South African health authorities on Tuesday issued a malaria alert after high numbers of malaria cases were reported.

The Department of Health said everyone is at risk of contracting malaria in malarious areas.

But children under five years of age, pregnant women, people with compromised immune systems, travelers from non-endemic areas and immigrant workers are at higher risk.

According to the department, high numbers of malaria cases are being reported in the malaria transmission areas in South Africa's northern region.

Vhembe and Mopani districts in Limpopo Province and Bushbuckridge in Mpumalanga Province are the most affected, the department said without disclosing the number of reported cases.

Compared to previous years, a modest increase in cases in the Kruger National Park and private game reserves in the area have been confirmed, department spokesperson Popo Maja said.

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This follows a very busy 2017 malaria season in the entire Southern African region, which peaked in April and May before extending into June.

Maja said high rainfall, humidity and ambient temperatures provide ideal conditions for malaria mosquito breeding and contributes to an increase in malaria cases.

According to the South African National Institute for Communicable Diseases, unusual malaria cases, affecting persons with no recent history of travel to malaria transmission areas, have been reported in Pretoria and some other nearby places.

One patient has died.

The key prevention strategy of the malaria control programs in endemic areas is spraying of households with long acting residual insecticides, or indoor residual spraying (IRS), which target indoor feeding mosquitos.

This IRS program is in progress in both Limpopo and Mpumalanga and is planned to target a larger area than in 2016, Maja said.

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