Emerging and Reemerging <Italic>Aedes</Italic>-Transmitted Arbovirus Infections in the Region of the Americas: Impli
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AJPH PERSPECTIVES Emerging and Reemerging Aedes-Transmitted Arbovirus Infections in the Region of the Americas: Implications for Health Policy The increasing geographical spread Marcos A. Espinal, MD, DrPH, Jon K. Andrus, MD, Barbara Jauregui, MD, MSc, Stephen Hull Waterman, and disease incidence of arboviral MD, MPH, David Michael Morens, MD, Jose Ignacio Santos, MD, MSc, Olaf Horstick, PhD (DrMed), FFPH, infections are among the greatest MPH, MSc, MBBS, Lorraine Ayana Francis, DrPH, MHA, and Daniel Olson, MD public health concerns in the Americas. The region has observed — an increasing trend in dengue in- he ever-increasing geo- symptomatic infections way ZIKV, like CHIKV, had not Tgraphical spread and rising above the numbers reported to previously circulated within cidence in the last decades, evolv- disease incidence of arboviral PAHO.9 the Western Hemisphere, and ing from low to hyperendemicity. (arthropod-borne virus) in- In 2005, CHIKV caused an resulted in an explosive outbreak Yellow fever incidence has also in- fections are among the most outbreak on the island of in the Americas, with its identi- tensified in this period, expanding significant public health concerns Comoros, followed by a large fication first on Easter Island, from sylvatic-restricted activity in the Americas.1,2 In addition to outbreak in India, resulting in Chile, in 2014, followed by to urban outbreaks. Chikungunya the reemergence of dengue virus more than 1 million cases and northeast Brazil in 2015, and started spreading pandemically in (DENV) and yellow fever virus significant postinfectious mus- then spreading throughout the 2005 at an unprecedented pace, (YFV), new arboviral pathogens culoskeletal sequelae. Sub- Americas. By late 2015, Zika had reaching the Americas in 2013. The once confined to specific regions sequently, CHIKV spread become one of the greatest global following year, Zika also emerged in of the world, such as chikungu- pandemically at an un- health crises in years and was theregionwithanexplosiveout- nya virus (CHIKV) and Zika precedented pace, reaching the associated with devastating con- break, carrying devastating congen- virus (ZIKV), recently resulted in Americas in 2013, rapidly genital abnormalities including ital abnormalities and neurologic pandemics associated with sig- resulting in more than 1.3 million microcephaly (Figure 1), – disorders and becoming one of the nificant morbidity.3 6 infections reported in more than Guillain-Barré syndrome, and greatest global health crises in years. Dengue infection is an Aedes- 43 countries.2,10 Incidence rates other neurologic disorders, and The inadequate arbovirus sur- borne disease caused by flavivi- climbed as high as 137.1 in- with the ability to spread by – veillance in the region and the lack ruses and is second only to malaria fections per 1000 person-years sexual contact.6,12 16 By late of serologic tests to differentiate as a cause of vector-borne disease among Nicaraguan children 2016, ZIKV transmission had among viruses poses substantial mortality and morbidity. For during the peak of the extended to 48 countries and challenges. The evidence for vec- several decades, the Americas epidemic.11 territories in the Americas, with a tor control interventions remains have observed an increasing trend weak. Clinical management re- in dengue incidence, evolving mains the mainstay of arboviral from low to hyperendemicity, ABOUT THE AUTHORS disease control. Currently, only Marcos A. Espinal is with Communicable Diseases and Environmental Determinants of with epidemics recurring ap- Health, Pan American Health Organization/World Health Organization, Washington, DC. 3 yellow fever and dengue vaccines proximately every 3 to 5 years. Jon K. Andrus is with the Department of Global Health, George Washington University are licensed in the Americas, with In 2010, 1.7 million dengue Milken Institute of Public Health, Washington, DC, and the Division of Vaccines and several candidate vaccines in Immunization, Center for Global Health, University of Colorado, Boulder. Barbara Jauregui cases were reported to the Pan is with the Department of Global Health, Milken Institute of Public Health, George clinical trials. American Health Organization Washington University. Stephen Hull Waterman is with the Dengue Branch, Division of The Global Arbovirus Group of (PAHO), an incidence rate of Vector-Borne Diseases, National Center for Emerging and Zoonotic Diseases, Centers for Experts provides in this article an Disease Control and Prevention, San Juan, Puerto Rico. David Michael Morens is with the 174.6 cases per 100 000 pop- Office of the Director, National Institute of Allergy and Infectious Diseases, National Institutes 7 overview of progress, challenges, ulation. In 2016, 2.2 million of Health, Bethesda, MD. Jose Ignacio Santos is with the Experimental Medicine Research and recommendations on arbo- cases were reported (220.0 Unit, Medical School, National Autonomous University of Mexico, Mexico City, Mexico. Olaf Horstick is with the Heidelberg Institute of Global Health, University of Heidelberg, viral prevention and control for 8 cases per 100 000 population), Heidelberg, Baden-Wuerttemberg, Germany. Lorraine Ayana Francis is with Communicable countries of the Americas. (Am J though rates were trending lower Diseases & Emergency Response, Caribbean Public Health Agency, Port-of-Spain, Trinidad. Public Health. 2019;109:387–392. in 2017.8 These rates are likely a Daniel Olson is with the Pediatric Infectious Disease Department, University of Colorado fi School of Medicine, and Epidemiology Department, Colorado School of Public Health, doi:10.2105/AJPH.2018.304849) signi cant underestimate; mod- Aurora. eling studies estimate as many as Correspondence should be sent to Jon Kim Andrus, 2811 Battery Place, Washington, DC 53.8 million DENV infections in 20016 (e-mail: [email protected]). Reprints can be ordered at http://www.ajph.org by clicking the “Reprints” link. Latin America and the Caribbean This article was accepted October 21, 2018. in 2010, including 13.3 million doi: 10.2105/AJPH.2018.304849 March 2019, Vol 109, No. 3 AJPH Espinal et al. Peer Reviewed Perspectives From the Social Sciences 387 AJPH PERSPECTIVES created an unprecedented situa- identifying novel emerging These limitations in the perfor- tion: the cocirculation of 4 im- pathogens, genotypes, and out- mance of existing laboratory portant human arboviruses breaks. Regional laboratory systems became even more evi- transmitted by the same mos- networks exist to facilitate lo- dent during the introduction of quito, primarily Aedes aegypti,in gistical support, technical exper- new pathogens in the region such the same time and place. Intense tise, and data sharing such as as ZIKV. and prolonged rainy seasons and PAHO’s Arbovirus Diagnosis an increase of 2 degrees centi- Laboratories Network of the Source . Photo courtesy of the Pan grade in average temperature Americas.22 Surveillance Diagnostics American Health Organization. Printed with permission. probably also contributed to an Data analysis, reporting, and Given the challenge in clinical abundance of vectors.4,20 De- data sharing systems also vary. differential diagnosis among FIGURE 1—Brazilian Mother forestation has been associated Although many countries require DENV, ZIKV, and CHIKV, in With Her Baby With with yellow fever and Zika mandatory reporting of all 2016, the PAHO Directing Microcephaly, a Consequence outbreaks. Migration of un- arboviral diseases, case reporting Council proposed to its member of an Intrauterine Zika Virus Infection: Recife, Brazil, 2016 vaccinated populations to en- is often not performed, especially states a strategy for comprehen- demic areas has also been a key within the private sector. Many sive surveillance of arboviral factor in yellow fever occurrence countries publish routine case diseases. This strategy is based on total of 707 133 reported cases. in South America.4,20 counts of suspected and con- the coordination and strength- These estimates are also likely a firmed arboviral disease cases, ening of epidemiological sur- significant underestimate as though the quality and timeliness veillance, integrated vector reporting is passive and, there- of reporting varies. The PAHO control, and laboratory fore, they do not capture Health Information Platform diagnosis.24 17,18 SURVEILLANCE asymptomatic cases. Currently, the inconsistent for the Americas is a real-time, The clinical differential di- For decades, YFV persisted in and inadequate surveillance in voluntary, electronic reporting agnosis of DENV, ZIKV, and the Americas as sylvatic cycles of system that facilitates rapid CHIKV is challenging and un- the region along with the lack of 23 transmission. Beginning in 1997, laboratory serologic testing that reporting of data in the region. derscores the importance of lab- YFV circulation in Brazil and can consistently differentiate be- Existing surveillance sys- oratory diagnostic tests. Antibody neighboring countries in- tween closely related flaviviruses tems, including syndromic, detection tests can distinguish fi tensi ed. In 2008, Asunción, poses substantial challenges to laboratory-based, and other (e.g., among the alphaviruses (e.g., fi Paraguay, experienced its rst respond adequately to these postmortem, clinician-based, CHIKV, Venezuelan equine urban yellow fever outbreak, diseases.21 event-based) systems are often encephalitis, Mayaro, and Ross which accounted for almost 50% not integrated, which limits their River viruses) and the flaviviruses