Which of the following is a potential outcome of untreated Bartonella bacilliformis infection?

Bartonella bacilliformis is a gram-negative bacterium primarily associated with two distinct clinical conditions: Oroya fever and verruga peruana. Oroya fever, also known as Carrion's disease, is characterized by acute hemolytic anemia, fever, and systemic symptoms. The bacterium is transmitted through the bite of infected sandflies, primarily in certain regions of Peru and Ecuador.

When Bartonella bacilliformis infection is left untreated, the development of Oroya fever represents a significant risk. The acute phase of this disease can lead to severe complications, including hemolytic anemia, which can result in a considerable drop in red blood cell counts and associated symptoms such as fatigue, weakness, and pallor. Additionally, if not managed appropriately, the infection can progress to the chronic phase, which may lead to further complications.

In contrast, while severe malnutrition, chronic pulmonary infections, and bacterial vaginosis are important medical concerns, they are not directly caused by Bartonella bacilliformis. Hence, among the listed outcomes, Oroya fever is the most relevant and critical consequence of untreated infection with this pathogen.