Q&A: Zika virus in mothers linked with microcephaly in babies in Brazil

microcephalyYou may have heard the news: Brazil is facing a startling outbreak of microcephaly, a rare condition in which an infant is born with a head much smaller than it should be. Microcephaly almost always causes significant brain damage and can be life threatening. The epidemic has been linked to a simultaneous influx of the mosquito-borne virus Zika, which was first detected in the country last April and is now spreading rapidly around the Americas.

Thriving spoke with Dr. Ganeshwaran Mochida, a pediatric neurologist at Boston Children’s Hospital who specializes in microcephaly, and Dr. Asim Ahmed, an infectious disease researcher at Boston Children’s who specializes in mosquito-borne illnesses, to find out more about the situation and what you can do to keep your family safe.

What is the Zika virus?

Ahmed: Zika is a mosquito borne virus that causes back and joint pain. It originated in Western Africa and shares many characteristics with the virus “chikungunya,” which means “bent over in pain” in the African Makonde language.  Zika is also similar to dengue, yellow fever, West Nile and Japanese encephalitis.

Zika was first detected in Brazil in April of 2015.

How is the rise in microcephaly linked to the Zika virus?

Ahmed: The first clue of a connection arose when mothers whose infants were diagnosed with microcephaly in utero started reporting a rash, which is a common symptom of the Zika virus.  Not long after, Zika was detected in the amniotic fluid of two pregnant women whose infants were diagnosed with microcephaly in utero.

So far, there has been no definitive clinical proof that the recent outbreak of microcephaly is linked to the Zika virus.  However, evidence of a causal relationship is quite strong.

Mochida:  And it keeps getting stronger. However, even if a clinical and epidemiological link is established, it will take a lot of time and effort to understand the biological basis of the condition.

There are lots of questions, such as:  How does the virus penetrate the placenta and get into the fetus’ brain? What types of brain cells are susceptible to infection? Does the virus eventually kill these infected brain cells, or does it trigger an inflammatory response?

What problems are associated with microcephaly?

MicrocephalydrawingMochida: Microcephaly is not a single disease.  It actually refers to a condition in which the brain (head) size is too small for age and gender.

The type and severity of problems related to microcephaly depend on the cause.  Common problems are cognitive and speech delay, motor impairment, and seizures. If the brain stem is affected, problems could be much direr because the brain stem controls vital functions such as breathing.  If a child born with microcephaly has intact vital functions, he or she may live into adulthood, likely with intellectual disability.

There are diverse causes for microcephaly.  Some are genetic, and some are non-genetic, such as intrauterine infections.  For example, the common infection cytomegalovirus (CMV) merely manifests in adults as flu-like symptoms which dissipate quickly.  However, if a pregnant mother contracts CMV, it can be transmitted to her fetus through the placenta and affect her unborn child’s brain cells.  The virus could then damage the brain, preventing it from growing at a normal rate.

The Zika virus could be acting similar to CMV, but more research is needed to find out.

How and when did the Zika virus become such a huge problem in Brazil?

Ahmed: In 2015, there were 2,782 cases of microcephaly in Brazil. That’s more than 8 times the total from the previous two years combined.

Exactly why the outbreak occurred is still being investigated. Some epidemiologists speculate that it could be related to the influx of foreign visitors to Brazil during the 2014 World Cup.  Global warming has also been suggested as a factor in Zika’s ability to flourish in a new environment; while it certainly couldn’t hurt, there are many more conditional factors about an environment that contribute to a disease outbreak.

Are there any treatments or medications for microcephaly?

Mochida: Unfortunately, there is currently no specific treatment or medication available for the many disorders associated with microcephaly.  However, therapeutic interventions such as speech, occupational and physical therapy and appropriate monitoring and management of potential complications can go a long way in improving a child’s life.  Therefore, everyone with a diagnosis of microcephaly should have a thorough evaluation by a specialist. If a genetic cause is identified, accurate genetic counseling for future pregnancies can be provided.

Have any other serious health issues been linked with the Zika virus?

Mochida: An increase in Guillain-Barré syndrome (GBS), a rare, acute disorder that causes paralysis, has been reported in the area where Zika virus infection is prevalent. Again, more evidence is needed to establish a connection. GBS can affect both males and females of all ages.

GBS is sometimes preceded by a viral or bacterial infection, but it is not caused by direct infection of the nervous system by external agents. Rather, the body’s immune system mistakenly attacks its own nervous system. Sometimes, a viral or bacterial infection seems to activate this process.

It’s also important to note that some congenital infections can have a wide variety of effects. For example, in the case of CMV, a child may not be born with microcephaly but could still be affected by hearing loss. Microcephaly is currently getting a lot of attention because it is such an obvious, observable defect, but it is possible that congenital Zika virus could impair a child’s development, hearing, and/ or vision even if the child does not have microcephaly. We need to monitor children born to mothers who had Zika during pregnancy carefully and over time to fully understand the complete spectrum of the condition.

Cases of Zika have now been reported in various areas of the United States. Could this virus plague our country?

Ahmed: It is a possibility. The variety of mosquito (Aedes) that carries and spreads Zika exists here as well as Brazil. Aedes-borne viruses have been known to follow a geographic pattern from Africa to South America to North America.

The Center for Disease Control (CDC) has launched a targeted surveillance and disease prevention program to monitor the Aedes mosquito population in the United States.

How can you protect yourself from the Zika virus?

Ahmed: People who are traveling to countries where the virus is undergoing in season transmission should be cautious.  Peak times for mosquito activity are typically dusk and dawn. Risk of mosquito-borne diseases can be lessened by avoiding outdoor activity during these times, wearing long clothing, using plenty of insect repellent, and using mosquito netting over beds.

Public health officials in many South American nations are also working to stop the spread of the virus on a large scale. For example, Brazil is spreading massive amounts of larvicide in its heavily affected northeast and southeast regions.

Editor’s note: This is an update on a post published on January 11, 2016.

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