WASHINGTON, United States (CMC) — The Pan American Health Organisation (PAHO) says experts are still grappling to understand the mosquito borne Zika virus even as the world marks one year since a global Public Health Emergency was declared due to the rapid spread of the virus from Brazil to 75 other countries, including most in the Caribbean and Latin America.

PAHO says experts are exploring ways to improve the response to outbreaks, including research on integrated management of the mosquitos that transmit the disease.

According to PAHO’s latest update, 48 countries and territories in the Americas have confirmed transmission of Zika virus disease through mosquitoes since 2015 and five countries in the Americas have reported sexually transmitted Zika cases.

To date 200,000 cases have been confirmed, more than half from Brazil, were 2,618 children born with confirmed congenital syndrome associated with Zika virus infection.

Globally, the risk assessment of Zika has not changed, and the virus continues to spread geographically to areas where competent vectors are present, PAHO said.

“Although a decline in cases of Zika infection has been reported in some countries, or in some parts of countries, vigilance needs to remain high,” the latest WHO assessment notes.

Dr Sylvain Aldighieri, PAHO’s Incident Manager for Zika, said that, when clusters of babies with microcephaly and cases of Guillain-Barré syndrome were reported at the same time and place as Zika virus outbreaks during the last months of 2015, PAHO published a series of alerts starting in December 2015.

“After PAHO mounted a robust regional response to the outbreak, a turning point came in January 2016 as research provided the first evidence regarding the link between Zika and microcephaly in babies born in Northeast Brazil,” he said.

PAHO said this led to the World Health Organization (WHO) declaration of a Public Health Emergency of International Concern (PHEIC) on February 1, 2016, adding that Zika spread rapidly not only through the Americas but also to other regions.

In the Americas, PAHO said it continues providing technical support to its member countries in all aspects of Zika surveillance and control, with a special focus on clinical management, laboratory services and controlling the mosquito vectors of Zika virus, which also transmit dengue, chikungunya and urban yellow fever.

A group of experts on Public Health Entomology has been meeting in Washington, aiming to issue updated guidance on controlling mosquitos and other vectors of disease, through improved surveillance, prevention, integrated vector management, and eventual control and elimination of vector-borne diseases, PAHO said.

It said regional partners are involved in vector control research, including pilot studies of new control methodologies such as mosquitoes infected by the Wolbachia bacteria.

PAHO said a crucial tool in the long-term fight against Zika is community education and participation in eliminating mosquito vectors and breeding sites.

While there is no treatment for Zika, PAHO said researchers are working on vaccines, with five potential vaccine candidates headed for clinical trials.

More than 1,500 research papers have been published on Zika, confirming that the virus can infect mothers and unborn children and kill brain cells, causing a variety of birth defects, PAHO said.

It said researchers continue to find a widening range of effects in “congenital Zika syndrome,” including brain abnormalities, neural tube defects, eye abnormalities, hearing problems, irritability, seizures, feeding difficulties and others.

PAHO said experts now consider Zika to be a long-term public health challenge, following the declaration by WHO’s Emergency Committee on Zika that the epidemic’s emergency phase was over.

As response continues, PAHO said longer-term efforts continue in ways to improve detection, prevention, care and support.

It said research is also focusing on ways to strengthen preparedness and response in affected countries.