Parasite elimination programs: home and away

To the Editor: The recent editorial by McCarthy and Garrow1 eloquently articulates a case for a coordinated national approach to controlling parasite infections in Aboriginal populations, based predominantly on the authors' experience with chemotherapeutic intervention in one remote community in Western Australia.

While sympathetic to their motives, I am not so optimistic about the outcome of their proposal. For 20 years, Queensland maintained a centrally coordinated Aboriginal health program designed to monitor and eradicate parasitic infections. The program, which used targeted chemotherapy as its core strategy, was very successful with regard to intestinal worms, suppressing trichuriasis almost to extinction (unpublished observation) and virtually eradicating hookworm.2 However, the prevalence of gut protozoan infections (such as giardiasis and cryptosporidiosis) was hardly affected, for the obvious reason that these are relatively short-lived and spread directly person-to-person, which means that personal hygiene is much more crucial to their control. Systematic surveillance ceased after the program was dismantled (for political reasons) in 1990, and anecdotal reports since indicate that hookworm is now returning to Queensland. Again, this is not surprising given the mobility of Indigenous people, and the ability of infective larvae of Ancylostoma duodenale, the local hookworm species, to persist in a dormant state in host tissues, where they are refractory to currently available treatment.3

In support of their case, McCarthy and Garrow presented lymphatic filariasis in Australia as but one successful precedent, implying that it was eradicated "through sustained control programs conducted by dedicated public health agencies . . . using effective drugs".1 This is not supported by historical facts; the disease did disappear from endemic areas, but well before effective chemotherapy became available, and for reasons that are still debatable4 (although mosquito suppression, resulting more from general improvements in living conditions with rising community affluence than from any coordinated activity, is the most likely explanation).

At the community level, parasitic infections of the gut represent not so much a primary problem as a symptom of a more fundamental societal malaise. They will disappear from Aboriginal communities only with a sustained improvement in living conditions (including nutrition, sanitation and personal hygiene), driven by the people themselves when armed with effective public health knowledge. This is a challenge that continues to dwarf the capabilities of all our governments and politicians, at all levels.