During British Science Week we look at the diversity of ongoing work across the UKHSA that works to protect the public from established and emerging threats to human health.
In this blog we focus on the activities of our Medical Entomology and Genesis Ecology (MEZE) team. Our scientists are responsible for assessing the emerging risk that arthropods (in the UK, primarily ticks and mosquitoes) can carry bacteria, viruses and parasites and cause disease.
Dr. Julian Medlock, who led the MEZE team, found the inspiration for his career in medical entomology in a diary he inherited from his great-grandfather who contracted malaria while in East Africa during World War I. Many years after recovering his footprint on the continent, he became enthusiastic about ecology, tropical diseases, and the natural environment.
The team’s role is to advise the UKHSA and the Department of Health and Social Care and other government advisory groups on the health risks of vector-borne diseases in the UK. Using the knowledge gained in the field, our entomologists work with local authorities to monitor and manage the risks and apply strategies to reduce the chances of establishing invasive species in our urban and rural areas.
The work style of an entomologist in the United Kingdom is seasonal, reflecting the life cycle and spread of the arthropods they study.
Typically, winter is used to analyze data collected in the warmer months when trends and field work are being done for any new identities in the UK. As an entomologist at the UKHSA, half the time is devoted to monitoring ticks that can spread Lyme disease, which is now endemic to the UK, and the rest of the time to mosquitoes and the germs they can carry.
What is vector borne disease?
“Vectors” are living organisms such as ticks and mosquitoes that can transmit infectious pathogens to humans or from animals to humans.
Globally, vector-borne diseases account for more than 17% of all infectious diseases and cause more than 700,000 deaths annually. These can be caused by parasites, bacteria or viruses, and infectious diseases, including malaria, dengue and yellow fever.
Although most illnesses and deaths due to vector-borne diseases occur in the tropics, there is a growing risk for mosquitoes and ticks in the UK, both established and invasive, and it is the job of UKHSA entomologists to monitor their spread and testing. For any disease they may be able to carry and pass between humans.
The reasons behind the increased risk include globalization of travel and trade, changes in land use and climate change.
Our team works closely with local authorities and other government agencies, including animal and plant health organizations, to coordinate national vector surveillance programs and conduct field-based research on the effects of climate and climate change on vectors and their pathogens.
The team provides expertise and practical assistance in the UK oversight areas where the acquired knowledge is applied to mitigate future threats to the UK.
In recent years we have seen small outbreaks of tropical diseases such as dengue fever in southern France. In the UK, invasive mosquito control systems are important to reduce these risks – and vector surveillance is an important part of fieldwork.
Where endangered mosquitoes are identified, we work with local authorities to implement control programs. The results of our study are also being used to reduce the suitability of wetlands for mosquitoes.
Towards the end of the summer of 2016 we detected the first Asian tiger mosquito eggs, Aedes albopictus, Southeast with subsequent identification in each of the next three years. We have also identified its population Culex Modestus Mosquitoes, which can transmit the West Nile virus and are now established in parts of Kent and Essex.
Although we have not yet seen any human cases of the virus in the UK, the knowledge that mosquitoes can be found in certain areas means that we can alert local health settings about the symptoms of the disease.
An important aspect of our surveillance work is the observation of diseases transmitted by ticks. In the UK, Lyme disease is the most well-known infection associated with ticks, but they carry other infections worldwide.
Hyaloma marginatum Ticks are known to carry the Crimean-Congo hemorrhagic fever virus, and although the virus has traditionally been found in Eastern Europe and Africa, recent cases of the disease have been reported in Spain, where ticks are more likely to migrate around migratory birds.
Given that the UK also sees a large number of migrations of these birds, we try to closely monitor the tick species found in the UK, researching the climate and habitat that sustains them, as well as import routes.
It is through our fieldwork and research that we have found ticks that have tested positive for the tick-borne encephalitis virus, an infection that is spread through tick bites.
Most people with TBE will have no symptoms; However, it can cause flu-like symptoms and, in a small number of cases, lead to more serious diseases involving the central nervous system.
The virus was detected in a small number of ticks in the Thetford Forest and an area bordering Hampshire and Dorset. Although the risk to the general public is very low, detecting the virus has allowed us to take precautionary measures to alert local areas and health care teams.
We also provide advice for local areas on how they can help more people become tick-conscious, as well as manage local settlements in the right way to maintain tick population control and reduce human exposure to ticks.
Like all insects, mosquitoes are able to complete their life cycle and digest their blood at a much faster rate at higher temperatures, and if our climate is warmer, this means that both our native mosquitoes may become more abundant and establish non-native species. Can
Mild winters and warm temperatures may increase the survival of tropical species and may even lead to the development of pathogens in mosquitoes. However, climate alone does not work. Mosquito movement is aided by globalization and the movement of mosquito eggs or adult shelter products or traffic.
The movement of the virus is facilitated by the worldwide travel of infected people. Combine these factors with a warmer climate and they provide a more conducive environment for disease transmission.
The future of vector-borne diseases in the UK
It is only a matter of time before we see that various diseases are being transmitted to humans in the UK by mosquitoes and ticks. In 2020, the Usutu virus was found in dead blackbirds in greater London, domestic mosquitoes were also infected, and warmer weather is likely to lead to the emergence of other mosquito-borne viruses.
Instead of waiting for more humanitarian incidents to occur and to investigate from the outset, the work of the MEZE team will ensure that we continue to build our skills to establish the right intervention at the right time to protect public health.