Rickettsia conorii infection with fatal complication

Abstract

Rickettsial diseases (RD) are a group of endotheliotropic infectious diseases caused by different species of genera Rickettsia. RD are not an uncommon disease and may be misdiagnosed during the evaluation of acute febrile illness due to a lack of reliable serological marker and diagnostic culture methods. Clinical manifestation of RD varies from febrile illness with rashes and myalgia to fatal complications such as shock and respiratory failure. We describe a case of a young male who presented initially with acute febrile illness, followed by shock and respiratory failure, and unfortunately succumbed to death. A post-mortem examination showed histological features of endotheliotropic infection, such as interstitial / perivascular edema in various organs and noncardiogenic pulmonary edema (suggesting increased vascular permeability) and evidence of vasculitis in the lung, liver, and intestines. Molecular studies performed from lung, liver, and kidney tissue confirm the diagnosis of spotted fever group rickettsial disease due to Rickettsia conorii.

Keywords: Autopsy; Fatal Outcome; Fever; Rickettsia Infections; Vasculitis.

Figure 1. A – Gross view of the cut surface of the lung showing focal brownish discoloration. Microphotographs of the lung; B – low power examination showing marked vascular congestion with pulmonary edema (H&E, 20X); C – pre-acinar pulmonary artery showing marked congestion and evidence of endothelitis in the form of endothelial cell swelling, extravasation of RBCs, and deposition of fibrin material in their wall (H&E, 200x); D – Fibrin in the arterial wall is better highlighted on Martius Scarlet blue stain (MSB, 200X).

Figure 2. A – Photomicrographs of the myocardium showing perivascular and interstitial edema (H&E, 100X); B – and mild mixed Inflammatory cell infiltrates (H&E, 200x).

Figure 3. A – Photomicrographs of the liver showing maintained lobular architecture with marked sinusoidal dilatation and congestion (H&E, 20X); B – Portal tract showing fibrin thrombus in the portal vein with near-complete occlusion of their lumina (H&E, 200x); C – Hepatic lobules show multifocal hepatocyte necrosis in Zone 1 (H&E, 200X); D – and Zone 2 region (H&E,400X).

Figure 4. Photomicrographs of: A – the spleen showing micro abscess (H&E, 200x); B – the kidney showing foci of interstitial nephritis in the medulla (H&E, 200x); C – small intestine showing marked vascular congestion and edema in mucosa and submucosa (H&E,100x); D – arterioles of intestinal submucosa showing marked congestion with fibrin deposition along the wall indicating vascular injury (H&E, 200x).

Figure 5. A – Gel picture depicting positive 434 bp PCR amplicon of 17kDa gene; B – Real-time PCR graph for OmpA gene of Rickettsia.