Climate change impact on parasitic infections

Impact of Climate Change on Parasitic Infections

Parasitic infections, caused by organisms thriving on or within other living organisms, pose a substantial global health challenge, affecting millions annually. These infections manifest with symptoms ranging from fever and fatigue to intestinal issues, skin rashes, or neurological symptoms. Traditionally associated with factors like contaminated food, water, bug bites, and undercooked meat, there’s a growing concern about the impact of climate change on parasitic infection transmission. As these new factors exert their influence on the environment, it’s vital for pharmacists and other healthcare professionals to understand the epidemiology of parasitic diseases, their symptoms, and treatment options.  

Recommended course: Climate Change and Parasitic Infections 

Epidemiology of common parasitic infections 

Common parasitic infections include: 

  • Protozoa: Single-celled parasites infecting various body parts, including blood, intestines, brain, skin, and eyes. Examples include Malaria, Toxoplasmosis, Giardiasis, Cryptosporidiosis, Trichomoniasis. 
  • Helminths: General term for parasitic worms, categorized into flukes, tapeworms, roundworms, and thorny-headed worms. They primarily infect the intestinal tract but can affect other tissues like the skin and brain. Examples include Pinworms, Tapeworm Infections, and Strongyloidiasis. 
  • Ectoparasites: Insects and arachnids burrowing into the skin, such as ticks, mites, lice, and fleas, usually localized on the skin. A common example is head lice. 

Malaria, Toxoplasmosis, Giardiasis 

Malaria, caused by a parasite transmitted by Anopheles mosquitoes, can be deadly if not promptly diagnosed and treated. While the risk in the United States is low, approximately 2,000 cases are reported annually, mostly among travelers to malaria-prone areas. 

Caused by the protozoan Toxoplasma gondii, Toxoplasmosis has three major genotypes, with type II prevalent in Europe and the United States. While infecting a large portion of the world’s population, clinically significant disease is uncommon, primarily affecting high-risk individuals like fetuses, newborns, and immunocompromised patients. 

Giardia, the most common intestinal parasitic disease in the U.S., affects over a million people yearly. Factors like children’s higher susceptibility, late summer spikes, and travel to areas with poor sanitation increase the risk. 

Cryptosporidium, Trichomoniasis, and worms 

Cryptosporidium, transmitted via the fecal-oral route, thrives in moist environments and is chlorine-tolerant, often spreading through contaminated water. With an estimated 823,000 cases in the U.S. annually, young children and individuals aged 15–44, especially females, are most affected, with international travel as a notable risk factor. 

Prevalence of trichomoniasis in the U.S. is 2.1% among women ages 14-59, with 9.6% in African American women. It is associated with poverty, lower education, and unmarried status. Trichomoniasis increases the risk of adverse outcomes in pregnant women and the transmission of HIV. 

Primarily a pediatric condition, pinworm infection is common in temperate regions worldwide, with transmission through direct contact or contaminated objects. Asymptomatic carriers are common, and treatment has a 90-95% cure rate, but reinfection is common. 

Tapeworms causing taeniasis are global, with specific risks for consuming raw or undercooked beef or pork. While rare in the U.S., taeniasis prevalence varies, with T. solium taeniasis seen among Latin American immigrants. 

Strongyloidiasis and head lice 

Widespread but most common in tropical and subtropical regions, Strongyloides infection prevalence varies, with increased risk in socioeconomically disadvantaged and rural populations. Contact with contaminated soil, particularly through agricultural activities, is a significant risk factor. 

Most common among preschool- and elementary-school-age children, head lice infestation is not related to cleanliness. Direct contact is the primary transmission mode, and an estimated 6-12 million infestations occur annually among children aged 3 to 11 in the U.S. 

What is the impact of climate change on parasitic infections and transmission? 

Climate change profoundly impacts atmospheric conditions, including temperature, precipitation, and weather patterns. These changes play a pivotal role in modifying parasite distribution, prevalence, and transmission, leading to the emergence or resurgence of parasitic diseases 

This effect is particularly pronounced in vector-borne diseases like malaria, where increasing temperatures create favorable environments for mosquito breeding. The shifts in geographic ranges and prevalence of parasites necessitate a proactive approach from healthcare providers. 

Climate effects on vector-borne parasitic diseases 

One of the most significant consequences of climate change on parasitic infections is the alteration of vector-borne diseases. Diseases transmitted by mosquitoes, such as malaria, traditionally associated with tropical regions, are experiencing changes in their geographic distribution. Elevated temperatures and altered rainfall patterns create conducive conditions for mosquito breeding, resulting in a higher prevalence of diseases like malaria in previously unaffected areas.  

Freshwater snails, crucial intermediate hosts for parasites causing diseases like schistosomiasis and fascioliasis, are affected by alterations in water velocity, temperature, and rainfall patterns. Changes induced by climate change in these factors can influence snail abundance and distribution, consequently affecting the dynamics of parasitic infection transmission. Predictions for certain regions of Africa and Asia indicate an elevated risk of schistosomiasis with rising temperatures. 

Protozoa-causing diseases like giardiasis and cryptosporidiosis, transmitted through contaminated water, are also impacted by climate change. Extreme weather events and shifts in precipitation patterns can lead to increased contamination of water sources, contributing to the spread of these parasitic infections. Inadequate wastewater treatment during flooding poses additional risks, as parasites may survive and remain infective in untreated water. 

Soil-transmitted parasites: Helminthiases and macroscopic parasites 

Soil-transmitted helminths, including hookworms, Ascaris lumbricoides, and Trichuris trichuria, exhibit prevalence changes due to climate-induced temperature and humidity alterations. Higher temperatures accelerate the development of larvae and increase survival rates, influencing the transmission dynamics of these helminthiases.

How pharmacists and healthcare providers can prepare for adaptation 

The consequences of global climate change on parasitic infections and public health are increasingly evident. The World Health Organization (WHO) recognizes climate change as a significant threat to global health, estimating an annual toll of 250,000 deaths from climate-related factors between 2030 and 2050.  

In response to this mounting concern, healthcare providers must be ready to implement effective measures to prevent and manage diseases influenced by climate change. Here are the reviews of health interventions for preventing climate-sensitive diseases and explore how healthcare providers can adjust to meet these challenges. 

Understanding climate-sensitive diseases 

Climate-sensitive diseases are those whose transmission and incidence are affected by climatic factors such as temperature, rainfall patterns, and climate variability. Examples include dengue, malaria, and American tegumentary leishmaniasis. The prevalence and distribution of these diseases are expected to rise as climate change creates favorable conditions for disease vectors and pathogens. 

The scoping review identifies health interventions at three levels: macro, meso, and micro. Each level corresponds to different aspects of management involving national/international health systems, local health systems, and individual elements. 

  1. Macro-level interventions: Healthcare professionals, including epidemiologists, programmers, and public health specialists, play a critical role at the macro level. Interventions include using early warning systems, implementing renewable energy strategies, and developing public policies sensitive to climate issues. Collaboration among decision-makers at national and international levels is essential for the effectiveness of these broad public health programs. 
  2. Meso-level interventions: Municipalities are the focus at the meso level, involving local health systems and broader economic and social structures. Urban planners and decision-makers are responsible for interventions such as risk mapping, insecticide spraying, water security plans, sanitation programs, and vaccination of animal reservoirs. Collaborative efforts at this level contribute to preventing climate-sensitive diseases within specific regions. 
  3. Micro-level interventions: The micro level targets individuals and requires a more personalized approach. Healthcare professionals at this level, including veterinarians, physicians, and nurses, implement interventions such as anxiety reduction strategies, health screenings, and protective measures like wearing light-colored clothing and using mosquito repellents. These interventions directly impact individuals and contribute to overall prevention efforts. 

Diagnosis, treatment, and management of parasitic infections  

Managing parasitic infections encompasses a comprehensive understanding of their transmission, diagnosis, treatment, and prevention.Parasites, ranging from single-cell protozoa to multi-cellular worms, thrive at the expense of their hosts. Protozoa like Giardia and Plasmodium can cause infections in the intestine or bloodstream. Worms such as hookworms and tapeworms lay eggs or larvae in the environment. 

Parasites typically infiltrate the body through the mouth or skin. Fecal-oral transmission occurs when contaminated hands or objects introduce parasites into the mouth. This is often due to insufficient handwashing, contaminated food or water consumption, or activities like swimming in polluted areas. Skin transmission involves parasites entering through direct skin contact or insect bites. 

Crucial to diagnosing parasitic infections is the laboratory analysis of various samples, including blood, stool, urine, skin, or sputum. Testing may involve identifying parasite proteins or genetic material, with multiple samples often needed for accurate identification. For intestinal parasites, microscopic examination of stool samples is a common diagnostic method. 

Antiparasitic medications are specifically prescribed to eliminate or reduce parasite numbers. The effectiveness of these medications is tailored to specific parasites, and treatment approaches may vary. Some parasitic infections resolve independently, while others necessitate targeted interventions using antibiotics or antifungal medications. 

Predicted changes impacting healthcare providers 

Healthcare professionals face several key challenges in managing parasitic infections across the globe. 

  • Globalization and travel: The surge in globalization and travel is likely to expose healthcare providers to patients who have contracted parasitic infections in various regions. That underscores the importance of a comprehensive understanding of the geographical distribution of parasites and the capacity to diagnose and treat infections acquired abroad. 
  • Climate change: Alterations in climate patterns can change the distribution of parasites and their vectors. Healthcare providers need to be ready to adapt to the evolving prevalence of parasitic infections in specific regions. They must also address emerging challenges related to diseases sensitive to climate variations. 
  • Immigration and vulnerable populations: Parasitic infections tend to be more prevalent in immigrants, international travelers, and populations with weakened immune systems. Healthcare providers should be equipped to handle the distinctive challenges faced by these vulnerable groups. These challenges encompass cultural considerations, healthcare accessibility, and potential delays in diagnosis. 
  • Antimicrobial resistance: The escalating threat of antimicrobial resistance jeopardizes the effectiveness of antiparasitic medications. Healthcare providers must stay abreast of emerging resistance patterns. They must collaborate with researchers and public health agencies to formulate strategies for responsible medication use. 
  • Vaccine development: Despite existing limitations, continuous research may lead to the creation of vaccines for additional parasitic infections. Healthcare providers will play a pivotal role in vaccine administration, education, and monitoring of the impact of vaccination on reducing the burden of parasitic diseases.