Last data update: May 06, 2024. (Total: 46732 publications since 2009)
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Query Trace: Chen TH[original query] |
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How did the 2022 global mpox outbreak happen? A travel-associated case 6 months earlier may provide important clues
Kreuze MA , Minhaj FS , Duwell M , Gigante CM , Kim AM , Crum D , Perlmutter R , Rubin JH , Myers R , Lukula SL , Ravi-Caldwell N , Sockwell D , Chen TH , de Perio MA , Hughes CM , Davidson WB , Wilkins K , Baird N , Lowe D , Li Y , McCollum AM , Blythe D , Rao AK . Travel Med Infect Dis 2023 55 102618 Approximately 6 months before an unprecedented global mpox outbreak was first identified in the United Kingdom, an adult man was diagnosed with mpox in Maryland, USA [1]. At the time of the investigation, the case was only the eighth monkeypox virus (MPXV) infection diagnosed in a non-African country during the preceding 3 years, all of which were associated with recent travel to Nigeria [2]. One of these 8 imported cases occurred in Texas, USA four months earlier; that case exhibited features clinically consistent with those classically reported in Africa (i.e., large and diffuse lesions, high fever and prodromal symptoms, umbilicated lesions in the same stage of development on specific anatomic surfaces) [3]. In contrast, the Maryland case was milder in severity and had signs that, at the time, were considered unusual for mpox. Several aspects of the Maryland case are noteworthy and in retrospect may offer clues to the origins of the 2022 global mpox outbreak, as well as explain how mpox might have spread undetected before emerging as a global outbreak. |
Reducing travel-related SARS-CoV-2 transmission with layered mitigation measures: Symptom monitoring, quarantine, and testing (preprint)
Johansson MA , Wolford H , Paul P , Diaz PS , Chen TH , Brown CM , Cetron MS , Alvarado-Ramy F . medRxiv 2020 2020.11.23.20237412 Balancing the control of SARS-CoV-2 transmission with the resumption of travel is a global priority. Current recommendations include mitigation measures before, during, and after travel. Pre- and post-travel strategies including symptom monitoring, testing, and quarantine can be combined in multiple ways considering different trade-offs in feasibility, adherence, effectiveness, cost and adverse consequences. Here we use a mathematical model to analyze the expected effectiveness of symptom monitoring, testing, and quarantine under different estimates of the infectious period, test-positivity relative to time of infection, and test sensitivity to reduce the risk of transmission from infected travelers during and after travel. If infection occurs 0-7 days prior to travel, immediate isolation following symptom onset prior to or during travel reduces risk of transmission while traveling by 26-30%. Pre-departure testing can further reduce risk if testing is close to the time of departure. For example, testing on the day of departure can reduce risk while traveling by 37-61%. For transmission risk after travel with infection time up to 7 days prior to arrival at the destination, isolation based on symptom monitoring reduced introduction risk at the destination by 42-56%. A 14-day quarantine after arrival, without symptom monitoring or testing, can reduce risk by 97-100% on its own. However, a shorter quarantine of 7 days combined with symptom monitoring and a test on day 3-4 after arrival is also effective (95-99%) at reducing introduction risk and is less burdensome, which may improve adherence. To reduce the risk of introduction without quarantine, optimal test timing after arrival is close to the time of arrival; with effective quarantine after arrival, testing a few days later optimizes sensitivity to detect those infected immediately before or while traveling. These measures can complement recommendations such as social distancing, using masks, and hand hygiene, to further reduce risk during and after travel.Competing Interest StatementThe authors have declared no competing interest.Funding StatementNo external funding supported this research.Author DeclarationsI confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.YesThe details of the IRB/oversight body that provided approval or exemption for the research described are given below:Centers for Disease Control and PreventionAll necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived.YesI understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).YesI have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable.YesOnly publicly available data informed this research. |
SARS-CoV-2 cases reported on international arriving and domestic flights: United States, January 2020-December 2021
Preston LE , Rey A , Dumas S , Rodriguez A , Gertz AM , Delea KC , Alvarado-Ramy F , Christensen DL , Brown C , Chen TH . Am J Public Health 2023 113 (8) e1-e5 Objectives. To describe trends in the number of air travelers categorized as infectious with SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2; the virus that causes COVID-19) in the context of total US COVID-19 vaccinations administered, and overall case counts of SARS-CoV-2 in the United States. Methods. We searched the Quarantine Activity Reporting System (QARS) database for travelers with inbound international or domestic air travel, a positive SARS-CoV-2 lab result, and a surveillance categorization of SARS-CoV-2 infection reported during January 2020 to December 2021. Travelers were categorized as infectious during travel if they had arrival dates from 2 days before to 10 days after symptom onset or a positive viral test. Results. We identified 80 715 persons meeting our inclusion criteria; 67 445 persons (83.6%) had at least 1 symptom reported. Of 67 445 symptomatic passengers, 43 884 (65.1%) reported an initial symptom onset date after their flight arrival date. The number of infectious travelers mirrored the overall number of US SARS-CoV-2 cases. Conclusions. Most travelers in the study were asymptomatic during travel, and therefore unknowingly traveled while infectious. During periods of high community transmission, it is important for travelers to stay up to date with COVID-19 vaccinations and consider wearing a high-quality mask to decrease the risk of transmission. (Am J Public Health. Published online ahead of print June 15, 2023:e1-e5. https://doi.org/10.2105/AJPH.2023.307325). |
Adapting Longstanding Public Health Collaborations between Government of Kenya and CDC Kenya in Response to the COVID-19 Pandemic, 2020-2021.
Herman-Roloff A , Aman R , Samandari T , Kasera K , Emukule GO , Amoth P , Chen TH , Kisivuli J , Weyenga H , Hunsperger E , Onyango C , Juma B , Munyua P , Wako D , Akelo V , Kimanga D , Ndegwa L , Mohamed AA , Okello P , Kariuki S , DeCock KM , Bulterys M . Emerg Infect Dis 2022 28 (13) S159-s167 Kenya's Ministry of Health (MOH) and the US Centers for Disease Control and Prevention in Kenya (CDC Kenya) have maintained a 40-year partnership during which measures were implemented to prevent, detect, and respond to disease threats. During the COVID-19 pandemic, the MOH and CDC Kenya rapidly responded to mitigate disease impact on Kenya's 52 million residents. We describe activities undertaken jointly by the MOH and CDC Kenya that lessened the effects of COVID-19 during 5 epidemic waves from March through December 2021. Activities included establishing national and county-level emergency operations centers and implementing workforce development and deployment, infection prevention and control training, laboratory diagnostic advancement, enhanced surveillance, and information management. The COVID-19 pandemic provided fresh impetus for the government of Kenya to establish a national public health institute, launched in January 2022, to consolidate its public health activities and counter COVID-19 and future infectious, vaccine-preventable, and emerging zoonotic diseases. |
'They can stigmatize you': a qualitative assessment of the influence of school factors on engagement in care and medication adherence among adolescents with HIV in Western Kenya
Wiggins L , O'Malley G , Wagner AD , Mutisya I , Wilson KS , Lawrence S , Moraa H , Kinuthia J , Itindi J , Muhenje O , Chen TH , Singa B , McGrath CJ , Ngugi E , Katana A , Ng Ang AL , John-Stewart G , Kholer P , Beima-Sofie K . Health Educ Res 2022 37 (5) 355-363 School-related factors may influence retention in care and adherence to antiretroviral therapy (ART) among adolescents with human immunodeficiency virus (HIV). We analyzed data from in-depth interviews with 40 adolescents with HIV (aged 14 -19 years), 40 caregivers of adolescents with HIV, and 4 focus group discussions with healthcare workers to evaluate contextual factors affecting adherence to ART and clinic attendance among adolescents, with a focus on the school environment. Informed by Anderson's Model of Health Services Utilization, transcripts were systematically coded and synthesized to identify school-related themes. All groups identified the school environment as a critical barrier to engagement in HIV care and medication adherence for adolescents with HIV. Adolescent participants reported inflexible school schedules and disclosure to school staff as the biggest challenges adhering to clinic appointments and ART. Adolescents described experiencing stigma and discrimination by peers and school staff and would adjust when, where and how often they took ART to avoid inadvertent disclosure. Boarding school students faced challenges because they had limited private space or time. Caregivers were often instrumental in navigating school permissions, including identifying a treatment supporter among school staff. Additional research engaging school staff may guide interventions for schools to reduce stigma and improve adherence and retention. |
Monkeypox in a Traveler Returning from Nigeria - Dallas, Texas, July 2021.
Rao AK , Schulte J , Chen TH , Hughes CM , Davidson W , Neff JM , Markarian M , Delea KC , Wada S , Liddell A , Alexander S , Sunshine B , Huang P , Honza HT , Rey A , Monroe B , Doty J , Christensen B , Delaney L , Massey J , Waltenburg M , Schrodt CA , Kuhar D , Satheshkumar PS , Kondas A , Li Y , Wilkins K , Sage KM , Yu Y , Yu P , Feldpausch A , McQuiston J , Damon IK , McCollum AM . MMWR Morb Mortal Wkly Rep 2022 71 (14) 509-516 Monkeypox is a rare, sometimes life-threatening zoonotic infection that occurs in west and central Africa. It is caused by Monkeypox virus, an orthopoxvirus similar to Variola virus (the causative agent of smallpox) and Vaccinia virus (the live virus component of orthopoxvirus vaccines) and can spread to humans. After 39 years without detection of human disease in Nigeria, an outbreak involving 118 confirmed cases was identified during 2017-2018 (1); sporadic cases continue to occur. During September 2018-May 2021, six unrelated persons traveling from Nigeria received diagnoses of monkeypox in non-African countries: four in the United Kingdom and one each in Israel and Singapore. In July 2021, a man who traveled from Lagos, Nigeria, to Dallas, Texas, became the seventh traveler to a non-African country with diagnosed monkeypox. Among 194 monitored contacts, 144 (74%) were flight contacts. The patient received tecovirimat, an antiviral for treatment of orthopoxvirus infections, and his home required large-scale decontamination. Whole genome sequencing showed that the virus was consistent with a strain of Monkeypox virus known to circulate in Nigeria, but the specific source of the patient's infection was not identified. No epidemiologically linked cases were reported in Nigeria; no contact received postexposure prophylaxis (PEP) with the orthopoxvirus vaccine ACAM2000. |
Reducing travel-related SARS-CoV-2 transmission with layered mitigation measures: symptom monitoring, quarantine, and testing.
Johansson MA , Wolford H , Paul P , Diaz PS , Chen TH , Brown CM , Cetron MS , Alvarado-Ramy F . BMC Med 2021 19 (1) 94 BACKGROUND: Balancing the control of SARS-CoV-2 transmission with the resumption of travel is a global priority. Current recommendations include mitigation measures before, during, and after travel. Pre- and post-travel strategies including symptom monitoring, antigen or nucleic acid amplification testing, and quarantine can be combined in multiple ways considering different trade-offs in feasibility, adherence, effectiveness, cost, and adverse consequences. METHODS: We used a mathematical model to analyze the expected effectiveness of symptom monitoring, testing, and quarantine under different estimates of the infectious period, test-positivity relative to time of infection, and test sensitivity to reduce the risk of transmission from infected travelers during and after travel. RESULTS: If infection occurs 0-7 days prior to travel, immediate isolation following symptom onset prior to or during travel reduces risk of transmission while traveling by 30-35%. Pre-departure testing can further reduce risk, with testing closer to the time of travel being optimal even if test sensitivity is lower than an earlier test. For example, testing on the day of departure can reduce risk while traveling by 44-72%. For transmission risk after travel with infection time up to 7 days prior to arrival at the destination, isolation based on symptom monitoring reduced introduction risk at the destination by 42-56%. A 14-day quarantine after arrival, without symptom monitoring or testing, can reduce post-travel risk by 96-100% on its own. However, a shorter quarantine of 7 days combined with symptom monitoring and a test on day 5-6 after arrival is also effective (97--100%) at reducing introduction risk and is less burdensome, which may improve adherence. CONCLUSIONS: Quarantine is an effective measure to reduce SARS-CoV-2 transmission risk from travelers and can be enhanced by the addition of symptom monitoring and testing. Optimal test timing depends on the effectiveness of quarantine: with low adherence or no quarantine, optimal test timing is close to the time of arrival; with effective quarantine, testing a few days later optimizes sensitivity to detect those infected immediately before or while traveling. These measures can complement recommendations such as social distancing, using masks, and hand hygiene, to further reduce risk during and after travel. |
Noncommunicable disease burden among HIV patients in care: a national retrospective longitudinal analysis of HIV-treatment outcomes in Kenya, 2003-2013
Achwoka D , Waruru A , Chen TH , Masamaro K , Ngugi E , Kimani M , Mukui I , Oyugi JO , Mutave R , Achia T , Katana A , Ng'ang'a L , De Cock KM . BMC Public Health 2019 19 (1) 372 BACKGROUND: Over the last decade, the Kenyan HIV treatment program has grown exponentially, with improved survival among people living with HIV (PLHIV). In the same period, noncommunicable diseases (NCDs) have become a leading contributor to disease burden. We sought to characterize the burden of four major NCDs (cardiovascular diseases, cancer, chronic respiratory diseases and diabetes mellitus) among adult PLHIV in Kenya. METHODS: We conducted a nationally representative retrospective medical chart review of HIV-infected adults aged >/=15 years enrolled in HIV care in Kenya from October 1, 2003 through September 30, 2013. We estimated proportions of four NCD categories among PLHIV at enrollment into HIV care, and during subsequent HIV care visits. We compared proportions and assessed distributions of co-morbidities using the Chi-Square test. We calculated NCD incidence rates and their confidence intervals in assessing cofactors for developing NCDs. RESULTS: We analyzed 3170 records of HIV-infected patients; 2115 (66.3%) were from women. Slightly over half (51.1%) of patient records were from PLHIVs aged above 35 years. Close to two-thirds (63.9%) of PLHIVs were on ART. Proportion of any documented NCD among PLHIV was 11.5% (95% confidence interval [CI] 9.3, 14.1), with elevated blood pressure as the most common NCD 343 (87.5%) among PLHIV with a diagnosed NCD. Despite this observation, only 17 (4.9%) patients had a corresponding documented diagnosis of hypertension in their medical record. Overall NCD incidence rates for men and women were (42.3 per 1000 person years [95% CI 35.8, 50.1] and 31.6 [95% CI 27.7, 36.1], respectively. Compared to women, the incidence rate ratio for men developing an NCD was 1.3 [95% CI 1.1, 1.7], p = 0.0082). No differences in NCD incidence rates were seen by marital or employment status. At one year of follow up 43.8% of PLHIV not on ART had been diagnosed with an NCD compared to 3.7% of patients on ART; at five years the proportions with a diagnosed NCD were 88.8 and 39.2% (p < 0.001), respectively. CONCLUSIONS: PLHIV in Kenya have a high prevalence of NCD diagnoses. In the absence of systematic, effective screening, NCD burden is likely underestimated in this population. Systematic screening and treatment for NCDs using standard guidelines should be integrated into HIV care and treatment programs in sub-Saharan Africa. |
Persistence of Ebola virus after the end of widespread transmission in Liberia: an outbreak report.
Dokubo EK , Wendland A , Mate SE , Ladner JT , Hamblion EL , Raftery P , Blackley DJ , Laney AS , Mahmoud N , Wayne-Davies G , Hensley L , Stavale E , Fakoli L , Gregory C , Chen TH , Koryon A , Roth Allen D , Mann J , Hickey A , Saindon J , Badini M , Baller A , Clement P , Bolay F , Wapoe Y , Wiley MR , Logue J , Dighero-Kemp B , Higgs E , Gasasira A , Williams DE , Dahn B , Kateh F , Nyenswah T , Palacios G , Fallah MP . Lancet Infect Dis 2018 18 (9) 1015-1024 BACKGROUND: Outbreak response efforts for the 2014-15 Ebola virus disease epidemic in west Africa brought widespread transmission to an end. However, subsequent clusters of infection have occurred in the region. An Ebola virus disease cluster in Liberia in November, 2015, that was identified after a 15-year-old boy tested positive for Ebola virus infection in Monrovia, raised the possibility of transmission from a persistently infected individual. METHODS: Case investigations were done to ascertain previous contact with cases of Ebola virus disease or infection with Ebola virus. Molecular investigations on blood samples explored a potential linkage between Ebola virus isolated from cases in this November, 2015, cluster and epidemiologically linked cases from the 2014-15 west African outbreak, according to the national case database. FINDINGS: The cluster investigated was the family of the index case (mother, father, three siblings). Ebola virus genomes assembled from two cases in the November, 2015, cluster, and an epidemiologically linked Ebola virus disease case in July, 2014, were phylogenetically related within the LB5 sublineage that circulated in Liberia starting around August, 2014. Partial genomes from two additional individuals, one from each cluster, were also consistent with placement in the LB5 sublineage. Sequencing data indicate infection with a lineage of the virus from a former transmission chain in the country. Based on serology and epidemiological and genomic data, the most plausible scenario is that a female case in the November, 2015, cluster survived Ebola virus disease in 2014, had viral persistence or recurrent disease, and transmitted the virus to three family members a year later. INTERPRETATION: Investigation of the source of infection for the November, 2015, cluster provides evidence of Ebola virus persistence and highlights the risk for outbreaks after interruption of active transmission. These findings underscore the need for focused prevention efforts among survivors and sustained capacity to rapidly detect and respond to new Ebola virus disease cases to prevent recurrence of a widespread outbreak. FUNDING: US Centers for Disease Control and Prevention, Defense Threat Reduction Agency, and WHO. |
Conveyance contact investigation for imported Middle East Respiratory Syndrome cases, United States, May 2014
Lippold SA , Objio T , Vonnahme L , Washburn F , Cohen NJ , Chen TH , Edelson PJ , Gulati R , Hale C , Harcourt J , Haynes L , Jewett A , Jungerman R , Kohl KS , Miao C , Pesik N , Regan JJ , Roland E , Schembri C , Schneider E , Tamin A , Tatti K , Alvarado-Ramy F . Emerg Infect Dis 2017 23 (9) 1585-1589 In 2014, the Centers for Disease Control and Prevention conducted conveyance contact investigations for 2 Middle East respiratory syndrome cases imported into the United States, comprising all passengers and crew on 4 international and domestic flights and 1 bus. Of 655 contacts, 78% were interviewed; 33% had serologic testing. No secondary cases were identified. |
Chikungunya virus disease outbreak in Yap State, Federated States of Micronesia
Pastula DM , Hancock WT , Bel M , Biggs H , Marfel M , Lanciotti R , Laven J , Chen TH , Staples JE , Fischer M , Hills SL . PLoS Negl Trop Dis 2017 11 (3) e0005410 BACKGROUND: Chikungunya virus is a mosquito-borne alphavirus which causes an acute febrile illness associated with polyarthralgia. Beginning in August 2013, clinicians from the Yap State Department of Health in the Federated States of Micronesia (FSM) identified an unusual cluster of illness which was subsequently confirmed to be chikungunya virus disease. Chikungunya virus disease previously had not been recognized in FSM. METHODOLOGY/PRINCIPAL FINDINGS: Information from patients presenting to healthcare facilities was collected and analyzed. During August 11, 2013, to August 10, 2014, a total of 1,761 clinical cases were reported for an attack rate of 155 clinical cases per 1,000 population. Among residents of Yap Main Island, 3% were hospitalized. There were no deaths. The outbreak began on Yap Main Island and rapidly spread throughout Yap Main Island and to three neighboring islands. CONCLUSIONS/SIGNIFICANCE: Chikungunya virus can cause explosive outbreaks with substantial morbidity. Given the increasing globalization of chikungunya virus, strong surveillance systems and access to laboratory testing are essential to detect outbreaks. |
Travel and border health measures to prevent the international spread of Ebola
Cohen NJ , Brown CM , Alvarado-Ramy F , Bair-Brake H , Benenson GA , Chen TH , Demma AJ , Holton NK , Kohl KS , Lee AW , McAdam D , Pesik N , Roohi S , Smith CL , Waterman SH , Cetron MS . MMWR Suppl 2016 65 (3) 57-67 During the 2014-2016 Ebola virus disease (Ebola) epidemic in West Africa, CDC implemented travel and border health measures to prevent international spread of the disease, educate and protect travelers and communities, and minimize disruption of international travel and trade. CDC staff provided in-country technical assistance for exit screening in countries in West Africa with Ebola outbreaks, implemented an enhanced entry risk assessment and management program for travelers at U.S. ports of entry, and disseminated information and guidance for specific groups of travelers and relevant organizations. New and existing partnerships were crucial to the success of this response, including partnerships with international organizations, such as the World Health Organization, the International Organization for Migration, and nongovernment organizations, as well as domestic partnerships with the U.S. Department of Homeland Security and state and local health departments. Although difficult to assess, travel and border health measures might have helped control the epidemic's spread in West Africa by deterring or preventing travel by symptomatic or exposed persons and by educating travelers about protecting themselves. Enhanced entry risk assessment at U.S. airports facilitated management of travelers after arrival, including the recommended active monitoring. These measures also reassured airlines, shipping companies, port partners, and travelers that travel was safe and might have helped maintain continued flow of passenger traffic and resources needed for the response to the affected region. Travel and border health measures implemented in the countries with Ebola outbreaks laid the foundation for future reconstruction efforts related to borders and travel, including development of regional surveillance systems, cross-border coordination, and implementation of core capacities at designated official points of entry in accordance with the International Health Regulations (2005). New mechanisms developed during this response to target risk assessment and management of travelers arriving in the United States may enhance future public health responses. The activities summarized in this report would not have been possible without collaboration with many U.S. and international partners (http://www.cdc.gov/vhf/ebola/outbreaks/2014-west-africa/partners.html). |
Measles outbreak associated with vaccine failure in adults - Federated States of Micronesia, February-August 2014
Breakwell L , Moturi E , Helgenberger L , Gopalani SV , Hales C , Lam E , Sharapov U , Larzelere M , Johnson E , Masao C , Setik E , Barrow L , Dolan S , Chen TH , Patel M , Rota P , Hickman C , Bellini W , Seward J , Wallace G , Papania M . MMWR Morb Mortal Wkly Rep 2015 64 (38) 1088-92 On May 15, 2014, CDC was notified of two laboratory-confirmed measles cases in the Federated States of Micronesia (FSM), after 20 years with no reported measles. FSM was assisted by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF), and CDC in investigating suspected cases, identify contacts, conduct analyses to guide outbreak vaccination response, and review vaccine cold chain practices. During February-August, three of FSM's four states reported measles cases: Kosrae (139 cases), Pohnpei (251), and Chuuk (3). Two thirds of cases occurred among adults aged >/=20 years; of these, 49% had received >/=2 doses of measles-containing vaccine (MCV). Apart from infants aged <12 months who were too young for routine vaccination, measles incidence was lower among children than adults. A review of current cold chain practices in Kosrae revealed minor weaknesses; however, an absence of historical cold chain maintenance records precluded an evaluation of earlier problems. Each state implemented vaccination campaigns targeting children as young as age 6 months through adults up to age 57 years. The preponderance of cases in this outbreak associated with vaccine failure in adults highlights the need for both thorough case investigation and epidemiologic analysis to guide outbreak response vaccination. Routine childhood vaccination coverage achieved in recent years limited the transmission of measles among children. Even in areas where transmission has not occurred for years, maintaining high 2-dose MCV coverage through routine and supplemental immunization is needed to prevent outbreaks resulting from increased measles susceptibility in the population. |
Evolution of Ebola virus disease from exotic infection to global health priority, Liberia, mid-2014
Arwady MA , Bawo L , Hunter JC , Massaquoi M , Matanock A , Dahn B , Ayscue P , Nyenswah T , Forrester JD , Hensley LE , Monroe B , Schoepp RJ , Chen TH , Schaecher KE , George T , Rouse E , Schafer IJ , Pillai SK , De Cock KM . Emerg Infect Dis 2015 21 (4) 578-584 Over the span of a few weeks during July and August 2014, events in West Africa changed perceptions of Ebola virus disease (EVD) from an exotic tropical disease to a priority for global health security. We describe observations during that time of a field team from the Centers for Disease Control and Prevention and personnel of the Liberian Ministry of Health and Social Welfare. We outline the early epidemiology of EVD within Liberia, including the practical limitations on surveillance and the effect on the country's health care system, such as infections among health care workers. During this time, priorities included strengthening EVD surveillance; establishing safe settings for EVD patient care (and considering alternative isolation and care models when Ebola Treatment Units were overwhelmed); improving infection control practices; establishing an incident management system; and working with Liberian airport authorities to implement EVD screening of departing passengers. |
Airport exit and entry screening for Ebola - August-November 10, 2014
Brown CM , Aranas AE , Benenson GA , Brunette G , Cetron M , Chen TH , Cohen NJ , Diaz P , Haber Y , Hale CR , Holton K , Kohl K , Le AW , Palumbo GJ , Pearson K , Phares CR , Alvarado-Ramy F , Roohi S , Rotz LD , Tappero J , Washburn FM , Watkins J , Pesik N . MMWR Morb Mortal Wkly Rep 2014 63 (49) 1163-7 In response to the largest recognized Ebola virus disease epidemic now occurring in West Africa, the governments of affected countries, CDC, the World Health Organization (WHO), and other international organizations have collaborated to implement strategies to control spread of the virus. One strategy recommended by WHO calls for countries with Ebola transmission to screen all persons exiting the country for "unexplained febrile illness consistent with potential Ebola infection." Exit screening at points of departure is intended to reduce the likelihood of international spread of the virus. To initiate this strategy, CDC, WHO, and other global partners were invited by the ministries of health of Guinea, Liberia, and Sierra Leone to assist them in developing and implementing exit screening procedures. Since the program began in August 2014, an estimated 80,000 travelers, of whom approximately 12,000 were en route to the United States, have departed by air from the three countries with Ebola transmission. Procedures were implemented to deny boarding to ill travelers and persons who reported a high risk for exposure to Ebola; no international air traveler from these countries has been reported as symptomatic with Ebola during travel since these procedures were implemented. |
Characteristics of a dengue outbreak in a remote Pacific island chain - Republic of the Marshall Islands, 2011-2012
Sharp TM , Mackay AJ , Santiago GA , Hunsperger E , Nilles EJ , Perez-Padilla J , Tikomaidraubuta KS , Colon C , Amador M , Chen TH , Lalita P , Munoz-Jordan JL , Barrera R , Langidrik J , Tomashek KM . PLoS One 2014 9 (9) e108445 Dengue is a potentially fatal acute febrile illness caused by four mosquito-transmitted dengue viruses (DENV-1-4). Although dengue outbreaks regularly occur in many regions of the Pacific, little is known about dengue in the Republic of the Marshall Islands (RMI). To better understand dengue in RMI, we investigated an explosive outbreak that began in October 2011. Suspected cases were reported to the Ministry of Health, serum specimens were tested with a dengue rapid diagnostic test (RDT), and confirmatory testing was performed using RT-PCR and IgM ELISA. Laboratory-positive cases were defined by detection of DENV nonstructural protein 1 by RDT, DENV nucleic acid by RT-PCR, or anti-DENV IgM antibody by RDT or ELISA. Secondary infection was defined by detection of anti-DENV IgG antibody by ELISA in a laboratory-positive acute specimen. During the four months of the outbreak, 1,603 suspected dengue cases (3% of the RMI population) were reported. Of 867 (54%) laboratory-positive cases, 209 (24%) had dengue with warning signs, six (0.7%) had severe dengue, and none died. Dengue incidence was highest in residents of Majuro and individuals aged 10-29 years, and approximately 95% of dengue cases were experiencing secondary infection. Only DENV-4 was detected by RT-PCR, which phylogenetic analysis demonstrated was most closely related to a virus previously identified in Southeast Asia. Cases of vertical DENV transmission, and DENV/Salmonella Typhi and DENV/Mycobacterium leprae co-infection were identified. Entomological surveys implicated water storage containers and discarded tires as the most important development sites for Aedes aegypti and Ae. albopictus, respectively. Although this is the first documented dengue outbreak in RMI, the age groups of cases and high prevalence of secondary infection demonstrate prior DENV circulation. Dengue surveillance should continue to be strengthened in RMI and throughout the Pacific to identify and rapidly respond to future outbreaks. |
The role of nodose ganglia in the regulation of cardiovascular function following pulmonary exposure to ultrafine titanium dioxide
Kan H , Wu Z , Lin YC , Chen TH , Cumpston JL , Kashon ML , Leonard S , Munson AE , Castranova V . Nanotoxicology 2014 8 (4) 447-54 The inhalation of nanosized air pollutant particles is a recognised risk factor for cardiovascular disease; however, the link between occupational exposure to engineered nanoparticles and adverse cardiovascular events remains unclear. In the present study, the authors demonstrated that pulmonary exposure of rats to ultrafine titanium dioxide (UFTiO2) significantly increased heart rate and depressed diastolic function of the heart in response to isoproterenol. Moreover, pulmonary inhalation of UFTiO2 elevated mean and diastolic blood pressure in response to norepinephrine. Pretreatment of the rats ip with the transient receptor potential (TRP) channel blocker ruthenium red inhibited substance P synthesis in nodose ganglia and associated functional and biological changes in the cardiovascular system. In conclusion, the effects of pulmonary inhalation of UFTiO2 on cardiovascular function are most likely triggered by a lung-nodose ganglia-regulated pathway via the activation of TRP channels in the lung. |
Effect of multi-walled carbon nanotube surface modification on bioactivity in the C57BL/6 mouse model
Sager TM , Wolfarth MW , Andrew M , Hubbs A , Friend S , Chen TH , Porter DW , Wu N , Yang F , Hamilton RF , Holian A . Nanotoxicology 2014 8 (3) 317-27 The current study tests the hypothesis that multi-walled carbon nanotubes (MWCNT) with different surface chemistries exhibit different bioactivity profiles in vivo. In addition, the study examined the potential contribution of the NLRP3 inflammasome in MWCNT-induced lung pathology. Unmodified (BMWCNT) and MWCNT that were surface functionalised with -COOH (FMWCNT), were instilled into C57BL/6 mice. The mice were then examined for biomarkers of inflammation and injury, as well as examined histologically for development of pulmonary disease as a function of dose and time. Biomarkers for pulmonary inflammation included cytokines, mediators and the presence of inflammatory cells (IL-1beta, IL-18, IL-33, cathepsin B and neutrophils) and markers of injury (albumin and lactate dehydrogenase). The results show that surface modification by the addition of the -COOH group to the MWCNT, significantly reduced the bioactivity and pathogenicity. The results of this study also suggest that in vivo pathogenicity of the BMWCNT and FMWCNT correlates with activation of the NLRP3 inflammasome in the lung. |
Public health needs assessments of Tutuila Island, American Samoa, after the 2009 tsunami
Choudhary E , Chen TH , Martin C , Vagi S , Roth J Jr , Keim M , Noe R , Ponausuia SE , Lemusu S , Bayleyegn T , Wolkin A . Disaster Med Public Health Prep 2012 6 (3) 209-16 OBJECTIVE: An 8.3 magnitude earthquake followed by tsunami waves devastated American Samoa on September 29, 2009, resulting in widespread loss of property and public services. An initial and a follow-up Community Needs Assessment for Public Health Emergency Response (CASPER) objectively quantified disaster-affected population needs. METHODS: Using a 2-stage cluster sampling method of CASPER, a household questionnaire eliciting information about medical and basic needs, illnesses, and injuries was administered. To assess response efforts, percent changes in basic and medical needs, illnesses, and injuries between the initial and follow-up CASPER were calculated. RESULTS: During the initial CASPER (N = 212 households), 47.6% and 51.6% of households reported needing a tarpaulin and having no electricity, respectively. The self-reported greatest needs were water (27.8%) and financial help with cleanup (25.5%). The follow-up CASPER (N = 207 households) identified increased vector problems compared to pre-tsunami, and food (26%) was identified as the self-reported greatest need. As compared to the initial CASPER, the follow-up CASPER observed decreases in electricity (-78.3%), drinking water (-44.4%), and clothing (-26.6%). CONCLUSION: This study highlights the use of CASPER during the response and recovery phases following a disaster. The initial CASPER identified basic needs immediately after the earthquake, whereas the follow-up CASPER assessed effectiveness of relief efforts and identified ongoing community needs. |
Epidemiology of a mumps outbreak in a highly vaccinated island population and use of a third dose of measles-mumps-rubella vaccine for outbreak control- Guam 2009-2010
Nelson GE , Aguon A , Valencia E , Oliva R , Guerrero ML , Reyes R , Lizama A , Diras D , Mathew A , Camacho EJ , Monforte MN , Chen TH , Mahamud A , Kutty PK , Hickman C , Bellini WJ , Seward JF , Gallagher K , Fiebelkorn AP . Pediatr Infect Dis J 2012 32 (4) 374-80 BACKGROUND: Despite high two-dose measles-mumps-rubella (MMR) vaccine coverage, a large mumps outbreak occurred on the U.S. Territory of Guam during 2009-2010, primarily in school-aged children. METHODS: We implemented active surveillance in April 2010 during the outbreak peak and characterized the outbreak epidemiology. We administered third doses of MMR vaccine to eligible students aged 9-14 years in 7 schools with the highest attack rates (ARs) between 5/18/2010-5/21/2010. Baseline surveys, follow-up surveys, and case-reports were used to determine mumps vaccine ARs. Adverse events post-vaccination were monitored. RESULTS: Between 12/1/2009-12/31/2010, 505 mumps cases were reported. Self-reported Pohnpeians and Chuukese had the highest relative risks (54.7 and 19.7, respectively) and highest crowding indices (mean: 3.1 and 3.0 persons/bedroom, respectively). Among 287 (57%) school-aged case-patients, 270 (93%) had ≥2 MMR doses. A third MMR dose was administered to 1068 (33%) eligible students. Three-dose vaccinated students had an AR of 0.9/1000 compared with 2.4/1000 among students vaccinated with ≤2 doses more than1 incubation period pos-intervention, but the difference was not significant (p= 0.67). No serious adverse events were reported. CONCLUSIONS: This mumps outbreak occurred in a highly vaccinated population. The highest ARs occurred in ethnic minority populations with the highest household crowding indices. After the third dose MMR intervention in highly affected schools, three-dose recipients had an AR 60% lower than students with ≤2 doses, but the difference was not statistically significant and the intervention occurred after the outbreak peaked. This outbreak may have persisted due to crowding at home and high student contact rates. |
Japanese encephalitis virus genotype replacement, Taiwan, 2009-2010.
Chen YY , Fan YC , Tu WC , Chang RY , Shih CC , Lu IH , Chien MS , Lee WC , Chen TH , Chang GJ , Chiou SS . Emerg Infect Dis 2011 17 (12) 2354-6 Genotype I of Japanese encephalitis virus first appeared in Taiwan in 2008. Phylogenetic analysis of 37 viruses from pig farms in 2009-2010 classified these viruses into 2 unique subclusters of genotype I viruses and suggested multiple introductions and swift replacement of genotype III by genotype I virus in Taiwan. |
Pulmonary exposure of rats to ultrafine titanium dioxide enhances cardiac protein phosphorylation and substance P synthesis in nodose ganglia
Kan H , Wu Z , Young SH , Chen TH , Cumpston JL , Chen F , Kashon ML , Castranova V . Nanotoxicology 2011 6 (7) 736-45 The inhalation of engineered nanoparticles stimulates the development of atherosclerosis and impairs vascular function. However, the cardiac effects of inhaled engineered nanoparticles are unknown. Here, we investigate the effects of ultrafine titanium dioxide (UFTiO(2)) on the heart, and we define the possible mechanisms underlying the measured effects. Pulmonary exposure of rats to UFTiO(2) increased the phosphorylation levels of p38 mitogen-activated protein kinase and cardiac troponin I, but not Akt, in the heart and substance P synthesis in nodose ganglia. Circulatory levels of pro-inflammatory cytokines, and blood cell counts and differentials were not significantly changed after pulmonary exposure. Separately, the incubation of cardiac myocytes isolated from naive adult rat hearts in vitro with UFTiO(2) did not alter the phosphorylation status of the same cardiac proteins. In conclusion, the inhalation of UFTiO(2) enhanced the phosphorylation levels of cardiac proteins. Such responses are likely independent of systemic inflammation, but may involve a lung-neuron-regulated pathway. |
Point-of-use membrane filtration and hyperchlorination to prevent patient exposure to rapidly growing mycobacteria in the potable water supply of a skilled nursing facility
Williams MM , Chen TH , Keane T , Toney N , Toney S , Armbruster CR , Butler WR , Arduino MJ . Infect Control Hosp Epidemiol 2011 32 (9) 837-44 BACKGROUND: Healthcare-associated outbreaks and pseudo-outbreaks of rapidly growing mycobacteria (RGM) are frequently associated with contaminated tap water. A pseudo-outbreak of Mycobacterium chelonae-M. abscessus in patients undergoing bronchoscopy was identified by 2 acute care hospitals. RGM was identified in bronchoscopy specimens of 28 patients, 25 of whom resided in the same skilled nursing facility (SNF). An investigation ruled out bronchoscopy procedures, specimen collection, and scope reprocessing at the hospitals as sources of transmission. OBJECTIVE: To identify the reservoir for RGM within the SNF and evaluate 2 water system treatments, hyperchlorination and point-of-use (POU) membrane filters, to reduce RGM. DESIGN: A comparative in situ study of 2 water system treatments to prevent RGM transmission. SETTING: An SNF specializing in care of patients requiring ventilator support. METHODS: RGM and heterotrophic plate count (HPC) bacteria were examined in facility water before and after hyperchlorination and in a subsequent 24-week assessment of filtered water by colony enumeration on Middlebrook and R2A media. RESULTS: Mycobacterium chelonae was consistently isolated from the SNF water supply. Hyperchlorination reduced RGM by 1.5 log(10) initially, but the population returned to original levels within 90 days. Concentration of HPC bacteria also decreased temporarily. RGM were reduced below detection level in filtered water, a 3-log(10) reduction. HPC bacteria were not recovered from newly installed filters, although low quantities were found in water from 2-week-old filters. CONCLUSION: POU membrane filters may be a feasible prevention measure for healthcare facilities to limit exposure of sensitive individuals to RGM in potable water systems. |
Measles outbreak associated with an international youth sporting event in the United States, 2007
Chen TH , Kutty P , Lowe LE , Hunt EA , Blostein J , Espinoza R , Dykewicz CA , Redd S , Rota JS , Rota PA , Lute JR , Lurie P , Nguyen MD , Moll M , Reef SE , Sinclair JR , Bellini WJ , Seward JF , Ostroff SM . Pediatr Infect Dis J 2010 29 (9) 794-800 BACKGROUND: Despite elimination of endemic measles in the United States (US), outbreaks associated with imported measles continue to occur. In 2007, the initiation of a multistate measles outbreak was associated with an imported case occurring in a participant at an international youth sporting event held in Pennsylvania. METHODS: Case finding and contact tracing were conducted. Control measures included isolating ill persons and administering postexposure prophylaxis to exposed persons without documented measles immunity. Laboratory evaluation of suspected cases and contacts included measles serologic testing, viral culture, detection of viral RNA by reverse-transcription polymerase chain reaction, and viral genotyping. RESULTS: The index case occurred in a child from Japan aged 12 years. Contact tracing among 1250 persons in 8 states identified 7 measles cases; 5 (71%) cases occurred among persons without documented measles vaccination. Epidemiologic and laboratory investigation supported a single chain of transmission, linking the outbreak to contemporaneous measles virus genotype D5 transmission in Japan. Of the 471 event participants, 193 (41%) lacked documentation of presumed measles immunity, 94 (49%) of 193 were US-resident adults, 19 (10%) were non-US-resident adults (aged >18 years), and 80 (41%) were non-US-resident children. DISCUSSION: Measles outbreaks associated with imported disease are likely to continue in the US. Participants in international events, international travelers, and persons with routine exposure to such travelers might be at greater risk of measles. To reduce the impact of imported cases, high measles, mumps, and rubella vaccine coverage rates should be maintained throughout the US, and support should continue for global measles control and elimination. |
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