Is there a link to na­ture’s de­struc­tion?

The Guardian - - World - John Vi­dal This piece is jointly pub­lished with En­sia, a non­profit en­vi­ron­men­tal me­dia out­let

Only a decade or two ago it was widely thought that in­tact nat­u­ral en­vi­ron­ments were the source of the pathogens that led to new dis­eases in humans such as Covid-19, the dis­ease caused by a coro­n­avirus that crossed over from wildlife to humans in China in De­cem­ber last year.

But a num­ber of re­searchers now think it is ac­tu­ally hu­man­ity’s de­struc­tion of bio­di­ver­sity which cre­ates the con­di­tions for new dis­eases. The dis­ci­pline known as plan­e­tary health is emerg­ing, fo­cus­ing on links be­tween peo­ple’s well-be­ing and other liv­ing or­gan­isms and en­tire ecosys­tems.

Is it hu­man ac­tiv­ity, such as road build­ing, min­ing, hunt­ing and log­ging, that trig­gered past epi­demics and is un­leash­ing new ter­rors to­day?

Re­search sug­gests that out­breaks of in­fec­tious dis­eases such as Ebola, Sars, bird flu and Covid-19 are on the rise. Pathogens cross to humans from other an­i­mals and many can spread quickly to new sites.

The US Cen­ters for Dis­ease Con­trol and Preven­tion es­ti­mates that three-quar­ters of “new or

‘Pathogens don’t re­spect the species bound­aries. I am not sur­prised about Covid-19’ Thomas Gille­spie Sci­en­tist

emerg­ing” hu­man dis­eases orig­i­nate in non­hu­man an­i­mals.

Kate Jones, a sci­en­tist and chair of ecol­ogy and bio­di­ver­sity at Univer­sity Col­lege London, says emerg­ing an­i­mal-borne in­fec­tious dis­eases are an “in­creas­ing and very sig­nif­i­cant threat to global health, se­cu­rity and economies”.

In 2008 Jones and a team of re­searchers iden­ti­fied 335 dis­eases that had emerged be­tween 1960 and 2004; at least 60% of those had come from other an­i­mals.

In­creas­ingly, says Jones, these dis­eases are linked to en­vi­ron­men­tal change and hu­man be­hav­iour. The dis­rup­tion of pris­tine forests, for in­stance, is bring­ing peo­ple into closer con­tact with wild species they may never have been near be­fore. The trans­mis­sion of dis­ease from wildlife to humans is a hid­den cost of eco­nomic de­vel­op­ment.

Eric Fevre, chair of vet­eri­nary in­fec­tious dis­eases at the Univer­sity of Liver­pool, says: “There are just so many more of us, in ev­ery en­vi­ron­ment. We are go­ing into largely undis­turbed places. The risk [of pathogens jump­ing from other an­i­mals to peo­ple] has al­ways been there.” The dif­fer­ence now though is that dis­eases are likely to spring up in both ur­ban and nat­u­ral en­vi­ron­ments. “We have cre­ated densely packed pop­u­la­tions where along­side us are bat, ro­dents birds, pets, other liv­ing things. That cre­ates in­tense in­ter­ac­tion and op­por­tu­ni­ties for things to move from species to species.”

Thomas Gille­spie, an as­so­ciate pro­fes­sor in the en­vi­ron­men­tal sciences depart­ment at Emory Univer­sity, At­lanta, says: “Pathogens do not re­spect species bound­aries. I am not at all sur­prised about the coro­n­avirus out­break. The ma­jor­ity of pathogens are still to be dis­cov­ered. We are at the very tip of the ice­berg.”

Humans, says Gille­spie, cre­ate the con­di­tions for the spread of dis­eases by re­duc­ing the nat­u­ral bar­ri­ers be­tween virus host an­i­mals and them­selves. “Ma­jor land­scape changes are caus­ing an­i­mals to lose habi­tats, which means species be­come crowded to­gether and also come into greater con­tact with [us].”

Yet, ac­cord­ing to Richard Ost­feld, se­nior sci­en­tist at the Cary In­sti­tute of Ecosys­tem Stud­ies, in Cal­i­for­nia, hu­man health re­search sel­dom con­sid­ers sur­round­ing nat­u­ral ecosys­tems.

"There's mis­ap­pre­hen­sion among sci­en­tists and the pub­lic that nat­u­ral ecosys­tems are the source of threats to our­selves. It’s a mis­take. Na­ture poses threats, it is true, but it’s hu­man ac­tiv­i­ties that do the real dam­age. The health risks in a nat­u­ral en­vi­ron­ment can be made much worse when we in­ter­fere with it.”

Feli­cia Keesing, pro­fes­sor of bi­ol­ogy at Bard Col­lege, New York, stud­ies en­vi­ron­men­tal changes’ in­flu­ence on ex­po­sure to in­fec­tious

dis­eases. “When we erode bio­di­ver­sity we see a pro­lif­er­a­tion of the species most likely to trans­mit new dis­eases to us, but there’s also good ev­i­dence that those same species are the best hosts for ex­ist­ing dis­eases.”

Dis­ease ecol­o­gists say pathogens also mi­grate to peo­ple from an­i­mals at mar­kets sell­ing fresh meat around the world. The mar­ket thought by the Chi­nese gov­ern­ment to be the start­ing point of the Covid-19 pan­demic was known to sell many wild crea­tures. “Wet mar­kets make a per­fect storm for cross-species trans­mis­sion of pathogens,” says Gille­spie.

But some sci­en­tists think bans on sales of live an­i­mals in ur­ban ar­eas or such mar­kets are not the an­swer. Delia Grace, a se­nior epi­demi­ol­o­gist with the In­ter­na­tional Live­stock Re­search In­sti­tute, in Kenya, says: “These mar­kets are es­sen­tial sources of food for hun­dreds of mil­lions of poor peo­ple.” Bans can force traders un­der­ground, where peo­ple may pay less at­ten­tion to hy­giene.

Change, ac­cord­ing to Jones, should come from both rich and poor so­ci­eties. De­mand from the “global north” for re­sources leads to the eco­log­i­cal dis­rup­tion that drives dis­ease, she says. “We must think about global biose­cu­rity, find the weak points and bol­ster the pro­vi­sion of health­care in de­vel­op­ing coun­tries.”

Brian Bird, a re­search vi­rol­o­gist at the One Health In­sti­tute, Univer­sity of Cal­i­for­nia Davis, says: “[The risks] were al­ways present and have been there for gen­er­a­tions. It is our in­ter­ac­tions with that risk which must be changed. We are in an era now of chronic emer­gency. Dis­eases are more likely to travel farther and faster than be­fore, which means we must be faster in our re­sponses. It needs in­vest­ments, change in hu­man be­hav­iour. We must lis­ten to peo­ple at com­mu­nity level.”

Get­ting across the mes­sage about pathogens and dis­ease to hunters, log­gers, mar­ket traders and con­sumers, is key, Bird adds.

Fevre ad­vo­cates re­think­ing ur­ban in­fra­struc­ture, and Bird stresses that the bot­tom line is to be pre­pared. “We can’t pre­dict where the next pan­demic will come from so we need mit­i­ga­tion plans to take into ac­count the worst pos­si­ble sce­nar­ios. The only cer­tain thing is that the next one will cer­tainly come.”


Tim­ber stacked in Min­dourou, Cameroon, with FSC sus­tain­able cer­ti­fi­ca­tion. Trans­mis­sion of an­i­mal-borne germs to peo­ple can fol­low for­est clear­ance

▲ A wild bat for sale in In­done­sia at one of the world’s many meat mar­kets

▲ A lizard for sale at a mar­ket in the Demo­cratic Repub­lic of the Congo

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