Murine Typhus
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The threat of disease in urban and suburban areas are the primary focus of interest in the public health field since community health and safety affects all people. Murine typhus (Endemic typhus) is a zoonotic disease transmitted by arthropod vectors that prevails in urban and suburban areas globally.
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Murine Typhus
- 1. Heather Melendez Dr. Mian HSCI 403 Vector-Borne Disease Control 17 November 2015
- 2. Murine typhus (Endemic typhus) is a zoonotic disease transmitted by arthropod vectors that prevails in urban and suburban areas. The etiological agent that causes disease are Rickettsia typhi and Rickettsia felis. The transmission of R. typhi and R. felis are associated with Ctenocephalides felis, the cat flea, and Xenopsylla cheopis, the rat flea. The reservoirs of Murine typhus are domestic cats, rats, and peridomestic opossums.
- 3. The pathogens R. typhi and R. felis are introduced by an arthropod ingesting a blood meal infected with the disease. The pathogen Rickettsia is an obligate intracellular coccobacillus alpha- proteobacterium. As the pathogen circulates in the flea’s body, the pathogens that replicate in the midgut epithelial cells are shed and excreted in the feces.
- 5. The rat is the host for the flea X. cheopis. The pathogen is introduced into the circulatory system of the rat and the Rickettsia is transmitted back to the flea on subsequent blood meals. The rat flea prefers to feed on rats; however, it will search for other hosts if rats are not available. The urban cycle is a route of infection common in overcrowded cities with unsanitary conditions.
- 6. In the suburban cycle, the reservoirs are feral and domestic cats and peridomestic opossums. Risk of domestic cats acquiring the infected fleas. Feral cats & opossums interact in suburban neighborhoods, entering backyards if food, water and nesting sites are available.
- 7. The incubation time of 7 to 14 days passes before onset of the illness. The onset begins with a fever that lasts 3 to 7 days and will cause a severe headache, myalgia, nausea, and vomiting. After one week, a maculopapular rash appears on the trunk and axilla parts of the body that lasts 1 to 4 days.
- 8. Misdiagnosis is common since the illness is similar to other dieases. Flea bites found on the body during a medical examination is indicator for doctors to consider testing for Rickettsia as a possible pathogen. The differentiation of R. typhi & R. felis are confirmed through PCR testing and sequencing of the genes.
- 9. Murine Typhus is a treatable illness with antibiotic therapy. The mortality rate with antibiotic use is 1% and 4% without antibiotic use The antibiotic, doxycycline has proven effective in killing both R. typhi and R. felis pathogens and so far, no resistance to the antibiotic treatment has occurred
- 10. Close and or cover any open cracks, crevices or openings that rodents, cats, or opossums can enter to hide or nest. Remove any overgrown foliage and clutter in the yard, which are ideal harborage sites. Remove all ripe fruit from trees and pick up fallen fruit. Remove all possible food and water sources such as bringing in pet food/water bowls at night. Cover all refuse containers tightly.
- 11. Outdoor pets on the property, ensure proper flea control is in use. Flea drops, collars, powders containing larvicides and adulticides, such as fenoxycarb, and permethrin. Mechanical methods such as washing bedding and vacuuming are an excellent way to prevent pesticide resistance. Vacuuming will remove up to 95% of emerging fleas, 90% of eggs, and 50% of larvae . If a flea infestation is out of control contact a local pest control specialist
- 12. Abdad, M. Y., Stenos, J., & Graves, S. (2011). Rickettsia Felis, an Emerging Flea-transmitted Human Pathogen. Emerging Health Threats, 4, 1-7. doi: 10.3402/ehtj.v4i0.7168 Abramowicz, K. F., Wekesa, J.W., Nwadike, C.N., Zambrano, M.L., Karpathy, S.E., Cecil, D., Burns, J., Hu, R., & Eremeeva, M.E. (2012). Rickettsia Felis in Cat Fleas, Ctenocephalides Felis Parasitizing Opossums, San Bernardino County, California. Medical & Veterinary Entomology, 26(4), 458- 462. doi: 10.1111/j.1365-2915.2012.01017.x Beaty, Barry J., & Marquardt, William C. (1996) The Biology of Disease Vectors, 146-155.
- 13. Civen, R., & Ngo, V. (2008). Murine Typhus: An Unrecognized Suburban Vectorborne Disease. Clinical Infectious Diseases, 46(6), 913-918. doi: 10.1086/527443 County of Los Angeles – Department of Health Service. (n.d.). What is Murine Typhus? County of Los Angeles- Department of Health Services. Retrieved from http://publichealth.lacounty.gov/vet/docs/mtyphus.pdf Rust, Michael K., & Michael W. Dryden. (1997). The Biology, Ecology, and Management of the Cat Flea. (1997). Annual Review of Entomology, 42(1), 451.