Climate change can be disastrous for Southeast Asia, which concentrates 30% of the world’s poor population

Publicação: 7 de February de 2020

Climate change has caused an increase and migration of vectors, an increase in epidemics and diseases, reduced productivity and increased spending on medicines and health care

Climate change is affecting the incidence of dengue and the spread of infection by two species of Aedes aegypti and Aedes albopictus

It is a fact: climate change is already one of the main public health emergencies in the world. High temperatures have led to the proliferation and migration of vectors to areas that previously did not have such transmitters, an increase in epidemics and the capacity for transmission and incidence of diseases, such as dengue. The article “The dengue epidemic and climate change in Nepal“, published in the scientific journal “The Lancet” in December 2019, it points out that the global vectoral transmission capacity of the dengue virus was reported as the highest ever recorded, rising to 9,1% for A. aegypti and 11,1 for A. albopictus, above the baseline of 1950’s, according to information from the “Lancet Climate Countdown 2018” report.

To learn more about the subject, the Communication Advisory of the Brazilian Society of Tropical Medicine (BSTM), interviewed Dr. Basu Dev Pandey, Director of the Hospital for Infectious and Tropical Diseases (STIDH), located in Kathmandu, Nepal.

Check the interview in full:

BSTM: Could you tell us the health effects of climate change in South Asia and Africa? Poor countries will suffer most from the effects of the health effects of climate change?

Dr. Basu Dev Pandey: In my opinion, climate change has enormous and diverse effects on human health all over the world. Rises in temperature and sea level and extreme weather events such as floods over lowland and landslides in the mountains cause water logging and contamination, which in turn exacerbate diarrheal diseases in South Asia and Africa. There are effects by extreme cold wave leading to cold-related diseases, including hypothermia, pneumonia and deaths every year in Nepal, India, Bhutan, Bangladesh, Pakistan and part of Afghanistan. Normally, lowland remind warm during winter season in the past and now there is extreme cold causing serious health problem mainly among the poor due to lack of warm clothes, food and shelter in South Asia and Africa. The spatial and temporal distribution of vector-borne diseases like dengue, chikungunya, Leishmaniasis has been projected to increase due to favorable temperatures, with resulting alterations of communicable disease dynamics in the past. The expansion of Leishmaniasis over the mountains, in altitude more than 2000 meters in Nepal which was free from the disease in the past could be one of the examples of impact on climate. The vector, now found in altitudes of over 2000 meters, can transmit dengue and other vector borne diseases. The outbreak of malaria in rural Mugu and Bajura districts over the mountains of Nepal in the year 2018 is a serious challenge in the resource constrains countries like Nepal, where elimination of Malaria is targeted by the year 2025.  Countries that lack resources will suffer most since there is limited funding, manpower to cope against the diseases, causing outbreak in the non-programme areas.

BSTM: Could you talk about the dengue epidemic and climate change in Nepal?

Dr. Basu Dev Pandey: I believe climate change is affecting the incidence of dengue infections spread by two species of Aedes mosquitoes: Aedes aegypti and Aedes albopictus. One recent estimate suggested the average annual maximum temperature of the country Nepal has risen by 0.056 degree Celsius over the past 40 years, and well over two degrees at higher elevations. Dengue transmission is highly sensitive to temperature through faster generation and hatching rates.  Dengue was first identified in 2004 in Nepal in the lowland Chitwan district of Teria region and all four serotypes been identified. The number of cases is increasing and expanding in the hilly region every year with a peak in every 3 to 4 years. In 2019, there were unexpected early rains, starting in late March. Normally the monsoon is expected by June and lasts for about 3 months. This year, the monsoon entered Nepal in the third week of June and a month later the country received the heaviest rainfall for a decade. Starting July, incessant rainfall for a week triggered flooding and landslides in many areas, especially in south-eastern districts. The Bagmati and Kamala river basins recorded historical extremes of rainfall, and Eastern Nepal and Kathmandu were hit by severe flooding. The first dengue fever case was reported on May, 2019 from Sunsari district in the east of the country followed by Makwanpur, south-west of Kathmandu, on July 2019, The outbreak then spread like wildfire reaching 67 out of 77 districts recorded 14,000 cases officially, which is grossly underestimated since all the febrile cases were not tested and the private hospital usually did not report the cases to the government.  Unusual low rainfall rises in the temperature, scarcity of water, presence of vector in high altitudes, and expansion of vector borne diseases in high altitudes is directly linked with the climate changes.

BSTM: What is the future of tropical diseases inside and outside the tropics in the face of global warming, particularly with regard to vector-borne diseases?

Dr. Basu Dev Pandey: The South-East Asia Region is home to 26% of the world’s population and 30% of the world’s poor. Because of its large population, the consequences of climate change could be disastrous for the region, which already has a disproportionately high burden of communicable diseases that is expected to increase in the foreseeable future as a result of climate change. Increased average temperatures could prolong peak periods for vector-borne diseases, and extreme weather events, including cyclones and floods, which can create ideal conditions for the spread of vector-borne and diarrheal diseases, such as cholera. In much of the region, dengue is spreading not only geographically, but in explosive outbreaks. It shows that there, rapid rises in the cases of dengue in the areas and expansion to new areas previously free from diseases, indicating serious threats of vector borne diseases. These all events indicate that number of tropical diseases is increasing in the numbers and emerging outside the Tropics. At the same time, the focus has been diverted and limited in term of resources and facilities. Many developed countries have lost their memory and are no longer prepared to cope the effect of climate change and pay less attention on training a health manpower to manage the cases if they face outbreak of vector borne diseases. On the other hand, developing countries lack resources and most of the countries either have no preparedness plan or nor functioning respond emergencies.

BSTM: What is your opinion about connections between climate change, species extinction, and natural calamities like floods and famines, all of which have impacts on global health?

Dr. Basu Dev Pandey: I feel, there is direct link between climate change, which leads species extension and adaptation. Lancet Climate Countdown Report, shows that the global vectoral capacity for the transmission of the dengue virus was reported the highest on record, rising to 9·1% for Aedes aegypti and 11·1% for Aedes albopictus, above the 1950s baseline. The climate change and the natural calamities like floods, famine, cyclone, extreme cold or heat waves all of which have direct impacts on global health and were particularly more prominent in the resources constrains countries in South Asia and Africa.

BSTM: Could you talk about the projections about global warming and the potential effects on food security, water, and changing patterns of diseases due to heat waves and vector-borne infections?

Dr. Basu Dev Pandey: Definitely global warming has great impact from farm to plates. In Nepal, Global Circulation Model outputs suggest that overall temperatures will increase between 0.5ºC and 2.0ºC by the 2030s and between 3.0ºC and 6.3ºC by the 2090s. Increase in melting of Himalayas leading to flooding and increase overflow of water will happen in one area and in the other area the source of water decreases leading to internal and external migration. There are instances where highly fertile lands are converted to desert where gross reduction of production occurs. These instances indicate that there will be severe food and water scarcity in the next few decades. The disproportionately affected by climate change are the poor, as shown by devastating floods in Bihar, India, and Eastern part of Nepal in 2009. The pattern of diseases changes is therefore due to extreme cold waves and heat waves. Also, there is emergence of vector borne diseases including dengue, which, for the first time, was notified in the Himalayan countries Nepal and Bhutan in 2004. Now 18 of out of 20 districts in Bhutan and 67 out of 77 districts of Nepal and in the in new area of Bangladesh affected by dengue in 2019 where the largest outbreak happened. At the same time, there is a high risk of emergence of other vector borne diseases, including Leishmaniasis, chikungunya and expansion of malaria to non-endemic districts.

BSTM: In your opinion, how is the insertion of themes related to health effects of climate change in the world scientific and political agenda?

Dr. Basu Dev Pandey: In my opinion, the magnitude of the problem makes it imperative to raise greater awareness of the threats of climate change, especially among the policy-makers. The insertion of themes related to health effects of climate change must be discussed to make aware the world scientific communities. Climate change and health impact should be a top political agenda. Engaging political leaders and policy makers has greater impact to fight against climate change and diseases. A country like Nepal, one of the highly affected due to climate change, has planned several activities including World Sagramatha (World Heritage Site – Mount Everest) conversation in April 2020.

BSTM: Would you like to add something?

Dr. Basu Dev Pandey: If all countries globally make a combined effort to tackle the effects of climate change on health, from the resulting evidence base will emerge the best practices and the lessons learnt will make a valuable contribution to global health. Most countries in the region lack adequate plans for disease and, lack of entomologists, lack vector surveillance, as well as control and emergency preparedness. An effective, sustainable response requires an assessment of health risks, integrated action, financial investment and multispectral collaboration, essential to frame work to support resource constraints countries.