Researchers inched closer to understanding the cause of a mysterious limb-weakening condition that has led to a rash of cases, mainly in kids, in the late summer and fall every other year since 2014, revealing new findings today based on new spinal fluid testing methods.
One of the new tools didn't find much direct evidence of enterovirus in the samples, but a new microchip testing method designed to detect antibodies resulting from enterovirus infection—an indirect but useful gauge—found evidence in several samples. A team from Columbia University and the Centers for Disease Control and Prevention (CDC) reported their findings today in mBio.
Acute flaccid myelitis (AFM) affects the spinal cord and is marked by onset of sudden weakness in one or more limbs. Spikes in cases have paralleled outbreaks of enterovirus D68 and enterovirus A71, which typically cause a mild respiratory infection. However, no direct cause has been identified.
CDC reports two new cases
In its latest update yesterday, the CDC said 13 AFM cases from 8 states have been confirmed so far this year, an increase of 2 from its report last month. Health officials are still investigating 76 suspected cases. Since the CDC began tracking cases in 2014 it has received reports of 574 illnesses.
Earlier this summer, the CDC issued a statement urging clinicians to be alert for AFM cases in the coming months.
New tests looked for direct and indirect evidence
For the study, researchers used a new tool called VirCapSeq-VERT to look for genetic evidence of the virus in the cerebrospinal fluid (CSF) of 13 children and 1 adult diagnosed with AFM in 2018. They also tested five CSF samples of people with other central nervous system diseases. The study was funded by the National Institutes of Allergy and Infectious Diseases (NIAID).
They found enterovirus genetic material (EV-A71) in the adult AFM patient and genetic material from another enterovirus called echovirus 25 in one of the non-AFM cases.
Then using a microchip assay called AFM-SeroChip-1 that they developed, they examined samples for enterovirus antibodies. They tested the same 14 AFM samples and looked at CSF samples from 10 adults with central nervous system conditions and 10 children with Kawasaki disease.
They found enterovirus antibodies in 11 of 14 AFM patients, and of those, 6 were positive for EV-D68, a strong indicator that enterovirus had been in the central nervous system. None of the samples from kids with Kawasaki disease had enterovirus antibodies.
In another part of the study, researchers tested CSF samples from the 14 AFM patients and 6 of the controls for tickborne diseases using a new test developed by the Columbia University's Center for Infection and Immunity (CII). All were negative
Though the investigation into other AFM causes continues, the team concluded that the study provides further evidence that enterovirus infection may play a role.
Nischay Mishra, PhD, a professor of epidemiology at CII and the research team's co-lead, said in a Columbia University press release that doctors and scientists have long suspected that enteroviruses, which are relatives of polio virus, are the cause of AFM, but there hasn't been any direct evidence to prove it.
"Further work is needed with larger, prospective studies; nonetheless, these results take us one step closer to understanding the cause of AFM, and one step closer to developing diagnostic tools and treatments," he said.
Aug 13 mBio study
Aug 13 NIAID press release
Aug 13 Columbia University press release
Aug 12 CDC AFM update
Jul 10 CIDRAP News story "CDC wants clinicians' help to solve acute flaccid myelitis riddle"
Watafiti wamekaribia kuelewa sababu ya hali ya udhaifu wa viungo ya mwili ambayo imesababisha mlipuko wa kesi, hasa kwa watoto, mwishoni mwa majira ya joto na kuanguka kila mwaka tangu 2014, ikifunua matokeo mapya leo kulingana na mbinu mpya za kupima umajimaji wa uti wa mgongo. Moja ya zana mpya hazikupata ushahidi mwingi wa moja kwa moja wa enterovirus katika sampuli, lakini njia mpya ya kupima microchip iliyoundwa kugundua kingamwili zinazotokana na maambukizo ya enterovirus - kipimo kisicho cha moja kwa moja lakini muhimu - ilipata ushahidi katika sampuli kadhaa. Timu ya wataalamu kutoka Chuo Kikuu cha Columbia na Kituo cha Kudhibiti na Kuzuia Magonjwa (CDC) walichapisha matokeo ya utafiti huo katika jarida la The New York Times. Acute flaccid myelitis (AFM) ni ugonjwa wa mgongo unaoathiri uti wa mgongo na unaonyesha udhaifu wa ghafla katika sehemu moja au zaidi ya mwili. Mlipuko wa maambukizi ya virusi vya enterovirus D68 na A71 unaathiri sana mfumo wa kupumua. Hata hivyo, hakuna kisababishi cha moja kwa moja ambacho kimetambuliwa. CDC imeripoti visa viwili vipya vya ugonjwa wa AFM, na ripoti ya hivi karibuni ya CDC imesema kuwa kesi 13 za AFM kutoka majimbo 8 zimethibitishwa hadi sasa mwaka huu, ongezeko la 2 kutoka ripoti yake ya mwezi uliopita. Wanasayansi wa afya bado wanafanya uchunguzi juu ya kesi 76 zinazodhaniwa kuwa za ugonjwa huo. Tangu CDC kuanza kufuatilia kesi za ugonjwa huo mnamo 2014, imepokea ripoti za magonjwa 574. Mwanzoni mwa mwaka huu, CDC ilitoa taarifa ya kuwahimiza madaktari kuwa makini kwa kesi za AFM katika miezi ijayo. Kwa ajili ya utafiti huo, watafiti walitumia chombo kipya kinachoitwa VirCapSeq-VERT kutafuta ushahidi wa maumbile ya virusi katika umajimaji wa cerebrospinal (CSF) wa watoto 13 na mtu mzima mmoja aliyegunduliwa na AFM mnamo 2018. Pia walichunguza sampuli tano za CSF za watu wenye magonjwa mengine ya mfumo wa neva wa kati. Utafiti huo ulifadhiliwa na Taasisi ya Kitaifa ya Madhara na Madhara (NIAID). Ugonjwa huo ulisababishwa na virusi vya enterovirus (EV71) katika mgonjwa wa AFM na virusi vingine vya EVD25 katika mgonjwa wa AFM. Kwa kutumia kipimo cha microchip kinachoitwa AFM-SeroChip-1, watafiti walichunguza sampuli za virusi vya enterovirus. Kwa mfano, uchunguzi wa AFM ulionyesha kwamba watu wazima 10 wenye ugonjwa wa mfumo wa neva na watoto 10 wenye ugonjwa wa Kawasaki walikuwa na ugonjwa huo. Katika wagonjwa 11 kati ya 14 waliopata ugonjwa wa AFM, wagonjwa 6 walipata antibodi za enterovirus, na 6 kati ya wagonjwa hao walikuwa na antibodi za EV-D68, dalili ya kwamba enterovirus ilikuwa katika mfumo wa neva wa kati. Hakuna sampuli yoyote kutoka kwa watoto wenye ugonjwa wa Kawasaki iliyokuwa na kingamwili za enterovirus. Katika sehemu nyingine ya utafiti, watafiti walichunguza sampuli za CSF kutoka kwa wagonjwa 14 wa AFM na 6 ya udhibiti kwa magonjwa yanayopitishwa na vimelea kwa kutumia mtihani mpya ulioundwa na Kituo cha Maambukizi na Kinga cha Chuo Kikuu cha Columbia. Ingawa uchunguzi wa sababu nyingine za AFM unaendelea, timu hiyo ilihitimisha kwamba utafiti huo hutoa ushahidi zaidi kwamba maambukizi ya enterovirus yanaweza kuwa na jukumu. Nishay Mishra, profesa wa epidemiolojia katika Chuo Kikuu cha Columbia, alisema katika taarifa ya gazeti la Columbia University kwamba madaktari na wanasayansi wamekuwa wakishuku kwa muda mrefu kwamba virusi vya enterovirus, ambavyo ni jamaa za virusi vya polio, ni kisababishi cha ugonjwa wa AFM, lakini hakuna ushahidi wa moja kwa moja wa kuthibitisha. "Utafiti zaidi unahitajika na masomo makubwa zaidi ya baadaye, hata hivyo, matokeo haya yanatuchukua hatua moja karibu na kuelewa sababu ya AFM, na hatua moja karibu na kuendeleza zana za utambuzi na matibabu. """ "Kama ilivyoelezwa katika taarifa ya NIAID ya Agosti 13, Chuo Kikuu cha Columbia cha Agosti 13, Uhakiki wa AFM wa CDC ya Julai 10, ""CIDRAP inataka msaada wa wataalamu wa kliniki kutatua fumbo la myelitis kali."""