Table 1. Diseases of pathogenic alphaviruses, mosquito vectors, and reservoir hosts.
| Medically relevant alphavirus | Antigenic clade | Confirmed or putative mosquito vector(s) species | Confirmed or putative reservoir host(s) | Disease manifestations |
|---|---|---|---|---|
| CHIKV | SFV | Aedes albopictus [128], Aedes aegypti, Aedes (subgenus Stegomyia) | Nonhuman primates [1] | Fever, polyarthralgia (frequently becomes recurrent), myalgia, rash, and headache |
| ONNV | SFV | Anopheles funestus, Anopheles gambiae [129] | Unknown | Similar to CHIKV with the addition of cervical lymphadenitis |
| MAYV | SFV | Haemagogus janthinomys [130], A. aegypti [131] | Nonhuman primates [132] | Identical to CHIKV |
| RRV | SFV | Culex annulirostris, Aedes vigilax [133] | Marsupials [134] | Identical to CHIKV |
| SFV | SFV | Aedes spp. [135] | Small mammals, birds, nonhuman primates [135] | Mild febrile illness in humans; infrequent myalgia and polyarthralgia; encephalitis can be induced in mice |
| EEEV | EEEV | Culiseta melanura [136], Culex erraticus [137] | Passeriformes birds [136] | Similar to CHIKV if there is no CNS involvement; encephalitic disease includes headache, vomiting, diarrhea, seizures, and coma |
| SINV | WEEV | Culex spp. [138] | Wild birds [139] | Arthralgia, rash, malaise |
| VEEV | VEEV | Culex (Melanoconion) spp. [140] | Small mammals [132] | Similar to EEEV; infection has lower mortality rate than EEEV |
| WEEV | WEEV | Culex tarsalis [141] | Wild birds [141] | Mainly subclinical or nonspecific febrile illness; can progress to encephalitis in rare cases |
Listed are the alphaviruses most frequently associated with disease outbreaks in humans. The reservoir hosts for these viruses include nonhuman primates, rodents, birds, and marsupials. Humans and equines represent either accidental hosts or are involved in epizootic transmission cycles. Mosquitoes from the Aedes and Culex genera are the major vectors of pathogenic alphaviruses, and at least 30 different species have been implicated.
CHIKV, Chikungunya; CNS, central nervous system; EEEV, Eastern equine encephalitis virus; MAYV, Mayaro; ONNV, O'nyong-nyong; RRV, Ross River; SFV, Semliki Forest; SINV, Sindbis; VEEV, Venezuelan equine encephalitis virus; WEEV, Western equine encephalitis virus.