Concurrent malaria and arbovirus infections in Kedougou, southeastern Senegal

Abstract

Background: Malaria is one of the leading causes of acute febrile illness (AFI) in Africa. With the advent of malaria rapid diagnostic tests, misdiagnosis and co-morbidity with other diseases has been highlighted by an increasing number of studies. Although arboviral infections and malaria are both vector-borne diseases and often have an overlapping geographic distribution in sub-Saharan Africa, information about their incidence rates and concurrent infections is scarce.

Methods: From July 2009 to March 2013 patients from seven healthcare facilities of the Kedougou region presenting with AFI were enrolled and tested for malaria and arboviral infections, i.e., yellow fever (YFV), West Nile (WNV), dengue (DENV), chikungunya (CHIKV), Crimean Congo haemorrhagic fever (CCHFV), Zika (ZIKV), and Rift Valley fever viruses (RVFV). Malaria parasite infections were investigated using thick blood smear (TBS) and rapid diagnostics tests (RDT) while arbovirus infections were tested by IgM antibody detection (ELISA) and RT-PCR assays. Data analysis of single or concurrent malaria and arbovirus was performed using R software.

Results: A total of 13,845 patients, including 7387 with malaria and 41 with acute arbovirus infections (12 YFV, nine ZIKV, 16 CHIKV, three DENV, and one RVFV) were enrolled. Among the arbovirus-infected patients, 48.7% (20/41) were co-infected with malaria parasites at the following frequencies: CHIKV 18.7% (3/16), YFV 58.3% (7/12), ZIKV 88.9% (8/9), DENV 33.3% (1/3), and RVF 100% (1/1). Fever ≥40 °C was the only sign or symptom significantly associated with dual malaria parasite/arbovirus infection.

Conclusions: Concurrent malaria parasite and arbovirus infections were detected in the Kedougou region from 2009 to 2013 and need to be further documented, including among asymptomatic individuals, to assess its epidemiological and clinical impact.

Fig. 1

Geographical distribution of arboviruses and malaria/arboviral co-infections in Kedougou. Green dots represent confirmed ZIKV infections. Blue and black triangles indicate RVF and CHIKV confirmed cases, respectively. Red dots represent YFV cases. Black stars indicate DENV cases. Small yellow dots represent co-infected patients

Fig. 2

Prevalence of malaria and arboviral infections from 2009 to 2013 in Kedougou. The monthly evolution of malaria infections frequency and prevalence as well as the frequency of arboviral infections from July 2009 to March 2013 in Kedougou. The solid black line with white dots represents the frequency of blood samples positive for malaria parasites; measures are given by the left-hand y-axis. The dotted red line with red asterisks corresponds to the ratio ‘number of samples positive to malaria’ divided by ‘total number of samples’. Vertical bars represent the frequencies of blood samples positive for arboviruses: red bars for YFV, blue bars for ZIKV, green bars for CHIKV, yellow bars for DENV-2, and dark grey bar for RVFV. Measures are indicated by the right-hand y-axis. Vertical dashed lines separate the plot by year and grey-shaded zones correspond to rainy seasons