The mosquito-borne chikungunya and Zika virus diseases have emerged from obscurity in recent years. Previously they were thought to be mild, and at most of limited geographic distribution and public health concern. Now, they are among arboviruses that are a significant public health priority worldwide. Dengue, chikungunya, and Zika viruses share the same mosquito vectors (Aedes subgenus stegomyia and diceromyia mosquitoes) (Fig. 141-1). The feeding and breeding behaviors of these mosquitoes greatly impact the epidemiology of the diseases they transmit. The vector mosquitoes prefer to live in subtropical and tropical regions of the world, and dengue, chikungunya, and Zika virus infections are endemic in these areas. The most important human vector for these diseases, A. aegypti, also called the house mosquito or yellow fever mosquito, has adapted to and lives in very close contact with humans. As a result, A. aegypti, together with Anopheles gambiae and funestus, two highly anthropomorphic malaria vector mosquito species in Africa1 are probably the most efficient mosquito-borne disease vectors in the world. They are also among the vectors that are most difficult to control.
Sylvatic and urban dengue, chikungunya, and Zika virus transmission cycles. (Source: James Gathany/CDC.)
In areas where more than one of these diseases are endemic, they can be difficult to distinguish clinically and patients can become infected with more than one virus at the same time.2 The public health impact of dengue, chikungunya, and Zika virus will likely increase even further as the human population in tropical and subtropical areas grows and urbanization continues. The disease incidence is predicted to increase most in areas with low or modest incomes and suboptimal housing conditions without intact walls, windows, and/or screens that can keep mosquitoes out.3
Dengue infections are caused by dengue viruses, which are single-stranded positive-sense RNA viruses that belong to the family Flaviviridae, genus Flavivirus. They are small (50 nm in diameter), enveloped viruses with three structural proteins and seven nonstructural proteins. The Flavivirus genus contains more than 40 human pathogens including West Nile virus, tick-borne encephalitis virus, yellow fever virus, and Zika virus.4 The dengue virus has four distinct but closely related dengue virus serotypes (dengue virus 1–4).5
Dengue virus infections can range from asymptomatic to a severe hemorrhagic disease with a potentially fatal outcome. After a 4- to 10-day incubation period, most persons develop a mild febrile illness or classic dengue fever (DF). Young children generally present with nonspecific fever symptoms. Older children and adults often develop classic DF, which is characterized by sudden onset of fever, severe headache, retroocular pain, and myalgias. Rash and joint pains are also common and many patients have ...