Science

Climate change clouds SA's plans to eradicate malaria

Sarah Wild

As the "malaria belt" widens, research shows that changing climates may be a major challenge to SA's ambitious plan to destroy the deadly disease.

Changing climates and the movement of risk areas mean that even if South Africa manages to eliminate malaria within its borders by 2018, the disease and mosquitos may adapt. (AFP)

South Africa plans to eradicate malaria inside its borders by 2018, but the changing climate may be one of its greatest obstacles. The country is one of the world's success stories in the fight against the deadly mosquito-borne disease. Between 2000 and 2012, malaria incidence and mortality decreased 89% and 85% respectively: from 64 500 to 6 847 malaria cases and from 460 to 70 deaths.

However, as the "malaria belt" widens, new climate research shows that changing temperatures and rainfall patterns may be a major challenge to South Africa's ambitious eradication target. "The [malaria] risk due to climate seems to increase over South Africa," says Cyril Caminade, from the Institute of Infection and Global Health at Liverpool University. "Malaria has been decreasing over the country ... But [the] climate may become more suitable for malaria."

Caminade and colleagues' research, published earlier this year in the Proceedings of the National Academy of Sciences journal, found "an overall global net increase in climate suitability and a net increase in the population at risk".

This risk is already skewed toward Africa. According to the World Health Organisation, in 2010 there were about 219-million malaria cases, with an estimated 660 000 malaria death. Ninety percent of all malaria deaths occurred in Africa, mostly among children under five.

'Increase of the malaria burden'
An added complication is that malaria is also being found at higher altitudes; areas that historically were not malaria prone. A study published in scientific journal Science earlier this month shows "evidence for an increase in the altitude of malaria distribution in warmer years ... [This] implies that climate change will, without mitigation, result in an increase of the malaria burden in the densely populated highlands of Africa and South America."

"When we talk about climate change, we expect an increase in not only malaria areas, but the distribution [of malaria and how it is transmitted] might change, causing new challenges for us," says Tiaan de Jager, director of the University of Pretoria's Centre for Sustainable Malaria Control. "It's all about the temperature, humidity, water suitable for breeding sites and larval development. Climate change [poses] more challenges to the strategy for malaria control."

South Africa spent an average of $25-million annually between 2009 and 2012 on malaria control, according to the Roll Back Malaria Programme country report.

The country's main tools for fighting malaria are indoor spraying of the DDT chemical in homes in high-risk areas, rapid diagnostics, technician training and disease treatment. There are also numerous research initiatives – from the habits of mosquitos to drug development – at universities and research councils around the country.

Malaria is endemic in Limpopo, Mpumalanga and KwaZulu-Natal, where there are eradication programmes for different stages of elimination – something which health authorities consider a hindrance as each area has to be addressed differently, rather than the implementation of a national blanket approach. But changing climate could mean that it may become endemic to other provinces as well.

Malaria control is complex
The problem of malaria control is complex. The disease is carried by a specific kind of mosquito, which infects humans. "We believe it's not one aspect of control that's going to solve the problem," De Jager said, adding that all aspects needed be investigated, from the mosquitos through to human patients, and all the transmission stages along the way.

But while health authorities try to bring localised malaria under control, the incidence of imported malaria is growing, particularly to areas where the disease is not endemic, such as Gauteng. "Between January and December 2012, 69% of all malaria cases (6 847 cases) reported were imported from Mozambique and Zimbabwe," the department of health said.

"Travelling malaria" is a major concern for South Africa, particularly when people travel to malaria areas in bordering countries during December and January – the peak malaria risk season – and return infected with malaria, or with mosquitos. Professor Anton Stoltz, an infectious diseases specialist based at Steve Biko Academic Hospital in Pretoria, says, "We don't have malaria in Gauteng, but [sometimes] when people come here, they bring [malaria] from somewhere else."

Speaking about two deaths at the Steve Biko Academic Hospital from malaria – when the patients had not left the province – he said: "We [with members of the National Institute for Communicable Diseases] tried to go and find the mosquitos. It was like looking for a needle in a haystack," Stoltz said. "In December, [when people] go north [to malaria-areas], there is a big chance they can bring mosquitos back."

De Jager said that it is possible the mosquitos can be brought into South Africa by accident in cars. "They spray aeroplanes for pest control when they enter and leave. Perhaps one should consider doing the same thing for motor vehicles. We are looking at border post research now," he said.

 "We can have effective strategies in South Africa, but if we don't address the bigger [regional] area, we are going to end up in trouble again."

'Funded by government'
Aaron Mabuza, Mpumalanga malaria control manager, says: "South Africa is in the fortunate position that malaria control is 100% funded by government. This has resulted in stable funding over many years, leading to the successful implementation of the national malaria control policy."

However, bordering countries are not as fortunate. While there have been successful cross-border initiatives – such as the Lubombo Spatial Development Initiative with South Africa, Mozambique and Swaziland, and the Moziza Initiative between Mozambique and Zimbabwe – the funding for these programmes has dried up.

There is a concern that the same thing will happen to South Africa if malaria is considered "eliminated". Phillip Kruger, Limpopo malaria control programme manager, says: "As the incidence of malaria declines in South Africa, there will likely be calls for re-allocating malaria control fund to deal with other pressing health needs in the country."

However, changing climates and the movement of risk areas mean that even if South Africa manages to eliminate malaria within its borders by 2018, the disease and mosquitos may adapt.


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