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Cryptosporidiosis: A Significant Threat to One Health

September 24, 2025
Muhmamad Arslan

Cryptosporidiosis: A Significant Threat to One Health

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Munwar Ali 1, Ali Hassan Nawaz2, Kun Li 1

1 College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, PR China; drmunwarali06@gmail.com, lk3005@njau.edu.cn

2 College of Animal Science and Technology, Nanjing Agricultural University, Nanjing 210095, PR China ah93163@gmail.com

Graphical abstract

Abstract

Cryptosporidium spp. is a protozoan parasite of critical One Health importance, posing a substantial threat to global public health and causing significant economic losses in the livestock industry. This extension article synthesizes current knowledge to comprehensively assess the cryptosporidiosis landscape. We elucidate its complex life cycle and high prevalence rates in human and animal populations, underscoring its profound zoonotic potential. The analysis highlights the primary transmission routes, particularly through water and food, by examining major global outbreaks to demonstrate the scale of contamination risk. The significant production losses associated with animal infections are also quantified. Crucially, this article consolidates integrated preventive and control strategies, research gaps, and future perspectives.

Introduction

Cryptosporidium, a genus of protozoan parasites, is responsible for cryptosporidiosis. It was first discovered in the early 20th century [1] and later attracted greater attention due to its increasing prevalence, wide host range, zoonotic potential, and its unique characteristics, which proved lethal in immunocompromised individuals [2]. It ranked fifth among 24 foodborne parasites worldwide [3]. Contaminated drinking and recreational water [4,5], consumption of vegetables [8], raw milk, and apple cider [5] lead to outbreaks. During 2010 to 2020, in 96.5% of Cryptosporidium-food-related pathologies, C. parvum was detected as an etiological agent [9].

The parasite can infect fish, amphibians, reptiles, birds, and mammals [10], resulting in huge economic losses to the veterinary sector [11] and zoonotic transmission. The 1993 Milwaukee waterborne outbreak affected 400,000 individuals with 69 deaths [12,13]. Between 2011-2016, 63% of Cryptosporidium-related waterborne outbreaks led to 4.2 million disability-adjusted life years (DALYs) [14]. According to the Global Enteric Multicenter Study (GEMS), cryptosporidiosis ranked as the second leading cause of diarrhea in infants, responsible for approximately 202,000 deaths annually [15]. Overall, cryptosporidiosis is an ever-increasing challenge to the food and water industry, negatively influencing both public health and livestock sectors [3,16].

Potential Risk Factors Fostering Cryptosporidium Spread

The spread of Cryptosporidium infection is linked to contact with contaminated animals, age, gender, poverty, illiteracy, sexual practices, population density, seasonal variations, swimming, immune status, occupational activities, natural disasters, and political disputes [16,17]. Seasonal variations rely on temperature, parasitic species, and water source [18]. Spring peaks may indicate livestock activities like calving, while late-summer surges correlate with recreational water use [19,20].

Infectious Life Cycle of Cryptosporidium spp.

The life cycle culminates in fecal release of contagious oocysts [24]. Upon ingestion, excystation releases sporozoites that invade intestinal epithelial cells, undergoing asexual (merogony) and sexual (gametogony) reproduction [25]. This produces thick-walled oocysts (shed into the environment) and thin-walled oocysts (causing autoinfection) [26]. The new generation can emerge in 12-14 hours [27]. Infection causes villus atrophy, inflammation, and secretory diarrhea [28,29]. In immunocompromised patients, infection can become chronic and extra-intestinal  (Figure 1) [30].

Figure 1. Infectious life cycle and pathogenesis of Cryptosporidium species

Figure 1. Infectious life cycle and pathogenesis of Cryptosporidium species

Cryptosporidium oocysts, after ingestion, complete their asexual and sexual life cycle in the epithelial cells. Upon completion of the infectious life cycle, thin-walled oocysts usually cause autoinfection within the same host, while thick-walled oocysts are released in the environment and infect new susceptible hosts (e.g., calves).

Zoonotic Transmission: Water and Foodborne

Humans are sensitive to diverse Cryptosporidium spp., particularly C. parvum and C. hominis [31,32]. C. parvum has an extremely wide host range and significant zoonotic potential due to livestock interactions [9,33]. C. andersoni has been found in humans in China [34,35], and C. bovis has been detected in humans with livestock contact [36,37]. C. suis has been detected in HIV patients in several countries [38,39]. Contaminated water is a primary vehicle for cryptosporidiosis (Figure 1); oocysts are highly resistant to chlorine, allowing them to bypass conventional water treatment [5,40].

Figure 2. Diverse pathways for the spread of Cryptosporidium oocysts

Figure 2. Diverse pathways for the spread of Cryptosporidium oocysts

This figure shows different transmission routes of Cryptosporidium oocysts between humans and animals involving different agricultural practices. By breaking transmission routes, the outbreaks can be prevented.

Cryptosporidium and Public Health

Cryptosporidium is classified as the 5th most significant foodborne parasitic infection globally [3]. Food exposure may occur during manufacturing, with oocysts harbored on fresh produce [41]. Swedish foodborne epidemics have been linked to contaminated arugula, parsley, and spinach juice [42,43]. Agriculture contributes to water contamination through farm-based effluents [44,45]. The use of contaminated water for irrigation and animal manure as fertilizer facilitates the spread [46]. Wildlife may also transmit C. parvum to the environment [47].

Cryptosporidium and Livestock

Prevalence of Cryptosporidium spp. is high: 27.8–60.4% in pigs, 18% in calves, and 28.5% in cattle [48,49]. In calves, species prevalence is age-dependent; C. parvum infects young calves, while C. bovis is prominent in older calves [50]. C. hominis has been detected in cattle, sheep, goats, and other animals, highlighting potential animal reservoirs for human infections [33,51]. Molecular studies have identified various species in wildlife, including C. scrofarum in wild boars and C. ubiquitum in hedgehogs [52,53], emphasizing the complex transmission cycles.

Preventive and Control Measures

Due to a lack of effective medications or vaccines, precautionary steps are essential. These include hand hygiene, boiling water, avoiding untreated water and raw food, and disinfecting contaminated surfaces. For animals, rotational grazing, colostrum management, and isolation of sick animals are recommended. Waste treatment methods like composting and anaerobic digestion reduce oocyst burden. Adopting a circular economy approach for agricultural waste is encouraged. Epidemiological investigations and One Health approaches are critical for control.

Research gaps and Future Perspectives

While the immunofluorescence antibody test (IFAT) is reliable, cost-effective molecular methods like PCR targeting the gp60 gene are needed for routine surveillance. Next-generation sequencing (NGS) can improve diagnostic accuracy. Research on gp60 protein host interactions, gut microbiota changes during infection, and genetic manipulation using CRISPR/Cas9 may reveal new therapeutic targets. MicroRNA regulation appears significant in host defense. Systematic studies on anti-Cryptosporidium mechanisms in different herds are needed. Better molecular understanding of transmission dynamics will aid in developing precisely adjusted control plans.

Conclusion

A variety of Cryptosporidium species and genotypes, with a broad host range, pose a major threat to food and water safety. Their zoonotic potential creates an increasing burden on public health and veterinary sectors. Frequent outbreaks worldwide call for urgent control measures. Current therapeutics are insufficient; development of an effective vaccine, improved control strategies, and potent drugs are essential to reduce cases and eliminate outbreaks.

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