New breath ex­am­i­na­tion for malaria

The dis­ease-caus­ing par­a­site may al­ter com­pounds hu­mans ex­hale nat­u­rally

The East African - - OUTLOOK - By CHRISTABEL LIGAMI Spe­cial Correspondent

Peo­ple with malaria ex­hale a dis­tinc­tive “breath­print,” in­sights sci­en­tists have used to de­velop a new breath test for di­ag­nos­ing the killer dis­ease in a group of African chil­dren, ac­cord­ing to a new study pub­lished in the Amer­i­can So­ci­ety of Trop­i­cal Medicine and Hy­giene.

The re­searchers say malaria is a prime can­di­date for breath-based di­ag­no­sis, a con­clu­sion based on past re­search that shows the dis­ease-caus­ing par­a­site in­vades the hu­man body, and may al­ter com­pounds hu­mans ex­hale nat­u­rally.

The same tech­nol­ogy — enose — could be used to de­velop a portable malaria breathal­yser and breath tests for other dis­eases as well.

It is the first study to iden­tify a spe­cific set of com­pounds in hu­man breath that can serve as di­ag­nos­tic mark­ers for malaria. The anal­y­sis is also the first to find that peo­ple with malaria ex­hale a com­pound iden­ti­cal to a plant-pro­duced vapour that is known to at­tract mos­qui­toes, which could be ac­cel­er­at­ing the spread of dis­ease.

“We were able to de­ter­mine whether the chil­dren were in­fected based on the com­po­si­tion of six dif­fer­ent com­pounds that were de­tectable in a sam­ple of their breath,” said Chad Sch­aber, who pre­sented the re­sults of the study, pro­duced by a team of bi­ol­o­gists and bio­engi­neers from Wash­ing­ton Univer­sity in St Louis in the US. “We took breath sam­ples from 35 chil­dren and we cor­rectly de­ter­mined whether they had malaria — for 29 of them, which is an 83 per cent suc­cess rate.”

The re­searchers say that sim­ple tools like breath-test­ing for di­ag­nos­ing malaria are ur­gently needed — both to di­rect life-sav­ing treat­ment to in­fected in­di­vid­u­als and to con­duct sur­veil­lance as part of a new global push to elim­i­nate and erad­i­cate the dis­ease.

The sci­en­tists re­port that the 83 per cent ac­cu­racy rate of their breath test was lower than the 90 per cent or bet­ter ac­cu­racy of other tests like rapid di­ag­nos­tic tests or the more labour and tech­nol­ogy-in­ten­sive method of ex­am­in­ing blood sam­ples with a mi­cro­scope. These blood sam­ple tests are con­sid­ered the gold stan­dard for malaria di­ag­no­sis yet chal­leng­ing to im­ple­ment in ru­ral, re­source-strapped ar­eas.

Now, the re­searchers hope to im­prove the suc­cess rate of their breath tests with fur­ther re­fine­ments to the tech­nol­ogy. A sim­i­lar study had not been done in an area where malaria nat­u­rally oc­curs, they said, where in­fec­tions are far more in­tense, or with chil­dren, who are more vul­ner­a­ble to the dis­ease than adults.

To de­velop a breath test, the re­searchers re­cruited 35 chil­dren aged three to 15 who had ar­rived at a pae­di­atric care cen­tre in Li­longwe, Malawi, suf­fer­ing from fever and other symp­toms that could in­di­cate malaria. The chil­dren had al­ready been tested for malaria — 17 tested pos­i­tive and 18 neg­a­tive. The goal of the study was to de­ter­mine whether a breath test could be de­vel­oped that could also dis­tin­guish the in­fected from the un­in­fected.

The chil­dren pro­vided a breath sam­ple by blow­ing into a sim­ple bal­loon-like bag. The sam­ple was then pumped into a tube packed with an ab­sorbent ma­te­rial, sealed and sent to a lab at Wash­ing­ton Univer­sity in St Louis. Re­searchers also ob­tained the orig­i­nal blood sam­ples taken from the chil­dren at the clinic to fur­ther val­i­date the malaria di­ag­no­sis by ex­am­in­ing them un­der a mi­cro­scope. The re­searchers then de­ter­mined that malaria in­fec­tions ap­peared to al­ter the con­cen­tra­tions of six dif­fer­ent com­pounds known to nat­u­rally oc­cur in hu­man breath.

They used this mea­sure to clas­sify the breath sam­ples as ei­ther in­fected or not with malaria. They then com­pared the breath di­ag­no­sis with the mi­cro­scopic anal­y­sis of blood sam­ples and found the breath test cor­rectly de­ter­mined malaria sta­tus for 83 per cent of the chil­dren stud­ied.

“The malaria par­a­site has been out­wit­ting hu­man in­ter­ven­tions for thou­sands of years, which is why we need these in­no­va­tive col­lab­o­ra­tions be­tween bi­ol­o­gists and engineers to de­velop new tools that can give us the up­per hand,” said the pres­i­dent of the Amer­i­can So­ci­ety of Trop­i­cal Medicine and Hy­giene, Pa­tri­cia Walker.

Pic­ture: File

A child is tested for malaria. Cur­rently, blood sam­ple tests are con­sid­ered the gold stan­dard for malaria di­ag­no­sis.

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