Climate Change and the Epidemiology of Infectious Diseases in the United States.

The earth is rapidly warming, driven by increasing atmospheric carbon dioxide and other gases that result primarily from fossil fuel combustion. In addition to causing arctic ice melting and extreme weather events, climatologic factors are linked strongly to the transmission of many infectious diseases. Changes in the prevalence of infectious diseases not only reflect the impacts of temperature, humidity, and other weather-related phenomena on pathogens, vectors, and animal hosts but are also part of a complex of social and environmental factors that will be affected by climate change, including land use, migration, and vector control. Vector- and waterborne diseases and coccidioidomycosis are all likely to be affected by a warming planet; there is also potential for climate-driven impacts on emerging infectious diseases and antimicrobial resistance. Additional resources for surveillance and public health activities are urgently needed, as well as systematic education of clinicians on the health impacts of climate change.

Infectious Diseases Physicians: Improving and Protecting the Public's Health: Why Equitable Compensation Is Critical.

Infectious diseases (ID) physicians play a crucial role in public health in a variety of settings. Unfortunately, much of this work is undercompensated despite the proven efficacy of public health interventions such as hospital acquired infection prevention, antimicrobial stewardship, disease surveillance, and outbreak response. The lack of compensation makes it difficult to attract the best and the brightest to the field of ID, threatening the future of the ID workforce. Here, we examine compensation data for ID physicians compared to their value in population and public health settings and suggest policy recommendations to address the pay disparities that exist between cognitive and procedural specialties that prevent more medical students and residents from entering the field. All ID physicians should take an active role in promoting the value of the subspecialty to policymakers and influencers as well as trainees.

Conveyance Contact Investigation for Imported Middle East Respiratory Syndrome Cases, United States, May 2014.

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.

Tracing Airline Travelers for a Public Health Investigation: Middle East Respiratory Syndrome Coronavirus (MERS-CoV) Infection in the United States, 2014.

OBJECTIVE: CDC routinely conducts contact investigations involving travelers on commercial conveyances, such as aircrafts, cargo vessels, and cruise ships. METHODS: The agency used established systems of communication and partnerships with other federal agencies to quickly provide accurate traveler contact information to states and jurisdictions to alert contacts of potential exposure to two travelers with Middle East Respiratory Syndrome Coronavirus (MERS-CoV) who had entered the United States on commercial flights in April and May 2014. RESULTS: Applying the same process used to trace and notify travelers during routine investigations, such as those for tuberculosis or measles, CDC was able to notify most travelers of their potential exposure to MERS-CoV during the first few days of each investigation. CONCLUSION: To prevent the introduction and spread of newly emerging infectious diseases, travelers need to be located and contacted quickly.

A survey of US travelers to Asia to assess compliance with recommendations for the use of Japanese encephalitis vaccine.

BACKGROUND: Japanese encephalitis (JE) vaccine is recommended for travelers to Asia whose itineraries increase their risk of exposure to JE virus. The numbers of travelers with such itineraries and the proportion of those who receive JE vaccine are unknown. We performed a survey to estimate the proportion of US travelers to Asia who receive JE vaccine according to the Advisory Committee on Immunization Practices (ACIP) recommendations. METHODS: We surveyed US residents ≥ 18 years old departing on 38 flights to Asia selected through a stratified random sample of all direct flights to JE-endemic countries from three US airports. We asked participants about planned itineraries and activities, sources of travel health information, JE vaccination status, and potential barriers to vaccination. Participants planning to spend ≥ 30 days in Asia or at least half of their time in rural areas were defined as "higher JE risk" travelers for whom vaccination should have been considered. RESULTS: Of 2,341 eligible travelers contacted, 1,691(72%) completed the survey. Among these 1,691 participants, 415 (25%) described itineraries for which JE vaccination should have been considered. Of these 415 higher JE risk travelers, only 47 (11%) reported receiving ≥ 1 dose of JE vaccine. Of the 164 unvaccinated higher JE risk travelers who visited a health care provider before their trip, 113 (69%) indicated that they had never heard of JE vaccine or their health care provider had not offered or recommended JE vaccine. CONCLUSIONS: A quarter of surveyed US travelers to Asia reported planned itineraries for which JE vaccination should have been considered. However, few of these at-risk travelers received JE vaccine.

Patterns of measles transmission among airplane travelers.

With advanced air handling systems on modern aircraft and the high level of measles immunity in many countries, measles infection in air travelers may be considered a low-risk event. However, introduction of measles into countries where transmission has been controlled or eliminated can have substantial consequences both for the use of public health resources and for those still susceptible. In an effort to balance the relatively low likelihood of disease transmission among largely immune travelers and the risk to the public health of the occurrence of secondary cases resulting from importations, criteria in the United States for contact investigations for measles exposures consider contacts to be those passengers who are seated within 2 rows of the index case. However, recent work has shown that cabin air flow may not be as reliable a barrier to the spread of measles virus as previously believed. Along with these new studies, several reports have described measles developing after travel in passengers seated some distance from the index case. To understand better the potential for measles virus to spread on an airplane, reports of apparent secondary cases occurring in co-travelers of passengers with infectious cases of measles were reviewed. Medline™ was searched for articles in all languages from 1946 to week 1 of March 2012, using the search terms "measles [human] or rubeola" and ("aircraft" or "airplane" or "aeroplane" or "aviation" or "travel" or "traveler" or "traveller"); 45 citations were returned. Embase™ was searched from 1988 to week 11 2012, using the same search strategy; 95 citations were returned. Papers were included in this review if they reported secondary cases of measles occurring in persons traveling on an airplane on which a person or persons with measles also flew, and which included the seating location of both the index case(s) and the secondary case(s) on the plane. Nine reports, including 13 index cases and 23 apparent secondary cases on 10 flights, were identified in which transmission on board the aircraft appeared likely and which included seating information for both the index (primary) and secondary cases. Separation between index and secondary cases ranged from adjacent seats to 17 rows, with a median of 6 rows. Three flights had more than one index case aboard. Based on previously published data, it is not possible to say how unusual cases of measles transmission among air travelers beyond the usual zone of contact investigation (the row the index case sat in and 2 rows ahead of or behind that row) may be. The fact that several flights had more than one infectious case aboard and that all but two index cases were in the prodromal phase may be of importance in understanding the wider spread described in several of the reviewed reports. Although the pattern of cabin air flow typical of modern commercial aircraft has been considered highly effective in limiting the airborne spread of microorganisms, concerns have been raised about relying on the operation of these systems to determine exposure risk, as turbulence in the cabin air stream is generated when passengers and crew are aboard, allowing the transmission of infectious agents over many rows. Additionally, the characteristics of some index cases may reflect a greater likelihood of disease transmission. Investigators should continue to examine carefully both aircraft and index-case factors that may influence disease transmission and could serve as indicators on a case-by-case basis to include a broader group of travelers in a contact investigation.

Reported cases of measles in international air travelers to the United States, August 2005-March 2008.

BACKGROUND: In countries with high rates of measles immunization, imported cases of measles represent an important continuing source of measles infection. METHODS: Airlines and state health departments report cases of suspected measles in international travelers to the Centers for Disease Control and Prevention Quarantine Stations. We reviewed these reports, maintained in an electronic database, to determine the demographic and epidemiologic characteristics of international air travelers infected with measles. RESULTS: We reviewed 35 confirmed cases of measles in air travelers and analyzed their demographic and epidemiologic characteristics. The median age of case travelers was 17 (range: 4 months-50 years). These travelers arrived from all regions of the world, including 10 countries with immunization rates of measles-containing vaccine below 90% and five others experiencing local outbreaks. Of 17 travelers for whom immunization status was known, 2 had been adequately immunized with at least two doses of a measles-virus containing vaccine, 9 were inadequately immunized, and an additional 6 infants had not been immunized because of age. CONCLUSIONS: Measles importations continue in the United States. Travelers should be aware of the importance of assuring up-to-date immunizations, especially when visiting countries experiencing a local measles outbreak. In addition, parents traveling with infants, and their physicians, should be aware of recommendations regarding the early administration of a dose of measles-containing vaccine for infants at least 6 months old traveling internationally.

TB transmission on public transportation: a review of published studies and recommendations for contact tracing.

SETTING: The risk of transmission when persons with active tuberculosis travel on buses or trains is uncertain and no recommendations have been published for contact investigations on these conveyances. DESIGN: We conducted a systematic review of the published studies of tuberculosis transmission among bus or train travelers. RESULTS: Twelve published reports were identified, including one retrospective cohort study and eleven contact investigations. One contact investigation involved train travelers and one involved students on a 6 h bus excursion. The remaining nine involved exposures on school buses or in commuter vans. In eight reports, evidence of tuberculosis infection was found in 8.7%-55% of those tested; six of these studies reported identifying 1-24 cases of active tuberculosis. CONCLUSIONS: These reports support the need to be alert to the possibility of tuberculosis transmission on buses or trains. However, they do not offer the quantitative estimate of risk needed for defining policy regarding contact tracing for persons exposed on buses or trains. Decisions to carry out contact investigations should take into account the proximity to the index case, duration of exposure, and other risk factors that may affect the infectiousness of the case or the susceptibility of the contact. Additional reports taking these factors into consideration would help clarify the risk of tuberculosis transmission on public transport.

Knowledge, attitudes, and practices of US travelers to Asia regarding seasonal influenza and H5N1 avian influenza prevention measures.

BACKGROUND: International travel is a potential risk factor for the spread of influenza. In the United States, approximately 5%-20% of the population develops an influenza-like illness annually. The purpose of this study was to describe the knowledge, attitude, and practices of US travelers to Asia regarding seasonal influenza and H5N1 avian influenza (AI) prevention measures. METHODS: We surveyed travelers to Asia waiting at the departure lounges of 38 selected flights at four international airports in New York, Chicago, Los Angeles, and San Francisco. Of the 1,301 travelers who completed the pre-travel survey, 337 also completed a post-travel survey. Univariate and multivariate logistic regression were used to calculate prevalence odds ratios (with 95% CI) to compare foreign-born (FB) to US-born travelers for various levels of knowledge and behaviors. RESULTS: Although the majority of participants were aware of influenza prevention measures, only 41% reported receiving the influenza vaccine during the previous season. Forty-three percent of participants reported seeking at least one type of pre-travel health advice, which was significantly higher among US-born, Caucasians, traveling for purposes other than visiting friends and relatives, travelers who received the influenza vaccine during the previous season, and those traveling with a companion. Our study also showed that Asians, FB travelers, and those working in occupations other than health care/animal care were less likely to recognize H5N1 AI transmission risk factors. CONCLUSION: The basic public health messages for preventing influenza appear to be well understood, but the uptake of influenza vaccine was low. Clinicians should ensure that all patients receive influenza vaccine prior to travel. Tailored communication messages should be developed to motivate Asians, FB travelers, those visiting friends and relatives, and those traveling alone to seek pre-travel health advice as well as to orient them with H5N1 AI risk factors.

Household effects of school closure during pandemic (H1N1) 2009, Pennsylvania, USA.

To determine the effects of school closure, we surveyed 214 households after a 1-week elementary school closure because of pandemic (H1N1) 2009. Students spent 77% of the closure days at home, 69% of students visited at least 1 other location, and 79% of households reported that adults missed no days of work to watch children.

Pretravel health preparation among US residents traveling to India to VFRs: importance of ethnicity in defining VFRs.

BACKGROUND: International travelers visiting friends and relatives (VFRs) in lower income countries experience high rates of travel-related infections. We examined demographic characteristics and pretravel preparation practices among US residents traveling to India to determine factors that may contribute to higher infection rates and that would allow for improved prevention strategies. METHODS: A cross-sectional study was conducted among US residents traveling to India in departure areas for flights to India at three US international airports during August 2005. Eligible travelers were US residents going to India who were English speaking and >or=18 years. Self-administered questionnaires were used to assess knowledge of and compliance with pretravel health recommendations. RESULTS: Of 1,574 eligible travelers, 1,302 (83%) participated; 60% were male and the median age was 37. Eighty-five percent were of South Asian/Indian ethnicity and 76% reported VFR as the primary reason for travel. More than 90% of VFRs had at least a college education and only 6% cited financial barriers as reasons for not obtaining travel health services. VFRs were less likely than non-VFR travelers to seek pretravel health advice, to be protected against hepatitis A or typhoid fever, and less likely to be taking appropriate antimalarial chemoprophylaxis. However, when stratified by ethnicity, travelers of South Asian ethnicity were less likely than other travelers to adhere to pretravel health recommendations, regardless of VFR status. CONCLUSIONS: Similar to previous studies, VFR status was associated with pretravel health practices that leave travelers at risk for important infectious diseases. This association differed by ethnicity, which may also be an important marker of nonadherence to pretravel health recommendations. These findings have important implications for identifying at-risk travelers and properly targeting prevention messages.

A new paradigm for quarantine and public health activities at land borders: opportunities and challenges.

The Institute of Medicine (IOM) report Quarantine Stations at Ports of Entry: Protecting the Public's Health focused almost exclusively on U.S. airports and seaports, which served 106 million entries in 2005. IOM concluded that the primary function of these quarantine stations (QSs) should shift from providing inspection to providing strategic national public health leadership. The large expanse of our national borders, large number of crossings, sparse federal resources, and decreased regulation regarding conveyances crossing these borders make land borders more permeable to a variety of threats. To address the health challenges related to land borders, the QSs serving such borders must assume unique roles and partnerships to achieve the strategic leadership and public health research roles envisioned by the IOM. In this article, we examine how the IOM recommendations apply to the QSs that serve the land borders through which more than 319 million travelers, immigrants, and refugees entered the U.S. in 2005.

Household responses to school closure resulting from outbreak of influenza B, North Carolina.

School closure is a proposed strategy for reducing influenza transmission during a pandemic. Few studies have assessed how families respond to closures, or whether other interactions during closure could reduce this strategy's effect. Questionnaires were administered to 220 households (438 adults and 355 children) with school-age children in a North Carolina county during an influenza B virus outbreak that resulted in school closure. Closure was considered appropriate by 201 (91%) households. No adults missed work to solely provide childcare, and only 22 (10%) households required special childcare arrangements; 2 households incurred additional costs. Eighty-nine percent of children visited at least 1 public location during the closure despite county recommendations to avoid large gatherings. Although behavior and attitudes might differ during a pandemic, these results suggest short-term closure did not cause substantial hardship for parents. Pandemic planning guidance should address the potential for transmission in public areas during school closure.

Epidemiological evidence of an early wave of the 1918 influenza pandemic in New York City.

The 1918 "Spanish flu" was the fastest spreading and most deadly influenza pandemic in recorded history. Hypotheses of its origin have been based on a limited collection of case and outbreak reports from before its recognized European emergence in the summer of 1918. These anecdotal accounts, however, remain insufficient for determining the early diffusion and impact of the pandemic virus. Using routinely collected monthly age-stratified mortality data, we show that an unmistakable shift in the age distribution of epidemic deaths occurred during the 1917/1918 influenza season in New York City. The timing, magnitude, and age distribution of this mortality shift provide strong evidence that an early wave of the pandemic virus was present in New York City during February-April 1918.