Enhancing case definitions for surveillance of human monkeypox in the Democratic Republic of Congo

Abstract

BackgroundHuman monkeypox (MPX) occurs at appreciable rates in the Democratic Republic of Congo (DRC). Infection with varicella zoster virus (VZV) has a similar presentation to that of MPX, and in areas where MPX is endemic these two illnesses are commonly mistaken. This study evaluated the diagnostic utility of two surveillance case definitions for MPX and specific clinical characteristics associated with laboratory-confirmed MPX cases.Methodology/Principal findingsData from a cohort of suspect MPX cases (identified by surveillance over the course of a 42 month period during 2009–2014) from DRC were used; real-time PCR diagnostic test results were used to establish MPX and VZV diagnoses. A total of 333 laboratory-confirmed MPX cases, 383 laboratory-confirmed VZV cases, and 36 cases that were determined to not be either MPX or VZV were included in the analyses. Significant (p<0.05) differences between laboratory-confirmed MPX and VZV cases were noted for several signs/symptoms including key rash characteristics. Both surveillance case definitions had high sensitivity and low specificities for individuals that had suspected MPX virus infections. Using 12 signs/symptoms with high sensitivity and/or specificity values, a receiver operator characteristic analysis showed that models for MPX cases that had the presence of ‘fever before rash’ plus at least 7 or 8 of the 12 signs/symptoms demonstrated a more balanced performance between sensitivity and specificity.ConclusionsLaboratory-confirmed MPX and VZV cases presented with many of the same signs and symptoms, and the analysis here emphasized the utility of including 12 specific signs/symptoms when investigating MPX cases. In order to document and detect endemic human MPX cases, a surveillance case definition with more specificity is needed for accurate case detection. In the absence of a more specific case definition, continued emphasis on confirmatory laboratory-based diagnostics is warranted.

Human Monkeypox

“…A clinical sign differentiating monkeypox from smallpox and chickenpox is the presence of enlarged lymph nodes, particularly submental, submandibular, cervical, and inguinal nodes. 71…”

Monkeypox — Enhancing public health preparedness for an emerging lethal human zoonotic epidemic threat in the wake of the smallpox post-eradication era

“…As with smallpox, the prodromal period of monkeypox infection starts with fever, headache, back pain, myalgia and asthenia followed by eruption of skin and mucosal lesions starting with the face (within 1-3 days after development of fever). The lesions evolve from maculopapular to fluid filled vesicles to pustules followed by crusting within 10 days and complete disappearance of the crusts within 3 weeks (Nigeria CDC, 2018;Osadebe et al, 2017). Whilst immunosuppression may be a risk factor for severe disease, the effects of HIV co-infection remain to be determined.…”

Varicella in Tshuapa Province, Democratic Republic of Congo, 2009–2014

“…Few data are available on varicella epidemiology in Africa and most are limited to specific sub-populations, such as HIV-positive populations or refugees [8][9][10][11][12][13][14][15][16]. Varicella epidemiology in temperate climates usually differs from that in tropical climates; in temperate climates most children are infected by 10 years of age while children in tropical climates acquire varicella at older ages and a higher proportion of young adults remain susceptible [17][18][19][20].…”

“…In monkeypox‐endemic areas, outbreaks may be associated with co‐occurrence of varicella cases . A monkeypox surveillance project in Tshuapa Province in DRC identified 383 (37%) cases with only VZV infection among 1025 suspected monkeypox cases 2009–2014 , providing an opportunity to better understand the epidemiology of varicella in DRC.…”