Japanese encephalitis virus is present in Asia and Oceania, from Japan to India, Pakistan and Australia. Outbreaks are erratic and spatially and temporally limited phenomena, occurring quite unpredictably. The virus is a leading cause of viral encephalitis in Asia, with 30 000 to 50 000 cases reported annually.
West Nile virus is a mosquito-borne flavivirus that is maintained in an enzootic cycle between mosquitoes and birds. Humans and horses are incidental dead-end hosts.
Sindbis virus is widely and continuously found in insects (the main vectors are Culex and Culiseta mosquitoes) and vertebrates in Eurasia, Africa, and Oceania. ECDC factsheet for health professionals
Meningococcal disease is caused by Neisseria meningitidis, a bacterium with human carriers as the only reservoir. It is carried in the nose, where it can remain for long periods without producing symptoms.
Yellow fever (YF) is a mosquito-borne infection, distributed in west, central and east Africa and in South America. The disease can cause a wide spectrum of symptoms, from mild to fatal. In severe cases there may be spontaneous haemorrhage. Mortality of these clinical cases can be as high as 80%, on a par with Ebola, Marburg and other haemorrhagic viral infections.
Most Zika virus infections are either asymptomatic or cause a mild illness with a transient maculopapular rash. However, there is scientific consensus that Zika virus is a cause of microcephaly, congenital nervous system malformations and Guillain-Barré syndrome.
Chikungunya is a viral disease transmitted by Aedes mosquitoes to humans. The word ‘chikungunya’ means 'that which bends up', an allusion to the posture of the suffering patients. The most common symptom is joint pain.