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Certainly asymptomatic disease can induce immunity and how. History has thrown up some astounding examples of Asymptomatic carrier. To illustrate the general principle behind the phenomenon of immunity in asymptomatic disease, or rather more accurately infection not disease, a couple of relevant examples are examined here.

Mary Mallon aka Typhoid Mary

Perhaps there’s no better place to start than with Mary Mallon, unfortunately memorialized by posterity with the unenviable moniker of Typhoid Mary. Mary was infected with Salmonella, the causative bacterium of Typhoid fever . While apparently never displaying any symptoms herself, working as a cook in and around New York, she spread typhoid fever at ~ every place of her employment, ~50 cases in all. A sanitation engineer, George Soper, was hired by one of the affected families, a wealthy one that moved from New York City to Oyster Bay, New York, in the summer of 1906. Those afflicted, six among the household of 11, included both employers and staff, namely the daughter, two maids, and the wife and daughter of the tenant, and a permanent gardener.  Doggedly working to uncover the source of their typhoid fever, Soper discovered that typhoid fever seemed to follow Mary Mallon wherever she went (See table below made using data from Soper, George A. “The work of a chronic typhoid germ distributor.” JAMA 48. June 15 (1907): 2019. http://www.lrwieland.com/pboothe…).

  • George A. Soper, a sanitation engineer, is employed to ascertain the cause of the Oyster Bay typhoid outbreak.
  • First, Soper rules out other variables such as water source, sewage, fruits, veg, other food, visitors with or visits to people with typhoid symptoms.
  • Soper’s crucial and unconventional insight then illuminates the way ahead. He wonders if a carrier could have entered the household.
  • Fitting the hypothesis, a new cook, Mary Mallon, had been hired three weeks prior to the typhoid outbreak, leaving their employment ~3 weeks after the outbreak starts.
  • This new cook the only variable left, Soper tracks her down, she’s uncooperative.
  • Undeterred, Soper tracks Mary Mallon’s work history backward and forward and finds it connects with other typhoid outbreaks.
  • Descriptions of Mary Mallon from her time, including by Soper, uniformly describe a healthy, energetic, even athletic person. Doubtless, she herself never appeared to suffer typhoid fever, i.e., retained effective anti-typhoid immunity, even though she was undoubtedly a carrier who transmitted the infection to many others who came down with the disease. In other words, she’s a classic example of a super-spreader.

Other relevant sources for Mary Mallon’s super-spreader story, including a couple of engrossing, detailed, step-by-step accounts by Soper himself on how he identified Mary Mallon as the source of several typhoid outbreaks in early 20th century New York:

1. Soper, George A. “The Discovery of Typhoid Mary.” British medical journal 1.4070 (1939): 37. http://www.ncbi.nlm.nih.gov/pmc/…

2. Soper, George A. “The curious career of Typhoid Mary.” Bulletin of the New York Academy of Medicine 15.10 (1939): 698. http://www.ncbi.nlm.nih.gov/pmc/…

3. Brooks, Janet. “The sad and tragic life of Typhoid Mary.” CMAJ: Canadian Medical Association Journal 154.6 (1996): 915. http://www.ncbi.nlm.nih.gov/pmc/…

4. Wald, Priscilla. “Cultures and Carriers:” Typhoid Mary” and the Science of Social Control.” Social Text (1997): 181-214. http://www.penelopeironstone.com…

5. Chan, Kit Yee, and Daniel D. Reidpath. ““Typhoid Mary” and “HIV Jane”: Responsibility, Agency and Disease Prevention.” Reproductive Health Matters 11.22 (2003): 40-50. http://miembros.cisidat.org.mx/a…

6. Marineli, Filio, et al. “Mary Mallon (1869-1938) and the history of typhoid fever.” Annals of gastroenterology: quarterly publication of the Hellenic Society of Gastroenterology 26.2 (2013): 132. http://www.ncbi.nlm.nih.gov/pmc/…

HIV-resistant Prostitutes in Nairobi, Kenya

  • In 1996, a Lancet study first reported that some commercial sex workers in Nairobi, Kenya, remained persistently seronegative, i.e., showed no circulating anti-HIV antibody response, despite daily exposure to many HIV-infected sex partners (1).
  • Instead several of these HIV-resistant individuals had detectable circulating anti-HIV cytotoxic CD8 T cells (2), i.e., disease resistance correlated with a different type of anti-HIV immune response, cytotoxic T cells and not antibodies.
  • Reduction in sex work, i.e., reduction in frequency of exposure to HIV, led to seroconversion (3), suggesting disease resistance correlated with greater frequency of exposure to HIV.

HIV Bibliography

1. Fowke, Keith R., et al. “Resistance to HIV-1 infection among persistently seronegative prostitutes in Nairobi, Kenya.” The Lancet 348.9038 (1996): 1347-1351.

2. Rowland-Jones, Sarah L., et al. “Cytotoxic T cell responses to multiple conserved HIV epitopes in HIV-resistant prostitutes in Nairobi.” Journal of Clinical Investigation 102.9 (1998): 1758. http://www.ncbi.nlm.nih.gov/pmc/…

3. Kaul, Rupert, et al. “Late seroconversion in HIV-resistant Nairobi prostitutes despite pre-existing HIV-specific CD8+ responses.” Journal of Clinical Investigation 107.3 (2001): 341. http://www.ncbi.nlm.nih.gov/pmc/…