Cases of malaria, dengue fever, Zika and other serious illnesses have reached alarming levels in Venezuela and are spilling over into neighboring countries, according to several recent studies.

These so-called vector-borne diseases—transmitted by mosquitoes or other organisms—have increased by as much as 400 percent in Venezuela in the last decade, according to a review study published in The Lancet in February. Spiraling economic and political turmoil have worsened the situation, as has the government’s apparent hostility toward researchers who publish epidemiological data—with reports of pro-government paramilitary groups smashing labs and even stealing experimental mice. “Last year we had more than 600,000 cases [of malaria] reported by the government,” says study co-author Maria Eugenia Grillet, a tropical disease ecologist at Central University of Venezuela in Caracas. She and her co-authors estimated there were actually around 1.2 million cases, taking into account underreporting and disease relapses, Grillet notes. (Relapses occur when a patient has recovered but still carries the malaria-causing parasite and later suffers a recurrence of symptoms.) She blames the increase on a lack of antimalarial surveillance, treatment and control, partly due to funding cuts. “Research in our universities and laboratories is almost completely paralyzed because there are no financing programs that allow us to cover the basic needs to carry out our experiments or fieldwork,” she says.

Venezuela was once a leader in vector-borne disease prevention and control. In 1961 the World Health Organization certified the South American nation as the first in the world to eliminate malaria from the majority of its territory; in fact the WHO used the malaria-eradication program Venezuela developed in the 1950s as a public health model. That and other efforts reduced the prevalence of many vector-borne diseases to manageable levels through the 1990s. But in recent years a confluence of events—some political and economic, others environmental—has reversed these gains.

In 2013 then-President Hugo Chávez died in office, and his close associate Nicolás Maduro became president in a controversial election. Under Maduro’s leadership public health initiatives have been curtailed and disease reporting has stalled. The Ministry of Popular Power for Health (MPPS) in 2015 stopped publishing its weekly bulletin of epidemiological statistics, which—except for a five-month hiatus in 2007—had been published continuously since 1938. Maduro fired Health Minister Antonieta Caporale in 2017, after her department issued a bulletin that reported rising infant and maternal mortality rates as well as increases of malaria, diphtheria and Zika cases. The next year the government eliminated the Venezuelan Center for Classification of Diseases, an organization that had provided the WHO and Pan American Health Organization with infection and mortality statistics. (Repeated phone and e-mail requests for comment to the MPPS were unanswered.)

The resulting lack of publicly available data on vector-borne diseases has forced researchers to look for alternative sources. Flor Herrera, a molecular biologist at Venezuela’s University of Carabobo, published a study in February in Emerging Infectious Diseases about malaria parasites in Sifontes, a southern municipality of Venezuela where most cases are occurring. Herrera says her team had to obtain data directly from staff at local health care facilities. “Before 2015 anybody had free access to epidemiological data,” but “the best way to corroborate [data] now is not possible,” she says. “You will not find anything.”

Some researchers who have insisted on publishing certain health data have faced reprisals. Lancet review co-author Oscar Noya says members of a pro-Maduro paramilitary group called Colectivo la Piedrita have repeatedly vandalized his laboratory at Central University because he reports malaria data to the Pan American Health Organization. Noya claims Colectivomembers smashed lab equipment, broke windows and destroyed computers. The most recent incident allegedly occurred last November—when Noya says the paramilitaries stole dozens of mice that had been infected with Chagas disease for an experiment. “In the last two years we have been attacked 74 times,” Noya says. “The purpose of that is intimidation. They [don’t want our group to] give more data about the health system in Venezuela.”

Setbacks Could Impact Entire Region

“We rely on successes in the past to help us maintain good public health,” says Tara Sell, a senior scholar at the Johns Hopkins Center for Health Security who was not involved in the Lancet study. “If those practices stop, we start sliding back—and it takes a lot of effort to arrest that backward momentum and get to where we were before.”

The review found there were fewer than 50,000 malaria cases in Venezuela in 2001, and rates remained close to that level for the next decade. But in 2013 the number of cases began to rise sharply. By 2016 there were more than 240,000; in 2017 the number jumped to about 412,000 and continued to climb. Regional epidemics—of chikungunya in 2014 and Zika in 2015—were amplified in Venezuela by the country’s economic crisis and shortages of medical supplies, according to the review. An unpublished study by one of its co-authors estimates Zika may be infecting up to 80 percent of pregnant women in Venezuela.

The review co-authors warn the crisis could spark an epidemic in neighboring countries, as Venezuelans are emigrating by the millions. The authors say Venezuelan migrants suffered 45 and 86 percent of malaria cases in the bordering northern Brazilian municipalities of Pacaraima and Boa Vista, respectively. But it is difficult to ascertain how many migrants may have brought disease with them, and how many were infected after they reached host countries. Co-author Martin Llewellyn, an epidemiologist at the University of Glasgow, acknowledges this uncertainty, and adds his team plans to conduct molecular epidemiology studies to determine the origins of infection.

Anna Stewart Ibarra, a tropical disease ecologist at the State University of New York’s Institute for Global Health and Translational Science, co-authored a forthcoming study in Emerging Infectious Diseases of malaria cases among Venezuelan migrants in Ecuador. Ibarra says international funding for surveillance in Ecuador dried up after malaria was eradicated in that nation’s border regions in 2011. “We’re being caught without resources and surveillance infrastructure in place, because global funding sources for these malaria control programs disappeared awhile ago,” she says. Regional vector-borne disease incidence is caused by myriad factors, Ibarra notes. “But the crisis in Venezuela is really pushing it over the edge.”

Environmental conditions may be exacerbating the already desperate situation. The 2015–16 El Niño cycle led to the warmest temperatures on record in Venezuela, and between 2013 and 2016 rainfall in the country was 50 to 65 percent lower than normal. Drought and elevated temperatures can contribute to the proliferation of mosquitoes that carry diseases, says Shlomit Paz, a climatologist at the University of Haifa in Israel who was not involved in the studies cited above. “We can see that all over the world there is an increase in vector-borne diseases, and the linkage with the change in climate is very clear,” she says.

Lancet review co-author Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine, says the situation in Venezuela could be an extreme example of a more general epidemiological phenomenon that is affecting the entire Western Hemisphere. “I think we’re starting to see this as a larger new normal in the Americas,” he says. “And I don’t think we really understand why that’s the case. Is it climate change, is it human migration, is it poverty? It’s a confluence of all those factors.”