Multiple Crimean-Congo hemorrhagic fever virus strains are associated with disease outbreaks in Sudan, 2008-2009

Abstract

Background: Crimean-Congo hemorrhagic fever (CCHF) activity has recently been detected in the Kordufan region of Sudan. Since 2008, several sporadic cases and nosocomial outbreaks associated with high case-fatality have been reported in villages and rural hospitals in the region.

Principal findings: In the present study, we describe a cluster of cases occurring in June 2009 in Dunkop village, Abyei District, South Kordufan, Sudan. Seven CCHF cases were involved in the outbreak; however, clinical specimens could be collected from only two patients, both of whom were confirmed as acute CCHF cases using CCHF-specific reverse transcriptase polymerase chain reaction (RT-PCR). Phylogenetic analysis of the complete S, M, and L segment sequences places the Abyei strain of CCHF virus in Group III, a virus group containing strains from various countries across Africa, including Sudan, South Africa, Mauritania, and Nigeria. The Abyei strain detected in 2009 is genetically distinct from the recently described 2008 Sudanese CCHF virus strains (Al-fulah 3 and 4), and the Abyei strain S and L segments closely match those of CCHF virus strain ArD39554 from Mauritania.

Conclusions: The present investigation illustrates that multiple CCHF virus lineages are circulating in the Kordufan region of Sudan and are associated with recent outbreaks of the disease occurring during 2008-2009.

Figure 1. Map of Sudan showing the location of Abyei and Al-fulah towns in Kordufan region, Sudan.

Figure 2. Phylogenetic relationship of Crimean-Congo hemorrhagic fever virus full length S segments.

Phylogenetic relationship of the S segment sequence of the CCHF virus Abyei and Al-fulah strains relative to previously published sequences was carried out using GARLI (v0.96b8) , with default settings to generate a maximum likelihood tree with bootstrap support values from 1000 replicates. The 50% majority rule tree is depicted. Each strain is listed by its location, strain name, and year of isolation when available with the Sudanese strains bolded.

Figure 3. Phylogenetic relationship of Crimean-Congo hemorrhagic fever virus full length M segments.

Phylogenetic relationship of the M segment sequence of the CCHF virus Abyei and Al-fulah strains relative to previously published sequences was carried out using GARLI (v0.96b8) , with default settings to generate a maximum likelihood tree with bootstrap support values from 1000 replicates. The 50% majority rule tree is depicted. Each strain is listed by its location, strain name, and year of isolation when available with the Sudanese strains bolded.

Figure 4. Phylogenetic relationship of Crimean-Congo hemorrhagic fever virus full length L segments.

Phylogenetic relationship of the L segment sequence of the CCHF virus Abyei and Al-fulah strains relative to previously published sequences was carried out using GARLI (v0.96b8) , with default settings to generate a maximum likelihood tree with bootstrap support values from 1000 replicates. The 50% majority rule tree is depicted. Each strain is listed by its location, strain name, and year of isolation when available with the Sudanese strains bolded.