Two more patients infected with the Zika virus have been reported in Missouri, the state Department of Health and Senior Services said Thursday.
That makes six cases of the mosquito-borne virus in the state since Zika became a prime health concern, with infections spreading across South America, Central America and the Caribbean.
Zika has been linked in pregnant women who contract the virus to a birth defect known as microcephaly, which leads to unusually small heads in newborns.
None of the six cases confirmed in Missouri was contracted in the state, the health department noted. The infections were found in people who had traveled to Missouri from other places.
Kansas has so far reported two cases, also people who had contracted the infection elsewhere, according to the Centers for Disease Control and Prevention, which has been mapping the spread and sources of the virus.
As of June 1, the CDC had counted 618 Zika infections in the United States and 1,114 in the U.S. territories.
Of the most recent Missouri cases, one was found in a male Missouri resident who had traveled to the Dominican Republic. The other was found in a male Massachusetts resident who was visiting Missouri. The Massachusetts resident had traveled to Puerto Rico, where more than 1,000 infections have been identified.
About 80 percent of people infected with Zika show no symptoms. Symptoms that do show are typically mild and include fever, rash, joint soreness and redness of the eyes.
There is no vaccine. The best prevention measure is to avoid mosquito bites in areas with virus transmission. The CDC recommends that pregnant women avoid traveling to those areas in South America, Central America and the Caribbean.
Early in infection, the virus can be found in the blood and passed through the infected person to a mosquito through a bite. The infected mosquito then can spread the virus to others.
Beyond mosquitoes, the virus can be transmitted through unprotected sex and blood transfusions. It can be passed to a developing fetus during pregnancy.
To avoid mosquito bites, the CDC recommends wearing EPA-registered insect repellent with DEET while outdoors, as well as long pants and long sleeves.