Malaria
fights back
In the last few years, an ambitious global policy to control malaria has
been implemented. However, despite the considerable means deployed,
efforts have often been compromised by the appearance of resistance in
the parasites to the treatments and in the mosquitoes to the insecticides,
as well as by social and economic obstacles.
Tenacious parasites
The effects of anti-malarial drugs can diminish, or even disappear, over time. Effectively, parasites are capable
of adapting and of becoming resistant, that is, capable of surviving treatments designed to eliminate them.
This is encouraged by the massive use of treatments composed of just one anti-parasite compound (monotherapy),
which gradually leads to the appearance of resistant strains of parasite, resulting in over-mortality from malaria.
Chloroquine, a drug that has been used for more than 50 years because of its efficacy, low cost and lack of side effects, has become ineffective as a result
of the parasite’s resistance to the compound. To prevent a repeat of this situation with the derivatives of artemisinin, another active ingredient discovered
more recently, the WHO has requested that it no longer be prescribed as a monotherapy and recommends that is be systematically associated
with other compounds.
Egg of the parasite on the wall
of the mosquito’s stomach.
Mutations
Over time, certain vector mosquitoes can develop resistance to the insecticides used to spray inside homes
or impregnate mosquito nets. This phenomenon is the result of a mutation in a gene in the Anopheles mosquito which
allows them to tolerate doses of insecticide that were previously fatal. The challenge for research is to identify
the genetic mechanisms responsible for this resistance and to develop new products capable of overcoming it.
Insecticides have proven their efficacy for several decades. Today, however, their negative impact on the environment and, possibly, on man, their loss of
efficacy, the heavy logistics and costs associated with using them stop them being used at a really large scale. For this reason, they are primarily used
at a small scale, or occasionally during epidemic outbreaks, during the rainy season.
Situations at risk
The dangers of malaria are often under-estimated by populations through a lack of
information, and it is sometimes difficult to obtain compliance with prevention campaigns
(particularly regarding the use of mosquito nets). In addition, in the poorest countries,
ineffective counterfeit drugs are sold at very low prices on the black market, or even
at the chemist’s. It is estimated that 38 % of the anti-malarial drugs on the market in
South-East Asia in 2001 were fake. According to the WHO, 200,000 deaths associated
with malaria could have been prevented if the drugs taken had been effective.
Many countries affected by malaria suffer from insufficiently developed public healthcare systems and drug distribution,
particularly in rural areas. One of things at stake when providing help with development is to support these countries
as a means of durably strengthening their healthcare infrastructures for better management of patients.
Itinerant drug seller
on the streets of Senegal.