An outbreak of a contagious disease emerges in Caracas, Venezuela. Hospitals are soon at capacity with sick patients. Essential drugs, IVs, PPE, and clinicians are in short supply. Millions of Venezuelans flee to neighboring countries amid a growing crisis and challenges in providing international humanitarian aid. This fictional scenario, part of the Clade X pandemic exercise hosted by the Johns Hopkins Center for Health Security in May 2018, is increasingly exhibiting a disconcerting resemblance to the reality in Venezuela. Thankfully, there have been no signs of a novel respiratory virus like that featured in the Clade X simulation; however, the ongoing political, economic, and humanitarian crisis is very real.

Venezuela is currently experiencing the re-emergence of several diseases that were previously eliminated, such as measles and diphtheria. The country has also experienced increases in cases of previously controlled diseases, including malaria and HIV. The return of these diseases has been attributed to the collapse of Venezuela’s healthcare system, including shortages of basic medicines and supplies, hospital shutdowns due to insufficient water and power, and the flight of doctors and other healthcare workers from Venezuela to other countries.

This week we call attention to what is known about the spread of these infectious diseases in Venezuela, and we examine the evidence of regional transmission. Of course, it should be noted that Venezuela is facing a range of other health and humanitarian challenges—including high maternal and child mortality, chronic food shortages, extreme poverty, and political violence. Since many of these conditions are linked (eg, malnourishment is associated with greater susceptibility to infection), infectious disease risks represent a single component of this complex crisis.

Rising Infectious Diseases Rates

Vaccine-Preventable Diseases

An analysis published January 30 by the CDC’s Emerging Infectious Diseases found rising rates of childhood vaccine-preventable diseases in Venezuela, notably diphtheria and measles. Until 2016, diphtheria transmission had not been reported in Venezuela for 24 years. There have been a total of 2,170 suspected (1,249 confirmed) cases of diphtheria from 2016 through October 29, 2018. The CDC analysis also found that measles transmission, which was interrupted in 2007 following mass vaccination campaigns, re-emerged in June 2017 to affect multiple Venezuelan states. A total of 9,101 suspected (6,395 confirmed) cases of measles were reported in Venezuela in 2017 and 2018, according to the most recent epidemiological update from WHO’s Pan-American Health Organization (Regional Office for the Americas; PAHO). Only an estimated 52% of the population has received a second dose of measles vaccination. According to the CDC analysis, the return of vaccine-preventable diseases is believed to be a result of the current crisis in Venezuela:

The weakening of Venezuela’s public health services has led to a breakdown of epidemiologic surveillance systems along with an interruption of the national immunization program, resulting in the decay of infection control practices. In addition, the ongoing massive internal and external exodus of Venezuela residents has become the amplifying factor of these outbreaks beyond Venezuela’s border.

Vectorborne Diseases

In a review published on February 21 in The Lancet Infectious Diseases, a group of experts found that Venezuela’s health crisis has impacted the spread and control of vectorborne disease. The researchers noted that the prevalence of malaria surged to approximately 411,000 cases of malaria in 2017, compared to fewer than 50,000 cases in 2010. According to one of the authors, that number is believed to have exceeded 1 million cases since the article was submitted last year. The researchers estimate that the incidence of dengue, chikungunya, Chagas disease, and Zika have also risen at a dramatic pace in recent years. The same researchers attribute the surge in vectorborne diseases to “decaying health-care infrastructure, a mass departure of trained medical personnel, and the decline of all public health programmes.” In addition, the resurgence of malaria is believed to be linked to clearing forests for illegal mining activities:

Highly mobile, often immunologically naive, human populations migrate from different regions of the country to mining areas in search of economic opportunities. Once people arrive, they live outdoors, constantly exposed to the risk of mosquito bites. Many internal migrants return to previous endemic malaria regions where viable anopheles vector populations exist, reintroducing malaria to areas where this infection had been previously eliminated.

HIV/AIDS and Tuberculosis

A July 2018 report (in Spanish) by PAHO, The Joint United Nations Programme on HIV/AIDS (UNAIDS), and the Venezuelan Ministry of Health noted that newly identified HIV cases increased by 24% and AIDS-related deaths increased by 38% between 2010 and 2016, in contrast to declines in these rates worldwide during the same period. According to Human Rights Watch, approximately 87% of the 79,000 registered individuals living with HIV in Venezuela are not receiving anti-retroviral treatment, due to widespread drug shortages. Tuberculosis cases are also on the rise in Venezuela. Human Rights Watch, in the article above, notes that the 2017 tuberculosis incidence rate was Venezuela’s highest in 40 years. Separately, 2 main tuberculosis clinics in Caracas reported to The New York Times a 40% or more increase in the share of new patients testing positive for tuberculosis in the past year alone.


Venezuela may also be susceptible to the re-emergence of poliomyelitis, as has been observed in other settings experiencing a disruption in health systems. In June 2018, unofficial reports of vaccine-derived polio virus (VDPV) in Venezuela led to fears that polio, previously eliminated in the country, might be able to circulate in undervaccinated populations. While VDPV was later ruled out by genetic sequencing tests, the situation highlighted the country’s possible vulnerability.

Regional Transmission of Diseases

As a result of the political and economic situation in Venezuela, migrants are fleeing to neighboring countries in record numbers. The UN Refugee Agency (UNHCR) and the International Organization for Migration (IOM) released new figures on February 22 showing that the number of Venezuelan refugees has reached 3.4 million. Of these, 2.7 million are being hosted in Latin American and Caribbean countries, including Brazil, Colombia, and Peru.

While migrant healthcare needs are wide-ranging, including emergency services, chronic diseases, nutrition, maternal and infant health, and psychological support, infectious diseases represent a growing area of concern. A September 2018 study in the Journal of Travel Medicine used mobility models to understand Venezuelan migration patterns and found evidence for the importation of measles, diphtheria, malaria, and HIV into neighboring countries. The authors note that the poor living conditions experienced by some Venezuelan refugees are important risk factors modulating their vulnerability to infection. The re-introduction of measles in Manaus, Brazil, which has reported 8,070 suspected (1,631 confirmed) cases as of November 2018, was determined to be “likely related” to the Venezuela outbreak, according to a study by Brazilian researchers.

The regional spread of diseases and subsequent need to treat affected displaced populations has placed a burden on neighboring countries’ health systems as well, especially in border regions. A November 2018 study by Human Rights Watch and Johns Hopkins University researchers, which included travel to Venezuela’s borders with Colombia and Brazil, found “a devastating health crisis” characterized by outbreaks of vaccine-preventable diseases and other serious health conditions. For instance, one of the researchers found that large numbers of HIV-positive migrants have fled to Brazilian border towns in search of treatment only to find that local hospitals were already overwhelmed with AIDS patients dying of opportunistic infections. Likewise, Colombia’s Vice Minister of Health warned of “immense challenges to [Colombia’s] health system,” with public hospitals struggling to accommodate refugee healthcare needs, including emergency services and vaccinations. Colombia is currently hosting the largest number of Venezuelan migrants, estimated at over one million as of November 2018.

In response, the UN announced in December that it was seeking $738 million in humanitarian aid to help Latin American countries accommodate the increase in Venezuelan migrants and provide them with health care, nutrition, and other services. PAHO also established 6 field offices (5 in Colombia and 1 in Brazil) and deployed additional personnel to border areas to provide technical support for vector control, disease surveillance and epidemiology, infection prevention and control, and laboratory services.


What began in Venezuela as an economic and political crisis has transformed in recent years into a significant health and humanitarian crisis. One symptom of the crisis, due in large part to the collapse of the healthcare system, is the tragic re-emergence of communicable diseases that were previously controlled or eliminated, such as malaria, measles, HIV/AIDS, and tuberculosis. Low vaccination coverage also puts Venezuela at risk for the re-emergence of polio. Finally, preliminary evidence suggests that outbreaks of several communicable diseases in neighboring Latin American countries have been linked to the Venezuelan refugee crisis. The influx of migrants has put increasing strain on the health systems in other countries in the region as they struggle to support the health needs of displaced populations.

In addition to addressing the political and economic problems underpinning the Venezuelan crisis, the international community, including WHO/PAHO, countries in the Americas, and humanitarian organizations, should work together to provide much-needed healthcare and humanitarian aid to Venezuela and the wider region. To protect the health of those affected by current and future outbreaks, more resources should be directed towards disease surveillance, infection prevention and control, vaccination services, vector control, and other critical public health improvements in Venezuela and neighboring countries. Ensuring that displaced populations have access to adequate living conditions, nutrition, and health services will also go a long way to limiting the spread of infectious diseases in the region.

Photo: Building windows in Caracas, Venezuela. Courtesy of Pixabay.

Outbreak Observatory aims to collect information on challenges and solutions associated with outbreak response and share it broadly to allow others to learn from these experiences in order to improve global outbreak response capabilities.