A Multidisciplinary Investigation of the First Chikungunya Virus Outbreak in Matadi in the Democratic Republic of the Congo

Abstract

Early March 2019, health authorities of Matadi in the Democratic Republic of the Congo alerted a sudden increase in acute fever/arthralgia cases, prompting an outbreak investigation. We collected surveillance data, clinical data, and laboratory specimens from clinical suspects (for CHIKV-PCR/ELISA, malaria RDT), semi-structured interviews with patients/caregivers about perceptions and health seeking behavior, and mosquito sampling (adult/larvae) for CHIKV-PCR and estimation of infestation levels. The investigations confirmed a large CHIKV outbreak that lasted February–June 2019. The total caseload remained unknown due to a lack of systematic surveillance, but one of the two health zones of Matadi notified 2686 suspects. Of the clinical suspects we investigated (n = 220), 83.2% were CHIKV-PCR or IgM positive (acute infection). One patient had an isolated IgG-positive result (while PCR/IgM negative), suggestive of past infection. In total, 15% had acute CHIKV and malaria. Most adult mosquitoes and larvae (>95%) were Aedes albopictus. High infestation levels were noted. CHIKV was detected in 6/11 adult mosquito pools, and in 2/15 of the larvae pools. This latter and the fact that 2/6 of the CHIKV-positive adult pools contained only males suggests transovarial transmission. Interviews revealed that healthcare seeking shifted quickly toward the informal sector and self-medication. Caregivers reported difficulties to differentiate CHIKV, malaria, and other infectious diseases resulting in polypharmacy and high out-of-pocket expenditure. We confirmed a first major CHIKV outbreak in Matadi, with main vector Aedes albopictus. The health sector was ill-prepared for the information, surveillance, and treatment needs for such an explosive outbreak in a CHIKV-naïve population. Better surveillance systems (national level/sentinel sites) and point-of-care diagnostics for arboviruses are needed.

Behavior of Adult Aedes aegypti and Aedes albopictus in Kinshasa, DRC, and the Implications for Control

“…This is in contrast to the chikungunya outbreak in Kongo Central (Matadi), during which the Ae. albopictus density was very high and the species was incriminated as the main vector driving the outbreak [9].…”

“…Yellow fever and chikungunya outbreaks-and a few dengue cases-have been reported in recent years in the Democratic Republic of the Congo (DRC) [3][4][5][6][7][8]. Yellow fever outbreaks have occurred recently in Muanda (2016, Kongo Central Province) and Kenge (2019, Kwango Province), and a chikungunya outbreak occurred in Matadi (2019, Kongo Central Province) [9]. Although Aedes aegypti is the primary vector for the chikungunya virus, the outbreak in Matadi was driven by Aedes albopictus, an invasive species that might change the epidemiology of this and other arboviruses in DRC [9][10][11].…”

First observation of Aedes albopictus (Skuse, 1894) (Diptera: Culicidae) in Tshuapa province (Boende), Democratic Republic of the Congo

“…albopictus in Africa was reported four decades ago (Nigeria) (Kraemer et al 2019), its presence in the Democratic Republic of the Congo (DRC) was only described for the first time in 2016 (Bobanga et al 2018). Three years later, we linked a major CHIK outbreak to its recent colonization in that area (the provinces of Kinshasa and Kongo Central during 2019-2020) (Selhorst et al 2020;Wat'senga Tezzo et al 2021;Weggheleire et al 2021). Indeed, Ae.…”

Lower Limb Paralysis Associated with Chikungunya in Kinshasa, the Democratic Republic of the Congo: Survey Report

“… Diagram of biological investigations of AFP cases (designed following a non-standardized investigation approach, except for the detection of poliovirus) [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 ]. …”