Measles in travelers: are we aware enough?

Using Locally Derived Seroprevalence Data on Measles, Mumps, Rubella, and Varicella by Birth Cohort to Determine Risks for Vaccine-Preventable Diseases During International Travel

BACKGROUND

Measles, mumps, rubella, and varicella (MMRV) were common childhood diseases in the United States prior to the introduction of their respective vaccines. Measles was declared eliminated in the United States in 2000. However, 628 cases were reported in 2014, the majority of which have been linked to international travel. The study team set out to investigate the seroprevalence of MMRV in our local population to determine whether such a process can lead to meaningful recommendations for assessing travelers at risk.

METHODS

We conducted a cross-sectional seroprevalence study using a quota sampling method. A total of 460 leftover serum samples were collected from individuals born prior to 1996, who live in the Lehigh Valley region of southeast Pennsylvania. The samples were allocated to five birth-year cohorts, and the seroprevalence of each cohort to MMRV was compared. Additionally, overall seroprevalence of each disease was compared with data from prior national studies. Gender differences within each birth cohort were also assessed.

RESULTS

The overall seroprevalence values of measles, mumps, rubella, and varicella were 85.8, 82.8, 96.6, and 97.4%, respectively. There were significant associations between seroprevalence and birth cohort for measles (p = 0.01) as well as mumps (p = 0.037). The overall seroprevalence for our study sample was significantly different from the national seroprevalence results of measles, mumps, and rubella.

CONCLUSIONS

Our study showed dramatically lower immunity rates for measles and mumps than those shown by prior national seroprevalence studies. The rates in many of the later birth cohorts born after 1966 were significantly lower than the rates reported as necessary to sustain herd immunity. Given that patients' immunization records are not always available or complete, collecting local seroprevalence data may be necessary to more accurately recommend antibody testing and vaccination during pre-travel assessments.

The spread of vaccine-preventable diseases by international travellers: a public-health concern

Vaccine-preventable diseases (VPDs) are costly at both the individual and societal levels. The most common VPDs recorded in travellers are enteric (typhoid or paratyphoid B) fever, acute viral hepatitis, influenza, varicella, measles, pertussis and bacterial meningitis. Travellers suffering from VPDs are frequently hospitalized, illustrating the point that VPDs are serious and expensive. Many travellers are not properly immunized before travel. In addition to individual consequences, VPDs can have public-health consequences if they are introduced or re-introduced by infected travellers returning to areas with susceptible populations. The international spread of poliomyelitis, Neisseria meningitidis serogroup W135 meningococcal infections, measles and influenza provides strong evidence of the role of international travel in the globalization of VPDs. The surveillance of the emergence, re-emergence or spread of VPDs is essential to adapt pre-travel advice and the responses to the VPD.

Differential diagnosis of dengue fever: beware of measles!

Febrile exanthema is a common symptom in returning travelers. In addition to cosmopolitan diseases, etiologies specific to the visited country must be considered. As an accurate diagnosis is important, clinical suspicion should be confirmed by laboratory tests. The case reports of three brothers returning from Indonesia highlight the possibility of misdiagnosis due to the clinical similarity and serological cross reactivity of dengue fever and measles.

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.

Toxic exanthems in the adult population

Frequently the internist is confronted with the nonspecific exanthematous eruption. While often a sign of a benign and self-limiting process, an exanthem also might herald the development of a more severe systemic syndrome. Infections, immune-mediated processes, drug reactions, a neoplasm, and familial syndromes with poor prognoses might all manifest initially with an exanthem. A thorough history and complete physical examination should be performed on all patients who present with an exanthem. Characterization of the exanthem morphology, other physical examination findings, and review of systems can help guide laboratory testing and ensure prompt diagnosis and early treatment of potentially life-threatening conditions. This article provides a brief overview of the conditions that must be considered in the evaluation of an ill patient with an exanthem.

The role of the traveler in emerging infections and magnitude of travel

Travel and trade have grown immensely. Travelers interact with people and microbes during their journeys, and can introduce infectious agents to new areas and populations. Studying illnesses in travelers is a source of knowledge into diseases of resource-poor regions and the control of these diseases. Travel-associated illnesses also serve to detect emerging infections.