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abstract & commentary
Synopsis: Hansen’s disease continues to be transmitted at an unabated rate along the Gulf coast of Texas.
Source: Taylor JP, et al. A continuing focus of Hansen’s disease in Texas. Am J Trop Med Hyg 1999;60:449-452.
Taylor and colleagues at the texas department of Health reviewed all 810 cases of Hansen’s disease reported to them for the years 1973 through 1997. During this time, the average number of cases reported annually ranged from 18-54, with 26-42 cases reported annually during the most recent period of 1993 through 1997. The average annual incidence rates ranged from 1.9-2.4 cases per million population. The areas of highest incidence were clustered along the Gulf coast, with one county (Goliad) having an average annual incidence rate of 96.1 cases per million. Seventy-seven percent of patients were white (51% Hispanic), 19% Asian, and 3.0% were African-American; 63% were male. Relative to the general population of the state, Asians and Hispanics were overrepresented among the cases and African-Americans were underrepresented.
The median age at onset of disease was 44 years (range, 2-87 years). Fifty-three percent were born in the United States, with two-thirds of those born in Texas. Approximately one-fourth each were born in Mexico and other countries—most commonly Vietnam, India, Phillipines, and Cambodia. Of the 56% who experienced the onset of their disease after arrival in the United States, 23% did not become ill until 10 years or more after migration. The diagnosis was made within one year of onset of illness in 56%. Three-fourths had multibacillary disease; loss of sensation was noted at diagnosis in 46% and deformity in 10%. A potential human source of infection was identified for 23%.
I once went to a Willie Nelson/Jerry Jeff Walker concert at Stanford. The sight of thousands of people in Palo Alto wearing cowboy boots and hats and waving stuffed armadillos was entrancingly bizarre. But this report has caused the intrusion of this memory into my consciousness. More than two decades ago, 4.7% of armadillos caught in the Gulf coast area were found to be leprous.1 The same year, leprosy was reported in Texas armadillo handlers and is also believed to occur in the adjacent state of Louisiana.2,3 However, while transmission from armadillos remains a possibility in some cases, this source cannot account for more than a tiny fraction of cases. Although leprosy has been assumed to be the result of person-to-person contact, the mechanism of transmission remains uncertain. The transmission by inhalation of organism from environmental sources remains a theoretical possibility.
There were 3.7 million registered cases of Hansen’s disease in the world in 1990, with a planetary prevalence of 7.10 cases per 10,000 population.4 In 1998, the regions with the highest detection rates of new cases of Hansen’s disease were some Pacific islands, southeastern and western Africa, and southeast Asia.5 Sixteen countries accounted for 92% of registered cases: Bangladesh, Brazil, Cambodia, the Democratic Republic of Congo, Ethiopia, Guinea, India, Indonesia, Madagascar, Mozambique, Myanmar, Nepal, Niger, Nigeria, Phillipines, and Sudan.6
Taylor et al point out that the incidence of Hansen’s disease in Texas has not changed significantly over the last six decades, although the proportion of cases born outside either the United States or Mexico has increased to 23.1% from less than 1.0%. In contrast to other states, such as Hawaii and Florida, the number of indigenous cases has not decreased in Texas, which now reports more than 60% of the indigenous cases in the United States, but only 25% of the total cases.7 The annual number of reports of Hansen’s disease in the years 1991 through 1995 ranged from 136-187.8
It is ironic that there has been no significant decrease in the number of autochthonously acquired Hansen’s disease cases in Texas over the decades at the same time that the number of cases worldwide is decreasing in response to the eradication activities of the World Health Organization. This plan is based primarily upon enhanced case finding and administration of appropriate therapy.6 Maybe they can try it in Texas.
1. Smith JH, et al. Reticuloendothel Soc 1983;34:75-88.
2. Lumpkin LR, et al. J Am Acad Dermatol 1983;9: 899-903.
3. Meyers WM, et al. Int J Lepr Other Mycobact Dis 1992;60(3):477-480.
4. Noorden SK. The epidemiology of leprosy. In: Hastings R, ed. Leprosy. 2nd ed. Edinburgh: Churchill Livingstone; 1994:29-45.
5. Weekly Epidemiological Record 1998;73:185-192. (Available on-line at http://www.who.int/wer)
6. Weekly Epidemiological Record 1998;73:177-184. (Available on-line at http://www.who.int/wer)
7. Mastro TD, et al. Am J Public Health 1992;82: 1127-1130.
8. Centers for Disease Control and Prevention, 1995. MMWR Morb Mortal Wkly Rep 1995;44:73.