A previously health man in his 50’s from Massachusetts was evaluated on January 7, 2016 for a febrile illness with rash, conjunctivitis, and arthralgia. He went to Costa Rica with 2 family members from December 19-26, 2015, and stayed in Nosara, in the northwestern coast of the country. The patient reported many mosquito bites.
The patient noted myalgias starting December 30, followed by a red rash, red face, red eyes, headache, and arthralgia. He presented to the Walk-In Center on January 2-3 (Day 4-5 of illness) where he had a low-grade fever and laboratory tests found leukopenia, lymphopenia, bandemia (19%), but normal platelets, basic metabolic profile, and negative malaria smears. C-reactive protein was mildly elevated: 18.7 mg/dL (normal <10 mg/dL). Serologic tests found immunity to rubella but not to rubeola. Dengue and chikungunya IgM and IgG were negative.
He was referred to our clinic, a GeoSentinel site, for evaluation. When seen on January 7 (Day 9 of illness), he was afebrile and had conjunctivitis and mild residual rash on his face and back, and backache. Laboratory examination was unremarkable, with resolution of bandemia. Rubeola IgM and IgG remained negative. Dengue and chikungunya serologies were done (Focus Diagnostics) which found a positive dengue IgM of 2.23 (reference range <0.90), negative dengue IgG, and negative chikungunya IgM and IgG. IgM ELISA and plaque reduction neutralization antibody tests (PRNT) for Zika and dengue were performed at CDC Fort Collins; both Zika IgM and dengue IgM were present, but the PRNT titer for Zika was >5120 and for dengue was <10.
The patient has recovered completely on follow up on January 25 (Day 27) and has received MMR vaccination. The 2 family members that also traveled to Costa Rica have remained well.
The PRNT results confirm the diagnosis of Zika infection in this traveler from the US who returned from Costa Rica and shows the cross-reactivity of dengue serologies with Zika, also a flavivirus. Zika infection has not been documented in Costa Rica previously and the case illustrates that Zika is likely circulating more widely than officially reported in the Americas. This case exemplifies the role of travelers as sentinels for outbreaks and for the expansion of pathogens to new geographic areas (1). GeoSentinel sites worldwide are reporting cases of Zika in returning travelers.
Zika has rapidly spread through South America, Central America, and the Caribbean since its initial recognition in Brazil in 2015 (2-4). The outbreak resembles the rapid spread of chikungunya in the Americas since its 2013 identification in the region (5). Costa Rica is a popular travel destination. Travelers to all areas where Aedes mosquitoes are present, including Costa Rica, should be advised to avoid day-biting mosquitoes to prevent dengue, Zika, and chikungunya. CDC Traveler’s Health (www.cdc.gov/zika), PAHO, and other health authorities have posted recommendations for mosquito bite protection and information regarding the possible association of Zika with microcephaly in Zika-infected pregnant women (2, 6, 7).
Lin H. Chen, MD, FACP, FASTMH (on behalf of Mount Auburn Hospital medical teams)
Director, Travel Medicine Center, Mount Auburn Hospital
Associate Professor of Medicine, Harvard Medical School
Site Director, GeoSentinel Surveillance Network
Cambridge, Massachusetts, USA
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2. PAHO. Zika Virus Infection. Available at www.paho.org/hq/index.php?option=com_topics&view=article&id=427&Itemid=41484&lang=en. Accessed January 19, 2016.
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