World Health Organization Vector‐Borne Diseases Update September 2024

Key points about vector‐borne diseases

+ According to the assessment of the World Health Organization,Vector‐borne diseases account for more than 17% of all infectious diseases and are responsible for more than 700,000 deaths worldwide each year. Vector‐borne diseases are caused by parasites, bacteria, or viruses.

+Malaria is a parasitic disease transmitted by Anopheles mosquitoes infected with malaria parasites. Currently, there are about 249 million cases of malaria and more than 608,000 deaths each year worldwide. , Most deaths occur mainly in children under 5 years of age.

+Dengue fever is the most common viral infection transmitted by the Aedes mosquito. More than 3.9 billion people living in more than 132 countries are at risk of dengue, with approximately 96 million symptomatic cases and an estimated 40,000 deaths each year.

+Other vector‐borne viral diseases include chikungunya fever, Zika virus fever, yellow fever, West Nile fever, Japanese encephalitis (all transmitted by mosquitoes), tick‐borne encephalitis (transmitted by ticks), and Oropouche fever (transmitted by Culocoides flies)..

+Many vector‐borne diseases can be prevented through protective measures and community engagement.

Overview of vector‐borne diseases

Vectorare living organisms that can transmit pathogens between humans or from animals to humans. Many vectors are blood‐sucking insects, when they feed on the blood of an infected host (human or animal), pathogens (parasites, bacteria and viruses) also enter the body of the blood‐sucking insect, then the pathogens multiply and the vector will transmit the pathogens to new hosts. Usually, when a vector is infected with a pathogen, it is capable of transmitting the disease for the rest of its life, each time it feeds on the next host.

(Source: vectorbase.org)

Culicoides spp transmit fever Oropouche

Vector‐borne diseases (Vector‐borne diseases)

Vector‐borne diseases in humans are caused by parasites, viruses and bacteria and are transmitted by vectors. Each year, more than 700,000 people die from diseases such as malaria, dengue fever, schistosomiasis, human African sleeping sickness, leishmaniasis, Chagas disease, yellow fever, Japanese encephalitis and filariasis onchocerciasis

The highest burden of vector‐borne diseases is concentrated in tropical and subtropical regions, and they affect poor people the most. Since 2014, major outbreaks of dengue, malaria, chikungunya, yellow fever and Zika have affected communities, claiming lives and overwhelming health systems in many countries. Other diseases include chikungunya, leishmaniasis and lymphatic filariasis. It becomes chronic and causes lifelong pain to the infected person and sometimes the infected person is stigmatized in the community.

Overlapping distribution Major vector‐borne diseases globally (Source: WHO)

The distribution of vector‐borne diseases is determined by a complex set of factors including demographics, physical environment, and society. Global travel and trade, unplanned urbanization, climate change, and the silent spread and adaptation of vectors all contribute to the spread of vector‐borne diseases.

Climate change impacts on vector‐borne diseases

Climate change significantly affects the pathogens (parasites, viruses and bacteria), vectors and hosts (disease reservoirs) that contribute to the transmission of many vector‐borne diseases. Some vectors have expanded their ranges and increased their activity periods. These trends are expected to continue as the global climate continues to warm.

List of vector‐borne diseases

World Health Organization Response

The “Global Vector Control Response (GVCR) 2017‐2030” was endorsed by the World Health Organization in 2017. It provides strategic guidance for countries and development partners to urgently strengthen vector control as a fundamental approach to disease prevention and response. Achieving these goals requires re‐alignment of vector control programmes, supported by increased technical capacity, improved infrastructure, surveillance systems and greater community mobilization. Ultimately, the strategy will support comprehensive implementation of vector control to achieve specific targets at country and global levels, thereby contributing to the achievement of the Sustainable Development Goals.

The WHO Secretariat provides strategic, normative and technical guidance to countries and development partners to strengthen vector control as a fundamental approach to disease prevention and response. Specifically, WHO responds to vector‐borne diseases by:

+ Provide evidence‐based guidelines to control vectors and protect people against infection

+ Provide technical assistance to countries so they can effectively manage cases and outbreaks

+ Support countries to improve reporting systems and capture the true burden of these diseases

+ Provide training (capacity building) on ​​clinical management, diagnosis and vector control with support from several Collaborating Centers

+ Support the development and evaluation of new tools, technologies and approaches to vector‐borne diseases including vector control and disease management technologies.

A key element in reducing the burden of vector‐borne diseases is behaviour change. The World Health Organization works with partners to provide education and public awareness, so that people know how to protect themselves and their communities from mosquito, tick, bug, fly and other vector bites.

Access to clean water and sanitation is a crucial factor in disease control and elimination. The World Health Organization works with various organizations and governments to improve water storage, sanitation and hygiene, which in turn helps control vector‐borne diseases in communities.