What you need to know:
- Climate change is re-writing disease alogirthim on earth.
- Bats can live up to 40 years, giving them adequate time to spread diseases.
Climate change, largely driven by human activities, now threatens our survival. Destruction of the environment and ecosystems is believed to have started about 12,000 years ago when the neolithic man became a hunter-gatherer in search of food.
This was soon followed by agricultural and industrial revolutions, activities that up to date contribute in releasing carbon emissions. As the world becomes warmer, diseases are becoming more lethal. The World Health Organization estimates that only nine countries had dengue fever in 1970.
Dengue fever is transmitted by a warm loving mosquito known as Aedes aegypti and as of 2019, it had spread the infection to 128 countries with 4.2 million cases globally, a 30-fold increase from 1970. It is projected, with unmitigated climate change, dengue fever will infect six billion or 60 per cent of world population by 2080.
Climate change is re-writing disease alogirthim on earth. Thawing of permafrost in the Arctic is releasing thousands of pathogens that have never seen daylight for tens of thousands of decades, the intensity and number of people being subjected to new diseases as a result of exposure to such novel pathogens is unknown.
The cholera causing bacteria, which thrives in warm areas, is now moving towards the North with a similar bacteria, which kills one in every five people it infects by invading and eating flesh in wounds known as Vibro vulnificus.
Covid-19 is caused by a coronavirus that is thought to have moved from horseshoe bats, whose habitat has been destroyed through agricultural activities and deforestation.
Bats can live up to 40 years, giving them adequate time to spread diseases. The mammals have an immune system that resists viruses that are lethal to humans and can travel 30 miles a day, enhancing their capacity to explore new human settlements and cause infections.
Covid-19 has infected 63 million people worldwide and killed 1.5 million. The 1918 influenza killed 50 million and HIV has killed 37 million people. Lethal viral disease outbreaks such as Ebola, Marburg, Chikungunya, Zika, Sars and Mars have all been traced to be enzootic sources, diseases that infect animals but jump to humans.
The Nipah virus, for example, was spread by bats that settled in human piggery farms. When pigs fed on bat urine contaminated pasture, the pigs became mild sickly but humans developed fever with 75 per cent fatality rate and a third of those who recovered had neurological conditions.
Nipah disease is more dangerous than Covid-19 because of high fatality rates but easy to control because it is transmitted only by symptomatic patients.
A recent study, which reported on migration of about 40,000 species of animals, wrote that 70 per cent of the species were in migration to cooler lands and waters as a result of climate change.
It is documented that about 1.7 million viruses are residing in mammalian and avian hosts and that an estimated 800,000 of the viruses are capable of jumping from the animals and cause infections in humans.
This portends a bleak future of frequent pandemics. By July this year, the Covid-19 economic impact was US$8 trillion, and if we have multiple novel pandemics circulating globally, then poverty, deaths and misery would be the trademark of human species.
We are unprepared. Developing nations are more affected by pandemics yet governments in these countries are lethargic to investing in a robust public health sector and scientific research.
Poor nations do not prioritise education and technology but are good at stealing public resources. Given the danger that lies ahead, there is no option for the world now but to restore our environment and invest in research.
Dr P.M Mutua, Makueni