Brazilian baby recently born with microcephaly, believed to be associated with his mother’s diagnosis as having the Zika virus. (AP/Felipe Dana)

Dr. Shlomit Paz, University of Haifa

University of Haifa researcher Dr. Shlomit Paz (

An Israeli preliminary study identified a correlation between the exceptionally hot and dry winter in northeast Brazil to the recent outbreak of the Zika virus, contradicting WHO findings.

A recent preliminary study, led by Dr. Shlomit Paz of the department of Geography and Environmental Studies at the University of Haifa and Professor Jan Semenza of the Stockholm-based European Center for Disease Prevention and Control (ECDC), identified a correlation between the exceptionally hot and dry winter of northeast Brazil and the recent outbreak of the Zika virus, which has led to numerous birth defects.

The main findings of the provisional research contradict the conclusions drawn by the World Health Organization (WHO), which declared a state of emergency last week over the outbreak of the virus.

According to WHO, the virus is associated with heavy rains in parts of Central and South America as a result of El Nino, a phenomenon that involves a substantial increase in Pacific Ocean water temperatures.

Preliminary research led by Haifa University, however, indicates that the relevant factor associated with the virus is in fact the wave of exceptionally hot and dry conditions, which have reached record levels in the latter half of 2015 in northeastern Brazil, where the Zika virus has broken out.

The university research argues that the outbreak is not attributable to heavy rains, saying instead that it is due to climate change and global warming patterns that have affected the planet over recent decades.

zika virus

The zika virus is caught through infected mosquitoes. (Andre Penner/AP)

“It is very preliminary research, but we found a linkage and overlap between regions in northeastern Brazil with extreme climatic conditions such as record-level extreme temperatures and a severe drop in water levels,” Paz told Tazpit Press Service (TPS).

She added that it is well known that the high temperatures encourage the growth rates of the Aedes mosquito population, through which the Zika virus is transmitted. The dry conditions, however, deprive the mosquitoes of the water they need for survival. In turn, the mosquitoes swarm around water containers left in the open by local residents.

“WHO’s conclusions are a mistake,” she said. “They talk about a linkage with El Nino and about extreme rainfalls… We found, however, that the main regions of the Zika outbreak were characterized by a severe drop in water levels.”

While Paz acknowledged that mosquitoes are known to prevail under conditions of intense rainfall, as suggested by WHO, she cited previous studies that demonstrate the correlation between dry conditions and the risk of an upsurge in mosquito populations.

“People don’t know it, but by putting all their water in open containers, they prepare very comfortable conditions for the mosquitoes,” she explained.

The Zika virus has been known to researchers for several decades, but the reason for the sudden severe outbreak has not yet been determined. “It is very important to highlight that the reasons are multifactorial and [that] the climate is only one of the factors that may have an impact, and that is very important. But it is not  the only factor,” Paz said.

She concluded that further research would take significant periods of time and that the University of Haifa is currently continuing its research through the collection and analysis of related data on a broader scale.

By: Alexander J. Apfel/TPS