Typhus vaccine
The typhus vaccine is designed to prevent typhus fever, a serious infection caused by the Rickettsia bacteria, which is primarily transmitted through arthropods like lice and fleas. Symptoms of typhus include high fever, severe headaches, rash, and potentially delirium, with untreated cases leading to severe complications or death. The vaccine has a historical significance, having been developed in the early 20th century, notably during times of war when outbreaks were common in overcrowded conditions. Traditional formulations of the vaccine used killed bacteria, while the current available vaccine is a live, attenuated version of R. prowazekii.
Though not mandatory for travel, vaccination is recommended for individuals visiting areas where typhus is endemic, particularly in parts of Asia, Africa, and South America. People with certain health conditions, such as egg allergies or recent acute infections, are advised against receiving the vaccine. Despite the decline in vaccine use due to effective pesticide applications, the typhus vaccine remains an important public health tool, particularly in preventing outbreaks in vulnerable populations. Good hygiene practices and repellents are also crucial for mitigating the risk of typhus.
Typhus vaccine
Definition
The typhus vaccine is administered to prevent the spread of typhus fever, a rickettsial infection.
Disease Characteristics
Typhus and its causal bacterium, Rickettsia , were identified in 1909 by Charles Nicolle, although the disease’s symptoms of fever, red rash, and delirium were described as early as 1489. Four related types of typhus are transmitted by arthropods (such as lice, fleas, mites, and chiggers) that carry distinct strains of Rickettsia. A large sore and a rash spread from the bite location within four to six days and may be accompanied by swollen lymph nodes.
Symptoms of acute typhus infection are severe headache, chill, high fever, rash, and stupor. Disease spreads rapidly in crowded areas, particularly in areas of Southeast Asia and South America. Typhus is fatal if not treated. Antibiotic treatment with doxycycline, tetracycline, or chloramphenicol provides a rapid cure. Epidemic typhus, the classic disease, is caused by R. prowazekii and is carried by lice; the disease may cause hypotension and neurologic impairment if untreated.
Vaccine History and Development
Early attempts to design vaccines against rickettsial infections focused on Rocky Mountain spotted fever. In 1932, a typhus vaccine was developed by Hans Zinsser to increase the body’s antibody response to dead bacteria. During World War II, vaccine need peaked in regions of fighting where the disease was endemic. By 1945, epidemics of typhus in US troops were controlled by the use of the pesticide dichloro-diphenyl-trichloroethane (DDT) to kill lice in crowded, unclean living quarters and by the use of the typhus vaccine to halt the infection’s spread.
Traditionally, typhus vaccines were made with killed, inactivated, whole-cell bacteria, but the marketed typhus vaccine comprised live, attenuated R. prowazekii that was harvested in egg yolk sacs. Live, attenuated typhus vaccine was available in freeze-dried, single- or multi-use vials that required storage at colder than 4° Celsius (39° Fahrenheit) until reconstitution. The injection was approved for ages six months and older.
Vaccination Risk Groups and Contraindications
Typhus is transmitted easily in overcrowded populations (such as prisons). Although the vaccine is not required by any country for entry, travelers to Asia should consider typhus vaccine to prevent scrub typhus, the most common form of disease in that area. The vaccine also may be necessary in areas with endemic outbreaks, such as Africa, South America, and Asia, and in areas with diseases that are resistant to antibiotics. Typhus has not been fully eradicated worldwide, and the disease prognosis depends on the risk for complications: older adults experience up to 60 percent mortality with epidemic typhus. Contraindications for receiving a typhus vaccine include a history of egg allergy, an acute infection at time of planned vaccination, and a history of long-term corticosteroid use.
Impact
The typhus vaccine was most useful during World War II, when vaccine administration prevented typhus epidemics among crowded troop populations. Vaccine use diminished greatly with the use of pesticides to kill lice and halt epidemics. The best prevention for typhus remains repellant use and good hygienic practices (such as regular laundering) to reduce lice and tick populations. No typhus vaccines are produced or in development by US manufacturers.
Bibliography
Chattopadhyay, S., and A. L. Richards. “Scrub Typhus Vaccines: Past History and Recent Developments.” Human Vaccines 3 (2007): 73-80.
Patel, Priyanka D. et al. "Efficacy of Typhoid Conjugate Vaccine: Final Analysis of a 4-year, Phase 3, Randomised Controlled Trial in Malawian Children." The Lancet, vol. 403, no. 10425, 3 Feb. 2024, pp. 459-468, www.thelancet.com/journals/lancet/article/PIIS0140-6736(23)02031-7/fulltext. Accessed 4 Feb. 2025.
Plotkin, Susan L., and Stanley A. Plotkin. “A Short History of Vaccination.” In Vaccines, edited by Stanley A. Plotkin, Walter A. Orenstein, and Paul A. Offit. 5th ed. Philadelphia: Saunders/Elsevier, 2008.