Bartonella bacilliformis is a unique bacterium known for causing a distinct human disease. This microorganism holds a notable place in medical history due to its discovery. Its study offers insights into how certain bacteria interact with human physiology to produce characteristic disease patterns.
The Bacterium Behind the Disease
Bartonella bacilliformis is characterized as a gram-negative, rod-shaped bacterium. This microorganism exhibits motility, possessing flagella that aid in its movement. Peruvian microbiologist Alberto Barton first identified this bacterium in 1905, observing what he described as endoglobular structures within red blood cells.
A unique aspect of Bartonella bacilliformis is its ability to infect human red blood cells and endothelial cells. This dual cellular tropism is central to the varied manifestations of the illness it causes.
Carrión’s Disease: Symptoms and Progression
Bartonella bacilliformis is the causative agent of Carrión’s Disease, an illness that unfolds in two distinct phases: an acute, severe stage known as Oroya Fever, and a later, chronic phase called Verruga Peruana. The acute phase, Oroya Fever, typically manifests around 21 to 60 days after exposure. This stage is marked by a sudden onset of high fever, severe anemia due to the destruction of red blood cells, and intense muscle pain.
Oroya Fever can lead to complications such as abdominal pain and, in some instances, organ damage. If left untreated, this acute phase can have a high case fatality rate, ranging from 40% to 85%, often complicated by secondary infections. Peripheral blood smears during this phase reveal numerous coccobacilli adhering to red blood cells.
Following the acute phase, or sometimes arising independently, is the chronic stage known as Verruga Peruana. This phase is characterized by the development of skin lesions, referred to as verrugas, which are reddish-purple vascular growths. These lesions can vary considerably in size and appearance, ranging from small nodules to larger, disfiguring tumors. While less severe than Oroya Fever, Verruga Peruana can persist for months or years, causing significant cosmetic concerns.
How it Spreads and Where it’s Found
The transmission of Bartonella bacilliformis occurs through the bite of infected sandflies, specifically those belonging to the Lutzomyia genus. These sandflies act as vectors, carrying the bacterium from an infected individual to a susceptible person during a blood meal, inoculating the bacteria into the capillaries.
This infection is geographically restricted, primarily found in specific high-altitude Andean valleys. Endemic regions for Bartonella bacilliformis include areas of Peru, Ecuador, and Colombia. The presence of the disease in these locations is directly linked to the habitat and distribution of the Lutzomyia sandfly vector.
Identifying and Treating the Infection
Several diagnostic methods are employed for accurate identification of Bartonella bacilliformis infection. During the acute phase of Oroya Fever, microscopic examination of peripheral blood smears can reveal the presence of the bacteria directly within red blood cells. Blood cultures are another common diagnostic tool, allowing for the isolation and identification of the bacterium in a laboratory setting.
Molecular tests, such as Polymerase Chain Reaction (PCR), are also utilized to detect the bacterial DNA, offering a sensitive method for diagnosis. Timely diagnosis is important, especially during the acute, life-threatening phase, to initiate appropriate treatment. Once diagnosed, treatment for Bartonella bacilliformis infection involves the administration of specific antibiotics.
The choice of antibiotic and the treatment regimen may vary depending on the phase and severity of the disease. Different medications or combinations might be used to target the acute anemic phase versus the chronic skin lesion phase. Common classes of antibiotics effective against Bartonella infections include tetracyclines, aminoglycosides, and macrolides.
Protecting Against Bartonella bacilliformis
Protecting against Bartonella bacilliformis infection focuses on preventing sandfly bites in endemic areas. Using insect repellents that contain DEET on exposed skin can help deter sandflies. Wearing long-sleeved clothing and long pants, especially during outdoor activities, provides a physical barrier against bites.
Sleeping under insecticide-treated bed nets can offer protection during nighttime hours, as sandflies are often most active from dusk to dawn. Avoiding outdoor activities during these peak biting hours, when sandfly populations are most prevalent, further reduces the risk of exposure. These personal protective measures are practical steps to minimize contact with the insect vector.