First tied with horrendous birth defects, then to nervous-system illness in adults, a small study has now tied Zika virus to deadly heart trouble.
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The study encompassed just nine Venezuelans of median age 47, six women and three men, who had no prior history of cardiovascular disease. All but one developed dangerous arrhythmia and two-thirds showed heart failure.
They were seen within one week of having Zika-type symptoms, tested positive for active Zika, and subsequently reported common symptoms of heart problems. The nine were followed for an average of six months, beginning in July 2016.
"Our report provides clear evidence that there is a relationship between the Zika virus infection and cardiovascular complications," stated Karina Gonzalez Carta, lead author of the study and a cardiologist and research fellow at Mayo Clinic. "Based on these initial results, people need to be aware that if they travel to or live in a place with known Zika virus and develop a rash, fever or conjunctivitis, and within a short timeframe also feel other symptoms such as fatigue, shortness of breath or their heart skipping beats, they should see their doctor."
The nine were extremely unlikely to have undiagnosed heart trouble beforehand.
"We have to concede the point that, prior to Zika infection, some patients may have had some underlying CV disease that was mild and did not cause symptoms," Carta explained to Haaretz. "If this was the case, aggravation of existing CV disease would represent a serious consequence of Zika infection. But at this point -- based on careful examination, patient interview, review of medical records, and extensive cardiac testing -- we think that the CV disease we saw was due entirely to Zika."
Heart disease in young women largely stems from congenital conditions, Carta explains. "These can be easily detected by the tests that were performed on these patients. None of these patients exhibited any underlying congenital abnormalities or evidence of other rare but well-defined causes of cardiovascular disease."
Nor could nasty habits be blamed in the stead of the virus: asked about the possibilities, Carta explained that cocaine is indeed a leading cause of heart attack in many U.S. inner cities, but the Venezuela patients did not present with acute heart attack.
The strain of Zika virus affecting Latin America, including the patients in this study, belongs to the Asian lineage, not the original African type, Dr. Carta told Haaretz. The Venezuela strain has been associated with the same kind of birth defects in newborns, such as microcephaly and devastating nervous system damage, and the nervous-system condition Guillain-Barre in adults, as the notorious Brazilian variant.
Guillain-Barre is a rare nervous system illness caused by the immune system itself attacking the nerve cells, which turns out to also be triggered by Zika, though not in all cases.
Zika is transmitted by mosquito, and Carta and the team at the Institute of Tropical Medicine in Caracas say they weren't "entirely surprised" by their findings, based on trends in other mosquito-borne diseases known to affect the heart, including the dengue and Chikungunya viruses. But the severity of the trouble caused, including rapidly progressive heart failure and potentially life-threatening arrhythmias, was unexpected. Nor have the patients since recovered.
Are adults with Zika likely, therefore, to die of heart trouble? Carta elaborates: "Our case report provides evidence that there is a relationship between Zika virus infection and cardiovascular complications. Of course, we do not know the true incidence rate By analogy, not everyone who gets measles has serious complications and dies, but some do."
Viral infections are frequently asymptomatic and, therefore, such infections are frequently not recognized as possible causes of heart disease, she adds. "The enormous variability of clinical symptoms may range from asymptomatic presentation to manifest heart failure rarely producing heart attacks," Carta says.
Zika symptoms usually include fever, rash, conjunctivitis, muscle and joint pain, malaise or headache, which typically last for two to seven days, according to the World Health Organization. The best way to prevent Zika is by preventing mosquito bites.
The disease is not endemic in Israel: the few cases encountered so far were of people who contracted Zika outside the country. The places with active local zika transmission, at this stage, include almost all of South America, Mexico and parts of the southern United States, India and southeast Asia, and parts of Africa.