Zika Virus is in the news, people are concerned about this epidemic expanding through the U.S. protectorates and threatening the continental U.S. and Hawaii. We’re at the early stages of understanding this virus and there is much misinformation and uncertainty surrounding this new global pathogenic threat. While the anxiety is wide-spread, the Center for Disease Control (CDC) assuaged our false presumptions in a recent online educational session, Zika update.
Dr. Joanne Cono, MD, ScM, Director of the Office of Science Quality of the CDC gave a live presentation regarding the latest Zika information available and answered a myriad of questions from health care practitioners. She acknowledged that the current outbreak is a rapidly evolving situation.
What is Zika Virus?
- It is a single-stranded RNA virus belonging to the Flaviviridae family of viruses.
- It is closely related to dengue fever, yellow fever, Japanese encephalitis and West Nile Virus.
- It is transmitted to humans mostly through mosquito bites by the Aedea (Stegomyia) species.
- This same species of mosquitoes also transmit dengue and chikungunya viruses.
- These mosquitoes lay their eggs in domestic water holding containers, are aggressive daytime biters but also bite at night, and live both indoors and out.
- The CDC estimates the range of these mosquitoes to be one third to one half of the continental US.
- Other modes of transmission of Zika include: intrauterine, perinatal, sexual and through exposure in the laboratory. Theoretical transmission includes blood transfusion and organ/tissue transplantation.
- The virus can be present longer in semen than in blood, but it is unknown exactly how long.
- It was discovered when the virus was isolated from a monkey in Uganda in 1947.
- Before 2007, only sporadic cases were reported in Africa and Southeast Asia.
- In 2007, the first outbreak was reported on Yap Island, Federated States of Micronesia.
You can watch a Q&A segment on the Zika Virus with Dr. Cono below.
From the Yap Island outbreak, we learned that the infection rate was 73 percent and the symptomatic attack rate was 18 percent. All age groups were infected but adults were seen to seek out medical care more often. There were no severe infections, hospitalizations or deaths reported in this outbreak. If you’d like to watch the full session now, please click the “watch now” button below.
In May 2015, the first locally acquired cases in the Americas were reported in Brazil. As of March 23, 2016, there are cases in 39 countries and territories in the Americas and it is expected to reach other countries. In the continental US, local vector spread disease has not yet been observed. There have been cases in returning travelers (312 cases as of March 30, 2016) and through sexual transmission (6 cases).
It is concerning that Zika virus can be transmitted sexually. Even if someone were to avoid an endemic area, they are still at risk. So far, the virus has been shown only to be transmitted from men to their sexual partners. It is unknown whether women can transmit the virus sexually.
The incubation period for Zika virus is 3-14 days. Most infected people are asymptomatic or only have mild symptoms. Many do not even seek medical care. The most common symptoms are:
- rash (which is non-distinctive from other viral illnesses)
- joint pains
- muscle pain and/or headache may be present
Typically, the symptoms last from a few days to a week. Fatalities and hospitalizations are rare.
There is rising evidence Guilliane-Barre Syndrome is a potential complication of Zika. In returning travelers to the US, Zika virus should be considered in any patient presenting with fever, rash, arthralgias or conjunctivitis within two weeks of their return.
What is known about the relationship between Guillaine-Barre Syndrome (GBS) and Zika virus?
- It is unclear how many people have developed GBS after being infected with Zika virus.
- In 2015 in Brazil, there were six confirmed cases of neurological syndromes in patients aged 2-57 following Zika virus infection. These included both GBS and Acute Disseminated Encephalitis.
- In 2014 in French Polynesia, there were 38 cases of GBS following Zika, all were in adults. There were a total of 28,000 people infected with Zika during this outbreak.
- In the US, there has been one case.
- In general, GBS risk seems to increase with increasing age.
Zika Update: Issues with Testing for Zika
It is imperative to distinguish Zika virus from dengue and chikungunya viruses. The same mosquitos transmit all three diseases and tend to occur in the same areas. Similarly, these diseases often present with similar symptoms. Co-infections with these diseases has not been observed. There are a number of blood tests that detect Zika virus. Dr. Cono said during the CDC Zika session the interpretation of these tests can be complex and confounding variables may make the diagnosis difficult. The CDC recommends healthcare providers work with local health departments to accurately interpret test results. Currently, there are no commercially available tests. IgM can remain positive for 12 weeks or longer.
There is no treatment available for Zika virus at the present time. Therapy consists of supportive measures. Aspirin and NSAIDs should be avoided until dengue is ruled out to eliminate the risk of hemorrhage. Zika is a national reportable disease and all cases must be reported to the health department. The health department should then report it to the CDC. To date, there is no vaccine, but researchers are working on developing one. The CDC is collaborating on vaccine research. The best prevention is avoiding mosquito bites. Additionally, the CDC advises pregnant women avoid travel to areas where Zika is present in any trimester of pregnancy.
Zika virus in pregnant women
- The information is still limited here.
- Pregnant women do not appear to be at increased risk of being infected.
- The disease does not appear to be more severe in pregnant women.
- There is a possible link between Zika and microcephaly. There is a small number of positive Zika test results in infants with microcephaly. The pattern is consistent with Fetal Brain Disruption Sequence. It is not known if this is a causal relationship and if there is any bearing on the timing in the pregnancy.
- Zika virus has also been linked with other birth defects: impaired growth, absent or poorly developed brain structure, eye defects.
- Pregnant women with possible Zika exposure can be offered serologic testing (IgM).
- The CDC advises pregnant women with male partners with Zika virus infection or exposure to use a condom the right way every time or abstain from sex for the duration of the pregnancy.
In children, most cases of Zika virus are asymptomatic or mild. The most common signs and symptoms include fever, rash, arthralgias and conjunctivitis. Children under the age of 19 had lower attack rates than adults. The CDC recommends Zika virus testing for any infants born with microcephaly or intracranial calcifications to women who lived in a Zika virus area during pregnancy or who tested positive for the virus. Additionally, if the test results of the mother are inconclusive, Zika virus testing on the infant should be done. If the infant is born to a mother who was in a Zika area during pregnancy and has other abnormalities, the CDC suggested testing the mother first. A woman who has traveled to a Zika endemic area should wait at least eight weeks before getting pregnant after returning. It is recommended men wait six months before having unprotected sex because it is not known how long Zika can remain in the semen. The CDC advises the use of condoms.
The CDC is actively working to prevent the spread of infection and to educate healthcare providers on the most up-to-date Zika information. They have over 100 CDC members responding to the Zika crisis. Also, they are collecting information to learn more about Zika in pregnancy. The CDC has developed two surveillance programs: US Zika Pregnancy Registry and Zika Active Pregnancy Surveillance System (ZAPSS). They will use this information to direct public health efforts and to guide testing and treatment recommendations for pregnant women infected with Zika. There is a 24/7 hotline available for clinicians with suspected cases of Zika: (770) 488-7100 or by email ZikaMCH@CDC.gov.
To continue receiving updated information, visit www.cdc.gov/Zika
Dr. Linda Girgis MD, FAAFP is a family physician who treats patients in South River, New Jersey and its surrounding communities. She holds board certification from the American Board of Family Medicine and is affiliated with both St. Peter’s University Hospital and Raritan Bay Hospital. She is an active blogger and active on social media.