Zika Virus Spreading Slowly into U.S.

Staff Writer

As expected, Zika infections that were not acquired in Latin America are beginning to surface, although in three very different ways, according to Mono County Public Health Officer Dr. Richard Johnson.

Here is the latest news release from Dr. Johnson about why the Zika virus is a growing threat and why living in the Eastern Sierra does not mean you are safe:

New York: A routine investigation by the New York City (NYC) Department of Health and Mental Hygiene (DOHMH) identified a nonpregnant woman in her twenties who reported she had engaged in a single event of condomless vaginal intercourse with a male partner the day she returned to NYC (day 0) from travel to an area with ongoing Zika virus transmission. She had headache and abdominal cramping while in the airport awaiting return to NYC. The following day (day 1) she developed fever, fatigue, a maculopapular rash, myalgia, arthralgia, back pain, swelling of the extremities, and numbness and tingling in her hands and feet. In addition, on day 1, the woman began menses that she described as heavier than usual. On day 3 she visited her primary care provider who obtained blood and urine specimens. Zika virus RNA was detected in both serum and urine by real-time reverse transcription–polymerase chain reaction (rRT-PCR).

Seven days after sexual intercourse (day 6), the woman’s male partner, also in his twenties, developed fever, a maculopapular rash, joint pain, and conjunctivitis. On day 9, three days after the onset of his symptoms, the man sought care from the same primary care provider who had diagnosed Zika virus infection in his female partner. The provider suspected sexual transmission of Zika virus and contacted DOHMH to seek testing for the male partner. That same day, day 9, urine and serum specimens were collected from the man. Zika virus RNA was detected in urine but not serum by rRT-PCR testing at the DOHMH Public Health Laboratory. The CDC Arbovirus Disease Branch confirmed all rRT-PCR results for urine and serum specimens from both partners.

During an interview with DOHMH on day 17, the man confirmed that he had not traveled outside the United States during the year before his illness. He also confirmed a single encounter of condomless vaginal intercourse with his female partner (the patient) after her return to NYC and reported that he did not engage in oral or anal intercourse with her. The man reported that he noticed no blood on his uncircumcised penis immediately after intercourse that could have been associated either with vaginal bleeding or with any open lesions on his genitals. He also reported that he did not have any other recent sexual partners or receive a mosquito bite within the week preceding his illness.

Independent follow-up interviews with the woman and man corroborated the exposure and illness history. The patients were consistent in describing illness onset, symptoms, sexual history, and the woman’s travel. This information also was consistent with the initial report from the primary care provider.

The timing and sequence of events support female-to-male Zika virus transmission through condomless vaginal intercourse. The woman likely was viremic at the time of sexual intercourse because her serum, collected 3 days later, had evidence of Zika virus RNA by rRT-PCR. Virus present in either vaginal fluids or menstrual blood might have been transmitted during exposure to her male partner’s urethral mucosa or undetected abrasions on his penis.

This case represents the first reported occurrence of female-to-male sexual transmission of Zika virus. Current guidance to prevent sexual transmission of Zika virus is based on the assumption that transmission occurs from a male partner to a receptive partner. Ongoing surveillance is needed to determine the risk for transmission of Zika virus infection from a female to her sexual partners. Providers should report to their local health department any patients with illnesses compatible with Zika virus disease who do not have a history of travel to an area with ongoing Zika virus transmission, but who had a sexual exposure to a partner who did travel.

Persons who want to reduce the risk for sexual transmission of Zika virus should abstain from sex or correctly and consistently use condoms for vaginal, anal, and oral sex, as recommended in the current CDC guidance. Guidance on prevention of sexual transmission of Zika virus, including other methods of barrier protection, will be updated as additional information becomes available (http://www.cdc.gov/zika

Florida: Florida health officials are investigating a Zika infection in Miami-Dade County that may be the first acquired within the state, according to an announcement late Tue [19 Jul 2016]. Health officials reported they are conducting an epidemiological investigation in collaboration with the federal Centers for Disease Control and Prevention (CDC).

No details were provided regarding the potential mode of transmission. Zika is primarily transmitted by the bite of infected Aedes aegypti and Aedes albopictus mosquitoes, though the CDC has also reported cases of the virus spreading through blood transfusions, from pregnant mothers to their newborn children, and by sexual transmission (from male to female, and more recently, also from female to male).

Note: Presumably, a viremic individual returned to Florida and provided an infectious blood meal for a vector mosquito that subsequently infected a local person. This is not surprising. In the past, there have been locally transmitted dengue viruses in Florida. The same vector mosquito transmits both viruses. Additional locally acquired cases where Aedes aegypti is present in the southern USA can be expected during this summer transmission season.

Utah: The CDC is assisting in the investigation of a case of Zika in a Utah resident who is a family contact of the elderly Utah resident who died in late June, 2016. The deceased patient had traveled to an area with Zika and lab tests showed he had uniquely high amounts of virus -- more than 100,000 times higher than seen in other samples of infected people -- in his blood. Laboratories in Utah and at the CDC reported evidence of Zika infection in both Utah residents.

State and local public health disease control specialists, along with CDC, are investigating how the 2nd resident became infected. The investigation includes additional interviews with and laboratory, testing of family members and health care workers who may have had contact with the person who died and trapping mosquitoes and assessing the risk of local spread by mosquitoes.

A CDC Emergency Response Team (CERT) is in Utah at the request of the Utah Department of Health. The team includes experts in infection control, virology, mosquito control, disease investigation, and health communications. "The new case in Utah is a surprise, showing that we
still have more to learn about Zika," said Erin Staples, MD, PhD, CDC's Medical Epidemiologist on the ground in Utah. "Fortunately, the patient recovered quickly, and from what we have seen with more than 13,00 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."

As of July 13, 1306 cases of Zika have been reported in the continental United States and Hawaii; none of these have been the result of local spread by mosquitoes. These cases include 14 believed to be the result of sexual transmission and 1 that was the result of a laboratory exposure.

The obvious question, Dr. Johnson said, is how did the caretaker become infected? "Mosquitoes are unlikely as the source of the virus in this situation because no competent mosquito species is believed to be present in Utah," he said. "The source of the virus must have been the elderly man who subsequently died. He is reported to have had a very high viremia. Presumably there were substantial amounts of virus in urine and saliva as well. The importance of virus in saliva or urine as a source of transmissible virus has not been established. Clearly, this is an unusual case. With over 1300 Zika virus infected individuals reported in the USA, the only locally acquired cases were sexually transmitted, until now."

The good news, according to Dr. Johnson, is that we do not have any evidence of having the right kind of mosquitoes to carry and transmit Zika infection in the Eastern Sierra. "However, travel to many countries in Latin America creates a risk, especially for pregnant or potentially pregnant females," he said. "Over the next few months, I would fully expect to see more cases that have been acquired in the Gulf States from Florida to Texas. Some California counties have the right kind of mosquito, but the numbers are lower, and sustained local transmission is not expected. Stay tuned!"

For more information, including how to protect yourself, go to:
www.cdc.gov/zika and/or www.cdph.ca.gov/zika