African tick bite fever in returning Swedish travellers. Report of two cases and aspects of diagnostics

Figures & data

Figure 1. R. africae infected Vero-cells showing rickettsial organisms stained red with Gimenez (a) and green with immunofluorescent anti-rickettsial goat anti-rabbit immunoglobulin (b). Original magnification × 1000.

Table 1. Summary of PCR results and immunofluorescent titres of acute and convalescent sera from Patients 1 and 2 using R. helvetica and R. africae as antigen, respectively.

Antigen	IFA titres/PCR Patient 1			IFA titres /PCR Patient 2
	Serum 1 G M		PCR swab	Serum 1 G M		Weeks s1-s2	Serum 2 G M		PCR biopsy
R. helvetica	<1/64	1/128	-	<1/64	<1/64	4	1/64	1/256	-
R. africae	1/64	1/128	Pos	1/64	1/64		1/128	1/256	Pos

Figure 2. Western blot analysis of IgG antibodies against R. africae whole cell antigen. Lane P2 demonstrates the lipopolysaccharide ladders (LPS) and specific reactions against spotted fever rickettsia proteins in the 110–150 kDa region for convalescent serum for Patient 2.