Catherine Machalaba
Catherine Machalaba
Topic: Ecosystems and health
Catherine Machalaba is the Program Coordinator for Health and Policy at EcoHealth Alliance, a scientific organization working at the intersection of global health, environment and capacity building...
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Number of questions: [3]
Posted on 28/09/2016 10:18:56
Im looking for conversion factors and standards to measure green house gas emission
Samuel Ndadzibaya (from Zimbabwe)
Dear Samuel,

Thanks for working on this important issue- climate change has many implications for human health, including vector-borne and zoonotic diseases, food and water security, heat stress, natural disasters, and more. We urgently need to work across sectors to reduce greenhouse gas emissions to protect health. Many of the processes linked to the drivers of climate change also contribute to disease burden (as seen with air pollution from burning of fossil fuels). I consulted a leading expert on climate change and health, Professor Andy Haines at the London School of Hygiene and Tropical Medicine and the Future Earth global sustainability research platform, who kindly recommended some resources for your question. The conversion factors would depend on the specific greenhouse gas emissions you refer to – and whether associated with energy, land use, or other, but the Intergovernmental Panel on Climate Change Working Group 1 report should have the information you seek:

The IPCC Working Group 2 has also covered the health effects of climate change, including adaptation and co-benefits of risk mitigation (in public health, the saying is "prevention is better than cure"!):

Kind regards, Catherine

Posted on 27/09/2016 09:05:04
ADD association pour le d?veloppement durablenous solicitons votre apuis intervenir a nos programme que sant? est un vollet tr?s sp?cial
Coulibaly Modibo (from Mali)
Dear Coulibaly,

Sincere thanks for reaching out. Health is a critical component of sustainable development. In addition to Sustainable Development Goal 3 (“Ensure healthy lives and promote well-being for all at all ages”) achievement of other goals (relating to protecting aquatic and terrestrial landscapes, disaster risk reduction, ensuring reliable nutrition sources, and more) may also support health of current and future generations. It is important that synergies be made across the different goals to achieve as much as possible.

I saw your follow-up point as well on health communications. Responses tend to be reactive in responding to both health and environment threats (i.e. once they have already occurred). Messaging is important to keep people aware of the benefits of proactive public health actions to prevent disease before it occurs, especially because prevention is typically vastly less expensive than resource-intensive response/control once a crisis occurs. A 2012 World Bank report estimated a roughly 10:1 return on investment for preventing emerging zoonotic diseases through strengthened veterinary and public health capacity. Media can also also be a superb forum to show how different sectors can play a role in supporting health. I think it’s a wonderful idea to develop health outreach programs via media sources such as radio, television, print, internet and mobile phones. Government authorities can also bring ministries (especially human health, agriculture, and environment, but also colleagues working on disaster risk reduction, land planning, and more) together to promote collaboration for integrated surveillance and control measures. I have some case studies I would be delighted to share if useful.

Merci beaucoup and my apologies for my poor French abilities—hopefully I have understood and addressed your question sufficiently; if not, please do not hesitate to contact me at

Posted on 27/09/2016 05:47:22
Dear Madam,

Which type ecosystem is supported to extreme breeding of mosquitoes in the country like India? And I have heard that mosquitoes have not survived in the country like France? Please elaborate what are the management is required for mosquitoes prevention.
Also tell us is any vaccine has developed by any country or the WHO to fight against vector generation diseases as Dengue, Chicken- guinea etc.

Manoj Kumar Jain
manoj jain (from India)
Dear Manoj,

Many thanks for your question! In fact there isn’t a simple answer – there are over 3,500 known mosquito species, with different suitable habitats (their ecological “niche”) and different preferred hosts for feeding. Not all of these carry pathogens harmful to people (for example, only ~40 species worldwide transmit malaria).

Integrated vector management systems are important for controlling vector-borne diseases. Preventing conditions favorable for their breeding is key, especially removing sources of standing water or treating it with larvicides. The use of bed nets and window screens may also be recommended in some regions with night-biting mosquitos to reduce potential for exposure to mosquito bites. Pesticides are sometimes used in certain regions, seasons with high mosquito activity, and/ or in outbreak situations – but there are many trade-offs that must be considered, including both health and environmental risk assessment given toxicity concerns (an issue in the U.S. in the 1950’s-60’s with the use of DDT for mosquito control after the pesticide entered waterways, was absorbed by aquatic animals, and through the food chain poisoned bald eagles, affecting the egg shells of their offspring and ultimately severely reducing their populations). Protecting ecosystems so we don’t introduce new risk is important (for example by creating conditions where new populations of mosquitos can become established), and some species actually help us with mosquito control- for example, insectivorous bats and birds consume insects, providing an ecosystem service that we can benefit from. The potential effects of environmental changes (e.g. land conversion such as deforestation) on vector ecology and associated health outcomes and their economic implications should be considered when planning development projects.

Vaccines are most certainly in development for these diseases, but are not broadly approved for human use. The CYD-TDV Dengue vaccine was licensed for use in Mexico in late 2015. Some vaccines can help us indirectly; for example, with Rift Valley Fever, a mosquito-borne virus, vaccination of agricultural species susceptible to infection can help break the transmission chain to prevent human cases (a good example of the “One Health” approach that addresses the interface between humans, animals and the environment).

The World Health Organization publishes good information about Dengue control measures, and some of the practices can be applied to address other vector-borne diseases:

Thanks again for your question and concern on this important topic.