In the USA, leprosy is considered a zoonosis and this classification has recently been accepted in Brazil. This review presents information regarding the role of wild armadillos as a source of M.
The most common causative agent is M. Recent research has shown variation in the genetic diversity of isolates from different continents, ethnic groups and host species 3.
In addition, its clinical manifestation is broad, with widely divergent immunological characteristics 4 , hindering the diagnosis. A susceptible individual, once infected, generally exhibits an incubation period of three to seven years until symptoms and physical signs of the disease are observed. Men are more affected than women, with signs in men usually starting in the second and third decade of life.
Children may be affected mainly in areas where leprosy has high endemicity 5. The disease mainly affects the skin and peripheral nerves, but the multibacillary form often affects the eyes, oro-nasal mucosa, testicles, bones and other tissues 6. The highest incidences are found in tropical and subtropical climates and, to date, it is a significant public health problem, especially in Asia, Africa and South America 7. In , , new cases of leprosy were reported by countries or territories 8.
However, the exact mechanism of transmission of the disease in the population is still debated, especially regarding environmental sources of M. Moreover, suspicions of the existence of infected animals such as armadillos and primates acting as environmental reservoirs and sources of M. Issues related to individual immunological susceptibility in the pathogenesis of infections by M. The recently reported presence of M. The objective of this manuscript is to review published studies on M.
We attempted to resolve conflicts between studies and to determine whether results could be summarized when individual studies were inconclusive or contradictory. We searched three electronic databases PubMed, Scielo, and Web of Sicence for observational and experimental studies published in indexed journals. This search strategy identified after de-duplication 58 articles describing leprosy in armadillos.
To circumvent the problem that the bacillus M. In , Kirchheimer and Storrs 15 achieved the spread of M. Currently, D. Some primate species Pan troglodytes , Cercocebus atys and Macaca fascicularis 18 and armadillos 19 are susceptible to M.
Table 1 shows published studies on the natural infection of M. These studies strengthen the hypothesis of armadillos as a zoonotic source of M. In , Walsh et al. In , Deps et al. These studies established that, in Southeast Brazil, armadillos can be considered a natural reservoir of M.
An epidemiological approach in the same area revealed that direct exposure through hunting or consumption of armadillo meat was associated with two-fold higher chance of leprosy in humans 34 , In addition, a standard single genotype SNP type for the strain of M. The possibility of an active participation of armadillos in the transmission of human leprosy is reinforced in areas with infected armadillos, where people affected by leprosy report no previous contact with infected individuals 36 - An association between leprosy and contact with armadillos has been reported mainly in people who handled or ate armadillos 34 - 36 , 38 - A case report from the USA describes a patient without travel history to endemic countries or contact with people infected with M.
The interaction between armadillos and M. Susceptible armadillo species from South America, such as D. This supports the belief that animal infections in the Americas originated from humans who migrated from the places of origin of M. In most of the infected animals, the agent is a single predominant M. On the other hand, Schmitt et al.
In Brazil, two species of armadillos, E. Subsequently, Frota et al. It is therefore highlighted that the most significant exposure to environmental M. Descriptions of infection patterns in wild armadillos remain scarce, and transmission mechanisms are unknown The transmission of M. The disease is growing in armadillos. And while these animals are not exactly the cuddly type to which humans are drawn, armadillo-to-human contact is spreading.
And, when the species do interact, armadillos are giving leprosy back. It is is spread mainly by aerosol infection, or coughing and sneezing, from human to human.
Typically, infection requires living in close contact with an untreated infected individual. Symptoms develop slowly, as long as three to seven years after infection. It is rare in the United States, with an average of less than cases diagnosed per year in the last 10 years, mostly in individuals who immigrated from foreign countries where the disease is prevalent. It is found mostly in tropical countries such as Brazil, India, Indonesia and other countries in Africa, southeast Asia and the Pacific Islands.
There were , new cases worldwide in Although drugs to treat and cure leprosy are cheap and available for free to anyone diagnosed with the disease, pockets of high incidence in dozens of countries have kept the numbers from declining much in the last few years. And, of course, they advise not to go hunting, skinning or eating them which is a rule the armadillos would probably appreciate, too.
Laura Clark is a writer and editor based in Pittsburgh. She's a blogger with Smart News and a senior editor at Pitt magazine. A nine-banded armadillo. Post a Comment. Giant armadillos are more rare and difficult to find, but they are also hunted for food because the animals can weigh as much as a Labrador retriever. However, he worries that because the researchers were able to analyse only 16 armadillos and humans, the results could be subject to change with broader sampling.
For his part, Spencer says that the Brazilian government gave him and his colleagues permission to sample just 30 armadillos in total. However, the team had to rely on local hunters to share parts of their kill for analysis, something only a handful of them were willing to do—perhaps out of fear of getting into trouble.
National Geographic National Geographic. By Jason Bittel.
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