Vaccine-preventable diseases have not just returned, but surged in crisis hit Venezuela, according to new research presented at this year's European Congress of Clinical Microbiology & Infectious Diseases (ECCMID) in Amsterdam, Netherlands (13-16 April). The study is by Dr Adriana Tami (University Medical Center Groningen, Netherlands and University of Carabobo, Venezuela) and Dr Alberto Paniz-Mondolfi (IDB Biomedical Research Institute, Barquisimeto, Venezuela), and colleagues.
Venezuela has plunged into a humanitarian, economic and health crisis of extraordinary proportions. This complex situation has progressed into a general collapse of Venezuela's health system, the dismantling of structures at the institutional, social and economic level affecting the life and wellbeing of the entire population. Some two thirds of the Venezuelan population currently live in extreme poverty, amid escalating violence. The country's crumbling healthcare infrastructure is now more typical of conflict zones or war-torn nations. More than 280,000 children are now perceived to be at risk of death from severe malnutrition.
In response, an ongoing exodus towards neighbouring countries has ensued. Emigrating individuals with infectious diseases may be unwillingly causing a spill-over of diseases beyond Venezuela's boundaries. This study provides new data on the resurgence and ongoing epidemics of measles and diphtheria and their disproportionate impact on indigenous populations.
The authors note that, since October 2014, there is a dire shortage of official epidemiological information in Venezuela; thus they did an active search of published and unpublished data. Data from the Americas were sourced from PAHO and from Venezuelan Health Observatory. Brazilian and Colombian data were accessed via their respective Ministries of Health.
In Venezuela, circulation of wild measles and diphtheria had not been reported since 2007 and 1992, respectively. Both diseases have recently re-emerged after a progressive interruption of the national immunisation program. Transmission is now present in most of the country. However, vulnerable indigenous populations such as the Yanomami inhabiting the Amazon region at the Venezuelan-Brazilian border, are mostly affected. There have been at least 100 cases and several deaths in this small population of 15.000 people, reported by a non-governmental agency that works with this vulnerable group.
"High morbidity and mortality rates are expected because these populations are immunologically naïve to measles," explains Dr Tami who has worked with these indigenous people in the Amazon forest. "Measles is presumed to have entered the Yanomami communities from Brazil after imported cases from Venezuela brought the disease to border populations of Brazil, before spreading back to Yanomami communities in Venezuela. Further spread of this epidemic wave could devastate the Yanomami people living in the Orinoco highlands of the Amazon, given that humanitarian aid to affected sites is limited or hard to deliver because of the seminomadic characteristics of these indigenous populations and the remoteness of the Yanomami territory."
The report provides data taken over a 16-month period (June 2017-October 2018) during which time a total of 7,524 suspected measles cases have been reported in Venezuela. Of these, 5,525 were confirmed representing 68% (5,525/8,091) of measles cases in the Americas reported, and also the most deaths from measles (73/85). The national coverage rate for the second dose of the measles vaccine was estimated at 52% according to the last reports from the Venezuela Ministry of Health. This estimate ranks Venezuela toward the bottom of vaccination coverage in the region, and estimates show measles vaccination is falling in all parts of the country.
Measles cases from Venezuela have been reported in Brazil, Colombia, Ecuador and Peru. Genetic analysis has confirmed that these cases have spread to these countries from Venezuela. Of all cases reported by Brazil's Ministry of Health in the state of Roraima (which borders Venezuela) through May 2018, a total of 68% corresponded to refugees from Venezuela, and 52.7% were in Warao Amerindians. The Colombia Ministry of Health has also reported 25 measles cases imported from Venezuela. Most cases were reported from bordering states that received a considerable migratory influx in 2018 and that also had received most of the 600,000 immigrants from Venezuela in 2017.
From January 2016 to October 2018, a total of 2,170 diphtheria cases have been reported to date with a lethality rate of 22%. In 2018, 96% (806/838) of diphtheria cases in the Americas region originate from Venezuela. Coverage of the minimum recommend 3 doses (although 4 is preferred) of diphtheria-tetanus-pertussis (DTP) vaccine has fallen from 84% in 2016 to 60% in 2017, and may not have reached 50% in 2018. Estimates suggest this could mean 3 million vulnerable Venezuelan children are now-exposed to this disease that should long have been consigned to the past.
Diptheria cases have also been reported in states of other countries that border Venezuela, and have been assumed to be transmitted from the many cases now occurring in Venezuela, though hard data to confirm this is not available at this time.
Although polio has not yet been reported in Venezuela, it is estimated that vaccination rates are now well below 80% and the authors believe it is only a matter of time before this disease, eliminated from the Americas in 1971, will make a comeback. The authors say: "The current reality in Venezuela is a conflux of plummeting vaccination coverages and ongoing outbreaks of other vaccine-preventable diseases. Combined with the weakening of surveillance programs, forced migrations, and a prolonged political, economic, and food crisis without foreseeable resolution, these factors have set the stage for potential re-emergence of poliomyelitis."
They conclude: "Action to halt the spread of vaccine-preventable diseases within Venezuela is a matter of urgency for the country and region. Global and regional health authorities should urge the Venezuelan government to allow establishing a humanitarian channel to bring relief efforts and adequate supplies for mass vaccination. Failure of timely action may bring a tsunami of new cases, not only in Venezuela but also other countries in the Americas."