In the Lancet of 5 February 1910 I discovered a most interesting little article about malaria on Antigua island (Carribean)...
From the article: "Every pond and stream throughout the island of Antigua has been stocked with mosquito-devouring fish-viz., Barbados "millions" (Girardinus poeciloides). Quinine, in packets containing three doses of three grains each, has been for several years obtainable for the sum of one penny a packet at all police stations throughout the island, and in order to still further encourage the people in the use of this drug the free distribution of quinine is shortly to be commenced. A by-law for the city of St. Johns was passed early in the year making it compulsory, under a penalty of 20 pounds, to screen with mosquito wire gauze all tanks, barrels, and other receptacles for storing water, and providing that all fountains, pools or ponds, or artificial excavations, made for any purpose in public or private property, which may contain water, shall be kept stocked with mosquito-destroying fish, or shall be kept covered with a film of petroleum oil. The introduction of this useful measure has done much to rid the city of the dangerous pests."
There are three interesting points in this little exerpt. First, an amazing operation in terms of size and intensity, to distribute mosquito-eating fish throughout the island, considering its size of 281 sq km. Second, to have ready access to quinine, and third, to fine those who pose a threat in terms of malaria by having standing water around the house. Simple and straightforward, and malaria declined as a result. That was a century ago.
Fifty years ago, in 1960, a paper on malaria in Antigua was published by Dr. Uttley, who reviewed the history of malaria on the island between 1857- 1960. He noted that P. falciparum was the dominent parasite, vectored by Anopheles quasalis, but also by An. albimanus. These vectors were considered zoophilic and DDT spraying, although it eradicated disease by 1952, merely led to 'Anophelism without malaria' on the island.
Uttley expressed concern that, following the disappearance of malaria from the island, any re-introduction of malaria could have devastating consequences for the population that would have lost its premunition against the disease. The likelihood of a gametocyte carrier entering the island, infecting mosquitoes, and subsequent transmission, however, was considered small. In fact, it did not happen.
That was 100 and 50 years ago. The island of Principe, off the West African coast is only 136 sq km. Last month, it was reported that the island is entering the pre-elimination phase, after intensive spraying campaigns, use of IPT for pregnant women, ACTs, LLINs, and larviciding, over the period 2003-2008. That's nearly seven years to reach this level of control and a prevalence (July 2009) of just under 1%.
The authors compared this success with that of Zanzibar and Bioko island, and attributed a larger impact on Principe to a combination of tools. However, in the Carribean control programmes in the 1950s eradicated malaria within 2-3 years, making one wonder why elimination is apparently more difficult these days.
Is coverage an issue? Spraying on Principe was done in more than 90% of the houses; not bad. Nets were not well used (~50% of those that received a net actually used it), but it seems hard to find a solid explanation for the persistence of malaria on the island.
Perhaps we need better insight into the control strategies of the past in order to find better explanations for the current difficulties to eradicate malaria on islands such as Principe, Bioko, Zanzibar, etc.