Pub­lic Health vexed by bac­terium

Toronto agency can’t find cause of 78% spike in M. avium cases

Toronto Star - - GREATER TORONTO AREA - THERESA BOYLE HEALTH RE­PORTER

There has been a mys­te­ri­ous 78-per-cent jump in the num­ber of Toron­to­ni­ans test­ing pos­i­tive for a bac­terium that can cause chronic lung in­fec­tions in peo­ple with pre-ex­ist­ing lung prob­lems and weak­ened im­mune sys­tems, the Star has learned.

Ac­cord­ing to Pub­lic Health On­tario, an av­er­age of 66 new cases of res­i­dents test­ing pos­i­tive for My­cobac­terium avium have ap­peared each month be­tween June 2014 and June 2015 — the most cur­rent num­bers avail­able. That’s up from an av­er­age of 37 new monthly cases in each of the pre­ced­ing 49 months.

“There is cause for con­cern here, but cer­tainly no cause for panic,” said Dr. Ray Copes, the agency’s chief of en­vi­ron­men­tal and oc­cu­pa­tional health, ex­plain­ing that not ev­ery­one in­fected with the bac­terium be­comes ill.

“You have to ask what’s go­ing on . . . We are not en­tirely sure of that yet,” he said.

Toronto Pub­lic Health has been un­able to find the source of the in­crease and has stopped in­ves­ti­gat­ing, said Dr. Christine Navarro, as­so­ciate med­i­cal of­fi­cer of health.

Respirol­o­gist Dr. Ted Mar­ras, an ex­pert in treat­ing those in­fected with M. avium, said he’s “dis­ap­pointed” by that.

Ex­trap­o­lat­ing from pre­vi­ous re­search, about 33 Toron­to­ni­ans may be get­ting sick from it monthly, he said.

Th­ese are typ­i­cally in­di­vid­u­als with un- der­ly­ing sus­cep­ti­bil­ity such as el­derly peo­ple, those who are HIV-pos­i­tive and those with pre-ex­ist­ing lung prob­lems, said Mar­ras, di­rec­tor of the non­tu­ber­cu­lous my­cobac­te­rial clinic at Toronto Western Hos­pi­tal and as­sis­tant pro­fes­sor of medicine at the Univer­sity of Toronto.

Most who be­come ill suf­fer lung dam­age and de­velop re­cur­rent lung in­fec­tions.

Mar­ras said he would like to see the spike in cases fur­ther in­ves­ti­gated. Ideally, he would like a sam­ple of pa­tient records an­a­lyzed to de­ter­mine ex­actly how many of those who test pos­i­tive are be­com­ing ill.

M. avium is an en­vi­ron­men­tal or­gan­ism found widely in soil and wa­ter.

It is most com­monly trans­mit­ted by in­hal­ing droplets of wa­ter that con­tain the or­gan­ism, with mu­nic­i­pal wa­ter sup­plies typ­i­cally be­ing the orig­i­nal source, Copes ex­plained.

“This is not some­thing that you get through drink­ing wa­ter as much as (through) wa­ter that is aerosolized that peo­ple could in­hale. That does hap­pen with show­ers, hot tubs and a num­ber of other uses of mu­nic­i­pal wa­ter,” Copes ex­plained. He em­pha­sized that Toron­to­ni­ans should not be afraid to drink tap wa­ter.

“It would be really in­ap­pro­pri­ate for peo­ple to stop drink­ing wa­ter in Toronto be­cause of this. I’ve known about this, and I am still drink­ing Toronto wa­ter,” he said.

The or­gan­ism is al­most al­ways present in mu­nic­i­pal wa­ter sup­plies and to­tal erad­i­ca­tion is un­likely, Copes ex­plained.

The bac­te­ria tend to grow in biofilms that line large wa­ter pipes in mu­nic­i­pal wa­ter dis­tri­bu­tion sys­tems and even smaller pipes in in­di­vid­ual build­ings, he said.

Many ju­ris­dic­tions in the de­vel­oped world have seen a grad­ual in­crease in pos­i­tive re­sults over the last decade, but a sud­den spike is un­usual, he con­tin­ued.

“You can see a point in time when some­thing changes,” Copes said, re­fer­ring to June last year. “There really does seem to be some­thing dif­fer­ent hap­pen­ing here.”

Asked whether Toronto Pub­lic Health has ruled out the city’s wa­ter sup­ply as the source of the in­crease, Navarro said: “TPH found there was no pat­tern in where peo­ple who tested pos­i­tive for the My­cobac­terium avium were lo­cated in the city, or any clus­ter­ing that could be re­lated to en­vi­ron­men­tal ex­po­sures such as wa­ter sup­ply, wa­ter tem­per­a­ture, wa­ter main re­place­ments or changes in wa­ter treat­ment.”

M. avium is not a re­portable dis­ease, mean­ing health prac­ti­tion­ers are not re­quired to re­port cases to mu­nic­i­pal pub­lic health units, as they are with food-borne ill­nesses and com­mu­ni­ca­ble diseases.

Test­ing for the bug is done through spu­tum sam­ples by On­tario Pub­lic Health, typ­i­cally as part of a big­ger workup of tests or­dered by treat­ing physi­cians. Only those physi­cians would know if pa­tients who tested pos­i­tive were ill. M. avium is less likely to cause ill­ness in healthy peo­ple. Symp­toms of M. avium lung dis­ease typ­i­cally in­clude cough, pro­duc­tion of spu­tum and fatigue. Some­times pa­tients suf­fer short­ness of breath, chest pain and weight loss. For most, it is chronic.

“It usu­ally ends up in some sort of life­long con­di­tion that at times can be­come very se­vere. In some pa­tients, it can be­come life-threat­en­ing and pro­gres­sively de­stroy more and more lung tis­sue,” Mar­ras said, adding that some pa­tients suf­fer only mi­nor symp­toms. Treat­ment is dif­fi­cult and con­sists of tak­ing three dif­fer­ent kinds of an­tibi­otics, he noted.

Com­pound­ing the prob­lem is that over the sum­mer, there was a short­age of one of the main drugs used to treat pa­tients. The Cana­dian Drug Short­age Data­base shows that drug man­u­fac­turer Valeant Canada ex­pe­ri­enced de­lays in ship­ping the drug, etham­b­u­tol.

It was back in stock by Septem­ber.

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