MEDICAL professionals, lagging far behind in the race between modern science and nature in the battle over one of the world's most voracious killers, could be saved by an obscure Chinese plant and research in a Hongkong laboratory, if enough money can be found. Malaria, once thought to be beaten, is staging a powerful comeback. Drugs and insecticides that were used to great success in the past are no longer proving 100 per cent effective. In many of Hongkong's neighbours - especially China, Thailand and Cambodia - strains of the malaria parasite have developed resistance to them. The disease claims over two million lives annually, and there are approximately 20 million sufferers worldwide, a conservative estimate since many victims live in rural areas and do not report the disease. In Asia, conventional drugs like chloroquine no longer work on complicated falciparum malaria and others like quinine are rapidly showing signs of ineffectiveness. Combinations of drugs can still be used to treat simple malaria but quinine for instance has serious side effects and is not considered safe for pregnant women and children. For those who suffer, the price of malaria's comeback is high. Victims talk of days filled with fever and chills. In some types, brain damage, renal failure and severe anaemia can result in death. Their hope, and the hope for millions of others as yet uninfected, lies in the Chinese plant, qinghao. Used for more than 2000 years in China to treat fevers, it was only in the early 70s that Chinese scientists isolated the chemical compound qinghaosu, and derived from it very effective anti-malarial drugs such as artesunate, arteether and artemether. But they found it difficult to extract enough qinghaosu. In 1989, Dr Richard Haynes, now Reader in the Department of Chemistry at the University of Science and Technology, and his University of Sydney colleague, Dr Simone Vonwiller, began research into the Qinghao plant and discovered that qinghao acid, another extract from the plant, was more abundant than qinghaosu and could also be converted to the same anti-malarial drugs. Artesunate, arteether and artemether are hailed by many as the most effective antimalarials, with arteether being capable of ridding the blood of parasites, usually within 24 hours. Most importantly, the parasites are not resistant to the drugs yet. ''So far, the indications have been good. Compared to the other drugs, the qinghao drugs have had no problems with resistance in a field situation,'' said Dr Haynes. But judging from its unregulated use in some countries, it seems inevitable that the drug will soon join the ranks of the others. Dr Haynes explains why a parasite develops resistance to a drug when it is not administered properly. Artemether is currently registered on a trial basis in Thailand and is sold indiscriminately at drugstores. A person may, without prescription, administer the drug to himself, not taking enough to kill the parasite. The parasites that survive develop a resistance and as they multiply, they carry the same drug-resistant strain. ''It is deplorable that people are abusing the drugs in such an unscrupulous fashion and it is largely irresponsible on their part,'' said Dr Haynes. Artemether is still not approved by Western scientists and health authorities, who are unconvinced of Chinese toxicology tests. They insist on a series of their own tests, which is delaying the proper marketing of artemether and increasing the risk of the parasite developing resistance to the drug. Nevertheless, the tests continue under French pharmaceutical company, Rhone Poulenc Rorer, and according to Dr Claude Faurant, a representative of the company, the dossier on the drug has already been completed. Supplementary tests which are required by some countries are being conducted now and it is expected that France will approve the drug at the end of the year. The Chinese themselves have their own toxicology tests, being carried out at the Guangzhou College of Traditional Medicine. According to Dr Haynes, the drugs have shown no degree of toxicity. ''It appears to be very safe,'' he said, ''with no adverse side effects.'' But he could not be sure if the drug would produce side effects later in the life of the patient. Artemether is already registered in several African countries and is being distributed in Asian countries like Thailand, Burma and Cambodia which have an urgent need to find a substitute for malaria resistant drugs. There are basically four parasites that are responsible for malaria - plasmodium vivax, plasmodium malariae, plasmodium ovale and plasmodium falciparum. These parasites are carried in the saliva of some 70 species of the female anopheles mosquito. As she draws blood from a victim, she will drop a few drops of her saliva into the victim's bloodstream as an anaesthetic. The parasites in the saliva will travel directly to the victim's liver, where it incubates between six to 16 days, depending on the type of parasite. At the end of this incubation period, the infected liver cells will rupture, spewing a tremendously increased number of parasites into the bloodstream. These will then invade the red blood cells, rapidly reproducing themselves in the same manner. The damage depends on the type of parasite. While plasmodium vivax is responsible for most malaria infections, plasmodium falciparum is the most dangerous, and with complications can cause among other things brain damage, renal failure and severe anaemia. According to 1991 figures from the Department of Health, 17.7 per cent of malaria sufferers in Hongkong were infected by this type of malaria. It is also this parasite that has proved most resistant to the drugs meant to destroy it. In Hongkong, drugs such as quinine, chloroquine and primaquine are used for malaria treatment, which is usually carried out in hospital, at least in the initial phase of the illness. Depending on the species of the malaria parasite, the duration of treatment may take between a few days, to over two weeks. The Department of Health also ensures that all urbanised areas are protected by effective vector control programmes. And the malaria-transmitting anopheles mosquito is found only in remote rural areas. This perhaps explains why there is no local transmission of malaria in Hongkong. The number of reported cases in the territory has also been decreasing steadily from 744 in 1989, to 82 in 1992, with the bulk of them imported. The real problem with contracting malaria overseas is that when you arrive back in Hongkong where the disease is relatively rare, the symptoms might belie the disease and doctors can inaccurately diagnose a common flu or fever. If you are infected by theplasmodium falciparum parasite, you could be dead in three days. Dr Haynes intends to continue research into the qinghao plant at the University of Science and Technology but is stalled by a lack of funds. He is currently spending valuable research time soliciting money. ''My laboratory is bare.'' he pleaded. He also believes there are many researchers in Hongkong who can help with the project. ''We are searching for better drugs than the ones we have now, and also looking into producing them synthetically. ''It is in our interest to develop a long-term solution to malaria and it will be good for Hongkong if it is done here.''