Army Malaria Institute - Its Evolution And Achievements. Fourth Decade (2nd Half): 2000-2005

The 2000-2005 quinquennium saw a marked drop in the number of Australian Defence Force (ADF) personnel suffering from malaria following the deployment of an Australian Army Malaria Institute (AMI) outbreak investigation team to Timor Leste and improved compliance with various prevention measures. The field evaluation of novel drug regimens using currently registered and new drugs also contributed to the reduced number of malaria cases overseas and after return to Australia. The main purpose of some of these studies was to determine the tolerability and effectiveness of more user friendly drug regimens, such as shorter courses of primaquine and 3-day courses of tafenoquine for post-exposure prophylaxis against vivax malaria. Clinical/field studies were also conducted with atovaquone/proguanil (Malarone (R)), loading doses of mefloquine, and a new artemisinin drug-artemisone. All of these investigations yielded positive results. Another landmark study-the first Phase III study in which weekly tafenoquine was taken for six months by non-immune individuals showed that Australian soldiers could be protected against both falciparum and vivax malaria while in Timor Leste without having to take a post-exposure primaquine eradication course upon return to Australia.In addition to documenting increasing drug resistance of malaria parasites in various parts of the Asia/Pacific region, molecular markers and changes associated with parasite resistance to antimalarial drugs were identified. An in vitro field test for assessing the drug susceptibility of Plasmodium vivax was also developed and, for the first time, successful transfection of P. vivax genes to continuously cultured P. falciparum enabled antifolate drugs to be screened in vitro for their activity against P. vivax. Furthermore, various laboratory/epidemiological studies and mathematical models were developed to investigate factors involved in the evolution and spread of drug resistance, such as mutation patterns, antigenic variation, loss of fitness, and inappropriate treatment.In ongoing efforts to improve protection against mosquito bites, the effectiveness of various repellents/insecticides applied to skin, clothing and tents were evaluated in military training areas in Queensland and the Northern Territory. Mosquito control measures, including the use of newly-developed tools, were instrumental in controlling the outbreak of both malaria and dengue fever in Timor Leste. Furthermore, investigations in Australia, Vietnam and China indicated the potential value of novel molecular-based and other tests for identifying and controlling the spread of mosquitoes transmitting malaria, dengue and Japanese encephalitis. In view of the ADF's increasing exposure to arboviral diseases, further clinical studies were conducted to assess the tolerability and immunogenicity of dengue and Japanese encephalitis vaccines and prelicensure studies were started to determine the effectiveness of new vaccines.