2011 vol. 35 no. 2 AUSTRALIAN AND NEW ZEALAND JOURNAL OF PUBLIC HEALTH 195© 2011 The Authors. ANZJPH © 2011 Public Health Association of Australia

doi: 10.1111/j.1753-6405.2011.00691.x

Armadillos and monkeys not the culpritsCharles Douglas

Public Health Physician, Kalgoorlie-Boulder Population Health Unit, Western Australia

Your otherwise excellent editorial by Niyi Awofeso, Leprosy control, public health paradigms and stigma (Aust NZ J Public health. 2011:35(1):9-11) contains an important error. He states that “[z]oonotic diseases like leprosy and HIV are more difficult to eradicate than diseases like smallpox which have no animal reservoirs.”

In the case of leprosy it almost certainly arose in humans, though it can affect other species such as the armadillo. HIV probably evolved from simian viruses into a human specific form. There is no evidence that in either disease other species are an important reservoir of infection and thus a barrier to their elimination.

Correspondence to: Dr Charles Douglas, Public Health Physician, PO Box 10492, Kalgoorlie WA 6433; e-mail: charlesrdouglas@bigpond.com

Author’s responseFirst, following extensive research, it is now believed that M.

leprae regressed from M. tuberculosis – a zoonotic pathogen1 – through a process of reductive evolution in which the M. tuberculosis genome underwent downsizing and accumulated more than 1,130 pseudogenes.2 So far, naturally acquired leprosy has been reported in wild nine-banded armadillos (Dasypus novemcinctus) and in three species of non-human primates (chimpanzees [Pan troglodytes], sooty mangabey monkeys [Cercocebus atys] and cynomolgus macaques [Macaca fascicularis]), thus qualifying leprosy as a zoonosis.3,4 Despite initial controversies about the origins of HIV-1 and HIV-2, it is now well established that HIV is a zoonosis. Evidence of simian immunodeficiency virus (SIV) infection has been reported for 26 different species of African nonhuman primates. Two of these viruses, SIVcpz from chimpanzees and SIVsm from sooty mangabeys, are the cause of HIV infection and acquired immunodeficiency syndrome (AIDS) in humans. Together, they have been transmitted to humans on at least seven occasions.5 Recent studies on the HIV-1 group M, a major HIV group responsible for current AIDS pandemic, indicate that new recombinant strains are arising continually, becoming a powerful force in the spread of HIV-1 globally.6

Second, infections which have zoonotic origins invariably develop intrinsic anatomical and biochemical variabilities which limit the sustained effectiveness of clinical and public health interventions to control them. This fact is best demonstrated with influenza A viruses. For example, pig cells express sialic acids that can be receptors for swine, human, and avian influenza strains and facilitate cross-species influenza transmission and the genesis of novel influenza strains.7 With leprosy, major differences have been found in single-nucleotide polymorphisms of strains obtained from different countries, a common characteristic of zoonotic infections and marker of biochemical variability. The impact of leprosy’s zoonotic origin on disease control is further complicated by the concomitant loss of catabolic and respiratory functions in its genome – following

mutation from M tuberculosis – which appears to have resulted in severe metabolic constraints that increase latency of infections and apparently limit effectiveness of therapies.2 The point I am making with respect to the zoonotic origins of HIV and leprosy constituting an encumbrance in prevention and control efforts is not that animal reservoirs continue to be common sources of human infection, but that, as with influenza A viruses, HIV and leprosy have greater potential to mutate, undergo complex incubation patterns in human hosts and are therefore more difficult to prevent or treat compared with an infectious agent like variola virus (smallpox) which resides exclusively in humans and is thus less prone to such changes.

References1. Michalak K, Austin C, Diesel S, Bacon JM, Zimmerman P, Maslow JN.

Mycobacterium tuberculosis infection as a zoonotic disease: transmission between humans and elephants. Emerging Infect Dis. 1988;4:283-7.

2. Monot M, Honore´ N, Garnier T, et al. On the origin of leprosy. Science. 2005;308:1040-2.

3. Walsh GP, Meyers WM, Binford CH, et al. Leprosy as a zoonosis: an update. Acta Leprol. 1988;6:51-60.

4. Rojas-Espinosa O, Løvik M. Mycobacterium leprae and Mycobacterium lepraemurium infections in domestic and wild animals. Rev Sci Tech. 2001,20:219-51.

5. Hahn BH, Shaw GM, De KM, De Cock KM, Sharp PM. AIDS as a zoonosis: scientific and public health implications. Science. 2000;287:607-14.

6. Ramirez A, Capuano AW, Wellman DA, et al. Preventing zoonotic influenza virus infection. Emerg Infect Dis. 2006;12:996–1000.

7. Takebe Y, Kusagawa S, Motomura K. Molecular epidemiology of HIV: tracking AIDS pandemic. Pediatr Int. 2004;46:238-44.

Correspondence to: Professor Niyi Awofeso, School of Population Health, University of Western Australia., M431, 35 Stirling Highway, Crawley, WA; e-mail: niyi.awofeso@uwa.edu.au

doi: 10.1111/j.1753-6405.2010.00692.x

Prevalence of head lice among children entering school in the ACT 2006–08Marian J. Currie

Academic Unit of Internal Medicine, Australian National University Medical School, Australian Capital Territory

Karen Ciszek, Marjan Kljakovic Academic Unit of General Practice, Australian National University Medical School, Australian Capital Territory

Francis J. BowdenAcademic Unit of Internal Medicine, Australian National University Medical School, Australian Capital Territory

Head lice infestation is common among young children with worldwide prevalence estimates ranging between 0.48% and 37.4%.1

Here we present data relating to head lice infestation drawn from the ACT Kindergarten Health Screen. Parents of children entering one of 110 ACT primary schools between 2006 and 2008 were asked to complete this questionnaire, described elsewhere.2 Response rates ranged from 85% to 89%. The following question concerning head lice was included:

“Head lice are highly prevalent in schools. How many separate

times have you had to remove lice from your child’s head (using

Letters