August 19, 2016
2 min read

Slow diagnosis, malaria limited response to 2015 Zambia plague outbreak

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Prompt diagnosis could have improved clinical outcomes during an outbreak of plague in the Eastern Province of Zambia, according to data recently published in MMWR.

Diagnoses during the 2015 outbreak — which sickened 21 people and killed three — were frequently complicated by malaria coinfection, Nyambe Sinyange, MSc, of the Zambia Field Epidemiology Training Program, and colleagues wrote, highlighting the need for swift molecular analysis and point-of-care diagnostics.

“Plague is probably underdetected in Zambia because of limited clinical recognition and laboratory capacity,” the investigators wrote. “Had the multiple subsequent cases not raised alarm, the initial cases in Nyimba would likely have been attributed to severe malaria, and plague might not have been recognized.”

After being alerted of possible plague on April 10, 2015, Sinyange and colleagues from the Zambia Ministry of Health conducted epidemiologic and laboratory investigations of 111 patients with recent fevers and suspected plague. Among the 82 patients who were hospitalized and available for physical examination or medical record review, the investigators identified 21 patients who met plague case definitions. All of these patients resided in the same village and were aged 3 to 18 years.

Sinyange and colleagues collected blood specimens from 11 patients and lymph node aspirates from three cases. Five of the blood samples and two of the aspirates tested positive for Yersinia pestis, representing six PCR-confirmed cases of plague.

Eighteen of the plague cases were evaluated for malaria infection by rapid diagnostic testing. Of these, 57% tested positive, including all six with molecularly confirmed plague.

Interviews with suspected cases revealed that all patients who met plague case definitions slept on reed mats placed on the floor. Public health conducted indoor spraying of more than 1,300 huts to reduce flea populations, and advised residents not to sleep on the floor.

Sinyange and colleagues suspected that the frequency of malaria diagnoses led local health care providers not to suspect Y. pestis infection, delaying appropriate antibiotic prescription and worsening clinical outcomes. To prevent similar responses during future outbreaks, they advocated efforts to increase awareness of plague in this region, and to improve the availability and use of appropriate diagnostics.

“PCR might improve detection, but will not influence clinical management given the long diagnostic delays,” they wrote. “A point-of-care diagnostic test could improve early diagnosis and guide appropriate therapy. Efforts to increase awareness of plague among frontline health workers can improve early case recognition and treatment.” – by Dave Muoio

Disclosure: The researchers report no relevant financial disclosures.