Vector Borne Diseases (VBD) (Human)
Primary reference(s)
OIE, 2019. Manual of Diagnostic Tests and Vaccines for Terrestrial Animals. World Organisation of Animal Health (OIE). Accessed 11 October 2020.
WHO, 2020. Vector-borne Diseases. World Health Organisation (WHO). Accessed 11 October 2020.
Additional scientific description
Vectors are living organisms that can transmit infectious pathogens between humans, or from animals to humans. Many of these vectors are bloodsucking insects, which ingest disease-producing microorganisms during a blood meal from an infected host (human or animal) and later transmit it into a new host, after the pathogen has replicated. Often, once a vector becomes infectious, they are capable of transmitting the pathogen for the rest of their life during each subsequent bite/blood meal (WHO, 2020).
Vector-borne diseases are human illnesses caused by parasites, viruses and bacteria that are transmitted by vectors. Every year there are more than 700,000 deaths from diseases such as malaria, dengue, schistosomiasis, human African trypanosomiasis, leishmaniasis, Chagas disease, yellow fever, Japanese encephalitis and onchocerciasis (WHO, 2020).
The burden of these diseases is highest in tropical and subtropical areas, and they disproportionately affect the poorest populations. Since 2014, major outbreaks of dengue, malaria, chikungunya, yellow fever and Zika have afflicted populations, claimed lives, and overwhelmed health systems in many countries. Other diseases such as Chikungunya, leishmaniasis and lymphatic filariasis cause chronic suffering, life-long morbidity, disability and occasional stigmatisation (WHO, 2020).
Vector-borne diseases account for more than 17% of all infectious diseases, causing more than 700,000 deaths annually. They may be caused by parasites, bacteria or viruses (WHO, 2020). Examples of vector borne diseases include:
- Malaria is a parasitic infection transmitted by Anopheline mosquitoes. Malaria causes an estimated 219 million cases globally, and results in more than 400,000 deaths every year. Most of the deaths occur in children under the age of 5 years (WHO, 2020).
- Dengue is the most prevalent viral infection transmitted by Aedes mosquitoes. More than 3.9 billion people in over 129 countries are at risk of contracting dengue, with an estimated 96 million symptomatic cases and an estimated 40,000 deaths every year (WHO, 2020).
- Other viral diseases transmitted by vectors include chikungunya fever, Zika virus fever, yellow fever, West Nile fever, Japanese encephalitis (all transmitted by mosquitoes), and tick-borne encephalitis (transmitted by ticks) (WHO, 2020).
- Other vector-borne diseases such as Chagas disease (transmitted by triatomine bugs), leishmaniasis (sandflies) and schistosomiasis (snails) affect hundreds of millions of people worldwide (WHO, 2020).
The table is a non-exhaustive list of vector-borne diseases, ordered according to the vector by which it is transmitted. The list also illustrates the type of pathogen that causes the disease in humans (WHO, 2020):
Vector | Disease caused | Type of pathogen | |
---|---|---|---|
Mosquito | Aedes | Chikungunya Dengue Lymphatic filariasis Rift Valley fever Yellow Fever Zika | Virus Virus Parasite Virus Virus Virus |
Anopheles | Lymphatic filariasis Malaria | Parasite Parasite | |
Culex | Japanese encephalitis Lymphatic filariasis West Nile fever | Virus Parasite Virus | |
Aquatic snails | Schistosomiasis (bilharziasis) | Parasite | |
Blackflies | Onchocerciasis (river blindness) | Parasite | |
Fleas | Plague (transmitted from rats to humans) Tungiasis | Bacteria Ectoparasite | |
Lice | Typhus Louse-borne relapsing fever | Bacteria Bacteria | |
Sandflies | Leishmaniasis Sandfly fever (phlebotomus fever) | Bacteria Virus | |
Ticks | Crimean-Congo haemorrhagic fever Lyme disease Relapsing fever (borreliosis) Rickettsial diseases (e.g. spotted fever and Q fever) Tick-borne encephalitis Tularaemia | Virus Bacteria Bacteria Bacteria Virus Bacteria | |
Triatome bugs | Chagas disease (American trypanosomiasis) | Parasite | |
Tsetse flies | Sleeping sickness (African trypanosomiasis) | Parasite |
Metrics and numeric limits
Not available.
Key relevant UN convention / multilateral treaty
International Health Regulations (2005), 3rd ed. (WHO, 2016).
WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) (1994) (WTO, 1994).
WTO and the World Organization for Animal Health (OIE) (WTO, 1998).
UN Recommendations on the Transport of Dangerous Goods (UNECE, no date).
Examples of drivers, outcomes and risk management
Previously relatively stable geographical distributions are now changing owing to a range of factors, including climate change, intensive farming, dams, irrigation, deforestation, population movements, rapid unplanned urbanisation, and phenomenal increases in international travel and trade (WHO, 2014).
Many vector-borne diseases are preventable, through protective measures, and community mobilisation (WHO, 2020).
The World Health Organization (WHO) has taken forward the Global Vector Control Response (GVCR) 2017–2030 (WHO, 2017) which was approved by the World Health Assembly in 2017. It provides strategic guidance to countries and development partners for urgent strengthening of vector control as a fundamental approach to preventing disease and responding to outbreaks. To achieve this a re-alignment of vector control programmes is required, supported by increased technical capacity, improved infrastructure, strengthened monitoring and surveillance systems, and greater community mobilisation. Ultimately, this will support implementation of a comprehensive approach to vector control that will enable the achievement of disease-specific national and global goals and contribute to achievement of the Sustainable Development Goals (UN, 2015) and Universal Health Coverage (WHO, 2020). Specifically, the WHO responds to vector-borne diseases by: providing evidence-based guidance for controlling vectors and protecting people against infection; providing technical support to countries so that they can effectively manage cases and outbreaks; supporting countries to improve their reporting systems and capture the true burden of the disease; providing training (capacity building) on clinical management, diagnosis and vector control with support from some of its collaborating centres; and supporting the development and evaluation of new tools, technologies and approaches for vector-borne diseases, including vector control and disease management technologies (WHO, 2020).
A crucial element in reducing the burden of vector-borne diseases is behavioural change. The WHO works with partners to provide education and improve public awareness, so that people know how to protect themselves and their communities from mosquitoes, ticks, bugs, flies and other vectors (WHO, 2020).
Access to water and sanitation is a very important factor in disease control and elimination. The WHO works together with many different government sectors to improve water storage and sanitation, thereby helping to control these diseases at the community level (WHO, 2020).
Rapid progress has been made in recent years in developing policy mandates, operational frameworks and pilot initiatives on health adaptation to climate change, including vector-borne disease as a particular priority. These present an excellent opportunity for a stronger and more coherent connection of applied research and public health policy (Campbell-Lendrum et al., 2015).
Applied research is nevertheless essential to ensure continued progress in reducing the burden of vector-borne diseases in the face of the additional challenges caused by anthropogenic climate change, along with rapid changes in other environmental and social determinants. To increase relevance to current health programming, there is a need to complement current work on detection and attribution of health effects to climate change, and modelling of future scenarios, with a more directly applied approach to assessing and managing climate-related risks in the present (Campbell-Lendrum et al., 2015).
References
Campbell-Lendrum, D., L. Manga, M. Bagayoko and J. Sommerfeld, 2015. Climate change and vector-borne diseases: what are the implications for public health research and policy? Philosophical Transactions of the Royal Society B, 370:20130552. doi:10.1098/rstb.2013.0552.
UN, 2015. Sustainable development. United Nations (UN), Department of Economic and Social Affairs. Accessed 27 April 2021.
UNECE, no date. UN Recommendations on the Transport of Dangerous Goods - Model Regulations Nature, Purpose and Significance of the Recommendations. Accessed 3 October 2020
WHO, 2014. A Global Brief on Vector-borne Diseases. World Health Organization (WHO).
WHO, 2016. International Health Regulations (2005), 3rd ed. World Health Organization (WHO). Accessed 3 October 2020.
WHO, 2017. Global vector control response 2017-2030. World Health Organisation (WHO). Accessed 27 April 2021.
WHO, 2020. Vector-borne Diseases. World Health Organisation (WHO). Accessed 9 October 2020.
WHO, 1994. The WTO Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement). World Trade Organization (WTO). Accessed 3 October 2020.
WHO, 1998. The WTO and the World Organization for Animal Health (OIE). G/SPS/GEN/775. Accessed 3 October 2020.