When to consider a Zika diagnosis

At last count, numbers of U.S. travel-related and home-grown Zika cases was continuing to rise. With rash being among the primary symptoms of this often asymptomatic illness, dermatologists are among the providers who might encounter these patients and should consider Zika as a possible diagnosis.

As of August 17, 2016, the CDC reported there were 14 locally acquired mosquito-borne Zika cases in the U.S.; 2,245 travel-associated cases; and one laboratory-acquired case. A small area of Miami, Fla., had documented five symptomatic and eight asymptomatic locally acquired Zika infections and, on a global scale, more than 60 countries or territories have reported new local Zika transmission, according to a viewpoint published August 8 in JAMA.¹

Zika spreads rapidly, according to Jose Dario Martinez, M.D., who practices internal medicine and dermatology in Monterrey, Nuevo Leon, Mexico.

“The Zika threat is bigger than dengue and chikungunya to the U.S., … because it can be transmitted in several ways, and Zika virus is more difficult to detect because most cases are asymptomatic, and suddenly you face the complications, such as Guillain-Barre, and, in unaware pregnant women, microcephaly,” says Dr. Martinez, an international fellow of the American Academy of Dermatology, who presented on Zika, dengue and chikungunya at AAD’s summer sessions earlier this year. “Cutaneous manifestations include an erythematous maculopapular rash that affects [the] trunk, extremities and the genitalia. Other features include non-purulent conjunctivitis, small joints arthralgia and low grade fever. Mucocutaneous affection include mouth enanthem and small purpuric lesions in soft palate.”

Zika fever, an emerging viral disease in The Americas, is transmitted mainly by the Aedes aegypti female mosquito. Zika virus is transmitted also from mother to fetus during the first trimester of pregnancy, by sexual intercourse or blood transfusion.

The incubation period is one week, according to Dr. Martinez.

What makes Zika difficult to diagnose is that more than 80% of patients are asymptomatic, according to Dr. Martinez.

There are important similarities and differences among Zika, dengue and chikungunya viruses, according to Dr. Martinez. Zika, dengue and chikungunya are transmitted by the same vector, occur in the same geographic area of the world, and clinically all three have in common rash, fever and joint pain. Unlike dengue, Zika does not have hemorrhagic manifestations, shock syndrome or high fever. And unlike chikungunya, in Zika there is no severe arthritis, periocular melanosis (depend on the skin color of the patient) and no vesicles or bullae in the genitalia area, Dr. Martinez says.

Zika complications include Guillain-Barre syndrome and microcephaly in newborns from mothers infected during the first trimester, according to Collin M. Blattner, D.O., dermatology resident, Silver Falls Dermatology and Allergy, Salem, Ore., and author of an article on Zika, published June 2016 in the Journal of the American Academy of Dermatology.²

New research³ suggests that while Zika is thought of as a transient infection in adults, without marked long-term effects, exposure to the virus might, in fact, have consequences on the adult brain. In the mouse model, the researchers show that certain adult brain cells, including those that replace lost or damaged neurons throughout adulthood and could be critical for learning and memory, may be vulnerable to infection.

Also read: How to counsel concerned patients about Zika

Next: What you need to do now

The dermatologist’s role

Dermatologists who have patients who have recently traveled and present with a rash or other Zika symptoms should keep Zika on their differential, according to Dr. Blattner.

“That’s where dermatologists come into play. You need to be extra vigilant with patients who have traveled, especially to nations where Zika is more endemic. South America is the big one right now, especially with Brazil and the Olympics,” Dr. Blattner says.

Dermatologists should consider testing those patients or referring them for testing, especially if the patient is a woman of childbearing age (pregnant or not), according to Dr. Martinez.

The recommended testing in the first week of disease includes the RT-PCR for Zika. During the second week, clinicians should test blood for IgM and IgG. And after two weeks, an RT-PCR urine test in those patients can detect the infection, according to Dr. Martinez.

There is concern that available testing for Zika might cross-react with other viruses, resulting in false positives, Dr. Blattner says.

Zika treatment is supportive therapy. There is currently no vaccine, although work is being done to find one. The National Institutes of Health (NIH) announced August 23, 2016 that it was testing three different vaccine approaches that were shown to protected rhesus macaques from infection with the Zika virus. The hope is that at least one of these will put researchers on the path to developing a safe and effective Zika vaccine for people.

Prevention is the best bet, for now. Recommended prevention strategies include getting rid of standing water, use of insect repellents, appropriate clothing and mosquito nets.

“The Zika virus can live in male semen for six months, so the use of condoms is highly recommended. Also, blood donors with history of traveling to endemic countries should be tested for Zika,” Dr. Martinez says.

Dermatologists should advise their patients who are going to travel to refrain from becoming pregnant. That warning could last for as long as a couple of years, according to Dr. Blattner.

“You should probably advise [women of childbearing age who want to get pregnant] against traveling to where Zika is endemic. That would be my personal take,” Dr. Blattner says. “If they get infected during the first trimester, they may not present with a maculopapular rash or flu-like symptoms. You need to be extremely careful … because this has so much impact on a baby’s life. I think we can’t understate the seriousness of Zika and we have to become more aware of it, if it does continue to spread in the U.S., especially with home-grown cases.”

Disclosures: Drs. Martinez and Blattner report no relevant disclosures.

References:

1.      Frieden TR, Schuchat A, Petersen LR. Zika Virus 6 Months Later. JAMA. 2016.

2.      Farahnik B, Beroukhim K, Blattner CM, Young J. Cutaneous manifestations of the Zika virus. J Am Acad Dermatol. 2016;74(6):1286-7.

3.      Li H, Saucedo-cuevas L, Regla-nava JA, et al. Zika Virus Infects Neural Progenitors in the Adult Mouse Brain and Alters Proliferation. Cell Stem Cell. 2016.