Posts or Comments 24 June 2024

Climate &Ecosystems &Elimination &Environment &Equity &Gender &Genetics &Monitoring &Mosquitoes &Research &Surveillance Bill Brieger | 25 Apr 2024 08:39 am

Drought, Malaria, and Climate Equity

The 2024 World Malaria Day Theme of “Gender, Health Equity, and Human Rights” cannot be divorced from the inequities of climate change wherein the countries that contribute the least to the problem suffer the most, including the deleterious effects of changing malaria geographics. The current severe drought in Zambia, Zimbabwe, and Malawi is a case in point.

As a recent headline in VOA news states, “UN officials in Zambia to assess worst drought in 20 years.” The government has declared a drought officially where it “has affected a total of 8 provinces across the country with highest impacts in Southern, Central, Eastern, North-western, Western, and Lusaka Provinces.”

Drought should not be confused with a “normal” dry season. What we are seeing in Southern Africa now is an extended dry period in what should have been the rainy season. A study in Mali suggests that adult malaria-carrying mosquitoes “have endured the dry season by aestivating—the hot-weather equivalent of hibernating.” Unfortunately, an extended dry period of a drought may be more difficult to endure for the adults, but possibly the eggs are more resistant. Additional studies paint a more complicated picture.

Weather cycles intensify with climate change. El Niño, which can lead to droughts also produces warming in higher elevations so there tends to be an increase in malaria transmission in areas in the highlands.

Research in Zambia published just two years ago reported increasing trends of malaria in areas covering over 47% of all health facilities, while a declining trend was seen in areas covering 27% of health facilities. The decreasing trend was noticeable in the south, where malaria risk is lowest, and current drought conditions higher. The authors stress the need for continued geographic surveillance and implementation of control strategies geared to the conditions in each area.

A systematic review of the effects of climate change identified “vector borne disease (including malaria, dengue and West Nile Virus)” as a major concern as well as “nutrition-related effects (including general malnutrition and mortality, micronutrient malnutrition, and anti-nutrient consumption),” which compromises the ability of children to fight disease. The review found different impacts of drought ranging from increase mortality a year after a drought, to the disappearance of some vector species. The lesson is that each country needs to monitor their situation carefully. For Zambia, UNICEF reports that, “significant number are children, at risk of food insecurity, acute malnutrition, and disease.”

Research on drought effects on malaria arose from a study that examined the effects of drought on malaria infection (genetic) complexity and transmission in lizards (Plasmodium mexicanum and Sceloporus occidentalis). The authors noted that, “relationship between rainfall and parasite prevalence is somewhat more ambiguous.” Thus, the authors recommended that more information is needed about human malaria parasites and drought since “drought may cause shifts in human disease outcomes independent of any changes to prevalence.”

The United Nations challenges us by observing that, “Due to the complex relationship between malaria and climate change, gaps in knowledge still exist in the mechanisms of the linkage.” Changes in temperature, rainfall, and humidity need to be monitored for effects on vectors, parasites, and human movement. The current situation requires a more nuanced and complex approach to interventions if malaria elimination can be achieved while also preventing gender discrimination, promoting health equity and preserving human rights.

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