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Rare Disease Day is February 28. Rare diseases have specific legal definitions that are tied to support from various governmental programs around the world. Patient registries are a key part of the call for funding for rare disease research and are needed to advance the research on tick-borne diseases like Lyme borreliosis, bartonellosis, and babesiosis.
What is a rare disease?
In the US, a rare disease is defined as a condition that affects fewer than 200,000 people. Because there are so many rare diseases, they affect about 1 in 10 people.
Although a large portion of rare disease advocacy is focused on genetic conditions, certain infectious diseases also fall into this category.
Bartonella: A global bacteria
Bartonellosis, caused by Bartonella species bacteria, is considered a rare disease. It is infrequently diagnosed, and certain species infections are less commonly seen.
Infections by various species of Bartonella are also known as Cat Scratch Disease, Trench Fever, or Carrion’s disease, depending on the species. The pathogen expands past borders and affects people all over the world. A lack of awareness of bartonellosis leads to missed and delayed diagnosis, which can lead to worsened disease outcomes.
Galaxy Diagnostics has the most sensitive test method available for confirmation of Bartonella species infections. Find out more about the Bartonella Digital ePCR test, which combines two sample enrichment technologies.
Peruvian Wart disease
Peru – Peruvian wart disease is caused by the Bartonella bacilliformis bacteria and is transmitted by biting sandflies. Peruvian wart disease happens in two phases. The first phase, or anemic phase, is characterized by bacteria entering and destroying red blood cells, causing anemia. This is the most dangerous phase and can cause death if it is not identified and treated right away. The second phase, or eruptive phase, is characterized by the appearance of blood warts.
Biting sandflies in Peru live in specific conditions. They only develop in areas with at least 80% humidity, and historically have not been found lower than 984 feet above sea level. Researchers in Peru are monitoring the vector’s migration pattern as infections are occurring at lower elevations.
From small to large
South Africa – Domestic house cats have historically been important reservoir hosts for Bartonella henselae, but the bacteria is also being found in big cats. In 2002, a study conducted at three wildlife ranches found the presence of B. henselae in lions. Researchers collected blood samples from 65 lions and ran serology test on 95% of the sample. After testing, 18 of the samples came back with antibodies levels high enough to suggest exposure to Bartonella henselae.
Scientists are unsure what role lions play as reservoir hosts. A reservoir is the most common place an infectious pathogen, like Bartonella species, lives, grows and multiples. Vectors such as fleas and ticks can transmit the pathogen to animals, humans, and their environments. While the most people do not have daily contact with lions, it is important to consider how they interact with smaller animals in their habitat.
One Health is the study of how humans, animals and the environment interact. Did interactions between house cats and larger cats, either directly or through a vector, lead to a broadening of reservoir hosts around the world? This is something that researchers continue to investigate.
Bartonella Down Under
Australia – After researchers identified Bartonella in rodents endemic to regions of Asia, Australian scientists began testing for the bacteria in their rodent population. A study conducted in 1999 found 11 Bartonella isolates in the blood of Melomys, Uromys and Rattus Species. Three new Bartonella spp were identified: B. rattaustrailiani, B. queenslandensis, B. coopersplainsensis. All were closely related to B. vinsonii, the third most common Bartonella species found in humans.
Rodents are not the most popular house pet, so why does the presence of Bartonella in these mammals matter? In 2021, Australia faced the worst mouse plague in current history. House mice (Mus musculus) invaded the eastern part of the country, destroying farms, houses, and the economy. They drove people out of their homes and disrupted the food supply chain. There were even reported case of mice biting hospital patients.
One aspect of rare infectious disease this outbreak highlights is the need to continually monitor for new species of infectious pathogens. New Bartonella species are identified regularly, but little is known about their impact on wild hosts, domestic livestock, and people.
Conclusion
Bartonellosis highlights some of the current difficulties in the response to rare disease. First, the rare disease focus has tended toward genetic diseases, but infectious diseases are multiplying as human encounters with wild areas increase and more species of pathogens—not just bacterial but also viral and fungal—are identified and tests developed.
Second, the lack of both physician awareness and quality diagnostic testing means that infectious diseases may be undercounted. The difficulty only compounds as more pathogens and more species and clades (subdivisions in taxonomy, including divisions of species) with potentially unique disease manifestations are identified.
On Rare Disease Day, one of the things we are highlighting is the importance of One Health approaches to awareness of zoonotic infectious disease risk and prevention in particular. One Health approaches have the potential to help us develop communities where the environment, wild and domestic animals, and people are protected from rare infections.
References
National Organization for Rare Disorders. (2020). Bartonellosis. https://rarediseases.org/rare-diseases/bartonellosis/
Pretorius, A-M. et al. (2004). Bartonella henselae in African lion, South Africa. Emerging Infectious Diseases, 10(12), 2257-2258. 10.3201/eid1012.031054 https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC3323402/
Gundi, V. A. K. B. et al. (2009). Bartonella rattaustraliana sp. nov., Bartonella queenslandensis sp. nov. and Bartonella cooperslainsensis sp. nov., identified in Australian rats. International Journal of Systematic and Evolutionary Microbiology, 59(12), 2956-2961. 10.1099/ijs.0.002865-0 https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/ijs.0.002865-0#tab2
Frank, H. K. et al. (2018). Global fingerprint of humans on the distribution of Bartonella bacteria in mammals. PLOS Neglected Tropical Diseases, 12(11), e0006865. 10.1371/journal.pntd.0006865 https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0006865#sec008
Centers for Disease Control and Prevention. (2012). Section 10: Chain of infection. In Principles of Epidemiology in Public Health Practice (3rd Ed.). https://www.cdc.gov/csels/dsepd/ss1978/lesson1/section10.html
Nogrady, B. (2021, July 12). Mice plague Eastern Australia in record numbers. The Scientist. https://www.the-scientist.com/news-opinion/mice-plague-eastern-australia-in-record-numbers-68963#:~:text=The%20mouse%20plague%20in%20eastern,holding%20hay%20together%20in%20bales.&text=%E2%80%9CIt%20was%20just%20unreal%2C%E2%80%9D,mess%20half%20a%20year%20later.
United States Environmental Protection Agency. (2021, November 16). About rats and mice. https://www.epa.gov/rodenticides/about-rats-and-mice
Gutiérrez, R. et al. (2015). Bartonella infection in rodents and their flea ectoparasites: An overview. Vector Borne and Zoonotic Diseases, 15(1), 27-39. 10.1090/vbz.2014.1606 https://www.ncbi.nlm.nih.gov/labs/pmc/articles/PMC4307031/