African health experts warn of climate change & rising vector-borne diseases
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Climate change has become a pressing public health crisis around the world, as disease patterns worsen and emerge in regions where they did not exist before. Rising temperatures can expand and extend the life cycle of disease-carrying vectors such as mosquitoes, ticks and parasites.
Health experts are particularly concerned about the role of climate change in the rise of vector-borne diseases in Africa’s low- and middle-income countries, which already face numerous health and socioeconomic disparities.
“It is crucial to acknowledge the gravity of the situation that we are facing today, especially around climate change, as it is no longer only an environmental concern, but it has evolved into a significant public health crisis with far-reaching implications for communities worldwide,” said Edward Miano, executive director of the Health Rights Advocacy Forum (HERAF).
He noted that climate change is worsening disease patterns, and diseases are emerging in areas where they did not exist before. A good example is that previously in Kenya’s highland regions, such as parts of the Rift Valley and Kericho county, malaria was not prevalent. But the disease has returned in recent years, a development that some experts say is linked to subtle changes in the region’s climate.
Miano spoke during a webinar that took place on April 4, jointly organized by HERAF, the African Medical and Research Foundation (AMREF) and the African Institute for Development Policy (AFIDEP). The webinar was meant for science and environmental journalists from across the African continent, as it aimed to shed light on the intersection of climate change and public health, with a specific focus on the escalating threats posed by vector-borne diseases in various African countries.
A study published in March in the journal Infectious Diseases of Poverty highlights that vector-borne diseases, which account for more than 17% of all infectious diseases, cause more than 700,000 deaths annually, posing a significant threat to global public health. Major diseases such as malaria and dengue fever are associated with the largest burden, affecting millions of people worldwide.
Worke Tafete is a former visceral leishmaniasis (VL) patient from Metemma, northwestern Ethiopia. Climate change is affecting the spread of VL, the largest parasitic killer after malaria. Changes in temperature and rainfall affect the geographic distribution of sandfly populations that cause this often-fatal disease.Image ©️ Sydelle Willow Smith/DNDi.
According to the World Health Organization (WHO), an estimated 3.6 billion people live in areas highly susceptible to climate change, with projections indicating that climate-related factors could contribute to an additional 250,000 deaths annually between 2030 and 2050. These projected deaths are primarily attributed to undernutrition, malaria, diarrhea and heat stress. And now, health experts add vector-borne diseases to that list as well.
Kenya, like many other regions, is largely affected by vector-borne diseases such as malaria, dengue fever and Rift Valley fever and is witnessing firsthand the profound impact of climate change on health outcomes, necessitating urgent action and collaboration across sectors, from health to agriculture, energy, tourism and marginalized communities.
Albeit this is not just a problem in Kenya. According to a 2022 study in the Iranian Journal of Public Health, there are many ways that climate change globally can extend and expand the life cycles of disease-carrying vectors such as mosquitoes, ticks and parasites. “Rising temperatures favor agricultural pests, diseases and disease vectors. Therefore, climate change has already made conditions more conducive to the spread of certain infectious diseases, including Lyme disease, water-borne diseases, and mosquito-borne diseases such as malaria and dengue fever,” the study’s authors write.
The researchers also warn that among climate-related diseases, mosquito-borne viral and parasitic diseases are the most worrying. These illnesses profoundly limit socioeconomic status and development in countries with the highest infection rates, as many are found in the tropics and subtropics. The disproportionate increase in average nighttime compared with daytime temperatures makes available ideal temperatures for the growth of vector insects and the spread of related diseases.
A city worker conducts a fogging campaign in Kirulapone, Colombo, Sri Lanka, to combat Aedes mosquitoes, which transmit dengue fever. Rising temperatures have led to increased survival and reproduction of these mosquitoes.
Image ©️ Xavier Vahed/DNDi.
Furthermore, the WHO estimates that the direct damage costs of climate change to health are expected to range from $2 billion to $4 billion per year by 2030, disproportionately affecting developing countries with weaker health systems.
Dr. Bernard Onyango, a senior research and policy analyst at AFIDEP, focused on the complex interplay between climate-related health hazards, exposed populations and vulnerability factors. He noted that climate hazards such as heat waves, rising sea levels, air pollution and changes in vector distribution and ecology pose significant challenges to public health systems. “As global climate and land use changes, they alter the distribution of reservoir hosts and vectors, making it challenging to predict and respond effectively,” Onyango said during the webinar.
He also reiterated the need for a gender-sensitive approach to climate change, as women and girls are disproportionately affected by events such as floods, droughts and heat waves compared with their male counterparts. This, according to him, is because the climate crisis is not gender-neutral. When extreme weather events like floods occur and affect health infrastructure, women often experience challenges like limited access to sexual and reproductive health rights services (SHR).
The consequences of this limited access to SHR include maternal and infant mortality and morbidity, unexpected pregnancies, unsafe abortions and the implications of sexual gender-based violence, which may result in increased sexually transmitted infections, heightened HIV transmission and mental health issues, including depression and trauma.
An Aedes aegypti mosquito photographed in Dar es Salaam, Tanzania. These mosquitoes transmit dengue fever, yellow fever and other dangerous diseases. Health experts are concerned about an increase in vector-borne diseases with climate change.
Image by Muhammad Mahdi Karim via Wikimedia Commons (GFDL 1.2).
Need for assessments
During the webinar, Dr. Martin Muchangi, director for population health and environment at AMREF Health Africa, said there is need to plan ahead by identifying and focusing on key priority areas before any interventions, such as destruction of vector breeding sites, are carried out. These include conducting vulnerability assessments within the health sector and the development of national health adaptation plans.
“For the interventions to work, then the Ministry of Health in Kenya must conduct vulnerability assessments to identify areas of focus in mitigating the spread of vector-borne diseases,” he said, adding that it is only after such assessments that policies and adaptation plans can be formulated and possibly be adopted in the country’s finance budget for implementation.
According to Muchangi, it is paramount to address climate and health illiteracy in the health sector, as there are very few experts in this field in countries such as Kenya. “We need to invite ourselves very strongly to start building the capacity of the health workforce so that at the end of the day, the doctors and the nurses attending to patients can be able to solve the challenges that are coming to the health sector with the climate change crisis,” he said.
He added that the training should extend to community health promoters who interact with communities at the grassroots level. “They [community health promoters] need to understand that when a phenomenon like drought is predicted, it means many things — from malnutrition to diseases.”
Holistic approach
Climate change is a resource taker, and addressing the multifaceted challenges posed by it requires a holistic and multisectoral approach that involves all sectors of society, from health to education and government. Community engagement and education are also crucial, as local communities play a vital role in building resilience and implementing effective adaptation strategies.
Responding to Mongabay in an email interview after the webinar, the East Africa director for the Drugs for Neglected Diseases initiative (DNDi), professor Samuel Kariuki stressed that all parties affected by climate change and its health effects should be involved in any interventions. “All stakeholders must be involved, ranging from communities affected, local authorities and national government, to play critical roles in preparedness and response to events that may happen following floods [and] drought that would affect spread of vector-borne diseases,” Kariuki said.
The Drugs for Neglected Diseases initiative (DNDi) team, led by East Africa director Samuel Kariuki (second from right), at the leishmaniasis treatment center in Amudat, Uganda. Climate change is contributing to an increased range for sandflies, which transmit the disease.
Image ©️ DNDi.
DNDi has been involved in tackling several of neglected tropical diseases (NTDs) listed by WHO, from doing discovery and innovation for new treatments to partnering with manufacturers to avail these treatments and then ensuring access for patients. Since 2003 when DNDi was founded, it has delivered 13 treatments for six of the most devastating NTDs, including mycetoma, pediatric HIV, Chagas disease, hepatitis C and visceral leishmaniasis, also known as kala-azar.
In the words of Kariuki, the prevalence of these NTDs has also been greatly affected by climate change.Take visceral leishmaniasis, the largest parasitic killer after malaria, which is fatal in 95% of cases if not treated and is transmitted by female sandflies, which thrive in environments at approximately 25° Celsius (77° Fahrenheit). “As temperatures rise, more areas become suitable for sandflies to multiply. Moreover, the sandflies are more active in warm and humid environments, which could increase the frequency of bites to humans and transmission,” the director noted.
Early warning systems
According to Kariuki, it is important for the national government and other stakeholders to work with the meteorological department that predicts weather patterns so they can warn communities regarding potential weather events that would bring along new outbreaks of diseases or increased burden of vector-borne diseases. “We must prepare in advance for these events so we have stockpiles to respond when necessary. Aside from this, we all should engage in mitigating climate change by playing our various roles and preventing activities that contribute to global warming,” he urged.
There’s also a need for increased investment in authentic and community-driven research initiatives. Collaboration between governments, scientific communities and funding bodies is essential to drive evidence-based interventions and foster scientific excellence. These efforts should transcend country borders, as there are many countries in sub-Saharan Africa and the Global North that need these new biomedical innovations.
“We must own the problems that we face and embrace innovations that will play a key role in mitigation against climate-sensitive diseases including NTDs. Listening to communities affected by these events for homegrown solutions and with partnerships that complement these efforts will provide long-term effective and sustainable solutions,” concluded DNDi’s Eastern Africa director.
Citations:
Alsop, Z. (2007). Malaria returns to Kenya’s Highlands as temperatures rise. The Lancet, 370(9591), 925-926. doi:10.1016/s0140-6736(07)61428-7
Obame-Nkoghe, J., Agossou, A. E., Mboowa, G., Kamgang, B., Caminade, C., Duke, D. C., … Voua Otomo, P. (2024). Climate-influenced vector-borne diseases in Africa: A call to empower the next generation of African researchers for sustainable solutions. Infectious Diseases of Poverty, 13(1). doi:10.1186/s40249-024-01193-5
