Authorities in California have verified two instances of dengue, a disease carried by mosquitoes that is uncommonly spread in the United States.

Two individuals in Southern California have contracted dengue fever despite not traveling outside the United States, a country where this mosquito-borne illness is uncommon, according to health officials.

Last month, officials confirmed that a resident of Pasadena had contracted dengue, but they are now in the process of recovering.

The Pasadena Public Health Department made an announcement stating that this is the initial instance of dengue in California that is not linked to traveling. Instead, it is an exceptionally uncommon case of local transmission within the continental United States.

According to health officials in Pasadena, the case is still being investigated. However, it seems that an individual contracted the dengue virus, then returned home and was subsequently bitten by a mosquito, which then transmitted the virus to a local resident.

Officials in Long Beach reported a new case of domestically acquired dengue on Wednesday. They also stated that the individual has since recovered.

The health departments of both cities stated that the likelihood of coming into contact with others was minimal.

Dengue is caused by several related viruses and is spread through the bite of infected Aedes mosquitoes. It is common in tropical areas and causes high fevers, headaches, nausea, vomiting, muscle pain and, in the most serious cases, internal bleeding leading to death.

Around four billion individuals, roughly half of the global population, reside in regions where dengue poses a threat. According to the U.S. Centers for Disease Control and Prevention, there are approximately 400 million cases of infection and 40,000 fatalities each year.

The global infection rate has been increasing, leading to new initiatives to combat it.

According to data from the CDC, there have only been 583 cases of dengue reported in the U.S. and its territories this year, with the majority (520) in Puerto Rico, followed by 62 in Florida and one in Texas. Dengue is not common in the U.S.

The recent incidences in California were not included in the total count.