Malaria, dengue, Zika fever or chikungunya. Some may sound more familiar to you and others less, but they are all infectious diseases transmitted by mosquitoes and pose a threat to human health, since there are still no vaccines. This translates into a staggering death toll: more than 700,000 a year worldwide.
There are around 3,500 species of mosquitoes in the world. Of all of them, only a few are responsible for the transmission of pathogens and parasites to humans and animals. Even so, it is estimated that more than half of the human population is exposed to the risk of contracting a disease transmitted by mosquitoes. In addition, with globalization and climate change, everything indicates that in the coming years the phenomenon of contagion of diseases through transmitting mosquitoes will increase.
In Europe, some of the mosquitoes responsible for the transmission of infectious diseases are invasive species, that is, not native to the area, but with a high capacity to adapt and thrive in urban and suburban environments. They are species of great epidemiological importance, since they have the capacity to transmit serious exotic diseases when their pathogens are introduced into Europe.
In this delicate context, research becomes an urgent need. This is the case of the two projects sponsored by the ”la Caixa” Foundation. The first of these is led by Dr. Frederic Bartumeus and its objective is to study, monitor and combat the spread of invasive mosquitoes capable of transmitting diseases caused by viruses such as dengue fever, Zika fever or chikungunya. As? Through an innovative real-time data collection and surveillance system based on new technologies and citizen science methods.
Aedes albopictus (tiger mosquito), Aedes aegypti (yellow fever mosquito), Aedes japonicus (Japan mosquito), Aedes koreicus (Korean mosquito) and Culex pipiens (common mosquito) are some of the species monitored in the project.
The Mosquito Alert application allows anyone to notify the possible discovery of one of the mosquitoes studied by means of a photo, as well as collect information on their activity (bites) and their breeding places. Along with the photo, the location of the observation and other information necessary to help in the identification of the species is collected. A team of expert entomologists is then in charge of validating the photos received. The result is published on a public online map. This information obtained complements scientific surveillance work and allows the generation of real-time risk models and maps with greater predictive capacity that can be used by public health managers to monitor and control these mosquitoes.
Dengue, Zika fever or chikungunya can cause fever and joint and muscle pain, among other symptoms, and sometimes hospitalization of patients is required. The virus is transmitted when one of the Aedes mosquitoes bites a person after being infected by previously biting another person infected with the virus. These diseases are not endemic in Spain. Until recently, all the detected cases had been from infected people arriving from other countries. However, in 2018 there were 6 local cases of dengue in people infected in our country. The spread of the tiger mosquito throughout the Iberian Peninsula and the recurring colonization attempts of the yellow fever mosquito in the Canary Islands increase the risk of outbreaks. Movements to countries where these mosquito-borne diseases are endemic have led to an increase in imported cases. For all these reasons, they can become a public health problem.
Preventing possible outbreaks of the West Nile virus in Spain, an endemic disease in our country, is the objective of a second project, led by Dr. Jordi Figuerola. This virus can be transmitted by some of the more than 60 autochthonous species of mosquitoes present in Spain. Although, during the last half century, Europe has been practically free of this type of pathology, in the last decade, the West Nile virus has re-emerged and its incidence and geographical distribution have increased. In Spain, in 2020, it caused 77 serious cases and eight deaths, most of them in Andalusia. Infection in humans usually does not produce significant symptoms: 80% of infections are asymptomatic and in 19% of cases there may be a little fever. However, in just under 1%, it can cause a serious illness known as West Nile virus fever, leading to encephalitis and sometimes even death.
Until now, the strategies for managing this disease were based on trying to control the spread of the virus using biocides against mosquitoes, once the first human cases of infection were detected. The project seeks to prevent the appearance of infection cases instead of reacting to their appearance in order to reduce the risk of transmission of this and other arboviruses among the population. The objective is to establish an early warning mechanism that allows, several weeks before an outbreak occurs, to strengthen mosquito control, reduce the possible circulation of the virus and prevent it from spreading to humans. To do this, distribution maps of the different mosquito species are drawn, breeding areas are identified and strategies are proposed to control the population of these insects using methods compatible with the conservation of the environment.
Every week, Figuerola and his team take mosquito samples to check if they have the virus, determine which species they belong to, and relate the circulation of the pathogen to meteorological parameters such as average temperature and rainfall, in addition to infectivity in humans. With this they hope to be able to forecast the risk of transmission based on environmental conditions and the abundance of mosquitoes.
These two important projects endorsed by the ”la Caixa” Foundation will be shared on June 21, 2023, at 7:00 p.m., in the online debate “Infectious diseases transmitted by mosquitoes: how can we prevent possible outbreaks in Spain?”, in which the two researchers will participate in front of each one of them. This activity is part of a cycle of conversations that serve to highlight the work of research and health professionals who receive aid from the institution, as well as becoming a meeting point between society and the scientific community. The debate can be followed free of charge by prior registration.
