A Technique that Facilitates the Epidemiological Study of Carrion’s Disease

 Using multi-locus sequencing, it is possible to type Bartonella bacilliformis, the bacterium that causes Carrion’s disease, directly from blood of patients during the febrile phase, according to a study led by Dr. Joaquim Ruiz, researcher at ISGlobal, in collaboration with researchers at the Universidad Peruana de Ciencias Aplicadas. The results, published in Plos Neglected Tropical Diseases, indicate that it represents a promising tool to perform epidemiological studies and understand the bacterium’s phylogenetic scenario.

Carrion’s disease is an endemic infection in low-income areas of the Andean regions of Peru, Ecuador and Colombia, where an estimated 1.7 million people are at risk of contracting the disease. It is characterized by a first febrile phase named Oroya fever that mainly affects children and has high levels of mortality, particularly in the absence or delay of treatment. It is followed by a second phase called “Verruga Peruana” (Peruvian wart) resulting in a series of cutaneous lesions. The causal agent, B. bacilliformis, is a fastidious slow-growing bacterium which is difficult to isolate and culture, and therefore very little is known on the phylogenetic relationship between clinical isolates during an outbreak

The authors of the study decided to test the multi-locus sequencing technique (i.e. that amplifies and sequences several house-keeping genes of the bacterium) directly from the blood of patients during an Oroya fever outbreak in northern Peru. From the 9 blood samples analyzed, a total of four different sequencing types (ST) were identified, of which ST1 was the most frequent and two new ST (ST9 and ST10) that were closely related to ST1 were described.    

The study shows that it is possible to perform multi-locus sequencing directly from blood of patients in order to study the phylogenetic evolution of B. bacilliformis. The authors conclude that these studies need to be extended to more patients and other areas in order to provide a better picture of the situation and associate specific STs of the bacterium with clinical symptoms and the severity or phase of the disease.   

Reference:

Pons MJ, Silva-Caso W, Del Valle-Mendoza J, Ruiz J. Multi-Locus Sequence Typing of Bartonella bacilliformis DNA Performed Directly from Blood of Patients with Oroya's Fever During a Peruvian Outbreak. PLoS Negl Trop Dis. 2016 Jan 29;10(1):e0004391.