Keep forests intact to prevent disease outbreaks


  • Letters
  • Tuesday, 31 Mar 2020

For years, scientists have been trying to warn us that deforestation will unleash infectious diseases onto human populations, but this has been conveniently ignored by politicians wanting to make a quick profit from issuing licences for logging and agricultural expansion.

Scientists from all over the world, including disease ecologists at Ecohealth Alliance who are studying malaria Sabah and Sawawak, warn that human activities in forested areas – such as forest-clearing, road-building, mining, hunting, and logging – cause major disruptions to ecosystems, which then causes diseases to spread from their natural wild hosts to new hosts, including humans. International travel then helps some of these diseases spread to other countries and continents, causing significant damage to human health and economies.

It is not merely the act of killing and consuming wildlife that contributes to the rise of zoonoses, namely, diseases that jump species from animals to humans. The mere act of rapid forest clearing, even without the hunting and poaching of wildlife that usually accompanies encroachment into forests, is enough to trigger chains of events that create the right conditions for deadly infectious diseases to spread to domestic animals and nearby human populations.

Even as far back as the 1990s, epidemiologists at the University of Florida’s Emerging Pathogens Institute found a link between forest clearing in the Peruvian Amazon and the rise in malaria cases. The Journal of Emerging Infectious Diseases has documented the steep increase in malaria cases in areas in Sabah and Sarawak where forested land has been cleared for agriculture. Mosquitoes and other pathogens proliferate in forest edges where the boundaries between human habitation and forested areas become blurred, and primates and other disease carriers wander into human habitation.

There are countless examples of direct pathogen spillover from wildlife to humans arising from forest clearing, hunting, poaching, and encroachment of agriculture and farmed animals into forests.

> Deforestation in South America is a factor in the transmission of rabies by vampire bats to cattle and humans.

> The Kyasanur Forest disease outbreak came after the encroachment of cattle and farms into Indian forests.

> The clearing of forests in Liberia for oil palm cultivation attracted forest-dwelling mice which then gave rise to the Lassa virus when humans came in contact with the faeces or urine of the mice.

> The Nipah Virus outbreak in 1999 was caused by rampant deforestation in Indonesia which resulted in fruit bats losing their forest habitat and venturing onto farms in Malaysia, where they spread the virus to pigs, which then jumped species to humans.

> HIV is believed to have arisen from the hunting of primates in central African forests.

> Ebola has been associated with hunting in Gabon and the Republic of Congo.

This does not mean that we need to clear forests and kill wildlife in order to eradicate disease. Many of these viruses exist harmlessly with their forest-dwelling host animals, because the animals have co-evolved with these viruses. It is human activity that makes humans unwitting hosts for these viruses and other pathogens.

To protect national and global biosecurity, it is imperative that we protect our forests and keep forests intact. Intact forests protect watersheds and water quality, are more resistant to fire and drought, regulate climate and weather patterns, provide habitat for a wide range of flora and fauna, and prevent wild species from crossing into human habitation and spreading diseases to domestic animals and humans.

Keeping forests intact provides more economic benefits over the long term than clearing them for agriculture and timber extraction. The economic benefits of logging are short-lived and can sustain only one to two generations at most. Intact forests absorb approximately 25% of the world’s human-generated carbon emissions and sequester far more carbon than logged, degraded or planted forests.

For generations, forested ecosystems have provided society with medicinal plants and compounds, and these medically-relevant species are often lost when forests are cleared, fragmented, or replaced with farms and monoculture plantations. Cleared and fragmented forests are less resilient to fire and drought, and the haze caused by forest and peat fires cause governments grave economic loss and increase healthcare costs.

A 2016 Harvard University study published in Environmental Research Letters reported that the 2015 human-caused forest fires in Indonesia caused more than 100,000 premature deaths across Indonesia, Malaysia, and Singapore. Can Malaysia keep on bearing the loss of human lives and increased healthcare costs arising from forest loss and declining air quality?

Ecohealth Alliance calculated that the Malaysian government spends around US$5,000 (RM21,000) to treat each new malaria patient in Sabah and Sarawak. The healthcare costs of testing and screening individuals for Covid-19 and of hospitalising and treating Covid-19 patients in Malaysia have not been disclosed yet, but we can assume it is tremendous, even before taking into account economic stimulus packages and financial aid for vulnerable groups.

Can Malaysia bear the healthcare and socioeconomic costs of managing and mitigating future zoonotic outbreaks arising from deforestation and human-wildlife interactions?

We know the answer is no, yet the continued destruction of Malaysia’s tropical rainforests and natural environment indicates that our leaders have not learned their lesson. State governments continue to degazette forest reserves and issue logging permits with impunity, and politicians from both sides of the political divide rush to fill their coffers with nary a thought for the environment, wildlife, or rural and indigenous communities.

Even as the nation is still reeling from the economic shock of the Movement Control Order, and Covid-19 infection rates and deaths continue to increase daily, the Selangor state government has decided to proceed with the degazettement of the Kuala Langat North Forest Reserve. It is doing so without giving environmental organisations and the affected local and Orang Asli communities the chance to consult, discuss, provide feedback or prepare for a public inquiry into the degazettement proposal.

Such cavalier disregard for the environment and for the voices of concerned citizens show how little our political leaders care about protecting biodiversity, safeguarding biosecurity, and mitigating climate change. This will return to haunt us in the form of droughts, floods, water and food insecurity, increased carbon emissions, poorer air quality, more human-wildlife conflicts – and a rise in tropical diseases.

As a propitiatory gesture, Selangor Menteri Besar Amirudin Shari has offered to replace the degazetted area with a “bigger area” in Kuala Selangor, Sabak Bernam, and Hulu Selangor as a substitute forest reserve. This mindset is problematic, as the biodiversity and complexity of natural forests and the ecosystem services they provide cannot be replicated or replaced so easily. We are rapidly losing forested areas to agriculture and development, and states will soon run out of suitable sites to gazette as replacement forest reserves. Tree-planting activities and the gazettement of secondary forests and degraded land cannot be a substitute for the protection of natural and intact forests for all the reasons listed above.

Science News magazine and the Global Biodefense journal have already identified Malaysia as the next ground zero for malaria infections. Global disease surveillance network USAID Predict has in 2017 identified at least 48 new viruses in Malaysian rainforest species, and only time will tell which of these viruses will be the next to jump species to humans. Considering the current rate of deforestation, our country will be susceptible to many types of tropical and zoonotic diseases.

Malaysia is currently still doing its best to contain the number of Covid-19 infections and deaths. It will take us months to deal with the socioeconomic fallout from the outbreak. If we don’t move fast to halt deforestation and protect our natural forests, we must then prepare to face the next zoonotic outbreak, and the ones after, that will arise from our callous disregard for the environment.

WONG EE LYNN

Petaling Jaya

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