Seroepidemiology of Chikungunya Virus Among Febrile Patients in Eight Health Facilities in Central and Northern Mozambique, 2015-2016

Background: The burden and spread of chikungunya virus (CHIKV) are rapidly increasing worldwide, but the epidemiology in Mozambique is barely known. The aim of this study was to determine the seroepidemiology of CHIKV in central and northern Mozambique. Methods: A cross-sectional study was conducted between March 2015 and May 2016 in eight health facilities situated in central and northern Mozambique to recruit 392 patients with undifferentiated febrile illness from outpatient clinics. Serum samples from each participant were screened using commercially available enzyme-linked immunosorbent assay for detection of anti-CHIK IgM and IgG antibodies. A subset of study samples (n=37) was further tested by the plaque reduction neutralization assay (PRNT). Results: The median age of participants was 23 years (IQR: 7-34), and 45.7% were female. The frequency of participants with seropositivity for IgM and IgG anti-CHIKV antibodies was 1.5% (6/392) and 28.6% (112/392), respectively. Patients with seropositivity for IgM anti-CHIKV were significantly younger. Frequency of patients with seropositivity for IgG anti-CHIKV increased with age. Frequency of patients with seropositivity for IgM anti-CHIKV was higher in Tete province, but most patients with seropositivity for IgG anti-CHIKV infection were from Cabo Delgado and Sofala provinces. Conclusions: Our data demonstrate serological evidence of CHIKV in central and northern Mozambique, expanding the limited evidence of the virus in the country. We recommend that CHIKV should be considered in the differential diagnosis of febrile illness throughout the country.