Elderly US traveler with viral load 100,000X the norm may have infected caretaker.
An elderly Utah resident who contracted Zika virus while traveling abroad may have mysteriously passed the virus on to a family caretaker, according to health officials who are investigating the "unique" and "surprising" case.
Officials from the Centers for Disease Control and Prevention confirmed Monday that both the elderly resident, who died in late June, and the caretaker, who has recovered, had tested positive for the virus. Yet, it's unclear how the caretaker became ill; the caretaker hadn’t done either of the two things thought to put one at risk of infection—that is, travel to an area where mosquitoes are transmitting the virus, or have sex with an infected person.
With mosquitoes being the primary transmission route for the virus, the circumstances could suggest that mosquitoes in Utah were responsible for spreading the virus, possibly from the elderly resident. It would mark the first time mosquitoes have been found spreading the virus within the continental US. But that scenario is extremely unlikely, health experts cautioned, because the two types of mosquitoes that commonly spread Zika, Aedes aegypti and Aedes albopictus, aren’t present in the area in which the two Utah residents lived. However, the CDC is now testing local mosquitoes to absolutely rule out this possibility.
Instead, the health experts suggested that the caretaker’s illness may represent the first non-sexual person-to-person transmission of the virus, potentially through contact with bodily fluids or airborne particles from the now-deceased elderly patient. While it may be alarming to consider Zika spreading through general contact, as do common illnesses such as the flu, health experts stress that this scenario, if true, appears to be an exceedingly rare.
“The new case in Utah is a surprise, showing that we still have more to learn about Zika,” Erin Staples, a medical epidemiologist for the CDC, said in a statement. But, she added, “from what we have seen with more than 1,300 travel-associated cases of Zika in the continental United States and Hawaii, non-sexual spread from one person to another does not appear to be common.”
“This is a unique case,” Michael Bell, another medical epidemiologist with the CDC, echoed during a press briefing. The elderly patient appeared to be exceptionally infectious, with virus blood counts more than 100,000 times higher than those seen in normal infected patients.
Such a high viral load may have been due to the fact that the elderly patient had an underlying medical condition that likely dampened the patient's immune system. The patient’s exact cause of death was not clear.
Now, local, state, and federal officials are investigating how the caretaker may have gotten the virus. In addition to testing mosquitoes, officials are talking with and testing the elderly patient’s family, plus other healthcare workers who had contact with the patients.
Zika mostly causes mild to unnoticeable illnesses in adults, but can cause severe birth defects when infecting pregnant women. The virus is primarily spread though mosquito bites, but has also been detected in several bodily fluids, including saliva, semen, breast milk, and blood.
Earlier this year, officials confirmed that Zika can spread from men to their partners during sexual contact. Last Friday, the CDC reported the first known case in which Zika was spread from a woman to her sexual partner. The CDC advises travelers, pregnant women, women who plan to become pregnant, and their sexual partners, to practice safe sex or abstinence.