Mass drug administration
Mass drug administrations were generally unsuccessful in interrupting transmission, but, in some cases, had a marked effect on parasite prevalence and on the incidence of clinical malaria.
In the following three years, 1955 to 1957, pyrimethamine administration was replaced with Dieldrin spraying to consolidate malaria control, which makes an assessment of the long-term effect of this MDA impossible.
[citation needed] During a pilot programme in Uganda in 1959 mass administration of chloroquine / pyrimethamine was combined with spraying of residual insecticides (DDT).
[15] Two large trials of MDA combined with household spraying with DDT were conducted in Cameroun and Upper Volta (Burkina Faso) in 1960–1961.
Because the investigators felt that the failure of the trial to interrupt transmission was due to operational inadequacies, they recommended a much larger and more sophisticated evaluation of insecticide spraying combined with MDA.
[citation needed] A mass drug administration campaign using S/P, artesunate and primaquine was completed in Moshi district, Tanzania in 2008.
[citation needed] Outside of sub-Saharan Africa one of the larger reported malaria-control projects using MDA took place in Nicaragua in 1981 following the overthrow of the Somoza regime.
[25] An estimated 70% of Nicaragua's total population (1.9 million people) received chloroquine and primaquine during the peak period of disease transmission (November).
However, the mass administration of antimalarials was not sustainable and, as with other malaria-control efforts, collapsed following the return of politically conservative forces.
[30] Here a mass administration of chloroquine was part of a programme of intensified surveillance, case management, health education, and residual spraying.
[citation needed] In 1984, MDA was added to the distribution of insecticide-impregnated bed nets (ITNs) in Sabah (Malaysia), but this failed to interrupt malaria transmission.
The only reported project with an MDA component which succeeded in permanently interrupting malaria transmission took place on the island of Aneityum, Vanuatu.
[34][35] Starting in September 1991, three malaria-control activities were employed – permethrin-impregnated bed nets, larvivorous fish and the administration of three antimalarials.
Following the first malaria-control phase from 1955 to 1962, which was mostly focused on malaria surveys, mass administrations were added to vector control measures and improved case management in 10 of China's 33 provinces.
The economic reforms instituted by Deng Xiaoping, which ultimately put an end to the provision of free health care through the central government and the emergence of resistance against the most widely used antimalarials modified the use of mass drug administrations after 1980.
MDAs are now targeted at high-risk populations, specifically non-immune migratory workers who receive repeated courses during the high transmission season.
Malaria-control measures, including MDA, as well as major ecologic changes during the second half of the last century are likely to have been responsible for the more than 100-fold reduction in malaria burden in China since the initial surveys in 1955.
Chloroquinized salt for malaria suppression was introduced by Pinotti in 1952 and gave promising results in a number of field trials and malaria-control programmes in Brazil.
As there were no shops in the catchment area, each family unit received fortnightly a quantity of salt from the local teacher or another member of the village community.
The explanation for this finding given by the author is that "the salt consumption by children was too small to reduce significantly the parasite reservoir of the younger age groups".
[citation needed] Between 1961 and 1965, the use of chloroquinized salt was made compulsory over an area of 109,000 km2 (42,000 sq mi) in Guyana, covering a population of 48,500 individuals.
[51][52] Whether MDAs can be considered successful or not depends on the expectation of what they might achieve; many studies do not define whether their main aim was to interrupt transmission or to control disease.
Only one project, conducted on Aneityum, a small isolated island in the Pacific, succeeded in permanently interrupting transmission using MDA as one of several malaria-control strategies.
[citation needed] The deficiencies in the study designs mentioned above reflect the evolution of research methodology over the last 50 years.
There are, with some notable exceptions, few properly designed and analysed cluster randomized trials conducted by health care researchers prior to 1978.
[citation needed] The present unpopularity of MDA is not only due to doubts regarding the health benefit of this intervention but to the fear that MDAs will facilitate the spread of drug resistance.
Payne has argued that the one common factor between these three epidemiologically diverse areas was widespread distribution of medicated salts prior to the emergence of chloroquine resistance.
In contrast, the administration of medicated salts is likely to result in drug levels undulating in the sub-lethal range, which reach a steady state after several doses have been administered.
[53] Medicated salt projects can be considered as large scale in vivo experiments designed to select resistant parasites.
There is a theoretical risk that administration of antimalarial drugs during the course of MDAs to women in the first trimester of pregnancy, some of whom may not know that they are pregnant, could lead to foetal abnormalities.
