The World Health Organization (WHO) has declared the Zika virus a public health emergency.  The Zika virus has been spreading since last year.  It made its way from Africa to a series of tiny islands in Micronesia.  Then it spread through the Pacific Ocean to Easter Island, off the coast of Chile.  From there, cases popped up in Brazil.  Now Zika has infected people in more than 20 countries in Central and South America and the Caribbean.

The mosquito-borne virus doesn’t seem to harm most of its victims but there’s increasing evidence that it can cause serious damage to the brains of fetuses.  In rare instances, it has caused devastating neurological problems in adults.  The potential harm to fetuses, though still unproven, was enough to prompt the World Health Organization to declare Zika a “public health emergency of international concern”.

Zika virus is primarily spread to people through mosquito bites.  It remains in the blood therefore it can be spread through blood to blood contact.  Spread of the virus through blood transfusion and sexual contact has been reported.  There have been three documented cases where it was transmitted through sexual contact, including one in Texas.   The most common symptoms of Zika virus disease are fever, rash, joint pain, and conjunctivitis (red eyes). The illness is usually mild with symptoms lasting from several days to a week. Severe disease requiring hospitalization is uncommon.  The virus usually stays in an infected person’s blood for about a week, sometimes longer.

The highest concern with the Zika virus is for pregnant women as it is believed to be causing a severe birth defect called microcephaly in fetuses of those infected during pregnancy.  Microcephaly is a rare condition where a baby’s head is much smaller than expected. During pregnancy, a baby’s head grows because the baby’s brain grows. Microcephaly can occur because a baby’s brain has not developed properly during pregnancy or has stopped growing after birth, which results in a smaller head size.

It can be an isolated condition, meaning that it can occur with no other major birth defects, or it can occur in combination with other major birth defects.  Babies with microcephaly can have a range of other problems, depending on how severe their microcephaly is. Microcephaly has been linked with a rash of problems such as seizures, vision problems, hearing loss, difficulty swallowing (leading to feeding issues), problems with movement or balance, intellectual disability (decreased ability to learn and function in daily life) and developmental delays, such as problems with speech or other developmental milestones (like sitting, standing, and walking).

These problems can range from mild to severe and are often life-long and in some cases, life-threatening.  Since it’s difficult to predict at birth what problems a baby will have from microcephaly, bthey often need close follow-up through regular check-ups to monitor growth and development.

Brazil’s Health Ministry estimates between 500,000 and 1.5 million people are infected with Zika in the country, but a ministry spokesman cautioned that this is just a rough estimate.  At the end of last year, the doctors in Brazil saw a sudden spike in reported microcephaly cases but in January, cases of the birth defect decreased substantially.  Weekly cases of microcephaly reported in the Brazilian state of Recife peaked at 194 at the beginning of last November but just 34 cases were reported statewide in January.  The drop in reported cases may be due to the awareness of the virus spreading.