Varicella in Tshuapa Province, Democratic Republic of Congo, 2009-2014.

OBJECTIVE: To describe varicella cases in Tshuapa Province of the Democratic Republic of the Congo identified during monkeypox surveillance. METHODS: Demographic, clinical and epidemiological data were collected from each suspected monkeypox case 2009-2014. Samples were tested by PCR for both Orthopoxviruses and varicella-zoster virus (VZV); a subset of VZV-positive samples was genotyped. We defined a varicella case as a rash illness with laboratory-confirmed VZV. RESULTS: There were 366 varicella cases were identified; 66% were ≤19 years old. Most patients had non-typical varicella rash with lesions reported as the same size and stage of evolution (86%), deep and profound (91%), on palms of hands and/or soles of feet (86%) and not itchy (49%). Many had non-typical signs and symptoms, such as lymphadenopathy (70%) and sensitivity to light (23%). A higher proportion of persons aged ≥20 years than persons aged ≤19 years had ≥50 lesions (79% vs. 65%, P = 0.007) and were bedridden (15% vs. 9%, P = 0.056). All VZV isolates genotyped from 79 varicella cases were clade 5. During the surveillance period, one possible VZV-related death occurred in a 7-year-old child. CONCLUSIONS: A large proportion of patients presented with non-typical varicella rash and clinical signs and symptoms, highlighting challenges identifying varicella in an area with endemic monkeypox. Continued surveillance and laboratory diagnosis will help in rapid identification and control of both monkeypox and varicella and improve our understanding of varicella epidemiology in Africa.

OBJECTIF: Décrire les cas de varicelle identifiés dans la province de Tshuapa en République Démocratique du Congo (RDC) au cours de la surveillance de la variole du singe (monkeypox). MÉTHODES: Des données démographiques, cliniques et épidémiologiques ont été recueillies pour chaque cas présumé de monkeypox entre 2009 et 2014. Les échantillons ont été testés par PCR pour les orthopoxvirus et le virus varicelle-zona (VZV); un sous-ensemble d'échantillons positifs au VZV a été génotypé. Nous avons défini un cas de varicelle comme une éruption cutanée avec confirmation du VZV en laboratoire. RÉSULTATS: 366 cas de varicelle ont été identifiés; 66% avaient 19 ans ou moins. La plupart des patients présentaient une éruption non typique de varicelle avec des lésions rapportées de la même taille et le même stade d'évolution (86%), profonds (91%), sur la paume des mains et/ou la plante des pieds (86%), sans démangeaisons (49%). Nombre d'entre eux présentaient des signes et des symptômes inhabituels, tels qu'une adénopathie lymphatique (70%) et une sensibilité à la lumière (23%). Une proportion plus élevée de personnes âgées de 20 ans et plus que de personnes âgées de 19 ans et moins avaient 50 lésions ou plus (79% contre 65%, p = 0,007) et étaient alitées (15% contre 9%; p = 0,056). Tous les isolats de VZV génotypés chez 79 cas de varicelle appartenaient au clade 5. Au cours de la période de surveillance, un décès possible lié au VZV est survenu chez un enfant de 7 ans. CONCLUSIONS: Une forte proportion de patients ont présenté une éruption de varicelle ainsi que des signes et symptômes cliniques non typiques, soulignant les difficultés rencontrées pour identifier la varicelle dans une zone endémique pour le monkeypox. Une surveillance continue et des diagnostics de laboratoire aideront à identifier et à contrôler rapidement le monkeypox et la varicelle et à améliorer notre compréhension sur l'épidémiologie de la varicelle en Afrique.

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

BACKGROUND: Human 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 FINDINGS: Data 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. CONCLUSIONS: Laboratory-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.