Assignment: Research Article Review Write a 2-page peer review of this journal a

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Assignment: Research Article Review

Write a 2-page peer review of this journal article.

Make sure to include the following: The review should include the following components:

1. Analyze the study design used by the authors in your chosen article. (Take apart the study; describe the design of the study conducted)

2. Discuss the strengths and limitations of the study design chosen.

3. Propose potential alternative study design that could have been used.

4. Discuss the article's public health implications.

( Jost M, Luzi D, Metzler S, Miran B, Mutsch M. Measles associated with international travel in the region of the Americas, Australia and Europe, 2001–2013: A systematic review. Travel Medicine and Infectious Disease. 2015. 13(1), 10-18. http://www.sciencedirect.com.ezproxy2.apus.edu/science/article/pii/S1477893914002130 ).

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Measles associated with international travel in the region of the Americas, Australia and Europe, 2001–2013: A systematic review

M. Jost1, ,

D. Luzi1, ,

S. Metzler1, ,

B. Miran1, ,

M. Mutsch,

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http://dx.doi.org.ezproxy2.apus.edu/10.1016/j.tmaid.2014.10.022

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Summary

Background

Travel volumes are still increasing resulting in a more interconnected world and fostering the spread of infectious diseases. We aimed to evaluate the relevance of travel-related measles, a highly transmissible and vaccine-preventable disease.

Method

Between 2001 and 2013, surveillance and travel-related measles data were systematically reviewed according to the PRISMA guidelines with extraction of relevant articles from Medline, Embase, GoogleScholar and from public health authorities in the Region of the Americas, Europe and Australia.

Results

From a total of 960 records 44 articles were included and they comprised 2128 imported measles cases between 2001 and 2011. The proportion of imported cases in Europe was low at 1–2%, which reflects the situation in a measles-endemic region. In contrast, imported and import-related measles accounted for up to 100% of all cases in regions with interrupted endemic measles transmission. Eleven air-travel related reports described 132 measles index cases leading to 47 secondary cases. Secondary transmission was significantly more likely to occur if the index case was younger or when there were multiple infectious cases on board. Further spread to health care settings was found. Measles cases associated with cruise ship travel or mass gatherings were sporadically observed.

Conclusions

Within both, endemic and non-endemic home countries, pretravel health advice should assess MMR immunity routinely to avoid measles spread by nonimmune travelers. To identify measles spread as well as to increase and sustain high vaccination coverages joint efforts of public health specialists, health care practitioners and travel medicine providers are needed.

Keywords

Measles;

Travel;

Importation;

Flight;

Mass gathering

1. Introduction

Measles is an acute viral infection of the respiratory system easily transmitted among humans, mainly through droplets by coughing or sneezing [1]. Symptoms include fever, cough, coryza, conjunctivitis and are followed by a generalized, specific maculopapillar erythematous skin rash with an incubation period of seven to 21 days following exposure. Hospitalization rates are high and especially among adults complications are relatively common. The virus is shed for several days before the typical rash appears, which increases the risk of silent transmission. Immunization is the best preventive measure [1]but the vaccination coverage varies between the different regions of the world.

Since 2002, the Region of the Americas (North, Central, South America and the Caribbean) has achieved and maintained measles elimination reaching sufficient vaccination coverages. Australia also has interrupted endemic measles transmission and recently, has achieved measles elimination [2] and [3]. However, in both regions, outbreaks still occur involving imported cases. In contrast, Europe, Africa and parts of Asia still suffer from endemic measles with outbreaks, e.g. between 2006 and 2009, 2011, and recently, in 2013. Therefore, spread of measles remains a relevant risk for non-immune international travelers and their contacts due to its easy spread and the varying regional vaccination coverage rates [4], [5] and [6]. By the end of 2020, the World Health Organization targets to eliminate measles in at least five WHO regions [1].

Imported measles cases to regions with interrupted measles transmission can have substantial consequences. Therefore, our aim was to assess the relevance of both, travel-associated and imported measles cases to identify shared challenges as well as to evaluate data by mode of transportation and travel characteristics, including mass events.

2. Methods

2.1. Literature extraction

A systematic review was performed according to the structured procedure described by the PRISMA guidelines [7]. To retrieve information, electronic databases (Medline, EMBASE, GoogleScholar) were searched for relevant articles published between 2001 and 2013 without any language restriction, as is shown in Fig. 1. The date of the last search was November, 9th, 2013. Reports might cover a broader time range but only cases that had occurred between 2001 and 2013 were included. Search terms included measles, infection, infect*, surveillance, notification, import*, importation, export*, exportation, travel*, international, abroad, vacation, holidays, student, education, business, expatriate, visiting friends and relatives (vfr), mass gathering, sport, games, festival, meeting, transport, flight, air, airplane, bus, train, ship. The term ‘measles’ was used separately as well as cross-referencing each other term. An asterix was used for abridged terms. Within articles the reference lists were checked for completeness.

Figure 1.

Study selection.

Figure options

Furthermore, Public Health authorities were searched separately including the World Health Organization, the European Centre for Disease Prevention and Control, the U.S. Centers for Disease Control and Prevention, and the Department of Health, Australia. Where possible, summary reports of surveillance data were selected.

Measles cases were documented through clinical and laboratory definition (IgM antibodies, virus identification through isolation or PCR). Links to secondary cases were included if case ascertainment was performed on an epidemiological basis or combined with genotyping and phylogenetic analyses. The case definition of imported cases varied among notification authorities. Therefore, confirmed imported or import-associated cases were included based on the judgments of the respective authorities. Mass gatherings were defined as a high number of persons at a specific location for a specific purpose for a defined period of time [8]. Exposure to air travel included not only the in-flight environment but also exposure in the airport, e.g. in the check-in area, the departure lounge or at the baggage claim.

2.2. Selection and analysis of references

Articles were included if they reported data about the importation status of measles cases in the Region of the Americas, Europe, and Australia. Duplicates and reports of preventive measures, e.g. measles vaccination, or disease-specific data were excluded. Out of scope of this review were references of measles among Irish-, Gypsy- or Roma-ethnic-traveler communities, adoption-related articles and those targeting refugees. Furthermore, educational or health care settings were not specifically investigated. Mainly full articles and reviews were targeted, but editorials, comments, letters and ‘grey’ literature were included if a substantial contribution to the topic was found. The title and abstracts of the remaining references were screened by two members of the students' group. For all included articles full-text analysis was performed.

3. Results

All of the 960 articles were covered by the search terms measles and travel* and measles and import*, respectively. A total of 44 were eligible for analysis as shown in Fig. 1. Overall, 29 reports included importation-related data with a total of 2128 imported cases recorded in 27 articles between 2001 and 2011 in the United States, Europe and Australia (Table 1). In eleven articles 132 air-travel associated cases were reported leading to 47 secondary cases (Table 2). Three articles targeted measles at mass gatherings and one reported measles on a cruise ship.

Table 1.

Overview of importation status of measles cases, United States, Europe and Australia, 2001–2012.

n.a.: not available.

a

Case definitions of imported measles:

-

In the United States, travel outside the country within 18 days of rash onset – unless symptoms began at least 7 days after the date on which a traveling companion developed symptoms – is required for a case to be considered imported [21].

-

According to the European Centre for Disease Prevention and Control's definition an imported case is defined as a case in which the source of infection was outside the country of residence, and the person in question was traveling abroad during the incubation period prior to the onset of the rash (measles: 7–18 days). Classification as an imported case is also supported by epidemiological and/or virological evidence of foreign-acquired infection. An ‘import-related case’ is a case epidemiologically linked to an imported case, as supported by epidemiological and/or virological evidence. All import-related cases are to be considered as indigenous cases [30].

-

Australia's definition of an imported case involves assessment on a case-by-case basis using epidemiological and virological evidence: a case public health authorities believe was acquired overseas based on international travel in the period before rash onset [35].

b

The percentage of imported cases is based on those with known importation status.

c

Time range included: in 2011 data from January to November 2011 and in 2012, data from January to March 2012.

Full-size table

Table options

Table 2.

Air travel associated measles cases, the Americas, Australia and Europe, 2001–2013.

n.a.: not available.

a

One duplicate reference was included to allow the identification of the additional secondary cases on the connecting flight b), from Australia to New Zealand.

b

Cases were already included in [43].

Table options

3.1. Imported measles

Following the interruption of endemic circulation in November 2002, the countries of the Americas counted a historically low number of measles cases from 2003 to 2010, with 1249 cases which were attributed to importations. However, in 2011, a surge of measles cases up to 1369 cases was reported in the Americas due to importation of viruses from large outbreaks in Europe and Africa [9]. This figure was more than eight times the previous annual average of 156 cases from 2003 to 2010 and resulted in sustained transmission in at least three countries (Canada, Ecuador and Brazil) [10]. Based on the outbreak in Ecuador the most affected age group was that of children aged <5 years. In 2012, the number of confirmed cases decreased to 142 and all of them were linked to importations. Most outbreaks in the Region had been linked to the genotypes of imported viruses D8, D4 and B3; the most common was B3 [10] and [11].

During 2001 to 2012, the median annual number of measles cases reported in the United States was 60 (range: 37–220), including 26 imported cases (range 18–80) and a median annual number of four outbreaks (range: 2–16), defined as three or more cases linked in time or place [12] and [13]. Of the total of 914 cases, 364 (40%) cases were importations and 550 (60%) were associated with importations [13], [14], [15], [16], [17],[18], [19], [20], [21] and [22]. The WHO Western Pacific Region contributed the largest number of imported cases from 2001 to 2004 [14] and [15] and in 2011, the WHO European Region was the origin for nearly half of the imported cases (33/72) [22]. From 2001 to 2010, 20% (2001) to 50% (2002) of the imported cases were younger than two years. None (2002) to 36.4% (2003) of those imported were represented by the 2- to 18-year-old. People older than 19 years were responsible for the remaining cases [23].

For Europe, nine reports included information about imported cases and estimates were based on patients with known importation status. The number of imported cases ranged from 37 (2001) to 620 (2012), indicating that 1%–10% of all measles cases were imported [24], [25], [26], [27], [28], [29], [30], [31] and [32]. They mainly originated from other European countries and from other regions with endemic transmission, such as South-East Asia and the Western Pacific region. No data regarding age groups of importations were found.

Since at least 2005, no endemic measles transmission was observed in Australia [2]. Therefore, most cases of measles are considered either imported or import-related, with a small number of locally acquired cases with no epidemiological or virologic link to an imported case [33], [34], [35] and [36]. The WHO South-East Asia Region and the WHO Western Pacific Region were identified as the main regions of origin [37] and 76% of people who imported measles to Australia were between 17 and 34 years old [37]. In 2012, the largest outbreak of measles since 1997 comprised 173 cases and was associated with an imported case from Thailand. A total of 112 cases were reported in 2013 with two thirds aged 15–39 years. A total of 66 imported and import-related cases were reported of which 27 were associated with travel to Indonesia, especially Bali [36].

3.2. Air travel associated measles transmission

Eleven reports targeted measles transmission during air travel [38], [39], [40], [41], [42],[43], [44], [45], [46], [47] and [48] as is shown in Table 2. For the USA, 77 primary cases and 12 secondary cases of measles spread in airplanes were described between 2004 and 2011. A total of 444 measles cases were notified in Australia from 2007 to 2011. Of those, 45 people (10%) took a total of 49 flights while infectious. Twenty secondary cases occurred among people on seven (14%; 95%CI 6–29) of the 49 flights, comprising only international flights (7/36 19%) and none of the 13 domestic flights that carried infectious people. For Europe three reports were identified: The Netherlands recorded three measles cases in 2007 resulting in four secondary patients. In Ireland and Finland/Estonia three index and two secondary cases each were identified. Secondary cases contributed not only to in-flight or airport-related spread but also resulted in nosocomial and family transmission [46] and [48].

With respect to the seating position, 22 of 40 secondary cases with data on their seating positions were seated in the same row or within two rows fore and behind of the index case; 18 were located outside this range, one of whom was a member of the cabin crew. Secondary transmission was significantly more likely to occur if the index case was younger or when there were multiple infectious cases on board [42] and [43]. Most of the affected persons had an unknown vaccination status, were incompletely or unvaccinated[42].

3.3. Cruise ship travel

One report described measles transmission among three crew members on a cruise ship sailing from Florida to the Caribbean between February and April, 2006. The great majority of the crew was unvaccinated (99%) [49].

3.4. Mass gatherings

Three articles regarding measles outbreaks between 2001 and 2012 were found to be associated with mass gatherings [50], [51] and [52]. Sport events and religious meetings were identified as potential sources for measles transmission. Both venues attracted visitors from countries or regions with different measles immunization coverage than the host country. Thereby, young people aged <1–19 years were more affected. They comprised the majority of primary, secondary and tertiary cases. Of note, measles transmission not only occurred during the events but was also related to air travel as depicted in Table 3.

Table 3.

Measles outbreaks associated with mass gatherings, 2001–2013.

n.a.: not available.

Table options

4. Discussion

Following the introduction of the MMR vaccine the measles incidence has dramatically decreased. In regions and countries with sustained high vaccination coverage (95%) measles is no longer endemic, such as in the region of the Americas and Australia. In those with lower coverages relevant outbreaks occur as there are large unprotected population groups where the highly contagious measles virus continues to circulate, such as in parts of Europe, Africa and Asia. Along with the increasing international travel volume un- and undervaccinated travelers are at-risk of contracting the disease at measles endemic destinations and to transport it to their home countries. When they return home to an endemic region they may contribute to larger outbreaks due to the significant number of unprotected locals. Alternatively, when they import the virus to a region with a high vaccination coverage (95%), outbreaks and local transmission are limited. But they may involve clusters of population groups with religious or philosophical exemptions. Then, there remain travel-acquired cases: as many as 95–100% of measles cases reported in the USA and Australia were travel-related, in contrast to Europe where only 1–10% of reported cases were travel-related. The direct impact of one region on another was illustrated in 2011 during which a substantial measles outbreak in Europe resulted in the largest outbreak in the USA in decades, and reflected the extensive travel between the two regions [53]. The majority of imported or import-related measles patients were unvaccinated or had unknown vaccination status. Increasing the vaccination coverage in the home country is therefore the most effective means for reducing travel-acquired disease and its transmission.

To avoid transmission, international travelers need to be fully protected and therefore, need to be advised and encouraged to be vaccinated with two doses of MMR vaccine and to carry a vaccination booklet with them for documentation. Otherwise acquired immunity against measles should be documented by laboratory evidence, physician-diagnosed measles, or birth before 1957 [54] (respective countries' recommendations are different varying between birth before 1957 and 1966). Therefore, seeking pretravel health advice is an excellent opportunity to receive neglected vaccinations or to complete vaccination schedules. To our knowledge, travel medicine practitioners usually check for routinely recommended immunizations including measles. In addition, they have to know global and regional measles vaccination coverages as well as outbreak data to fully inform vaccination-reluctant travelers about their risks of acquiring and spreading measles. For example, this also includes communication about the differing vaccination coverages within Europe [55]. However, only few studies reported on whether measles-affected travelers had received travel health advice and case numbers were low but tended to show that only a minority of measles-affected adult tourist travelers had visited travel health centers [6].

Measles is a notifiable disease in almost all countries. To achieve the elimination goals enhanced case-based surveillance activities, public health capacities, evidence-based communication and regional and international collaboration need to be strengthened[55] and [56]. The extent to which e.g. detailed travel-related data is publicly available, either as publications or as web-based data differed between regions. This fact was a limitation for this review. Furthermore, the comparability of estimates of imported measles between countries is hampered based on different case definitions (Table 1). As the Australian case definition may be more sensitive and less specific than the United States' criteria, this fact may result in different case numbers when compared to the USA[35].

Air and cruise ship travel face similar challenges in identifying spread of measles among passengers. However, it will be hardly possible to obtain precise estimates of affected passengers as they go undetected unless they seek medical care. Furthermore, no secondary patients are expected to occur while on board as the average duration of the flight and the cruise (seven days) are shorter than the incubation time of measles (7–21 days) [57], [58], [59] and [60]. Although contact tracing guidelines differ between countries [42], [43] and [61], modern communication tools may facilitate contacting potentially exposed passengers. Passengers should be rapidly informed to contact their health care center in case they are not protected.

Overall, air transport-related measles spread had occurred infrequently. For example in the USA, less than 1% of those 954 passenger-contacts for whom outcome reports were received had acquired measles, or 4% (9/249) of those with no, or unknown vaccine or disease history [42]. Data was inconsistent regarding the transmission risk in relation to a longer duration of international flights and with respect to the seating position of the infected contacts. However, spread of measles during international air travel was not rare if there was an infectious case on board and it was increased by multiple infectious cases on board [42] and [43]. Also further spread to family members and health care workers were described [46] and [48]. This fact highlights the need for health-care providers to be protected themselves as well as to suspect measles in patients who present with clinically compatible symptoms and who report recent travel exposure. Thereby comprised are mass gatherings. Though rare events, they represent special at-risk situations for measles transmission as they were mainly attended by young participants and include crowded conditions [50], [51], [52] and [62].

5. Conclusions

Ongoing initiatives are needed to eliminate measles. Therefore, a vaccination coverage of at least 95% with both first and second routine dose of measles-containing vaccine needs to be obtained and sustained globally. Within both, endemic and non-endemic home countries pretravel health advice should therefore cover MMR immunity routinely to avoid measles spread by nonimmune travelers. In 2016, the Region of the Americas is the venue of the 31st Summer Olympic Games. This raises the possibility of measles importation from other regions of the world [10] and [63]. For the planning of such events international and interdisciplinary expertise and cooperation including public health, travel and mass gatherings medicine and health care are necessary and rapid information sharing needs to be in place [64], [65] and [66].

Year United States Europe Australia All cases n
(reference) Imported casesa
n Import-associated cases: Known origin unknown (n, %) WHO region mainly contributing Imported casesa
nb
(reference) WHO region mainly contributing All cases
(n) Imported casesan
(reference) WHO region mainly contributing 2001 116 [14] 54 (47%) 37 (32%)
25 (21%) Western Pacific 37 (1%) [25] Europe
South-East Asia
Western Pacific n.a. 2001–2006: 44 [2] n.a. 2002 44 [14] 18 (41%) 19 (43%)
7 (16%) Western Pacific 84 (1%) [25] 31 [33] n.a. 2003 56 [14] 24 (43%) 21 (37%)
11 (20%) Western Pacific
Europe n.a. n.a. 92 [33] n.a. 2004 37 [15] 27 (73%)
13 (48%) infectious during flight 6 (16%)
4 (11%) Western Pacific
South-East Asia n.a. n.a. 44 [33] n.a. 2005 66 [16] 24 (36%)
8 (33%) infectious during flight 38 (58%)
4 (6%) Europe
South-East Asia n.a. n.a. 10 [33] n.a. 2006 55 [17] 31 (56%) 21 (38%)
3 (5%) Europe
Western Pacific 126 (4%) [24,26] Europe
South-East Asia 125 [33] n.a. 2007 43 [18] 29 (67%) 12 (28%)
2 (5%) Western Pacific
South-East Asia 84 (4%) [24,27] Europe
South-East Asia 12 [33] n.a. n.a. 2008 140 [19] 25 (18%) 104 (74%)
11 (8%) Europe 218 (5%) [28] n.a. 65 [33] n.a. n.a. 2009 71 [20] 21 (30%) 38 (53%)
12 (17%) Europe
South-East Asia 101 (2%) [29] n.a. 105 [33,37] 2009–2011:
128 (35%) [35] South-East Asia
Western Pacific [37] 2010 64 [21] 39 (61%) 17 (27%)
8 (12%) Europe
South-East Asia 217 (3%) [30] Europe
Africa 69 [33] n.a. 2011 222 [22] 72 (32%) 128 (58%)
22 (10%) Europe 725 (2%)c[31] n.a. 193 [33]
import-associated 53 (27%) [34] n.a. 2012 51 [13] n.a. n.a. n.a. 41 (3%)c[32] n.a. 199 [36] n.a. n.a. Total (2001–2011) 914 364 (40%) 550 (60%) 1592 172

Explanation / Answer

Measels is an infectious disease mainly considered to affect children but it can occur in persons of every age. There are 54 cases of measels reported in 16 states of US namely Florida, Georgia, Hawaii, New York, Texas, Utah, California, Alabama, North Carolina, Massachusetts, Colarado, Connecticut, Illinois, Tennesse, Arizona, Texas. There were 189 cases were reported in 2015 from 24 states of US where as in 2014 about 667 cases were reported.

Study design:

The data related to travel and surveillance related data of US were collected from googls scholar, medlines, NCIRD (national center for immunization and respiratory diseases) and other heatlh authorities of US and the articles were reviewed under the PRISMA guidelines. Of the 500 articles only 35 articles were reviewed.

Findings :

Majority of people who got infected were unvaccinated

Measels is common in various parts of the world including Europe, Asia, Pacific, Africa.

Travellers from these parts are transmitting measels to the US.

Measels can be transmitted to the community in US where the people are unvaccinated

In 2015 the measels was spread due to a large outbreak in an amusement park in California. An infected person who was a traveller visited the park which cause a large outbreak. Although no source was identified.

In 2014 there were about 23 measels outbreak in US. Out of that one of the outbreak which consists of 383 cases were the largest and were caused in the Amish community in Ohio which were unvaccinated. This was associated with the Phillipinnes measels outbreak.

Strength and limitation of data

The limitation is that the travel related data related which is publically available differ from region to region. Also very few studies contain data about the vacinnation history of the infected people. Also the case definations of measles from differ from country to country.The strength is that the data covers a huge and vast compile of information from 2014 -2015 which is summarised

To increase the data reliablity the survelliance programmes in hospitals, airports must be intensified. The persons travelling to US must also contained detailed reports about their own as their family complete medical history.

Conclusions

the international travellers visiting to the country should be encourged to get proper dosage of MMR vaccines.Also they must carry a vaccination booklet for the documentation. Also before travelling they should get pre health advice. The suveillance progrmmes and the vacinnations programmes as well as health care facilites in hospitals, clinics should be strengthend in order to eliminate the measles. The international collaboration and regional communications should be enhanced

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