mosquito-borne diseases They are much more than a simple summer nuisance: they are behind millions of infections worldwide each year, and some can be fatal. Although the overall risk in Spain remains moderate, climate change, international travel, and the spread of species like the tiger mosquito are changing the landscape, and this should be kept firmly in mind.
If ever you wondered What types of diseases can mosquitoes transmit, what symptoms do they cause, and how can you protect yourself? You and your family will find a comprehensive and practical guide here, tailored to our context. We'll cover everything from classic diseases like malaria and yellow fever to dengue, Zika, and chikungunya, which are increasingly discussed in the media and medical consultations.
What exactly are mosquito-borne diseases?
When a female mosquito bites to feed on blood, It not only extracts blood: it can also ingest viruses or parasites These microorganisms are present in the person or animal being bitten. They multiply inside the mosquito without causing it harm and, in the next bite, travel in its saliva to the next victim, human or animal.
Any infection that is transmitted in this way, from the mosquito to the person through the biteIt is considered a mosquito-borne disease. Within this group, we find pathologies caused by viruses (such as dengue, Zika, chikungunya, yellow fever, or West Nile virus) and others caused by parasites, such as malaria.
Across the globe, the impact is enormous: It is estimated that hundreds of millions of people are infected each year In addition to dengue, there are also cases of Zika, chikungunya, yellow fever, malaria, and other less well-known but also serious infections, such as some viral encephalitis.
Not all mosquitoes are the same: Different species act as vectors for different diseases.For example, mosquitoes of the Aedes genus (including the tiger mosquito) are implicated in dengue, Zika, and chikungunya, while those of the Anopheles genus transmit malaria. The actual risk to each person depends on where they live, what areas they travel to, and what time of year it is.
It is worth remembering that, in everyday language, “Zancudo” and “mosquito” are the same insectAlthough the term "zancudo" is more commonly used in some Latin American countries. In any case, we are referring to small blood-sucking flying insects that need blood to complete their life cycle.
Main mosquito-borne diseases
Within the wide range of pathologies linked to mosquito bites, There is a group of particularly common and relevant diseases due to the severity of their complications or their capacity to generate epidemic outbreaks. Among the most important are:
First is the malaria or paludismPlasmodium, caused by parasites of the genus Plasmodium (especially P. falciparum), is transmitted by Anopheles mosquitoes and is endemic in many tropical and subtropical areas. Although it is not endemic to Spain, it can occur in travelers returning from at-risk areas.
Another large group consists of the Aedes mosquito-borne arboviruses, especially Aedes aegypti and Aedes albopictus (tiger mosquito). This includes dengue, Zika, and chikungunya. These infections have traditionally been prevalent in tropical and subtropical regions, but in recent years their incidence has increased in Europe and the Mediterranean.
In addition, we find diseases such as yellow fever, West Nile virus, and various viral encephalitides (Japanese encephalitis, Eastern and Western equine encephalitis, St. Louis encephalitis, Crosse encephalitis, among others). Although some are concentrated in certain regions of the world, international travel means they must be considered in the context of global health.
Finally, there are other less high-profile but relevant agents, such as the heartworms in animals (cardiopulmonary dirofilariasis)These diseases particularly affect dogs and cats. Although they are not usually a direct problem for people, they are part of the same vector-borne transmission cycle and require veterinary control.
Aedes mosquitoes, climate change and the situation in Spain
In the specific case of our environment, Mosquitoes of the Aedes genus are gaining prominenceAedes albopictus, known as the tiger mosquito, has established itself in many locations in the Spanish Mediterranean basin and continues to expand inland.
This mosquito can transmit dengue, Zika and chikungunyaAlthough most cases diagnosed in Spain are still imported (people who become infected during a trip to endemic areas), episodes of local transmission have already been detected, especially in Mediterranean areas where the tiger mosquito is well established.
The increase in temperatures and changes in rainfall patterns linked to Climate change favors the expansion of these vectorsThis is because they extend their active season and the areas where they can survive and reproduce. Globalization, with its constant flows of travelers and goods, also helps introduce new mosquito species to regions where they didn't previously exist.
For now, local transmission in Spain remains infrequent, but The risk is clearly increasingThis reality necessitates strengthening surveillance systems, health education, and strategies to control breeding grounds. Mosquitoes in urban and peri-urban environments.
Many official guidelines emphasize that, in order to understand and reduce this emerging risk, It is crucial to understand how these diseases are transmitted and what factors contribute to their spreadFrom this knowledge, preventive measures are derived that each person and each community can put into practice.
General symptoms of mosquito-borne diseases
The signs and symptoms caused by an infected mosquito bite They depend entirely on the agent involved.However, many of these diseases share a fairly similar initial presentation, which sometimes complicates diagnosis based solely on clinical observation.
In a large number of cases, especially in healthy people, The infection can go virtually unnoticed. or manifest with very mild symptoms, similar to the flu. This does not mean there is no risk, but rather that the body manages to control the pathogen without developing severe forms.
They appear relatively frequently sudden onset fever, severe headache, general malaiseMuscle and joint pain, extreme fatigue, nausea, vomiting, or skin rashes. In some viruses, such as dengue, retro-orbital pain (behind the eyes) and marked myalgia are typical.
In more severe cases, certain mosquito-borne diseases can cause Brain inflammation (encephalitis), neurological disorders, hemorrhagesMultiple organ failure or respiratory compromise. These complications, although infrequent at the population level, are responsible for most hospitalizations and deaths.
It is advisable to be alert if, after a bite or after a trip to an endemic area, the following symptoms appear high fever, severe headache, severe muscle or abdominal pain, extensive rash, or signs of bleedingIn such cases, it is necessary to consult a healthcare professional as soon as possible to rule out serious infections such as severe dengue or complicated malaria.
Mosquito bites: local reactions and mosquito syndrome
Beyond infections, mosquito bites also cause local skin reactions that can be very bothersomeIt is common for a small, red, raised welt that itches intensely to appear a few minutes after the bite.
These injuries usually disappear in a few days without the need for specific treatmentespecially if persistent scratching is avoided. However, in some people—particularly children—a much more pronounced inflammatory response is observed, with large bumps, redness, and disproportionate itching.
This exaggerated condition, with significant swelling, a hives-like rash, or swelling around the eyesIt is sometimes called "mosquito syndrome." It is not an infectious disease, but an intense immune reaction to the insect's saliva, and usually requires symptomatic treatment with antihistamines or topical corticosteroids under medical supervision.
Keep in mind that Scratching continuously can break the skin and facilitate secondary bacterial infections.That's why it's recommended to keep children's nails short, clean the area well, and use soothing products recommended by a healthcare professional or pharmacist.
If the bites are accompanied by fever, severe general malaise, or signs of local infection (heat, suppuration, increasing pain)It is advisable to consult with a doctor to rule out complications or an underlying mosquito-borne illness.
Risk factors for bites and infections
Not everyone has the same risk of being bitten or contracting a mosquito-borne disease; There are environmental and personal factors that have a significant influenceFactors that increase the likelihood of being bitten include heavy sweating, the use of perfumes or colognes with a floral scent, and the emission of carbon dioxide when breathing.
To live or spend a prolonged time in areas where mosquitoes are very active This is another clear risk factor. Areas with stagnant water (unmaintained ponds, buckets of water, old tires, flowerpots that collect rainwater, etc.) are veritable breeding grounds where mosquitoes lay their eggs.
People who do a lot of outdoor activities, especially without using repellent or protective clothingThey have greater exposure. This includes everyone from those who work outdoors to those who play sports or enjoy patios and gardens during peak mosquito activity hours.
From an infection standpoint, the risk clearly increases when traveling to tropical or subtropical regions where mosquito-borne diseases are endemicTravel to sub-Saharan Africa, Southeast Asia, Latin America, or certain areas of the Pacific involves a much higher level of exposure to malaria, dengue, Zika, chikungunya, or yellow fever.
Finally, there are groups that are especially vulnerable to developing severe forms of these infectionsThese groups include young children, the elderly, pregnant women, and people with chronic illnesses or weakened immune systems. For them, prevention and early consultation for symptoms are even more important.
Diagnosis of mosquito-borne diseases
The diagnosis usually begins with a good medical history, in which A history of recent travel to endemic areas is a key piece of informationIn a person with sudden onset of fever, severe headache, muscle or joint pain, marked malaise, nausea, vomiting, or skin rashes, having been in an area with circulation of dengue, Zika, chikungunya, or malaria in recent weeks provides a great deal of guidance to the healthcare professional.
In the case of arbovirus infections such as dengue, the laboratory test of choice is usually a PCR technique to detect the genetic material of the virus in the blood, especially in the first few days of the illness. Specific antigen detection tests or serology (antibody detection) can also be used depending on the stage the patient is in.
For malaria, the diagnosis relies on the visualization of the parasite in a peripheral blood smear (thick blood smear or blood smear), rapid antigen detection techniques, and, in more specialized settings, PCR. Rapidly identifying the Plasmodium species is essential for choosing the most appropriate treatment.
Doctors also assess general laboratory parameters, such as platelet counts, liver and kidney function, or inflammation markersThese tests help detect severe forms such as severe dengue or complicated malaria. In cases of suspected viral encephalitis, neuroimaging tests or cerebrospinal fluid analysis may be indicated.
An important point is that some drugs, such as aspirin or certain anti-inflammatories, can Increase the risk of bleeding in infections such as dengueTherefore, in cases of fever in travelers from at-risk areas, it is recommended to avoid these medications until this disease is ruled out.
Treatment of mosquito-borne diseases
Many viral diseases are transmitted by mosquitoes They do not have a specific treatment that eliminates the virusIn these cases, the strategy is based on supportive treatment: rest, good hydration, control of fever and pain with appropriate medications, and monitoring for the possible appearance of complications.
In mild cases, it is usually sufficient to drink plenty of fluids, rest and use antipyretics or analgesics as recommended by the doctor. It is vital to avoid dehydration related to fever and vomiting, and to consult again if warning signs appear, such as bleeding, extreme drowsiness, difficulty breathing, or persistent abdominal pain.
Regarding dengue fever, it is emphasized that [the following should not be used]: aspirin or non-steroidal anti-inflammatory drugs (ibuprofen, naproxen, etc.) until the disease is ruled out due to the risk of promoting bleeding. In children, aspirin is also contraindicated because of the possibility of triggering Reye's syndrome, a very serious condition.
Malaria is an important exception, because it does have highly effective specific treatmentsThe ideal approach involves starting therapy as soon as possible, preferably within the first 24 hours of the onset of symptoms, as this reduces the duration of the illness, prevents complications, and avoids many deaths.
The current mainstay of malaria treatment, especially malaria caused by Plasmodium falciparum, are the artemisinin-based combinations (combination therapies with artemisinin or ACTs). However, the emergence and spread of parasite resistance to these drugs is a major global concern, because there are hardly any equally effective alternatives ready for widespread use.
To prevent resistance from spreading, health authorities recommend Do not use artemisinins as monotherapybut always in combination with other antimalarial drugs. Monotherapy is not only less effective, but it also increases the likelihood that the parasites will evolve into resistant strains, further complicating disease control.
Organizations such as the WHO insist on the need for to continuously monitor the effectiveness of malaria drugs and provide technical support to countries with a high disease burden to strengthen this surveillance. This allows for the timely detection of emerging resistance and the adaptation of treatment guidelines.
Prevention of mosquito-borne diseases
The best strategy against these pathologies is always avoid the bite of the mosquito that acts as a vectorTo achieve this, there is a set of complementary measures that, when combined, significantly reduce the risk both in domestic settings and when traveling to endemic areas.
In general, it is recommended Install and maintain the mosquito nets in good condition Check windows, doors, and ventilation points, repairing any damage immediately. Doors and windows without screens should be kept closed, especially during peak mosquito activity hours.
In areas where the risk is high, it is very useful Use mosquito nets over beds, cribs, or baby strollersespecially at night. When camping or spending the night outdoors, using mosquito nets specifically designed for tents or hammocks significantly reduces bites.
Clothing is also a significant barrier: long-sleeved shirts or t-shirts, long trousers and closed shoes They reduce the surface area of exposed skin. In some circumstances, it is recommended to tuck socks into trousers to further limit the mosquito's entry points to the skin.
When possible, it can be helpful to avoid being outdoors at dawn and dusk are times when many mosquito species are most activeAlthough some Aedes mosquitoes also bite during the day, reducing time outdoors during these key hours decreases the total number of potential bites.
Proper use of repellents and insecticides
Insect repellents are a basic pillar of prevention, but It is essential to choose the right product and use it correctly.The most effective repellents usually include as an active ingredient DEET, picaridin, lemon eucalyptus oil, IR3535, para-menthane-diol (PMD) or 2-undecanone.
These compounds They keep mosquitoes away for several hoursAlthough the exact duration of protection varies depending on the product, concentration, and environmental conditions, DEET is generally one of the active ingredients that provides the longest-lasting protection. However, all products require close adherence to label instructions.
Before applying a repellent, you must Read the package instructions carefullyIf using a spray format, it should be applied outdoors, away from food and drinks, and never spray directly on the face; it is better to spray first on the hands and then spread carefully, avoiding eyes and mouth.
If sunscreen is also used, the recommendation is First apply the sunscreen, wait about 20 minutes, and then apply the insect repellent.It is not a good idea to use products that combine both in a single application, because they usually require reapplying the mixture more frequently than necessary for the repellent, increasing exposure to the insecticidal substance.
Regarding safety, these repellents are considered Safe for adults and children if used correctlyHowever, there are important restrictions: DEET should not be used on babies under 2 months old, nor should icaridin be used on babies under 6 months old. Many products containing lemon eucalyptus oil or para-menthane-diol are not recommended for children under 3 years old, so it is essential to always check the labeling.
In addition, it is advised not to apply repellent. under clothing, on irritated, sunburned, cut, or rash-ridden skin and prevent children from having the product in their hands, as they could put it in their mouths. Once exposure to mosquitoes has ended, it is a good practice to wash the skin with soap and water to remove any repellent residue.
Treated clothing and control of the vector mosquito
In high-risk contexts or prolonged stays in endemic areas, one can resort to permethrin treatments on clothing and camping equipmentPermethrin is an insecticide and repellent that is applied to fabrics, but never directly to the skin.
There are garments and mosquito nets that have been pre-treated at the factory, as well as Spray products for impregnating clothing, tents or sleeping bagsAlways follow the manufacturer's instructions, as effectiveness is usually maintained for several washes or for a specific period of use.
To avoid reducing protection, it is recommended Do not wash impregnated mosquito nets too frequently or expose them to direct sunlight for extended periods.since radiation and detergents can degrade permethrin and shorten its lifespan.
At the community level, major vector control strategies focus on reduce the density of adult mosquitoes and their breeding groundsAmong the most effective measures are the use of insecticide-treated mosquito nets and indoor fumigation with residual insecticides in areas of high transmission.
These interventions can be complemented by the Control of stagnant water where mosquitoes lay their eggsCleaning gutters, frequently emptying children's pools, changing the water in birdbaths, removing old tires, or storing flowerpots upside down are simple actions that greatly reduce the number of mosquitoes in patios and gardens.
In the home environment, maintain gutters and drains free of leaf accumulationDraining fire pits if they fill with water and regularly checking areas where moisture accumulates helps break the mosquito's reproductive cycle. The key is to prevent water from standing for several days at a time.
Vaccinations and chemoprophylaxis in travel
In addition to physical and chemical measures, there are vaccines and preventative medicines for some mosquito-borne diseasesThe best known are the vaccines against yellow fever, dengue fever and Japanese encephalitis, which are recommended depending on the destination and type of trip.
In the case of dengue fever, currently There is no vaccine marketed for general use in Spain.Although some countries in endemic areas have already approved vaccines for certain population groups, this situation may change over time, so it is always advisable to check the most recent official recommendations.
There are treatments for malaria. chemoprophylaxis drugs These medications are taken before, during, and after travel to at-risk areas, depending on the chosen drug and the local epidemiology. These medications do not replace personal protective measures against bites, but they significantly reduce the likelihood of developing the disease if exposed.
Pregnant women, young children, the elderly, or those who have chronic diseases or immunodeficiencies They should consult especially soon at an international vaccination center or with their reference professional to assess the most appropriate preventive measures before traveling.
In general, it is advised that all travelers to areas at risk of malaria, dengue, Zika or other vector-borne diseases take precautions. receive prior advice based on official guidelines and the current epidemiological situationwhich can change rapidly in response to outbreaks or climate change.
When to see a doctor and what to keep in mind
It is important to seek medical attention if, after one or more mosquito bites, symptoms appear symptoms that suggest an infection beyond the local reactionThe presence of fever, severe headache, marked muscle or joint pain, unusual rashes, or significant general malaise are warning signs.
You should also consult urgently if you observe Signs of severity such as difficulty breathing, confusion, extreme drowsiness, persistent abdominal pain, bleeding, or purple spots on the skinThese symptoms may correspond to severe forms of dengue, complicated malaria, or other infections that require hospital admission.
In the context of exaggerated local reactions (mosquito syndrome), it is recommended to consult a healthcare professional if the The swollen area is very extensive, affecting the face or eyesor if the child or adult is especially uncomfortable despite the usual measures.
In all cases, it is very helpful to tell the doctor. if there has been recent travel to tropical or subtropical areas in recent weeks, as well as the use or non-use of repellents, mosquito nets, and other preventative measures. This information greatly facilitates guiding the diagnosis and deciding which tests to perform.
Knowing the type of mosquito present in the area, remembering the approximate date of the bite, and describing how the symptoms evolved helps build a complete medical history which accelerates both the diagnosis and the implementation of timely treatment.
With everything we've seen, it's clear that Mosquito-borne diseases combine a huge global impact with many possibilities for preventionUnderstanding how they are transmitted, recognizing their symptoms, consistently applying personal and community protection measures, and seeking prompt medical advice if you suspect you may have an infection are the best tools to keep these infections at bay in our daily lives and when traveling to high-risk areas.
