A mosquito-borne virus linked to birth defects and paralysis has been detected in Hawaii for the first time in years.

The state’s health department revealed one confirmed case of Zika virus and two cases under surveillance.

The confirmed case was a person who had traveled from overseas, while officials have pinpointed two individuals who ‘may have been exposed’.

All three patients spent their time on the island of Oʻahu and in the sparsely-populated north shore neighborhoods of Waialua and Haleʻiwa. It is the first reported case of Zika in Hawaii since 2019.  

Zika virus is transmitted by the Aedes species of mosquito, which also spread dengue and chikungunya viruses. 

They are common in Texas, Florida and elsewhere in the US, particularly in the south.

Most adults do not become seriously ill from the infection, but in rare cases it can cause damage to the nerves, brain, or spinal cord as well as a blood disorder that can result in bleeding, bruising or slow blood clotting.

Zika infection during pregnancy can also cause serious birth defects and is linked to pregnancy complications, including miscarriage, stillbirth and preterm birth. 

The Zika virus has landed in Hawaii, with two individuals exposed to the paralysis-causing infection

In the US, Zika virus cases are mostly travel-associated, with limited local transmission. The number of cases has varied significantly year to year, with a high point in 2016. 

In that year, there were over 5,000 travel-associated cases, with 224 locally acquired cases. However, following this high, the number of cases dropped significantly, to over 400 in 2017 and in 2023, there were just 7 confirmed cases.

Hawaii’s health department says it is currently monitoring mosquito activity in the affected areas and will ‘implement further control measures as needed’. 

Residents and tourists alike are being urged to take additional precautions to reduce mosquito breeding and avoid bites. 

Some of the recommendations on a health advisory include wearing insect repellent at all times while outdoors and dressing in loose-fitting long-sleeved shirts and pants.

Islanders have also been instructed to check their insect screens are intact, with doors kept closed. 

Meanwhile, any standing water around homes and buildings should be removed, as this is where mosquitos tend to breed.

Once it takes hold in a human host, the Zika virus can be spread between people during unprotected sex, and from pregnant mothers to their children. 

The virus has been found in semen, vaginal fluids, saliva, urine and breast milk. 

Zika virus symptoms are typically mild and may include fever, rash, headache, joint pain, red eyes and muscle pain. Symptoms typically last a few days to a week.

About 80 percent of Zika infections are asymptomatic. 

There is no preventive vaccine or treatment, according to the CDC.

Once it takes hold in a human host, the Zika virus can be spread between people during unprotected sex, and from pregnant mothers to their children

Fetuses’ brains can be affected by the virus when it is passed on from the mother and it can cause microcephaly.

Microcephaly is a condition in which babies’ heads are unusually small, which can lead to seizures, delayed development and other disabilities.

The virus can also increase the risk of unborn children developing Guillain-Barre syndrome – an uncommon illness in which the immune system attacks the nerves and can cause muscle weakness and paralysis.

While Hawaii has the mosquito species capable of transmitting Zika, health officials say the virus is not established in the region. 

Mosquito-borne disease experts are concerned that as global temperatures continue to rise, warmer, more humid weather will become the norm in new places, making those locations the perfect breeding grounds for mosquito populations to flourish.

And as temperatures heat up and mosquitoes migrate to places they previously couldn’t thrive in, their extended reach and longer lifespans give them ample opportunity to spread diseases in new parts of the world.

To date, Zika has been most prevalent in Central and South America, Africa and South East Asia.

There was an outbreak of the virus in Brazil’s capital, Rio de Janeiro, in 2016, and there were fears that year’s Olympic Games would have to be cancelled after more than 200 academics wrote to the World Health Organization warning about it.