Questions about the Zika Virus

For the World Health Organization (WHO), the Zika virus constitutes a “public health emergency of global reach.” This virus usually has mild symptoms, but causes severe malformations in unborn babies. It is being spread on almost every continent, through forty countries.

The outbreak of the Zika virus, which originated in Brazil, has now reached forty countries. The number of cases is quite small, but its increasing spread suggests that the epidemic has not peaked, prompting the World Health Organization (WHO) to declare an emergency to global public health.

Brazil is by far the most affected country, with over 1.5 million cases. The virus continues to spread rapidly in neighboring countries, such as Colombia, with 20,000 cases reported, and El Salvador, with 5,000 cases. The recent discovery of a case of sexual transmission does not reassure the health authorities.

Is Asia the most vulnerable?

The Asian continent is perhaps the most vulnerable. Asia, say experts, may be the next field of propagation because of its environment, population density of many slums, and the presence of the Egyptian mosquito, the virus vector. The summer monsoon in India is fueling the fears of health authorities. Both Indonesia and Thailand have identified a positive case.

This disease is mild in most cases, but can be a danger to pregnant women. Fetuses of infected mothers are at high risk of developing defects.

This arbovirus became known in 1947, when it was discovered in Uganda. But the cases reported have long remained few, and little disturbing symptoms. In 2013 and 2014, an epidemic was already declared in French Polynesia. However, it remained at a much lesser extent than when it started affecting Brazil late in 2015, and than how it is currently spreading around the world.

Was the 2014 World Cup a giant incubator?

The silent spread of Zika was favored by the nature of its symptoms. They are close to simple flu-like symptoms. In 80 percent of cases, the infected person develops symptoms. Consequently, the first outbreaks were not taken seriously.

According to The World Health Organization, this Brazilian epidemic took root during the football World Cup 2014, which operated as a “giant incubator.” The Olympics, which are set for 2016, may make the fight against this virus more complicated. Brazil has already recommended pregnant women not to attend Olympic competitions.

The Aedes aegypti mosquito, responsible for transmitting the Zika virus, has already hit 1.5 million Brazilians as of January 2016.

Concern rises against the Zika virus. Spreading explosively, it is strongly suspected to cause neurological disorders, Guillain-Barre syndrome, and congenital malformations, microcephaly.

Recently, the World Health Organization (WHO) experts declared the outbreak constitutes a “public health emergency of global reach.”

Transmitted by mosquitoes, such as dengue or chikungunya, the virus has already reached 1.5 million people in Brazil, and 3 to 4 million cases are expected in the Americas in 2016. Imported cases have been identified in Europe, including five in metropolitan France. Charged with having weakly reacted during the Ebola outbreak, WHO has announced a series of recommendations to improve the fight against this new threat. One of the priorities is to increase the monitoring of cases of Guillain-Barré and microcephaly in areas affected by the Zika virus, to determine if it is directly involved, or if other factors are involved. WHO is also advocating an intensified research in developing treatments and vaccines. No measure of travel or trade restrictions is however envisioned.


Zika is an arbovirus transmitted by the bite of Aedes mosquitoes (aegypti and albopictus). From the family of flaviviruses, such as dengue or yellow fever, Zika was identified for the first time in a rhesus macaque monkey in a Ugandan forest in 1947,as mentioned above. It was then isolated in humans in 1952, in Uganda and Tanzania.

The first outbreak occurred in the Yap Islands (Micronesia) in 2007, where it reached three-quarters of the population. Other cases followed, in French Polynesia in October 2013 to April 2014, and Brazil in May 2015. The first Brazilian cases have been described in two newspaper publications in May and June 2015. Since October 2015, the virus spread in Central American countries.

Guyana and Martinique in turn are in epidemic phase. “This is the third epidemic arbovirus after dengue and chikungunya, and probably not the last,” said François Bourdillon, general director of the National Institute of Health Surveillance (VS). “The spread of Zika was extremely fast globally.”

Questions have been raised, wondering if this is a mutant virus. This is what could explain the recent explosion of cases, according to experts quoted in “New Scientist”. The assumption seems unlikely, however, in the eyes of other specialists surveyed. The analysis of the entire genome of the Zika virus circulating in Brazil shows a similarity “almost complete” with the strains causing the outbreak which occurred in 2013 and 2014 in the Pacific. This information comes according to a study conducted by researchers at the Institut Pasteur in French Guiana, published in “The Lancet” on January 16.

Hard to identify, the infection is asymptomatic in three quarters of cases. Symptoms, when present, appear three to twelve days after the bite, as a rash with or without fever. To this can be added fatigue, headaches and body aches. The virus can also manifest as conjunctivitis – the swelling of hands or feet. These symptoms usually disappear within two to seven days, says WHO. A priori, this is an immunizing infection, which means that you can not contract the virus twice. Zika and its effects in humans remain poorly understood, however, concede specialists.

The virus genes can be identified through blood tests, urine or saliva. But the window is short. “The virus is present in the blood between three to five days, in urine for about ten days and in saliva between three to five days. There are no data on breast milk,” said Isabelle Leparc-Goffart, coordinator of the National Center for Arboviruses.

In case of a negative result despite suggestive symptoms of a Zika virus infection, a serological diagnosis (antibody test) is performed only by the some particular centers.

Concurrent circulation of dengue and chikungunya (close to Zika) complicates diagnosis, both clinical and biological. The results can be falsely positive because of serological cross-reactivity between these viruses.


This is one of the main concerns. While the evidence is not yet formally established, it is now highly likely that a Zika virus infection during pregnancy can cause serious abnormalities of brain development, such as microcephaly (too small brain size and head circumference, often associated with brain damage). The most severe form of the disease can lead to death in utero or in the first days of life.

Early in 2016, parallel to the outbreak of Zika virus, the local health authorities in Brazil have identified more than 4,000 suspected cases of microcephaly. Microcephaly is a rare malformation. In the United States, between two and 12 cases are reported per 10,000 live births, according to the Center for Disease Control (CDC). It can cause a severe handicap, with psychomotor disorders, motor, intellectual, isolated or associated.

Studies are underway to formally establish the link and answer the many unsolved issues.

“For other viruses, such as cytomegalovirus, the placenta acts as a barrier,” says Professor Yves Ville, head of the maternity Necker Hospital (AP-HP), Paris. “An infection in pregnant women is not always passed on to her fetus. It is established that the damage to the unborn child depends on the time the virus reaches the fetus. When the infection occurs early in the first quarter, it’s often the law of all or nothing: either no injuries or major damage, often resulting in a miscarriage. A later passage may have more modest impacts (intrauterine growth restriction) and reversible. It is likely the same for Zika.”


In France, Health Minister Marisol Touraine released the following message. The High Council for Public Health (HCSP) has updated its recommendations on this virus on January 22. These include the organization “of information, monitoring and a strengthened management of all pregnant women in epidemic areas of Zika virus, even when these women are not suspected of being affected or Zika virus. ” The HCSP also recommends the establishment of a “surveillance system and specific alert to the detection of neurological birth defects or not.”

Microcephaly may be suspected on ultrasound in the second trimester of pregnancy, from 18 to 20 weeks. There is a diagnostic test of fetal infection by Zika virus isolation in amniotic fluid following amniocentesis.

In Martinique, where the first indigenous case of Zika was detected in December 2015, six pregnant women infected with the virus have been identified.

Faced with numerous calls from pregnant women returning from an epidemic area, worried about their future child, Yves City opened a specialized consultation Zika Necker, on February 1.


“Transmission is almost exclusively Vector,” notes the report of the HCSP. But the Texas health authorities have issued a case of sexual transmission between a traveler who contracted Zika in Venezuela and his partner after his return.

Previously, six days after his return from a trip to Senegal in 2008 for work on malaria, the American researcher Brian Foy had shown clinical signs of concern. Four days later, it was the turn of his wife, who remained in the United States. Both were infected by Zika. Another study, published in February 2015, mentions the presence of the virus in the semen of a 44-year-old man living in Tahiti (French Polynesia), fifteen days after the onset of symptoms.

However, this was still considered inadequate argument recently, according to the authorities to prove transmission by sexual contact. The Texas case has however led the Centres for Disease Control (CDC) recommend the use of condoms to prevent the spread of the virus.

Cases of infection during childbirth have also been reported, without significant consequences for the health of the newborn. As for the transmission through blood transfusion, even if it has never been demonstrated, the risk can not be ruled out, notes the HCSP. The American Red Cross recommends people who visited affected areas to refrain from donating blood for 28 days after their return.


No. In an interview with Reuters, Gary Kobinger, a researcher from the University of Laval (Quebec) stated that a vaccine against the Zika virus could be tested in humans in September, and made available before end of the year. This is a DNA vaccine, a collaboration between the University of Pennsylvania, the pharmaceutical company Inovio, and the South Korean group GeneOne Life Science.

“There will probably be no safe and effective vaccine against the virus Zika for several years,” said Anthony Fauci, director of the American Institute of Allergy and Infectious Diseases (NIAID).

NIAID is exploring several approaches, one with a DNA vaccine, based on his experience of a vaccine for West Nile virus, another with an attenuated virus. In an article published January 13 in the “New England Journal of Medicine,” Fauci stressed that the search for a vaccine protecting against Zika could benefit from the technologies used for other flaviviruses.

Barack Obama, who proved to be on the offensive against Ebola, wants to take the initiative on the Zika virus, while calling to avoid panic and stressing on the difference between the two viruses . The US president will ask Congress to release $1.8 billion in emergency funding for prevention and research, announced the White House this Monday. Obama added that the proposal will be “quick to vote.” “This is something that we must take seriously,” Obama said in an interview on CBS.

The European Medicines Agency EMA has announced that an expert group will be established to accelerate the development of treatments and vaccines against the Zika virus.

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