Zika virus is receiving a huge amount of attention currently as it reaches pandemic levels. Zika virus was detected in 1947 in Zika Forest in Uganda. It was subsequently identified in humans in 1952 in Uganda and the United Republic of Tanzania. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Asia and the Pacific. It is transmitted by daytime-active Aedes mosquitoes including the species A.aegypti and A.albopictus. The World Health Organization has predicted the virus will spread, as the mosquitoes that carry the virus are found in almost every country in the Americas.
According to the CDC, only 1 in 5 people infected with the Zika virus become ill, so many do not even know they are carrying the virus. For those who do experience symptoms, the signs can range from a fever, rash, joint pains, red eyes, headache and muscle pain lasting up to a week. The consequences of being infected can be costly. From October 2015 to January 2016, there were almost 4,000 cases of babies born with microcephaly in Brazil that has been linked to mothers being infected with Zika virus. Before then, there were just 150 cases per year. Although Zika virus has not been confirmed to be the cause of microcephaly, the increasing incidence of the neural abnormality has persuaded several Latin American countries to advise women to delay pregnancy, and Public Health England has advised British men to use condoms for 28 days after returning from an affected country.
Experts have proposed that destruction of forests has resulted in the human population coming into contact with Zika virus. Furthermore, it is believed the growth of cities and even an increase in rubbish are factors behind its rapid proliferation.
Deforestation has been linked to the spread of various diseases such as malaria and ebola. Land cleared for agriculture or urbanisation can collect rainwater better than rainforests. The water can be used as breeding grounds for mosquitoes that carry diseases such as Zika virus.
In the case of malaria, Jonathan Patz and Sarah Olson of the University of Wisconsin reported deforested areas in Kenya were hotter as there were no trees to have a cooling effect. The higher temperatures resulted in a shortened mosquito life cycle, favouring the survival and spread of the vector.
“There are many other factors that have contributed to the emergence [of Zika], but the principal drivers have been human population growth, unplanned urban growth, globalization and lack of effective vector control,” says Peter Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine.
Urban waste can provide a breeding ground for the mosquitoes. “You see not only poverty, but the environmental degradation, uncollected garbage, discarded tires filled with water, areas of un-drained water,” says Durland Fish, a professor of microbial diseases and also forestry and environmental studies at Yale University.
Although there are many suggestions that building dams results in environmental degradation, the dams may be more deadly that originally thought.
Research has suggested that dam construction in sub-Saharan Africa may be responsible for “at least 1.1 million new malaria cases in Africa every year,”. It is believed that water collected by dams can create habitats for malaria-transmitting mosquitoes. The same principle can be applied to suggest why Zika virus is spreading so rapidly.
As the climate of the planet changes, the risk of deadly diseases permeating to new regions of the world increases.
“Globally, temperature increases of 2-3ºC would increase the number of people who, in climatic terms, are at risk of malaria by around 3- 5%, i.e. several hundred million,” concludes the WHO. “Further, the seasonal duration of malaria would increase in many currently endemic areas.”
Rutgers University found, climate change should worsen that spread:
The land area with environmental conditions suitable for Ae. albopictus populations is expected to increase from the current 5% to 16% in the next two decades and to 43%-49% by the end of the century.