Vectorborne Diseases: Zika, Yellow Fever, Dengue, and Chikungunya

Vector-borne diseases are among the most complex of all infectious diseases to prevent and control. In recent years, several viruses have spread to new regions and immunologically naïve populations, with significant implications for local populations and international travelers. Zika virus, chikungunya virus, and dengue virus are all primarily transmitted to humans via several species of Aedes mosquitoes. Yellow fever virus is transmitted to people primarily through the bite of infected Aedes or Haemagogus species mosquitoes. Dengue, chikungunya and Zika viruses can all cause symptoms of fever, joint pain, rash, conjunctivitis, muscle aches, and headache. Yellow fever virus can cause symptoms of fever, chills, severe headache, back pain, nausea, vomiting, fatigue, and weakness. Many infections caused by these vector-borne viruses are asymptomatic or are associated with a short course of mild illness, but severe health outcomes are also associated with each of these pathogens. Studies have found that 5-60% of patients with chikungunya report persistent joint pain for months or years after their illness. As many as 5% of all patients with dengue can develop severe, life-threatening disease, including dengue hemorrhagic fever or dengue shock syndrome. Zika virus infection during pregnancy can cause microcephaly and other severe fetal brain defects, and CDC is investigating the link between Zika and Guillain-Barré syndrome. Approximately 15% of yellow fever illnesses progress to a more severe form of infection, characterized by high fever, jaundice, bleeding, and eventual shock and failure of multiple organs. A vaccine is available for yellow fever virus; there are currently no FDA-approved vaccines for dengue, chikungunya, or Zika. There is no specific treatment for chikungunya, dengue, yellow fever, or Zika virus infection. Diagnosis of these illnesses can be difficult given the similarity in symptoms and potential cross-reactivity of tests. Clinicians should consider the patient’s clinical features, places and dates of travel, activities, and epidemiologic history of the location where the presumed infection occurred.


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