Infectious Diseases Smite the North. Climate Change Partly to Blame

The Northern States of the US, have witnessed a worrying trend of emerging infectious diseases. This is a result of the changes in the environment brought about by erratic climatic conditions. While these diseases have always existed in the wild, the depletion of wildland, as well as disasters like fires, are bringing the wild animals closer to humans.

As wildlife gets closer to people, diseases whose origins can be traced to animals become more common. Over time, humans’ natural defense systems against disease are depleted as incessant illnesses take their toll. This, in turn, makes humans more susceptible to these and other diseases. Then there are climatic disasters like floods that only exacerbate the problem due to contamination of natural water sources.

An Array of Infectious Diseases

According to the CDC Volume 26 report on emerging diseases, zoonotic pathogens have been the top cause of emerging diseases. The following are some of the emerging infectious diseases threatening populations in the Northern states.

Heartland virus

According to the CDC, HRTV is transmitted by ticks, with white-tailed deer, raccoons, and other mammals being hosts.

The first case of emerging diseases from zoonotic pathogens was in 2009, where two cases of Heartland virus (HRTV) were reported in Missouri. Additional cases were then reported in Arkansas, Tennessee, Kansas, Kentucky, Oklahoma, Georgia, Indiana, and South Carolina.

According to the CDC, the virus was transmitted by ticks, with white-tailed deer, raccoons, and other mammals being hosts. In 2018 and 2019, multiple cases were reported across the Northern states where the ticks were sighted in campgrounds and private residential properties.

Dengue virus

The rash that commonly forms during the recovery from dengue fever with its classic islands of white in a sea of red.

In 2018, the North Carolina Health and Human Sciences Department got a case of dengue virus infection. Dengue virus is a highly infectious mosquito-borne infection. The patient was interviewed and had no history of recent travel to areas with the disease.

Eastern equine encephalitis virus

This diagram illustrates the methods by which the arbovirus Eastern equine encephalitis virus (EEEV) reproduces and amplifies itself in avian populations within temperate regions, and is subsequently transmitted to human beings and horses, as the dead-end hosts through the bite of a number of different mosquito species.

EEE (Eastern equine encephalitis) virus has been around for centuries. Before 2019, there were an average of eight reported cases annually. However, in 2019, the numbers rose sharply, with the CDC naming it one of the most severe arboviral diseases in Northern America.

By the end of the year, there was a recorded fatality rate of 64% among patients 70 years and older, and a 22% fatality rate among younger patients. The risk of EEE virus infection rises with changes in climate, especially extensive rain that encourages mosquito breeding.

Lyme disease

National Lyme disease risk map with 4 categories of risk. Map Source: ReliefWeb.

Lyme disease first emerged, and became an epidemic, in the 1970s in Connecticut. The origin was traced to bites from deer ticks. The deer ticks have rapidly spread to other regions, including Northern Wisconsin, Illinois, Michigan, Nebraska, Indiana, and even Northern Canada.

By 2018, there were more than 33,000 cases of Lyme reported, though CDC asserts the numbers of unreported cases could be 10 times more. Lyme disease has also been reported in New York as well as Long Island. There is a rationale that fronts the idea that as daily average temperatures increase due to climate change, ticks’ rate of survival increases, which leads to a notable increase in the abundance of ticks. That said, research into this is still quite limited.

Cryptosporidiosis

Cryptosporidium LifeCycle

Cryptosporidiosis was first reported in New York City in mid-1994. By 2018, close to 4,000 cases were diagnosed in New York. The disease is caused by ingesting water or food contaminated with fecal parasites.

This is because New York City’s water supply is largely unfiltered and the occasional floods don’t make the conditions any easier. The situation is being monitored by the NYC Health and Mental Hygiene Department.

Common Causes of Emerging Infectious Diseases

Michael Peercy, an epidemiologist working with a large Native American tribe in Oklahoma, discusses vector-borne and infectious disease cycle changes and their link to climate change.

About 60% of the disease-causing pathogens come from animals. These could be animals that have found their way to human habitats due to diversity loss through deforestation, wildfires, and changing land use. In a considerable number of cases, introducing farming in previous wild habitats has contributed to the emergence and spread of infectious vector-borne diseases.

Deer ticks are one of the most common causes of emerging infectious diseases. Deer are getting closer to the human population due to continued deforestation as well as wildfires. The deers are only hosts and are never affected.

However, infected ticks can fall off their hosts, and when they bite a human, they transmit infectious diseases. Deer ticks need a warm environment, and the Northern States couldn’t support their survival. However, as the Northern regions get warmer, they become better breeding grounds for these ticks. Climate change has turned some previously inhabitable areas into potential breeding grounds for pathogen carriers.

Dealing with Emerging Diseases

Climate change impacts a wide range of health outcomes. This image illustrates some of the significant impacts of climate change, their effects on exposure, as well as the possible health outcomes resulting from these exposure changes. Source: CDC

The The Northern United States' public health sectors must be adequately prepared to sufficiently deal with today and tomorrow's emerging diseases and infections. Both domestic and global surveillance systems are somewhat inadequate against the strains of diseases that are emerging today.

Waterborne and food-borne diseases, for example, are not always easily recognized or detected. These diseases are not a big problem in developed countries. However, in developing countries, unsafe drinking water and poor water sanitation have greater devastating effects than a combination of terrorism, war, and weapons of mass destruction.

In such places where hospitals are usually many miles away, the mortality rate can be quite high. But given that waterborne and food-borne diseases are preventable, a single death resulting from these diseases is one too many. Additionally, with regular self-medication, these infections can become drug-resistant.

Keeping tabs on infectious diseases in the Northern USA is usually dependent on a voluntary arrangement between the local health departments, the state, and the CDC. As such, in most cases, the reports are limited to known infectious diseases. Therefore, the reporting of emerging diseases could be incomplete, hence late detection.

Council for State and Territorial Epidemiologists recently conducted a survey that documented the inadequacies of emerging disease surveillance. According to the survey, there were a limited number of professionals who were dedicated to surveillance of emerging infectious diseases. Additionally, persistent underfunding of the U.S. public health system creates gaps in the country’s readiness to deal with infectious disease outbreaks.

Is a Climate-induced Pandemic on the Horizon?

Governments and communities alike have a role to play in preventing and preparing for emerging infectious diseases. The CDC plays a vital role in educating communities and individuals on their roles in readiness for emerging health pandemics. It also facilitates local public health departments in preparing for eventualities when dealing with disease outbreaks.

Public Health Emergency Preparedness is one of the cooperative agreements that help with funding preparedness for public health emergencies. Emergency Response Funding has in the past been used to handle health emergencies, especially for emerging infectious diseases.

The CDC also provides an array of resources and tools that are vital to health departments when it comes to strategic planning and preparedness to handle emerging infectious diseases.

As we move into the future, the possibility of a climate-induced pandemic is likely to become more apparent. To prepare, states across the country, as well as the federal government, must put in place clear measures to mitigate these challenges.

Augurisk is a risk assessment platform for Climate Change, Natural Hazards and Societal Risks. We help people and businesses assess climate risks associated with their properties, so they can better prepare for the future.