COMOROS: The battle against malaria lies in the balance

03 Dec 2010
IRIN News
On arrival in Moheli, an island in the Comoros archipelago, you have to prove that you are taking, or have taken, anti-malarial drugs, otherwise you will have to swallow a pill provided by the authorities.

The precaution is part of a three-year campaign sponsored by the governments of Comoros and China to control or even eradicate the mosquito-borne disease by eliminating the parasites that cause malaria from the population, thereby preventing transmission of the disease.

Mosquitoes feed off an infected host, ingesting the gametocyte forms of the parasite, which then transform into infectious sporozoites and are transferred to the next human hosts when the infected mosquito bites them.

In Africa the most dangerous and prevalent malarial parasite is Plasmodium falciparum. Symptoms of the disease include fevers, vomiting, diarrhoea, anaemia, convulsions and muscle spasms, and appear about 10 days, but often longer, after a human host has been infected.

Rachadj Attoumani, who is responsible for Moheli's malaria surveillance, told IRIN that there has not been "one recorded death from malaria [on the island] ... whereas before about two or three people died each month," since the campaign began in October 2007.

The main components of the project are the mass distribution of anti-malarial drugs produced by the Chinese pharmaceutical company, Artepharm, a DDT spraying campaign, and insecticide-treated nets - which now cover 90 percent of the island's beds - provided by the World Health Organization.

Moheli has about 42,000 people, of whom about 82 percent have taken anti-malarial drugs; those who have not were either not on the island, or had refused, Attoumani said.

The drug campaign required "sensitization" of the recipients, but many, including Attoumani, had experienced debilitating and recurring malaria, and the opportunity to rid their systems of it had provided the incentive.

The medication is a formulation based on artemisinin and piperaquine that the producers say on their website "has a synergistic effect which reduces the infectivity of the [malarial] gametocytes and clears the gametocytes in their early stage, therefore blocking malaria transmission."

There has been concern about the anti-malarial drug from some quarters, as it has not been subjected to any rigorous scientific peer review.

The roll-out of the course of medication island-wide - assisted by a team of 11 researchers from China's Guangzhou University of Traditional Medicine - began with two tablets administered in the first 48 hours, a single dose on the tenth day, and then at intervals of ten days for the next six months.

Children between the ages of one and seven years were given the drug in a soluble granular form, but babies and pregnant women were excluded from the campaign.

Surveillance ahead of the project found that rates of infection varied across the island, but all leant towards endemic levels. Ndremeani had the highest rate of malarial parasites - 94 percent of the villagers were infected - in Hagnamoida 48 percent were infected, but in Fomboni, the island's capital, only about 10 percent of the people were infected.

In the immediate aftermath of the mass drug programme, malarial parasites were reduced to 0.5 percent among the population, and were currently hovering around 1.5 percent, Attoumani said.

Islands as anti-malarial experiments

Islands have often been seen as ideal for malarial elimination because population movements are limited and the land mass is isolated, and a range of approaches have been tried.

The Mediterranean island of Sardinia, where malaria is thought to have arrived in 502 BC during the Carthaginian conquest, has been known since classical times as the "unhealthy island". Between 1946 and 1950 the Rockefeller Foundation spent millions of dollars on trying to eradicate mosquitoes - the vector for the disease - by spraying 267 tons of DDT. The experiment did eliminate malaria, but the stated objective of ridding the island of mosquitoes was not achieved.

On the neighbouring French island of Corsica a multi-pronged approach was adopted. Marshland was drained and now delivers 60 percent of the island's agricultural production. Systematic DDT spraying campaigns were carried out, coupled with the large-scale distribution of the anti-malarial medication, quinine, and the introduction of Gambusia fish, which feed on mosquito larvae, led to the eventual eradication of malaria.

Mauritius was exposed to the mosquito-borne disease in 1865 and two years later experienced an epidemic that killed between an eighth and a quarter of the population in a calendar year. After a long campaign of indoor spraying, the island was declared malaria-free by the World Health Organization in 1973.

Aneityum, one of the 80 inhabited islands of Vanuatu in the southwest Pacific, successfully eliminated malaria using a similar approach to what is being tried in Moheli.

During a period of about two months in 1991 the entire population of 718 people were administered weekly doses of chloroquine, pyrimethamine/sulfadoxine (Fansidar) and primaquine, and all slept under insecticide-treated nets. A monitoring programme over the next nine years recorded only two instances of malaria, both a consequence of infections from outside of the island.

Risks of re-infection

However, the scale of the Moheli experiment sets it apart from the experience of Aneityum Island, but reducing the malarial parasite on the Comorian island is not without risk.

Attoumani said when people had malarial parasites there was also a level of immunity, but after treatment this immunity tailed off, and should "someone be infected with malaria, the symptoms will develop quickly".

In the 1940s and '50s the French colonial government in Madagascar began a DDT spraying and disease monitoring programme to control malaria in the highland regions of the country, but in the 1970s, more than a decade after independence, this came to a halt. A malaria epidemic subsequently broke out in the area and is estimated to have killed 40,000 people in five years.

In 11 of Moheli's 26 villages, monitoring laboratories staffed by single operators with a few months' training, who are paid US$20 a week, take blood samples and rapidly diagnose any malarial parasites with the aid of a microscope.

Benechieq Chema, 28, studying for his baccalaureate, is on call every day in the laboratory in the village of Wanani, with a population of about 2,500 people in a banana, cassava and potato farming area about 20 km from Fomboni. He told IRIN that "maybe a couple of people will come", complaining about a fever and want to be tested for malaria.

"If someone tests positive [for malaria], which is very rare, I immediately give them [anti-malarial] medicine, as well as their family, and then inform [Fomboni] about the case," he said.

However, it is the friends or family returning to Moheli from visits or work on the neighbouring Comorian islands of Anjouan and Grand Comore, where malaria remains at high levels, that pose the greatest risk of an outbreak.

Nationwide roll-out?

Although the two main points of entry, the airport and seaport, have strict malaria controls in place, an aid worker who declined to be named, told IRIN that in reality "you cannot hermetically seal the island".

Comoros is a nation of seafarers and it is not unusual for people to arrive on Moheli on small fishing boats without going through a formal point of entry. A Moheli resident who preferred to remain anonymous told IRIN that occasionally the officials were not at their posts when a plane or ferry arrived.

Attoumani said the key to sustaining very low rates of malarial infection on Moheli, or even eliminating the disease, was the other two islands in the archipelago.

The government of Comoros is encouraging better transport links between the islands as a way of fostering greater national unity because the three-island nation has endured more than 20 coups and secession attempts since independence from France in 1975, but this also increased the risk of malaria transmission between the islands.

Attoumani said China had dispatched medicines and microscopes to the Comoros for the roll-out of the initiative on Anjouan and Grand Comore - which have much larger populations - but the Comoros government did not have the financial resources to pay staff for the monitoring component of the programme.

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