Acute occupational inhalation injuries-United States, 2011-2022

BACKGROUND

Inhalation injuries due to acute occupational exposures to chemicals are preventable. National surveillance of acute inhalation exposures is limited. This study identified the most common acute inhalation exposure-related incidents by industry sector among US workers.

METHODS

To characterize inhalation-related injuries and their exposures during April 2011-March 2022, state and federal records from the Occupational Safety and Health Administration (OSHA) Occupational Safety and Health Information System (OIS) accident database were analyzed. Industry-specific injury, hospitalization, and fatality rates were calculated.

RESULTS

The most frequent acute inhalation incidents investigated by OSHA were caused by inorganic gases (52.9%) such as carbon monoxide (CO) or acids, bases, and oxidizing chemical agents (12.9%) such as anhydrous ammonia. The largest number of fatal and nonfatal injuries were reported in the manufacturing (28.6%) and construction (17.2%) sectors.

CONCLUSIONS

Workers were affected by acute inhalation exposures in most industries. Using this surveillance, employers can recognize frequently-occurring preventable acute inhalation exposures by industry, such as inorganic gases in the manufacturing sector, and implement prevention measures. Training of workers on exposure characteristics and limits, adverse health effects, and use of protective equipment by exposure agent can prevent inhalation injuries.

Progressive Massive Fibrosis Identified at Federally Funded Black Lung Clinics in the US

This study of US Black Lung Clinics (established to treat coal miners) reports the prevalence of progressive massive fibrosis identified through June 2023.

Assessment of the Respiratory Health of Working US Coal Miners Since 2014-Radiography, Spirometry, and Symptom Assessments

OBJECTIVE

The aim of the study is to summarize Coal Workers' Health Surveillance Program findings since 2014, focusing on prevalence of radiographic pneumoconiosis and abnormal spirometry by region.

METHODS

Analysis included the most recent Coal Workers' Health Surveillance Program encounter for working miners during October 1, 2014-June 30, 2022. Central Appalachia consists of Kentucky, Virginia, and West Virginia.

RESULTS

Pneumoconiosis prevalence was highest among underground miners, with 318 (6.2%) having radiographic evidence of disease. Central Appalachian miners were more likely to have evidence of pneumoconiosis (relative risk = 4.1 [3.4-5.0]) and abnormal spirometry (relative risk = 1.4 [1.2-1.6]) compared with all others.

CONCLUSIONS

Central Appalachia is a hotspot for pneumoconiosis, as well as for other indicators of respiratory impairment in coal miners. Outreach for occupational respiratory health surveillance should focus on those areas most heavily affected, ensuring that miners are not hindered by perceived or actual barriers to this secondary intervention.

Submission of mandatory respiratory health examinations among US coal miners participating in the Coal Workers' Health Surveillance Program

BACKGROUND

Mandatory examination requirements for US coal miners newly entering the workforce have been in place since the 1969 Coal Act mandated chest radiographs and were updated to include spirometry with promulgation of the 2014 Mine Safety and Health Administration Dust Rule. Compliance with the mandatory respiratory screening series is described using data from the National Institute for Occupational Safety and Health Coal Workers' Health Surveillance Program (CWHSP).

METHODS

Among all radiographic and spirometry submissions to the CWHSP during 30 June 1971-15 March 2022, new underground coal miners who began work in the industry after 30 June 1971, and new underground, surface miners and contractors who began work after new regulations were implemented 1 August 2014, were identified and included in analysis.

RESULTS

Of the 115 093 unique miners who participated in the CWHSP and whose estimated entry into mining occurred during 30 June 1971-15 March 2019, 50 487 (43.9%) received their initial mandatory radiograph, and 15 452 (13.4%) submitted their initial and 3-year mandatory radiographs. Since new regulations were implemented, compliance with initial radiographs appeared to improve (80%) but compliance with 3-year radiographs remained low (11.6%). Compliance with spirometry testing was also low for initial (17.1%) and follow-up screenings (2.7%).

CONCLUSIONS

The majority of new coal miners eligible for health surveillance did not receive a baseline radiograph or spirometry test through the CWHSP even though coal mine operators are required by law to provide these. Ensuring coal miners' regular participation in health surveillance from early in their careers is an important way to monitor and protect their respiratory health.

Increased odds of mortality from non-malignant respiratory disease and lung cancer are highest among US coal miners born after 1939

OBJECTIVES

Coal miners suffer increased mortality from non-malignant respiratory diseases (NMRD), including pneumoconioses and chronic obstructive pulmonary disease, compared with the US population. We characterised mortality trends from NMRD, lung cancer and ischaemic heart disease (IHD) using data from the Federal Black Lung Program, National Coal Workers' Health Surveillance Program and the National Death Index.

METHODS

We compared mortality ORs (MORs) for NMRD, lung cancer and IHD in former US coal miners to US white males. MORs were computed for the study period 1979-2017 by birth cohort (<1920, 1920-1929, 1930-1939, ≥1940), with a subanalysis restricted to Central Appalachia.

RESULTS

The study population totalled 235 550 deceased miners, aged >45 years. Odds of death from NMRD and lung cancer across all miner birth cohorts averaged twice those of US males. In Central Appalachia, MORs significantly increased across birth cohorts. There was an eightfold increase in odds of death from NMRD among miners born after 1940 (MORBC≥1940 8.25; 95% CI 7.67 to 8.87). Miners with progressive massive fibrosis (PMF) were younger at death than those without PMF (74 vs 78 years; p<0.0001). We observed a pattern of reduced MORs from IHD in coal miners compared with national and regional counterparts.

CONCLUSION

US coal miners have excess mortality from NMRD and lung cancer compared with total US and Appalachian populations. Mortality is highest in the most recent birth cohorts, perhaps reflecting increased rates of severe pneumoconiosis.

Chronic Obstructive Pulmonary Disease Mortality by Industry and Occupation - United States, 2020

Chronic obstructive pulmonary disease (COPD), a progressive lung disease, is characterized by long-term respiratory symptoms and airflow limitation (1). COPD accounts for most of the deaths from chronic lower respiratory diseases, the sixth leading cause of death in the United States in 2020.* Workplace exposures and tobacco smoking are risk factors for COPD; however, one in four workers with COPD have never smoked (2-4). To describe COPD mortality among U.S. residents aged ≥15 years categorized as ever-employed (i.e., with information on their usual industry and occupation), CDC analyzed the most recent 2020 multiple cause-of-death data^† from 46 states and New York City.^§ Among 3,077,127 decedents, 316,023 (10.3%) had COPD^¶ listed on the death certificate. The highest age-adjusted** COPD death rates per 100,000 ever-employed persons were for females (101.3), White persons (116.9), and non-Hispanic or Latino (non-Hispanic) persons (115.8). The highest proportionate mortality ratios (PMRs)^†† were for workers employed in the mining industry (1.3) and in food preparation and serving related occupations (1.3). Elevated COPD mortality among workers in certain industries and occupations underscores the importance of targeted interventions (e.g., reduction or elimination of COPD-associated risk factors, engineering controls, and workplace smoke-free policies) to prevent COPD from developing and to intervene before illness becomes symptomatic or severe.

Postexposure progression of pneumoconiosis among former Appalachian coal miners

BACKGROUND

The prevalence of pneumoconiosis among working United States underground coal miners has been increasing for the past two decades, with the highest rates of disease observed among miners in the central Appalachian states of Kentucky, Virginia, and West Virginia. Surveillance for this disease in the United States focuses on working coal miners, who continue to be occupationally exposed to dust. This study examines the radiographic evidence for postexposure progression of pneumoconiosis in a population of former coal miners no longer occupationally exposed to coal mine dust who were seen at a community radiology clinic in eastern Kentucky.

METHODS

Data were obtained and analyzed from clinical records of former coal miners who had a clinic encounter during January 1, 2017-August 1, 2019, a recorded final year of employment, and ≥2 postemployment digital chest radiographs. Radiographs were classified according to the International Labour Office guidelines by at least two B Readers. A final summary pneumoconiosis severity score (range, 0-13), accounting for both small and large opacities, was assigned to each chest radiograph. Progression was defined as an increase in severity score between a miner's radiographs over time.

RESULTS

Data for 130 former coal miners were analyzed. All miners were male and most (n = 114, 88%) had worked primarily in Kentucky. Information on race/ethnicity was not available. The most common job types were roof bolters (n = 51, 39%) and continuous miner operators (n = 46, 35%). Forty-one (31.5%) miners had evidence of radiographic disease progression after leaving the workforce, with a median of 3.6 years between first and latest postretirement radiograph. A total of 80 (62%) miners had evidence of pneumoconiosis on their latest radiograph, and two-thirds (n = 53) of these were classified as progressive massive fibrosis (PMF), the most severe form of the disease.

CONCLUSIONS

Postexposure progression can occur in former coal miners, emphasizing the potential benefits of continued radiographic follow-up postemployment. In addition to participating in disease screening throughout their careers to detect pneumoconiosis early and facilitate intervention, radiographic follow-up of former coal miners can identify new or progressive radiographic findings even after workplace exposure to respirable coal mine dust ends. Identification of progressive pneumoconiosis in former miners has potential implications for clinical management and eligibility for disability compensation.

Respiratory health of American Indian and Alaska Native coal miners participating in the Coal Workers' Health Surveillance Program, 2014-2019

BACKGROUND

In 2014, a federal rule reduced occupational exposure limits to coal mine dust and expanded medical surveillance eligibility beyond underground miners to surface and contract coal miners. This expansion may have provided an opportunity for more American Indian and Alaska Native (AI/AN) coal miners to participate in screening, since many surface coal mines are located near AI/AN communities and may employ AI/AN miners. Therefore we sought to better understand the respiratory health of AI/AN coal miners by characterizing prevalence of coal workers' pneumoconiosis (CWP), progressive massive fibrosis (PMF), and abnormal lung function in this population.

METHODS

Descriptive analysis of 1405 chest radiographs and 627 spirometry test results for AI/AN miners who participated in the Coal Workers' Health Surveillance Program (CWHSP) during 2014-2019 was conducted.

RESULTS

Most AI/AN miners (0-25+ years of tenure) were western United States residents (82.3%) and active surface miners (76.9%) with no underground tenure. Among miners with at least 10 years of tenure, prevalence of CWP was 3.0%, and of PMF was 0.3%. Lung function abnormalities were seen in 9.0% with primarily restrictive patterns.

CONCLUSIONS

The prevalence of CWP, PMF, and lung function abnormality among active and former AI/AN coal miners was higher than seen in a larger CWHSP study of active western miners working primarily underground with 10+ years of tenure. Interventions that eliminate or control coal mine dust exposure, identify miners with CWP early, and limit respiratory disease progression and complications remain vital for eliminating the preventable adverse health effects of coal mining. Comprehensive demographic data on the coal mining workforce are needed to improve CWHSP participation assessment.

Assessment of pneumoconiosis in surface coal miners after implementation of a national radiographic surveillance program, United States, 2014-2019

BACKGROUND

Pneumoconiosis can occur in surface coal miners. The Coal Workers' Health Surveillance Program (CWHSP) has only included surface coal miners as part of its regular disease surveillance since 2014. This analysis identifies the prevalence of pneumoconiosis among working surface coal miners participating in the CWHSP since their initial inclusion, through 2019.

METHODS

Working surface coal miners who had chest radiographs through the CWHSP from January 1, 2014 through December 31, 2019 were included in this analysis. Demographic information, mining tenure and occupation, and radiographic classifications according to the International Labour Office system were included from each miner's most recent encounter with the CWHSP. Prevalence ratios were calculated comparing the prevalence of the disease by region and occupation by log-binomial regression.

RESULTS

Pneumoconiosis was present in 109 (1.6%) surface coal miners, including 12 miners with progressive massive fibrosis, the most severe form of the disease. After taking surface mining tenure into account, surface miners in Central Appalachia (prevalence ratio [PR], 3.2; 95% confidence interval [CI], 2.2-4.7) and surface miners who worked as a driller or blaster (PR, 2.1; 95% CI, 1.3-3.5) were at increased risk of pneumoconiosis.

CONCLUSION

The occurrence of pneumoconiosis in surface coal miners supports including them within a systematic respiratory health surveillance program. The current surveillance findings are consistent with past findings of pneumoconiosis, particularly silicosis, in surface mining occupations such as drilling and blasting.

Interaction between host genes and Mycobacterium tuberculosis lineage can affect tuberculosis severity: Evidence for coevolution?

Genetic studies of both the human host and Mycobacterium tuberculosis (MTB) demonstrate independent association with tuberculosis (TB) risk. However, neither explains a large portion of disease risk or severity. Based on studies in other infectious diseases and animal models of TB, we hypothesized that the genomes of the two interact to modulate risk of developing active TB or increasing the severity of disease, when present. We examined this hypothesis in our TB household contact study in Kampala, Uganda, in which there were 3 MTB lineages of which L4-Ugandan (L4.6) is the most recent. TB severity, measured using the Bandim TBscore, was modeled as a function of host SNP genotype, MTB lineage, and their interaction, within two independent cohorts of TB cases, N = 113 and 121. No association was found between lineage and severity, but association between multiple polymorphisms in IL12B and TBscore was replicated in two independent cohorts (most significant rs3212227, combined p = 0.0006), supporting previous associations of IL12B with TB susceptibility. We also observed significant interaction between a single nucleotide polymorphism (SNP) in SLC11A1 and the L4-Ugandan lineage in both cohorts (rs17235409, meta p = 0.0002). Interestingly, the presence of the L4-Uganda lineage in the presence of the ancestral human allele associated with more severe disease. These findings demonstrate that IL12B is associated with severity of TB in addition to susceptibility, and that the association between TB severity and human genetics can be due to an interaction between genes in the two species, consistent with host-pathogen coevolution in TB.

Pneumoconiosis progression patterns in US coal miner participants of a job transfer programme designed to prevent progression of disease

OBJECTIVES

Pneumoconiosis prevalence and severity among US coal miners has been increasing for the past 20 years. An examination of the current approaches to primary and secondary prevention efforts is warranted. One method of secondary prevention is the Mine Safety and Health Administration-administered part 90 option programme where US coal miners with radiographic evidence of pneumoconiosis can exercise their right to be placed in a less dusty area of the mine. This study focuses on characterising the progression of disease among US coal miners who participated in the National Institute for Occupational Safety and Health-administered Coal Workers' Health Surveillance Programme (CWHSP) and exercised their part 90 job transfer option.

METHODS

Chest radiograph classifications of working underground coal miners who exercised their part 90 job transfer option during 1 January 1986 to 21 November 2016 and participated in the CWHSP during 1 January 1981 to 19 March 2019 were analysed.

RESULTS

513 miners exercised their part 90 option and participated in the CWHSP at least once during this time period. Of the 149 miners with ≥2 radiographs available, 48 (32%) showed progression after exercising part 90 and had more severe disease prior to exercising, compared with miners who did not progress (severity score of 2.8 vs 1.7, p=0.0002).

CONCLUSION

The part 90 job transfer option programme is not routinely used as intended to prevent progression of pneumoconiosis among US coal miners. The one-third of miners who participated in part 90 and continued to progress, exercised their part 90 option at a later stage of disease compared with non-progressors.

Cyclosporiasis Epidemiologically Linked to Consumption of Green Onions: Houston Metropolitan Area, August 2017

ABSTRACT

During July 2017, Texas public health officials noted an increase in the number of reported cyclosporiasis cases. They detected a cluster in the Houston metropolitan area that involved four locations of a Mediterranean restaurant chain, restaurant A. A case-control study was conducted among patrons of restaurant A to identify a common food vehicle among items containing fresh produce. In matched case-control ingredient-level analyses that included both probable and confirmed cases, consumption of green onions, red onions, tomatoes, and cabbage was significantly associated with illness. A substantial percentage of case patients reported consumption of green onions, and only green onions remained statistically significantly associated with illness, whether probable and confirmed cases were included in analyses (matched odds ratio: 11.3; 95% confidence interval: 2.5 to 104.7), or only confirmed cases were included in analyses (matched odds ratio: 17.6; 95% confidence interval: 2.5 to 775.7). These results provide evidence that green onions were the likely vehicle of infection. It was not possible to trace the green onions to their source due to the need to redirect public health resources to Hurricane Harvey response efforts in Texas.

HIGHLIGHTS

Continued increase in prevalence of r-type opacities among underground coal miners in the USA

INTRODUCTION

Respirable crystalline silica exposure has been implicated in the resurgence of coal workers' pneumoconiosis (CWP) in the USA. A 2010 report found an increasing prevalence of r-type opacities, which are associated with silicosis lung pathology, on the radiographs of working underground coal miners in central Appalachia. This analysis updates that report by assessing the prevalence of r-type opacities during 2010-2018 compared with earlier decades.

METHODS

Data from the Coal Workers' Health Surveillance Program were used to calculate the prevalence of r-type opacities on radiographs of working underground coal miners. The data were restricted to radiographs taken during 1 January 1980 to 15 September 2018. The presence of r-type opacities was defined as an r-type classification for either the primary or secondary shape/size of small opacities. Prevalence ratios for r-type opacities were calculated using log binomial regression.

RESULTS

Radiograph classifications for 106 506 miners were included in analysis. For the USA overall, the prevalence of r-type opacities among miners with radiographs taken during 2010-2018 compared with 1980-1989 has increased (PR 2.4; 95% CI 1.9 to 3.0). For central Appalachia, the proportion of r-type opacities observed increased when comparing 1980-1989 to 2010-2018 (PR 6.0; 95% CI 4.6 to 7.9).

CONCLUSIONS

The prevalence of r-type opacities on the radiographs of Appalachian underground coal miners continues to increase, implicating exposure to crystalline silica in respirable coal mine dust. The current findings underscore the importance of monitoring and controlling exposure to silica in coal mines.

Pre-Zika descriptive epidemiology of microcephaly in Texas, 2008-2012

BACKGROUND

There are limited population-based studies on microcephaly. We characterized the epidemiology of microcephaly in Texas during a 5-year period (2008-2012), prior to the Zika epidemic in the Western hemisphere (2015). The associations of suspected risk factors were compared across four clearly defined case groups.

METHODS

Data from the Texas Birth Defects Registry were used to calculate the prevalence of congenital microcephaly and crude and adjusted prevalence ratios using Poisson regression. Twelve maternal and infant factors were assessed across case groups, which included total (explained + unexplained), explained (e.g., syndromic), unexplained, and severe unexplained microcephaly (head circumference <3^rd percentile).

RESULTS

The birth prevalence for total and total severe microcephaly were 14.7 and 4.8 per 10,000 livebirths, respectively. For explained and unexplained cases, significantly elevated risks were noted for mothers who were older (35+), less educated (≤12 years), diabetic (pre-pregnancy or gestational), or had a preterm delivery. Unlike explained cases, however, mothers who were non-White or smoked had an increased risk for unexplained microcephaly. Furthermore, young maternal age (<20), multiparity, and higher BMI reduced the risk for unexplained microcephaly. For severe unexplained cases, the risk profile was similar to that for all unexplained cases-with the exception of null associations noted for diabetes and birth year.

CONCLUSIONS

We found that risk patterns for microcephaly varied across case groupings. Risk factors included maternal race/ethnicity, age, and smoking during pregnancy. Among severe unexplained cases, notable positive associations were seen among mothers who were non-Hispanic Black or less educated, while inverse associations were noted for obesity.

A chromosome 5q31.1 locus associates with tuberculin skin test reactivity in HIV-positive individuals from tuberculosis hyper-endemic regions in east Africa

One in three people has been infected with Mycobacterium tuberculosis (MTB), and the risk for MTB infection in HIV-infected individuals is even higher. We hypothesized that HIV-positive individuals living in tuberculosis-endemic regions who do not get infected by Mycobacterium tuberculosis are genetically resistant. Using an “experiment of nature” design that proved successful in our previous work, we performed a genome-wide association study of tuberculin skin test positivity using 469 HIV-positive patients from prospective study cohorts of tuberculosis from Tanzania and Uganda to identify genetic loci associated with MTB infection in the context of HIV-infection. Among these individuals, 244 tested were tuberculin skin test (TST) positive either at enrollment or during the >8 year follow up, while 225 were not. We identified a genome-wide significant association between a dominant model of rs877356 and binary TST status in the combined cohort (Odds ratio = 0.2671, p = 1.22x10^-8). Association was replicated with similar significance when examining TST induration as a continuous trait. The variant lies in the 5q31.1 region, 57kb downstream from IL9. Two-locus analyses of association of variants near rs877356 showed a haplotype comprised of rs877356 and an IL9 missense variant, rs2069885, had the most significant association (p = 1.59x10^-12). We also replicated previously linked loci on chromosomes 2, 5, and 11. IL9 is a cytokine produced by mast cells and T_H2 cells during inflammatory responses, providing a possible link between airway inflammation and protection from MTB infection. Our results indicate that studying uninfected, HIV-positive participants with extensive exposure increases the power to detect associations in complex infectious disease.

Approximately one-third of the world’s population has been exposed to Mycobacterium tuberculosis, the bacterium that causes tuberculosis. A small number of those infected develop active disease; however, there is a substantial portion of exposed people who do not even show evidence of an immunological response. These people who appear to resist infection, as measured by a negative tuberculin skin test, represent a subpopulation from which we can learn about resistance. We used a genome-wide approach to study the genetic basis of this resistance in unique cohorts of hypervulnerable, HIV-positive individuals from Uganda and Tanzania, in which exposure was virtually assured. We identified one locus that was highly significantly associated and conferred more than 70% protection from infection. The most significant variant, rs8773656, was near IL9 and SLC25A48, and a haplotype including this variant and a missense mutation in IL9 was even more significantly associated with negative skin tests. Although it is impossible based solely on our data to determine the causal variant or genes, IL9 is an attractive candidate as its product has previously been associated with bronchial hyperresponsiveness, thereby providing a possible link between inflammation and protection from Mycobacterium tuberculosis infection.

Associations of Toll-Like Receptor and β-Defensin Polymorphisms with Measures of Periodontal Disease (PD) in HIV+ North American Adults: An Exploratory Study

Polymorphisms in toll-like receptor (TLR) and β-defensin (DEFB) genes have been recognized as potential genetic factors that can influence susceptibility to and severity of periodontal diseases (PD). However, data regarding associations between these polymorphisms and PD are still scarce in North American populations, and are not available in HIV+ North American populations. In this exploratory study, we analyzed samples from HIV+ adults (n = 115), who received primary HIV care at 3 local outpatient HIV clinics and were monitored for PD status. We genotyped a total of 41 single nucleotide polymorphisms (SNPs) in 8 TLR genes and copy number variation (CNV) in DEFB4/103A. We performed regression analyses for levels of 3 periodontopathogens in subgingival dental plaques (Porphyromonas gingivalis [Pg], Treponema denticola [Td], and Tannerella forsythia [Tf]) and 3 clinical measures of PD (periodontal probing depth [PPD], gingival recession [REC], and bleeding on probing [BOP]). In all subjects combined, 2 SNPs in TLR1 were significantly associated with Td, and one SNP in TLR2 was significantly associated with BOP. One of the 2 SNPs in TLR1 was significantly associated with Td in Caucasians. In addition, another SNP in TLR1 and a SNP in TLR6 were also significantly associated with Td and Pg, respectively, in Caucasians. All 3 periodontopathogen levels were significantly associated with PPD and BOP, but none was associated with REC. Instrumental variable analysis showed that 8 SNPs in 6 TLR genes were significantly associated with the 3 periodontopathogen levels. However, associations between the 3 periodontopathogen levels and PPD or BOP were not driven by associations with these identified SNPs. No association was found between DEFB4/103A CNV and any periodontopathogen level or clinical measure in all samples, Caucasians, or African Americans. Our exploratory study suggests a role of TLR polymorphisms, particularly TLR1 and TLR6 polymorphisms, in PD in HIV+ North Americans.

A Locus at 5q33.3 Confers Resistance to Tuberculosis in Highly Susceptible Individuals

Immunosuppression resulting from HIV infection increases the risk of progression to active tuberculosis (TB) both in individuals newly exposed to Mycobacterium tuberculosis (MTB) and in those with latent infections. We hypothesized that HIV-positive individuals who do not develop TB, despite living in areas where it is hyperendemic, provide a model of natural resistance. We performed a genome-wide association study of TB resistance by using 581 HIV-positive Ugandans and Tanzanians enrolled in prospective cohort studies of TB; 267 of these individuals developed active TB, and 314 did not. A common variant, rs4921437 at 5q33.3, was significantly associated with TB (odds ratio = 0.37, p = 2.11 × 10(-8)). This variant lies within a genomic region that includes IL12B and is embedded in an H3K27Ac histone mark. The locus also displays consistent patterns of linkage disequilibrium across African populations and has signals of strong selection in populations from equatorial Africa. Along with prior studies demonstrating that therapy with IL-12 (the cytokine encoded in part by IL12B, associated with longer survival following MTB infection in mice deficient in CD4 T cells), our results suggest that this pathway might be an excellent target for the development of new modalities for treating TB, especially for HIV-positive individuals. Our results also indicate that studying extreme disease resistance in the face of extensive exposure can increase the power to detect associations in complex infectious disease.

CCR2, CCR5, and CXCL12 variation and HIV/AIDS in Papua New Guinea

Polymorphisms in chemokine receptors, serving as HIV co-receptors, and their ligands are among the well-known host genetic factors associated with susceptibility to HIV infection and/or disease progression. Papua New Guinea (PNG) has one of the highest adult HIV prevalences in the Asia-Pacific region. However, information regarding the distribution of polymorphisms in chemokine receptor (CCR5, CCR2) and chemokine (CXCL12) genes in PNG is very limited. In this study, we genotyped a total of nine CCR2-CCR5 polymorphisms, including CCR2 190G >A, CCR5 -2459G >A and Δ32, and CXCL12 801G >A in PNG (n=258), North America (n=184), and five countries in West Africa (n=178). Using this data, we determined previously characterized CCR5 haplotypes. In addition, based on the previously reported associations of CCR2 190, CCR5 -2459, CCR5 open reading frame, and CXCL12 801 genotypes with HIV acquisition and/or disease progression, we calculated composite full risk scores, considering both protective as well as susceptibility effects of the CXCL12 801 AA genotype. We observed a very high frequency of the CCR5 -2459A allele (0.98) in the PNG population, which together with the absence of Δ32 resulted in a very high frequency of the HHE haplotype (0.92). These frequencies were significantly higher than in any other population (all P-values<0.001). Regardless of whether we considered the CXCL12 801 AA genotype protective or susceptible, the risk scores were significantly higher in the PNG population compared with any other population (all P-values<0.001). The results of this study provide new insights regarding CCR5 variation in the PNG population, and suggest that the collective variation in CCR2, CCR5, and CXCL12 may increase the risk of HIV/AIDS in a large majority of Papua New Guineans.