Emerging and Reemerging Aedes-Transmitted Arbovirus Infections in the Region of the Americas

Implications for Health Policy

Marcos A. Espinal, MD, DrPH; Jon K. Andrus, MD; Barbara Jauregui, MD, MSc; Stephen Hull Waterman, MD, MPH; David Michael Morens, MD; Jose Ignacio Santos, MD, MSc; Olaf Horstick, PhD (DrMed), FFPH, MPH, MSc, MBBS; Lorraine Ayana Francis, DrPH, MHA; Daniel Olson, MD

Disclosures

Am J Public Health. 2019;109(3):387-392. 

In This Article

Integrated Case Management and Vector Control

Response to Aedes-transmitted arboviral infections can benefit from integrated approaches to case management and vector control, which can improve the response to Aedes-transmitted arboviral infections. A combination of resources and efforts such as water, sanitation, and hygiene; maternal, newborn, and child health; and integrated management of childhood illness, among others, are needed for more effective and timely solutions.[27,28]

Case Management

Asymptomatic arbovirus infections are common. Symptomatic cases are often mild and resolve spontaneously after 1 to 2 weeks. However, some arboviral infections result in high fever, hemorrhage, meningitis, encephalitis, hepatitis, and other serious clinical outcomes and even death, causing a significant clinical and socioeconomic burden.[29] Clinical diagnosis is challenging, initial prodromes are similar, and sensitivity and specificity of clinical algorithms to distinguish CHIKV, DENV, YFV, and ZIKV have not been estimated.[30] As noted, serologic diagnosis may be impeded by cross-reactivity among related viruses.

In the absence of specific antiviral agents, case management of arboviral disease is symptomatic and supportive. The aim is to prevent mortality by monitoring for shock and hemorrhage and managing exacerbated underlying medical conditions. In areas where Aedes-transmitted arboviral disease is endemic, cases should be monitored until clinically stable.[31]

Several recent studies have addressed possible therapeutic options, including the use of traditional antiviral compounds, the synthesis of designer compounds, high-throughput and in silico screening for existing products with possible efficacy, and the use of nucleic acid compounds, therapeutic monoclonal antibodies, and drugs that target host cell proteins.[2] However, none are routinely recommended, and they essentially need further research.

Vector Control

The number of arthropod species potentially capable of transmitting arboviruses is enormous, though 2 mosquito species, A aegypti and Aedes albopictus, are the primary and most important vectors for arboviruses that infect humans in the Americas. A aegypti is primarily an urban, peridomestic, and indoor mosquito and is the main vector for DENV, CHIKV, ZIKV, and YFV. A albopictus is a secondary vector for these pathogens but has a more extended geographical range than A aegypti and, thus, may play a significant role in arboviral transmission in some regions.[32,33]

Early results of genome sequencing indicate that mosquitoes carry large numbers of known and unknown viruses that infect humans and, because of their high mutation rates, many new pathogenic arboviruses may potentially emerge. In accordance, vector control has a potentially predominant role in the context of arboviral control, as is the case with the integrated vector management strategy of the World Health Organization (WHO).[34]

Vector-control methods for Aedes control can be broadly divided into biological, chemical, and environmental.[35] Biological methods include Bacillus thuringiensis israelensis (Bti), larvivorous fish, and copepods for the control of larval stages. The use of the bacteria Wolbachia, genetically modified mosquitoes, and mosquitoes modified by sterile insect technique are currently being evaluated for public health use.[36] Chemical methods include insecticides for residual sprayings, such as peridomestic or intradomiciliary spraying (including indoor residual spraying); long-lasting insecticide treated materials or insecticide-treated nets or insecticide-treated curtains, mostly targeting adult mosquitoes; and larvicides to control larval stages. Environmental methods target productive breeding sites, such as emptying of water containers, waste management, provision of piped water or physical barriers, window screens, and water container covers. Community involvement is considered a crucial element for any vector-control strategy.[37]

Recently a WHO handbook recommended the use of contingency planning, including an algorithm to predict and detect dengue outbreaks.[38] Although global eradication of mosquito vectors is not possible, routine vector control and emergency operations can significantly reduce vector populations.[35] However, in many countries, integrated vector control is poorly implemented.[39,40] For an integrated approach, combining different vector-control methods following the integrated vector management concept requires an assessment of the specific diseases and vectors to be targeted.[41,42] However, the use of chemical methods is almost always included, particularly indoor residual spraying, insecticide-treated nets, and insecticide-treated materials. Biological methods and environmental methods may also be used. In general, the effectiveness of vector control, in terms of primary prevention of transmission, has been assessed for dengue but remains controversial.[36,43]

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