Human Arboviruses Infections
المؤلف:
Stefan Riedel, Jeffery A. Hobden, Steve Miller, Stephen A. Morse, Timothy A. Mietzner, Barbara Detrick, Thomas G. Mitchell, Judy A. Sakanari, Peter Hotez, Rojelio Mejia
المصدر:
Jawetz, Melnick, & Adelberg’s Medical Microbiology
الجزء والصفحة:
28e , p557-558
2025-12-13
39
There are several hundred arboviruses, of which about 100 are known human pathogens. Those infecting humans are all believed to be zoonotic, with humans the accidental hosts who play no important role in the maintenance or transmission cycle of the virus. Exceptions are urban yellow fever, chikungunya, Zika, and dengue. Some of the natural cycles are simple and involve infection of a nonhuman vertebrate host (mammal or bird) transmitted by a species of mosquito or tick (eg, jungle yellow fever, and Colorado tick fever). Others, however, are more complex. For example, tick-borne encephalitis can occur after ingestion of raw milk from goats and cows infected by grazing in tick-infested pastures where a tick–rodent cycle is occurring.
Individual viruses were sometimes named after a dis ease (dengue, yellow fever) or after the geographic area where the virus was first isolated (St. Louis encephalitis, West Nile fever). Arboviruses are found in all temperate and tropical zones, but they are most prevalent in the tropics with its abundance of animals and arthropods.
Diseases produced by arboviruses may be divided into three clinical syndromes: (1) fevers of an undifferentiated type with or without a maculopapular rash and usually benign; (2) encephalitis (inflammation of the brain), often with a high case fatality rate; and (3) hemorrhagic fevers, also frequently severe and fatal. These categories are somewhat arbitrary, and many arboviruses may be associated with more than one syndrome.
The degree of viral multiplication and its predominant site of localization in tissues determine the clinical syndrome. Thus, individual arboviruses can produce a minor febrile ill ness in some patients and encephalitis or a hemorrhagic diathesis in others. Notably, Zika virus can pass through the placenta and infect fetal tissue, so it has become a major cause of birth defects in regions where transmission occurs.
Arbovirus infections occur in distinct geographic distributions and vector patterns (Figure 1). Each continent tends to have its own arbovirus pattern, and names are usually suggestive, including Venezuelan equine encephalitis, Japanese B encephalitis, and Murray Valley (Australia) encephalitis. Many encephalitides are alphavirus and flavivirus infections spread by mosquitoes, although the group of California encephalitis diseases is caused by bunyaviruses. On a given continent, there may be a shifting distribution depending on viral hosts and vectors in a given year. There can also be major shifts in viral distribution to new areas with conditions permissive for further transmission, as evidenced by the introduction of West Nile, chikungunya, and Zika viruses from the Old to New World continents.
Fig1. Known distributions of selected flaviviruses causing human disease. A: Yellow fever virus. B: Dengue virus. C: St. Louis encephalitis virus. D: Japanese B encephalitis virus. E: Murray Valley encephalitis virus. F: Tick-borne encephalitis virus. G: West Nile virus. (Reproduced with permission from Monath TP, Tsai TF: Flaviviruses. In Richman DD, Whitley RJ, Hayden FG [editors]. Clinical Virology, 2nd ed. Washington DC: ASM Press, 2002. ©2002 American Society for Microbiology. No further reproduction or distribution is permitted without the prior written permission of American Society for Microbiology.)
Several arboviruses cause significant human infections in the United States (Table1). The numbers of cases vary widely from year to year.
Table1. Summary of Major Human Arbovirus and Rodent-Borne Virus Infections That Occur in the United States
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