuse, 48.25% had history of syringe sharing. CONCLUSION: The prevalence of HAV, HEV and HSV2 were higher than the general population while low prevalence of syphilis was seen among homeless peoples who are at high risk of sexually transmitted infection (STD). Our findings highlighted that significant healthcare needs of sheltered homeless people in Tehran are unmet and much more attention needs to be paid for the health of homeless people.

Correction to: Prevalence of HIV-1 transmitted drug resistance in recently infected, treatment-naïve persons in the Southwest of Iran, 2014-2015.

The author would like to correct the error in the online published article. The correct details are given below for your reading.

CRF35-AD as the Main Circulating Genotype of Human Immunodeficiency Virus Type 1 Infection in Iran: A Phylogenetic and Demographic-Based Study.

Finding the predominant circulating subtype of human immunodeficiency virus type 1 (HIV-1) and surveying co-infection with other infectious viruses are crucial to making preventive decisions. To this end, 50 Iranian HIV-positive patients made up of 37 men and 13 women were selected. Most of the HIV-positive patients (70%) were intravenous drug users (IDUs), and 48 and 32% of patients were co-infected with HCV and HBV, respectively. The rate of simultaneous infection with HIV, HCV, and HBV was found to be 6%. The p17 region of the gag and the c2-v5 region of the env genes were sequenced and then clustered by phylogenetic analyses. CRF35-AD was specified as the predominant circulating subtype among different high-risk groups. In our survey, most of the patients in the IDU group had co-infections with HCV and HBV. Some possible reasons for the increased transmission risk of HIV in IDUs could be low levels of education, poor hygiene and housing conditions, and limited access to health services.

Prevalence of HIV-1 transmitted drug resistance in recently infected, treatment-naïve persons in the Southwest of Iran, 2014-2015.

The emergence and transmission of drug resistant HIV mutants is a major concern, especially in resource-limited countries with expanding antiretroviral therapy. Studies have recently reported the prevalence of HIV-1 transmitted drug resistance (TDR) mutations in certain Iranian cities; however, no information is currently available about the level of TDR, as well as the nature of the circulating HIV-1 subtypes, in the Southwestern bordering province of Iran, Khuzestan. Herein, we used a WHO-recommended TDR survey method to classify the prevalence of TDR in indigenous people of Khuzestan province. For this purpose, between March 2014 and February 2015, blood samples were collected from 52 newly diagnosed, antiretroviral treatment-naïve, HIV-1 infected persons aged from 18 to 30 years. TDR mutations were determined by sequencing the protease (PR) and reverse transcriptase (RT) genes and interpreted using the WHO drug resistance mutations surveillance list. HIV-1 subtypes were characterized by sequencing the PR-RT, C2-V5, and p17 regions of the pol, env and gag genes, respectively. Two participants had non-nucleoside reverse transcriptase inhibitor (NNRTI) resistance mutations, specifically K103N in one individual and K101EK/K103KN/G190AG in the other. No nucleoside reverse transcriptase inhibitor (NRTI) or major protease inhibitor (PI) mutations were identified. HIV-1 subtyping revealed that all participants were infected with HIV-1 CRF35_AD. According to the WHO sequential sampling method, the prevalence of HIV-1 TDR in the sampling area (Khuzestan province) was classified as moderate for NNRTIs and low for NRTIs and PIs. This is the first HIV-1 drug resistance threshold survey in the Khuzestan province of Iran and shows a predominance of NNRTI TDR mutations in this area.

Amino Acid Changes in the HIV-1 gp41 Membrane Proximal Region Control Virus Neutralization Sensitivity.

Most HIV-1 vaccines elicit neutralizing antibodies that are active against highly sensitive (tier-1) viruses or rare cases of vaccine-matched neutralization-resistant (tier-2) viruses, but no vaccine has induced antibodies that can broadly neutralize heterologous tier-2 viruses. In this study, we isolated antibodies from an HIV-1-infected individual that targeted the gp41 membrane-proximal external region (MPER) that may have selected single-residue changes in viral variants in the MPER that resulted in neutralization sensitivity to antibodies targeting distal epitopes on the HIV-1 Env. Similarly, a single change in the MPER in a second virus from another infected-individual also conferred enhanced neutralization sensitivity. These gp41 single-residue changes thus transformed tier-2 viruses into tier-1 viruses that were sensitive to vaccine-elicited tier-1 neutralizing antibodies. These data demonstrate that Env amino acid changes within the MPER bnAb epitope of naturally-selected escape viruses can increase neutralization sensitivity to multiple types of neutralizing antibodies, and underscore the critical importance of the MPER for maintaining the integrity of the tier-2 HIV-1 trimer.

Spatio-Temporal History of HIV-1 CRF35_AD in Afghanistan and Iran.

HIV-1 Circulating Recombinant Form 35_AD (CRF35_AD) has an important position in the epidemiological profile of Afghanistan and Iran. Despite the presence of this clade in Afghanistan and Iran for over a decade, our understanding of its origin and dissemination patterns is limited. In this study, we performed a Bayesian phylogeographic analysis to reconstruct the spatio-temporal dispersion pattern of this clade using eligible CRF35_AD gag and pol sequences available in the Los Alamos HIV database (432 sequences available from Iran, 16 sequences available from Afghanistan, and a single CRF35_AD-like pol sequence available from USA). Bayesian Markov Chain Monte Carlo algorithm was implemented in BEAST v1.8.1. Between-country dispersion rates were tested with Bayesian stochastic search variable selection method and were considered significant where Bayes factor values were greater than three. The findings suggested that CRF35_AD sequences were genetically similar to parental sequences from Kenya and Uganda, and to a set of subtype A1 sequences available from Afghan refugees living in Pakistan. Our results also showed that across all phylogenies, Afghan and Iranian CRF35_AD sequences formed a monophyletic cluster (posterior clade credibility> 0.7). The divergence date of this cluster was estimated to be between 1990 and 1992. Within this cluster, a bidirectional dispersion of the virus was observed across Afghanistan and Iran. We could not clearly identify if Afghanistan or Iran first established or received this epidemic, as the root location of this cluster could not be robustly estimated. Three CRF35_AD sequences from Afghan refugees living in Pakistan nested among Afghan and Iranian CRF35_AD branches. However, the CRF35_AD-like sequence available from USA diverged independently from Kenyan subtype A1 sequences, suggesting it not to be a true CRF35_AD lineage. Potential factors contributing to viral exchange between Afghanistan and Iran could be injection drug networks and mass migration of Afghan refugees and labours to Iran, which calls for extensive preventive efforts.

Effect of low-level laser therapy (685 nm, 3 J/cm(2)) on functional recovery of the sciatic nerve in rats following crushing lesion.

Previous studies have shown that low-level laser therapy (LLLT) promotes posttraumatic nerve regeneration. The objective of the present study was to assess the efficacy of 685-nm LLLT at the dosage of 3 J/cm(2) in the functional recovery of the sciatic nerve in rats following crushing injury. The left sciatic nerves of 20 male Wistar rats were subjected to controlled crush injury by a hemostatic tweezers, and the rats were randomly allocated into two experimental groups as follows: control group and laser group. Laser irradiation (685 nm wavelength; 15 mW, CW, 3 J/cm(2), spot of 0.028 cm(2)) was started on the postsurgical first day, above the site of injury, and was continued for 21 consecutive days. Functional recovery was evaluated at 3 weeks postoperatively by measuring the sciatic functional index (SFI) and sciatic static index (SSI) at weekly intervals. The treated rats showed improvement in motion pattern. The SFI and SSI results were significant when comparing two groups on the 14th and 21st postoperative days (p < 0.05). There were intra-group differences detected in laser group in different periods (p < 0.05). Low-level laser irradiation, with the parameters used in the present study, accelerated and improved sciatic nerve function in rats after crushing injury.

Vulnerability of homeless people in Tehran, Iran, to HIV, tuberculosis and viral hepatitis.

BACKGROUND: Homeless people are at risk of contracting communicable infectious diseases, as they indulge in risky behaviours and lifestyle. This study was conducted to determine the prevalence of the aforementioned infections and related risk behaviours among homeless people in Tehran. METHODS: In this study a convenience sample of 593 homeless individuals was studied. The ELISA method was used for the detection of HIV, HCV and HBV. Clinical symptoms, sputum cultures, acid fast bacilli smears, and chest X-rays were used to identify active pulmonary tuberculosis, and the Interferon Gamma Release Assay (IGRA) test was used to identify latent tuberculosis. RESULTS: The prevalence of HIV, HBV, HCV and latent tuberculosis was 3.4%, 2.6%, 23.3% and 46.7%, respectively. Active pulmonary tuberculosis was found in 7 persons (1.2%). Injection drug use was an independent risk factor for HIV, HCV and HBV infections. Older people had a higher proportion of Mycobacterium tuberculosis infection (OR: 2.6, 95%CI: 1.9, 3.7) and HCV positivity (OR: 1.7, 95% CI: 1.1, 2.5). CONCLUSION: Our findings highlighted that much more attention needs to be paid to the health of homeless people.

Prevalence of transmitted HIV drug resistance in Iran between 2010 and 2011.

OBJECTIVE: Drug-resistant (DR) HIV emerges during combined antiretroviral treatment (cART), creating concern about widespread transmission of DR-HIV as cART is expanded in resource-limited countries. The aim of this study was to determine the predominant HIV-1 subtypes and prevalence of transmitted DR mutations among antiretroviral-naïve patients in Iran. DESIGN: To monitor transmission of DR HIV, a threshold surveillance based on the world health organization (WHO) guidelines was implemented in Iran. METHODS: For this HIVDR threshold surveillance study, blood samples were collected from 50 antiretroviral-naïve HIV-1-infected patients. Antiretroviral-resistant mutations were determined by sequencing HIV-1 protease, reverse transcriptase and integrase regions. The HIV-1 subtype was determined by sequencing the p17 and C2-V5 regions of the gag and env genes, respectively. RESULTS: Phylogenetic analyses of the sequenced regions revealed that 45 (95.7%) of 47 samples that were successfully obtained were CRF35_AD. The remaining two cases were subtype B (2.1%) and CRF01_AE (2.1%). Consistent results were obtained also from Env and Gag sequences. Regarding prevalence of transmitted DR viruses, two cases were found to harbor reverse transcriptase-inhibitor-resistant mutations (4.3%). In addition, although not in the WHO list for surveillance of transmitted mutations, 13 minor protease-inhibitor-resistant mutations listed in the International AIDS Society-USA panel of drug resistance mutations were found. No DR mutations were detected in the integrase region. CONCLUSIONS: Our study clarified that CRF35_AD is the major subtype among HIV-1-infected patients in Iran. According to the WHO categorization method of HIVDR threshold survey, the prevalence of transmitted drug resistant HIV in Iran was estimated as moderate (5-15%).

Molecular epidemiology of HIV type 1 infection in Iran: genomic evidence of CRF35_AD predominance and CRF01_AE infection among individuals associated with injection drug use.

To understand the molecular epidemiology of HIV-1 infection in Iran, we conducted the first study to analyze the genome sequence of Iranian HIV-1 isolates. For this cross-sectional study, we enrolled 10 HIV-1-infected individuals associated with injection drug use from Tehran, Shiraz, and Kermanshah. Near full-length genome sequences obtained from their plasma samples were used for phylogenetic tree and similarity plotting analyses. Among 10 isolates, nine were clearly identified as CRF35_AD and the remaining one as CRF01_AE. Interestingly, five of our Iranian CRF35_AD isolates made two clusters with 10 Afghan CRF35_AD isolates in a phylogenetic tree, indicating epidemiological connections among injection drug users in Iran and Afghanistan. In contrast, our CRF01_AE isolate had no genetic relationship with any other CRF01_AE isolates worldwide, even from Afghanistan. This study provides the first genomic evidence of HIV-1 CRF35_AD predominance and CRF01_AE infection among individuals associated with injection drug use in Iran.