Treatments designed to combat tropical infectious diseases are lacking, so the best thing travelers to these regions of the world can do is defend themselves against mosquito bites, according to Stephen K. Tyring, MD.

“We have no specific therapies for these infections,” explained Dr. Tyring of the University of Texas in Houston.

“Therefore, the best management is to avoid mosquito bites [by using] DEET, protective clothing, etc.,” he said in an interview prior to the Caribbean Dermatology Symposium.

Blanchable macules and papules typically start on the face or trunk, 3-5 days after the febrile phase of Zika virus, and spread to the fingers and feet.

In terms of cutaneous presentations, Dr. Tyring highlighted the Zika rash, which consists of “blanchable macules and papules.” This rash typically occurs on the face or trunk, and spreads to the fingers and feet, becoming more diffuse as it gets closer to the extremities. However, it’s important to note that symptoms occur in only about 20% of those with infection, and if symptoms do present, this typically isn’t for 2-12 days until after the infection occurs.

“Treatment [of Zika virus infections] is supportive,” he said, because currently, there are no vaccine and no antiviral therapy aimed specifically at treating Zika virus infections. It’s also important for clinicians to rule out dengue and chikungunya when testing for Zika virus, and to avoid prescribing NSAIDs and aspirin until a definitive diagnosis is made, to avoid causing hemorrhaging.

Dr. Tyring also advised refraining from sexual contact with any individuals who have been to tropical areas and may have been exposed to the Zika virus.

The Centers for Disease Control and Prevention recommends: “People with a partner who traveled to an area with Zika can use condoms or not have sex. If the traveler is female: Use condoms or do not have sex for at least 8 weeks after her return from an area with Zika (if she doesn’t have symptoms), or for at least 8 weeks from the start of her symptoms (or Zika diagnosis) if she develops Zika. If the traveler is male: Use condoms or do not have sex for at least 6 months after his return from an area with Zika (if he doesn’t have symptoms), or for at least 6 months from the start of his symptoms (or Zika diagnosis) if he develops Zika. This extended period is because Zika stays in semen longer than in other body fluids.”

Dr. Tyring also discussed the cutaneous manifestations and other symptoms of the flavivirus infections dengue and chikungunya.

“[About] 40% of the world’s population live in areas where there is a risk of dengue transmission, [and] the World Health Organization estimates that 50 to 100 million infections occur yearly, including 500,000 DHF [dengue hemorrhagic fever] cases and 22,000 deaths,” mostly in children, he said in his presentation at the meeting provided by Global Academy for Medical Education.

This hematoxylin-eosin-stained photomicrograph depicts the cytoarchitectural changes found in a liver tissue specimen extracted from a dengue hemorrhagic fever patient.

With dengue, Dr. Tyring advised clinicians to look for “white islands in a sea of red” as a sign of the characteristic dengue rash, in addition to petechiae and ecchymoses. There also may be conjunctival hemorrhages. Other symptoms include abdominal pain, vomiting, nosebleeds, gum bleeding, black tarry stools, irregular breathing, and drowsiness or irritability.

The tourniquet test is a useful tool to determine if a patient has dengue fever. This involves taking the patient’s blood pressure, then inflating the cuff to a point midway between the systolic and diastolic blood pressure, and maintaining it for 5 minutes. Deflate the cuff and wait for 2 minutes; then count the petechiae below the antecubital fossa. A positive test result is 10 or more petechiae per square inch, according to the CDC definition.

A relative of dengue, the chikungunya virus can present in the form of a morbilliform rash, nasal hyperpigmentation, purpuric macules, and erythema, the latter of which can sometimes be accompanied by ulcers. In addition to dermatologic symptoms (occurring in 40%-75% of patients), joint pain and fever also are associated with a chikungunya virus infection.

“Redness, swelling, and pain of the scrotum and groin region” also can occur, while “ulceration on the vulva in women has occasionally been reported in other outbreaks,” Dr. Tyring explained.

For further reading on this matter, Dr. Tyring recommended a report by Nawas et al. entitled, “Emerging infectious diseases with cutaneous manifestations” (J Am Acad Dermatol. 2016 Jul;75[1]:1-16) and a 2008 JAMA study on dengue and DHF coauthored by Anthony S. Fauci, MD (299[2]:214-6).

Dr. Tyring reported no relevant financial disclosures. Global Academy and this news organization are owned by the same parent company.

Watch for cutaneous manifestations of tropical infectious diseases