Infectious Disease Outbreaks Correlated To Deforestation, Forest Conversion

Commercial plantations, land abandonment, and grassland conversion to forests are potentially detrimental and these are no substitute for preserving the world's existing forests.

A new study published in the Frontiers in Veterinary Science has found that deforestation, commercial palm plantation, and certain types of reforestation are correlated with the increasing outbreaks of infectious disease.

The vector-borne diseases like those carried by mosquitos and ticks–as well as zoonotic diseases, like Covid-19 which jumped from an animal species into humans are potentially contributed by the changes in the forest the study found when it studied the first global look of the diseases.

The lead author Dr Serge Morand, who has joint positions at the Centre National de la Recherche Scientifique (CNRS) in France and Kasetsart University in Thailand said, “We do not yet know the precise ecological mechanisms at play, but we hypothesise that plantations, such as oil palm, develop at the expense of natural wooded areas, and reforestation is a mainly monospecific forest made at the expense of grasslands.”

“Both land-use changes are characterized by loss of biodiversity and these simplified habitats favor animal reservoirs and vectors of diseases.”
The negative impact of biodiversity and human health generally is widely recognized by the land use and disease outbreaks deforestation.

According to reports, deforestation in Brazil has already been linked to malaria epidemics, but the consequences of deforestation and forest cover globally changes human health and epidemics have not been studied in detail.

Morand and his colleague looked at changes in forest cover around the world between 1990 and 2016, to understand these effects better. These results were then compared by the local population densities and outbreaks of vector-borne and zoonotic diseases. They also looked at reforestation and afforestation specifically which included the conversion of natural grasslands and abandonment of agricultural land.

However, there are several studies that had prior claimed that both afforestation and palm oil plantations likely play a role in further spreading disease vectors. They found that both deforestation and afforestation had significant correlations to disease outbreaks after confirming the past hypotheses.

A strong association was found between deforestation and epidemics (such as malaria and Ebola) in tropical countries like Brazil, Peru, Bolivia, Cameroon, Indonesia, Myanmar and Malaysia, and the Democratic Republic of Congo.

In contrast, temperate regions like the USA, China, and Europe showed clear links between afforestation activities and vector-borne diseases like Lyme disease.

However, their approach did not show any difference between the different types of reforestation activities but they did find a significant increase in disease outbreaks in countries with expanding palm oil plantations.

In the region of China and Thailand, this was especially striking where there was relatively little deforestation.

These areas appeared particularly susceptible to mosquito-borne diseases like dengue, zika, and yellow fever. Healthy forests for a healthy planet These results suggest that careful forest management is a critical component in preventing future epidemics.

Commercial plantations, land abandonment, and grassland conversion to forests are potentially detrimental and these are no substitute for preserving the world’s existing forests.

“We hope that these results will help policymakers recognize that forests contribute to a healthy planet and people, and that governing bodies need to avoid afforestation and agricultural conversion of grasslands,” says Morand.

“We would also like to encourage research into how healthy forests regulate diseases, which may help better manage forested and planted areas by considering their multidimensional values for local communities, conservation, and mitigation of climate change.”

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