Many Flaviviruses are mosquito-borne viruses that can causes disease in humans and animals including Dengue virus (DENV), West Nile virus (WNV), yellow fever virus (YFV), Japanese encephalitis virus (JEV) and tick-borne encephalitis virus (TBEV). These viruses are highly pathogenic to humans causing extensive morbidity and mortality and most importantly, their recent re-emergence and global spread is a current growing public health issue. Currently, DENV alone causes an approximate 50 million infection cases annually and WNV infections have been reported in the five continents. Despite the existence of licensed vaccines for YFV, JEV and TBEV, a major challenge remains given there are no specific and effective antiviral therapies against flaviviral infections.
Considering the homologies between flaviviral replication strategies, it may be possible to identify broad-spectrum compounds with both prophylactic and therapeutic activity against different flavivirus strains. Because the steps involved in compound discovery to their clinical use are protracted and expensive, studies should include testing existing clinically approved drugs as antivirals. Melaleuca alternifolia extracts are good candidates to be explored for novel uses as they have been extensively studied and their composition, chemistry, safety and toxicity are well documented. Melaleluca alternifolia concentrate (MAC) is obtained from the further purification of Tea Tree Oil (TTO) and is a new product exhibiting promising antimicrobial and anti-cancer activities.