What is Zika virus and how do we avoid infection?

Hospitalists are specialists in the care of patients who are in a hospital. At Sharon Hospital, that person for the past 17 years has been Dr. Mark Marshall, director of the Hospitalist Program and hospital chief of staff. Send medical queries to him at mark.marshall@sharonhospital.com; any questions that we use will be presented anonymously.

How does a disease go from obscurity to a global emergency? The World Health Organization (WHO) has declared Zika an “international public health emergency.” We spoke with a colleague, Dr. Cesar Prinzac, an internal medicine physician living and working in Rio. He says the impact of Zika on travel and lifestyle in Brazil has been “huge.” He adds that pregnant women with financial means have “moved to Florida” for their first trimester. Repellent sales have “skyrocketed” and “panic spread out.” 

He believes that for those of us living in Connecticut, there’s no reason to panic.

He describes Brazil as being “mosquito-friendly” in that severely affected areas in Brazil have poor sanitation. Mosquitoes breed all year and people spend a lot of time outdoors doing things like “walking the streets and waiting for the bus.” 

Dr. Prinzac does not think there will be a large outbreak in America. He says “New York has seasons and people stay at home in air-conditioned homes when it’s hot.” 

Much of the discussion in the press recently regarding the current outbreak of illness caused by the Zika virus in Brazil and other countries stems mainly from the devastating birth defect — microcephaly — that seems linked to infection with the virus in pregnant women. 

Children with microcephaly have abnormally small brains and are often severely intellectually disabled. Zika virus illness is also associated with Guillain–Barré syndrome, an acute polyneuropathy that may cause severe muscle weakness or paralysis. People with Guillain–Barré syndrome may become so weak they need mechanical support for their breathing. 

2016 Summer Olympics

An outbreak of Zika has been ongoing in Brazil since early 2015. This summer, the Olympic Games will be hosted by the city of Rio de Janeiro. This has magnified the interest in this story even more.

Zika virus is mainly spread by the bite of an infected Aedes mosquito. These are the same mosquitoes that spread the dengue and chikungunya viruses. Zika was first identified in Uganda in 1947 in rhesus monkeys and was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Since that time, outbreaks of Zika virus disease have been recorded in Africa, Asia, the Pacific Islands and South and Central America. 

In the continental United States between Jan. 1, 2015, and Feb. 24, 2016, there have been 107 travel-related cases of Zika virus disease reported to the Centers for Disease Control and Prevention. There were no reported cases of mosquito-acquired Zika virus in the U.S. during that time. 

There have also been reports of sexually transmitted Zika virus infection in the U.S. These appear to have occurred in women who had sex with men who were infected outside the country. 

Zika virus usually remains in the blood of an infected person for about a week, but it can be found longer in semen. It has not been isolated from breast milk. Once a person has been infected, protective antibodies develop, resulting in lifelong immunity.

Most people infected with Zika virus do not become ill. Of the approximately 20 percent who become ill after a bite from an infected mosquito, their symptoms are usually mild and, like other similar viruses, may include fever, muscle pain, headache, rash, joint pain and conjunctivitis. 

The time from mosquito bite to symptoms for Zika virus is not known, but is most likely a few days to a week with symptoms lasting for two to seven days. 

Links to Guillain-Barré

According to the WHO, during outbreaks in French Polynesia and Brazil in 2013 and 2015, health authorities reported possible neurological complications caused by Zika virus. In Brazil, there has been an increase in Guillain-Barré syndrome as well as an increase in babies born with microcephaly. Investigators point to increasing evidence of a link between Zika virus and microcephaly and Guillain-Barré syndrome. Further study is ongoing.

Treating and avoiding Zika

The diagnosis of Zika virus illness requires a high index of suspicion. In the right setting, and with mild illness, the diagnosis may be made on clinical grounds without blood testing. During the first week after onset of symptoms, Zika virus disease can be diagnosed by performing specific polymerase chain reaction (PCR) testing on the blood. Virus-specific antibodies usually develop toward the end of the first week of illness.

There is no specific medication to treat Zika virus infections. Treatment focuses on relief of symptoms and supportive care. Adequate rest and hydration is paramount. Medications such as acetaminophen can be used to relieve fever and pain. It is suggested to avoid aspirin and other non-steroidal anti-inflammatory drugs especially in children and teenagers because of the risk of Reye’s syndrome. 

For those who become ill with Zika virus, it is important to prevent mosquito bites for the first full week of illness as the virus can be passed from an infected person to another Aedes mosquito. An infected mosquito can then spread the virus to other people through their bites. 

If traveling to an affected area, prevent mosquito bites by wearing light-colored long-sleeved shirts and long pants. Use DEET containing insect repellents. (Do not use insect repellent on babies younger than 2 months of age.) Stay in places with window and door screens to keep mosquitoes outside.  Clean or cover containers regularly that can store water, such as buckets, drums, flower pots and tires.

The Centers for Disease Control provides the American public with up-to-date information on its website. The WHO began posting notices about Zika in October  2015. Dr. Margaret Chan, the director general of the WHO, recently went to Brazil and met with President Dilma Rousseff. 

Dr. Chan said, “A coordinated international response is needed to improve surveillance … to intensify the control of mosquito populations, and to expedite the development of diagnostic tests and vaccines to protect people at risk.”

Mark J. Marshall, DO,MA,FACP,FHM, is board certified in Internal Medicine and Palliative Medicine, chair section of Hospital Medicine, and chief of staff at Sharon Hospital. Douglas Finch, MD,FIDSA, is a hospitalist and the infection control director for Sharon Hospital.