After a meeting on Monday, the World Health Organization have declared that the current Zika virus outbreak constitutes a Public Health Emergency of International Concern.

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The WHO Emergency Committee convened on February 1, 2016, and discussed the Zika outbreak for nearly 4 hours.

The decision was made due to the strongly suspected causal relationship between Zika virus during pregnancy and microcephaly, although this link has yet to be scientifically proven.

Dr. Margaret Chan, director-general of the World Health Organization (WHO), accepted the recommendations of 18 experts and advisers who convened to discuss the outbreak and recent rise in neurological disorders by teleconference.

"In their view, a coordinated international response is needed to minimize the threat in affected countries and reduce the risk of further international spread," Dr. Chan states. "I have accepted this advice."

Locally transmitted Zika virus was first reported in Brazil in May 2015. Since this first reported case, health authorities have estimated that around a million suspected cases have occurred in the country.

At the same time, health authorities have also observed a significant increase in the number of detected cases of microcephaly and Guillain-Barré Syndrome affecting fetuses and newborns.

In French Polynesia, a similar increase in central nervous system malformations was recorded alongside a Zika epidemic in 2014. The similarity between this cluster of cases and those reported in Brazil led the WHO to their decision.

How is Brazil tackling Zika?

Brazil's Health Minister Marcelo Castro told Reuters that the situation was serious and worrying. "The microcephaly cases are increasing by the week and we do not have an estimate of how many there will be," he explained.

Due to the lack of a vaccine for the virus - something that the US Centers for Disease Control and Prevention (CDC) have previously said will not become available this year - the Brazilian authorities are targeting the Aedes aegypti mosquito that transmits the virus.

Soldiers have been mobilized to search house to house for breeding grounds, while the president has signed an emergency decree giving health workers permission to inspect any homes and properties for still water deposits favored by the mosquitos for laying their eggs.

WHO call for a 'coordinated international response' to Zika

In a summary of the Emergency Committee meeting, Dr. Chan describes the response that is needed going forward:

"A coordinated international response is needed to improve surveillance, the detection of infections, congenital malformations, and neurological complications, to intensify the control of mosquito populations, and to expedite the development of diagnostic tests and vaccines to protect people at risk, especially during pregnancy."

The WHO state that surveillance of microcephaly and Guillain-Barré Syndrome should be both standardized and enhanced, particularly in regions affected by Zika transmission. Research should focus on trying to determine whether or not there is a causative link between the virus and these neurological disorders.

As research and investigative efforts are stepped up, Dr. Chan states that the most important protective measures are the control of mosquito populations and the prevention of mosquito bites in at-risk individuals, placing specific emphasis on pregnant women.

The Committee also suggests that health services in areas affected by Zika transmission should be prepared for potential increases in the number of cases of neurological disorders such as microcephaly and Guillian-Barré Syndrome.

Despite this, Dr. Chan reports that "the Committee found no public health justification for restrictions on travel or trade to prevent the spread of Zika virus."

The WHO faced criticism from some quarters in the wake of the recent Ebola crisis, with some health experts questioning the organization's ability to respond effectively to global health crises. In November, a Medical News Today spotlight feature asked, "how can the WHO get back its teeth?"

This latest declaration represents not just a new battle against disease, but also a response to the WHO's detractors.