Tropical diseases in Tenerife had a detrimental effect on the inhabitants in the past, but today they must be monitored.
This year, the Canary Islands have shown a significant meteorological contrast compared to last year. Periods of drought and smog have given way to periods of high humidity and heavy rainfall. These are conditions that can promote new diseases. In this regard, we interviewed Jacob Lorenzo, director of the University Institute of Tropical Diseases and Public Health of the Canary Islands. Based on his extensive experience, he explains how these climate changes create conditions that could lead to new epidemiological risks.
What tropical diseases in Tenerife are currently emerging?
The heavy rainfall has created numerous puddles where water and natural waste accumulate. This creates the perfect environment for insects like mosquitoes and ticks, known for their disease transmission, to multiply. In short, during heavy rainfall, the risk of contracting diseases transmitted by these small vectors increases.
Which mosquitoes are involved?
As I mentioned, puddles where water collects are the perfect breeding grounds for them. Common mosquitoes, which bother us in the summer, have a lifecycle of 10 to 15 days. This means that shortly after a period of heavy rainfall, we will see a significant increase in these insects, leading to more bites. But it’s not just the common mosquitoes. In some areas, particularly sensitive ones, other types of mosquitoes may also be present. For example, the tiger mosquito, named for the stripes that adorn its body and give it a distinctive appearance, is known to be very aggressive. Additionally, we find Aedes aegypti, a close relative of the tiger mosquito, which easily reproduces in environments with high humidity and abundant water.
What risks do they pose to the Canary Islands?
Currently, two invasive mosquitoes have been observed: the tiger mosquito and the Aedes aegypti mosquito. The first is originally from Southeast Asia, and the second from the north coast of Africa, so they are not native to our region. They are concerning because they can transmit diseases such as dengue, Zika, and chikungunya. Moreover, heavy rainfall and stagnant water create the perfect environment for these mosquitoes to lay their eggs and reproduce, increasing the risk of outbreaks.
What measures is the Institute taking?
Since 2013, the Directorate-General for Public Health of the Canary Islands has implemented a program to monitor and control the arrival of invasive mosquitoes. This plan focuses on key locations such as ports, airports, greenhouses, and areas where plants are traded, as these are ideal places for female mosquitoes to lay their eggs. To achieve this, approximately 1,300 traps have been placed across the archipelago, which are checked weekly. These traps detect both adult mosquitoes and eggs and larvae, helping to respond quickly to any increase in their numbers. Thanks to these efforts, we are actively working to prevent these insects from multiplying and endangering our health.
Where have the latest tiger mosquitoes gone?
Until a few weeks ago, an alarm was triggered, and a total of 18 detection reports were recorded. These reports were concentrated at strategic locations, such as ports – particularly the cruise terminals in Santa Cruz de Tenerife and Las Palmas de Gran Canaria – and in some greenhouses, especially on Tenerife. Additionally, the invasive Aedes aegypti mosquito raised concerns in the Piletas neighborhood on Gran Canaria. The good news is that we haven’t found any adult mosquitoes or larvae from this mosquito for the last nine weeks, confirming the effectiveness of our monitoring and control measures. The alarm has not yet been deactivated, as the European Centre for Disease Prevention and Control has informed us that 18 months must pass since the last detection.
West Nile fever is rarely discussed. Is it likely to reach the Canary Islands?
We currently have a national plan to monitor and combat insects that can transmit diseases, such as mosquitoes and ticks. This active surveillance program is aimed at detecting viruses and other pathogens in these insects and other vectors. Although it was initially mentioned that West Nile fever could be transmitted through tick bites, it is important to clarify that the main transmitter of this disease is the common mosquito of the Culex genus, which is known for its outbreaks in regions like Andalusia.
At the same time, ticks are monitored because, in certain cases, they can transmit other pathogens. Thanks to studies conducted by the Institute in collaboration with the Directorate-General for Public Health, no viruses have been found in common mosquito or tick populations on the Canary Islands so far. This gives us peace of mind, as there are currently no outbreaks of these diseases in our region.
Which emerging disease is receiving too little attention?
We must be vigilant about the West Nile virus. This virus is mainly transmitted through the bite of the female Culex mosquito, the same mosquito that bothers us in the summer. This mosquito is widespread and found throughout Europe and many other parts of the world. The problem begins when these females bite migratory birds, particularly those from Africa, as they are the ones who first transmit the virus. Once infected, mosquitoes can transmit the virus to other birds and sometimes to humans.
Do birds also get bitten by this mosquito?
Yes. We always think of herons and larger birds, but we must not forget smaller birds, such as sparrows. House sparrows, as their name suggests, come from North Africa. Although we find sparrows cute, they can be carriers of the West Nile virus. In recent outbreaks in Andalusia and Extremadura, they have been observed as ‘multipliers’ of the virus, facilitating its spread. Therefore, it is important to monitor not only mosquitoes but also these birds.
What measures are being taken?
An extensive monitoring system has been implemented, which tracks both mosquitoes and migratory birds. Blood samples are taken from birds at strategic locations, such as the Doñana station, to detect if they carry the virus and to analyze their migratory routes. This strategy allows us to accurately map the spread of the virus and take timely action to prevent outbreaks.
If a tropical disease were to break out on the Canary Islands tomorrow, would we be prepared?
While we have an advanced entomological prevention and surveillance program – making us a national and international reference – our experience teaches us that there is always a risk of new pathogens, as seen with previous pandemics. Despite our preparations, recent dengue outbreaks in the Caribbean and Africa highlight global issues, particularly the unequal distribution of vaccines and treatments. This reminds us that, alongside our local efforts, stronger international coordination is needed to address these problems.
Is there a dengue vaccine?
The dengue vaccine exists, but its availability is limited in certain areas. Therefore, it is essential to take political measures to ensure fair distribution and to guarantee that both treatments and preventive measures reach all affected individuals. Decisive and coordinated political action is essential to close this gap and protect public health. If we do not address the root cause of the problem, we will ultimately bear the consequences. What we saw with SARS-CoV-2 has shown us that if we ignore the underlying causes that lead to the emergence of new viruses, we only open the door to future health crises. Therefore, it is of great importance to take comprehensive measures, both politically and in terms of public health, to completely prevent tropical diseases in Tenerife.
Have tropical diseases influenced the history of the Canary Islands?
The Canary Islands have been the scene of major health challenges throughout history. Yellow fever hit Tenerife particularly hard, with a devastating epidemic between the 19th century and 1943, until the Aedes aegypti mosquito, responsible for its transmission, was eradicated. At its most devastating moment, yellow fever claimed the lives of one-fifth of the population, leaving an indelible mark on the history of the Canary Islands. But yellow fever was not the only threat.
Did they mostly arrive through the ports?
The bubonic plague reached the Canary Islands through maritime trade, with ships full of rats carrying infected fleas. The impact was devastating, not only in terms of human casualties but also in the social and economic consequences it left on the archipelago. Interestingly, some studies suggest that these episodes may have influenced the origin of the famous island rivalry. The rivalry between islands, which today manifests in cultural and sporting areas, may have its roots in historical events such as epidemics, which affected different regions unequally.
Were these the causes of the differences between the two provinces?
Some historians suggest that the severe cholera outbreak on Gran Canaria caused one of the first major rifts between the islands. To prevent the spread of the disease, Tenerife and other islands closed access to the inhabitants of Gran Canaria, creating a sense of isolation and rejection. While the island conflict has deeper roots in economic, political, and social issues, this health crisis may have intensified the differences between territories and left a mark on inter-island relations that persists to this day.
The closure of beaches in Tenerife due to wastewater problems is causing great concern. Beyond the impact on tourism, how does this pollution affect human health and marine biodiversity?
Tropical diseases in Tenerife can be indirectly caused by discharges into the ocean. Pollution poses a serious threat to coastal ecosystems. When large amounts of organic material and microorganisms reach the water, they disrupt the natural balance, affecting both marine fauna and flora. One of the key indicators of water quality is the presence of Escherichia coli, a bacterium that can cause gastrointestinal issues in humans and whose concentration determines the viability of bathing areas. However, beyond the public health risk, the damage to the marine environment is profound and often irreversible. Excess organic material causes changes in the habitat of native species, promoting the growth of invasive algae that can displace local biodiversity.
Conclusion
Tropical diseases in Tenerife and the other Canary Islands present an ongoing challenge, especially given the changing climatic conditions that promote the spread of disease vectors. Although significant steps have been taken to monitor and combat these diseases, it remains essential to stay vigilant and implement the necessary measures to protect public health. Through intensive cooperation at both local and international levels, the spread of tropical diseases can be effectively controlled, ensuring that the Canary Islands remain a safe destination for both residents and tourists.
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Tropical diseases in Tenerife ©
Source: diariodeavisos.espanol.com
Theme: Interview with Jacob Lorenzo, director of the Instituto Universitario de Enfermedades Tropicales y Salud Pública de Canarias.
