Resistance to cheap and effective drugs poses one of the greatest threats to malaria control.
In much of sub-Saharan Africa, chloroquine - the mainstay of treatment for the past 40 years - is virtually useless today as a first line drug.
Its widely deployed successor is low-cost, shows few side effects and is given as a single dose.
However resistance to sulfadoxine-pyrimethamine (SP) is already a serious concern.
"We were incredibly lucky with chloroquine," says Robert Ridley of the World Health Organization's (WHO) tropical disease research programme. "Chloroquine has lasted far longer than it had any right to given the way it was used and abused and mass-used."
The WHO says that when the treatment failure rate of a drug is between nought and five per cent, countries should be aware of the need to change.
As it rises to ten per cent, preparations should be underway so that the switch has taken place before failure levels reach 25 per cent.
By the end of the 1990s, parasite resistance to chloroquine averaged 78 per cent across Tanzania.
Change may have been long overdue but SP, which became the new first line drug for mild malaria in 2001, is far from ideal as resistance already ranges from six to 34 per cent.
"It's an interim policy," admits Zul Premji, a member of the national task force responsible for the switch.
"The huge cost of replacing cheap drugs like chloroquine and SP with more expensive combinations means Tanzania will have to think very carefully about its next step."
In Tanzania, research has shown that more than 80 per cent of the patients who attend a health care facility have already treated themselves with antimalarials.
Media scare stories focusing on a handful of adverse reactions to SP have not helped convince people of its benefits.
In addition, there are still significant stocks of chloroquine that retailers are trying to sell.
“Huge numbers of people do not go to the public sector to get their drugs,” says Alasdair Unwin of the national malaria control programme.
“They go to the local shops or a local pharmacy and we have a real problem ensuring that the quality of the drugs they get in the private sector is good, and secondly ensuring that the private sector is helping consumers to use the right medicines in the right doses at the right time.”
When chloroquine and SP fail, the next recommended treatment options are at least ten times more expensive.
“When you look at the cost of the drugs, the population will simply not buy the full dose,” says Premji.
He also fears that the speed with which the new artemesinin-based derivatives take effect could prove a liability.
“Incorrect use is definitely going to be a problem. People will stop the treatment after two days because they feel better and then become ill again in a few weeks.”
Lack of access
In May 2001, Novartis agreed to supply its newest anti-malaria drug, Coartem, to the WHO at cost for distribution to developing countries.
Cost price works out at around $2.40 for full adult treatment - far less than the same therapy in Switzerland (SFr63 or $45) where it goes under the brand name Riamet - but still a significant proportion of public health expenditure in a country like Tanzania, which spends about $3 per person per year.
However, price is not the only reason why very little Coartem has been distributed to patients in Africa so far.
"It's clear that the WHO's reach is very much farther than our reach could ever be, but it is not far enough," says Linda Stephen, Coartem product manager at Novartis.
"They deliver to ministry of health stores who in turn deliver to their clinics but the question remains what happens beyond those clinics for people who live several days' walk away."
Novartis has designed special packs with instructions in pictures and symbols to reach people who cannot read
"Because the dosing is weight related, we developed four different kinds of pack and colour coded them," says Stephen.
"We also illustrated directions for use... with suns and moons depicting when to take the medication and in what quantity."
Such efforts threaten to be derailed if quality control is minimal and counterfeit drugs find their way onto the market. .
The WHO estimates that on average ten to 20 per cent of medicines in developing country markets are sub-standard – counterfeit or poor quality.
“We need to ensure that the quality of drugs in the retail sector is good, that the regulatory processes work and that people have access to those drugs when they need it, which is within 24 hours,” says Unwin.
Cost of drugs, weak health care infrastructure, inadequately trained staff, difficulties of physical access and delay in seeking treatment all conspire against the needy.
“If malaria is treated with the right drugs, you can be completely cured,” says Kamini Mendis of the WHO’s Access to Treatment team. “If you don’t treat this disease, it can become progressively more severe and can result in death.”
“We think the very high burden in Africa – about a million deaths in children under five years of age – is because these children are not treated early enough and the disease progresses into the complicated form.”
swissinfo, Vincent Landon
Tanzania's new treatment policy was introduced in 2001.
Resistance to the drug chloroquine averaged 78 per cent.
SP is the new first line drug for mild malaria followed by amodiaquine.
Quinine is drug of choice for severe cases.
The failure rate of SP already ranges from six to 34 per cent.
Next recommended options are at least ten times more expensive.