By Beatrice Cooney, Jasmine Coulombe & Leah Hiscott

Introduction

Bartonella quintana infection, colloquially known as trench fever, is a vector-borne disease that is primarily transmitted by the human body louse. It was first described during World War I when it infected over 1 million soldiers in Europe. Upon its emergence, military medical officials were baffled by the symptoms arising in the soldiers – the characteristics of the condition were unlike anything they had seen before. Patients were suffering from severe headaches and dizziness; muscle pain and stiffness in the legs (particularly the shins); as well as relapsing fever. Doctors debated whether this was the emergence of a new disease or if it was an older one making a comeback, until it was officially recognized as a novel condition in the summer of 1916.

Trench fever is rarely fatal but it is extremely debilitating, which posed a significant efficiency problem for the armies affected by it. Infection is associated with a variety of clinical conditions such as chronic bacteremia, the presence of bacteria in the bloodstream; endocarditis, an infection of the lining of the heart; lymphadenopathy, a disease of the lymph nodes; and bacillary angiomatosis, which causes lesions on the surfaces of many different organs. Trench fever is thus a gateway to much more serious health concerns.

B. quintana has not since caused an epidemic to the scale of WWI, but it is not eradicated either. Since the 1990’s, B. quintana has reemerged as “urban trench fever” among impoverished and homeless populations that are subjected to unsanitary and crowded conditions that lend itself to the parasites that could transmit the infection. 

B. quintana is a facultative, intracellular, Gram-negative rod with the human body louse, Pediculus humanus corporis, typically acting as its vector. The lice primarily infest clothing and the unhygienic and crowded conditions of the trenches during the war aided in its proliferation. B. quintana multiples in the intestines of the louse and is passed on to humans via the spreading of its feces on damaged skin. The lice also bite their victims, injecting an anesthetic that prompts an allergic reaction that leads to scratching, which only further facilitates B. quintana’s transmission.

Fig.1: Dorsal view of a female body louse, Pediculus humanus var. corporis. Some of the external morphologic features displayed by members of the genus Pediculus include an elongated abdominal region without any processes, and three pairs of legs, which are all equal in length and width. Source: CDC Public Health Image Library.

Fig 2: Example of lesions caused by scratching, allowing a route of transmission for the bacteria to humans through the louse feces in the abrasions. Source: Foucault, C., Brouqui, P., & Raoult, D. (2006). Bartonella quintana Characteristics and Clinical Management. Emerging Infectious Diseases, 12(2), 217-223. https://dx.doi.org/10.3201/eid1202.050874.

Source & cause of the outbreak

With its first appearance during WWI, trench fever was thought to be some type of infection and was typically compared to malaria due to the omnipresence of fever, a cardinal sign of infection. Thanks to careful observation of cases coming into the infirmary, it was correctly postulated that the condition might be carried by a parasite found in the trenches. Physicians named voles or mice as the vector, shedding light on the horrendous conditions in the trenches until body louse was dubbed the culprit of the disease. This was supported by the fact that the disease was especially prevalent in the winter, when flies and mosquitos were absent from the trenches. By the end of 1916, most had agreed that louse transmitted B. quintana, as this was the most common parasite found in the trenches. However, the definitive experimental proof was still lacking. By 1917, two years after its first appearance, both the British and the Americans set up committees dedicated to tracking down the transmissive agent of the disease. The Americans concluded that it was the bite of the louse that transmitted the disease, making it the vector. However, it was the British that demonstrated that it was the transmission of louse excreta into the damaged skin that conveyed the causative agent. It is now known that mature louse can live for up to 30 days.

The infection itself is sudden, persistent and unpleasant. At the time of infection, it is common to experience a fever lasting between 2 to 6 days, accompanied by headaches, back and leg pain, and a fleeting rash. Recovery can take up to two months and relapse, even 15 years later, is common; about five percent of cases become chronic. The bacteria carried by the lice infect the blood, bone marrow, and skin of its patients and can be detected even after treatment and recovery. Today, the disease is treated with antibiotics, typically chlortetracycline, but others options are available as well. 

Ending the outbreak

Despite the slow response to the outbreak containment, treatment ended up being extremely successful. Even before the real causative agent was discovered, trench fever was recognized as a serious issue likely arising from the abhorrent conditions endured by soldiers. After identification, the “Department of Government Circular Memorandum No. 16” was outlined as a reference for better health. Although many of the suggestions were unrealistic for those on the front lines, serious effort was made nonetheless. Regular showers every other week were demanded, and mobile delousing stations moved around base camps in an effort to eradicate the source. The most effective effort, however, came at the end of the war. For fear that the disease might spread to Britain’s general population, strict sanitation regimes were implemented for all soldiers returning home. Thankfully, this was successful and the British population was able to avoid the disease many of their soldiers were due to suffer from for the rest of their days.

Aftermath

Research continued into the root cause of trench fever, despite the fact it was not prevalent in the general population after the outbreak during the war, it did reappear as a small epidemic in the German troops on the Eastern front during World War II. Furthermore, it still appears today in homeless and immunocompromised populations. As B. quintana was not cultured during the outbreak in the first World War, work slowly continued to try and isolate the bacterium causing trench fever. While the disease was putatively linked to louse infestation, the bacterium itself was not isolated until 1961 by J William Vinson of Harvard University and Henry Fuller of Walter Reed Army Institute of Research. As this occurred after WWII, the defensive strategies for the second war focused on preventing louse infestation by providing better hygiene for soldiers, as well as soldiers tended to be more spread out and mobile. After the second World War, antibiotic susceptibility testing and genome sequencing occurred and therefore lead to a better understanding of the transmission of the disease and its treatment.

Conclusion

The outbreak of trench fever posed a significant hurdle for armies during WWI, leading to a loss in soldiers and an increased demand for medical care. The slow response to determine the cause of the disease, due to the lack of knowledge at the time regarding the classification of bacteria, was detrimental to the war effort. However, as the war ended, the disease was well contained and extreme preventative measures halted the spread to the general public. While trench fever is still seen today in niche populations, general understanding, prevention, and treatment of the disease has greatly increased, alleviating the threat of future outbreaks.

References

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Atenstaedt, R. L. (2006). Trench fever: the British medical response in the Great War. Journal of the Royal Society of Medicine, 99(11), 564-568. doi:10.1258/jrsm.99.11.564

European Centre for Disease Prevention and Control. (n.d.). Facts about Bartonella quintana      infection. Retrieved November 15, 2019, from European Centre for Disease Prevention and Control website: https://www.ecdc.europa.eu/en/bartonella-quintana-infection-trench-fever/facts

Foucault, C., Brouqui, P., & Raoult, D. (2006). Bartonella quintana Characteristics and Clinical Management. Emerging Infectious Diseases, 12(2), 217-223. https://dx.doi.org/10.3201/eid1202.050874.

Holmes, F. (2006). Trench Fever in the First World War. Retrieved from University of Kansas Medical Center website: http://www.kumc.edu/wwi/index-of-essays/trench-fever.html

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Ruiz, J. (2018). Bartonella quintana, past, present, and future of the scourge of World War I. Apmis, 126(11), 831–837. doi: 10.1111/apm.12895