Cryptosporidiosis in Renal Transplant Recipients: Uncovering Risk Factors, Treatment Strategies, and the Role of Food Handlers in Transmission

Introduction

Diarrhea is a common yet underestimated complication of kidney transplantation, significantly impacting the quality of life and leading to serious complications such as dehydration, malabsorption, and increased risk of graft loss. Renal transplant recipients (RTRs) are particularly vulnerable to various diarrhea-causing organisms, including Clostridium difficile, Cytomegalovirus, Norovirus, and Cryptosporidium. This article focuses on Cryptosporidiosis, a parasitic infection that poses a significant health risk to immunocompromised individuals. Immunosuppressive therapy, while essential for preventing organ rejection, weakens the immune system, leaving RTRs more susceptible to infections like Cryptosporidium, which can cause severe illness and in some cases, be life-threatening.¹ Studies have shown a 10–30% prevalence of Cryptosporidium infection in RTRs with chronic diarrhea.^1,2 The disease severity is further compounded by its potential to cause acute graft dysfunction and prolong hospitalizations. Research indicates that 18–83% of RTRs with cryptosporidiosis experience renal graft dysfunction, which can lead to graft loss in severe cases.^3,4 While the prevalence of Cryptosporidium infections varies by region and population, it is significant among individuals with compromised immunity.⁵ Several factors, such as the type of immunosuppressive regimen, food handling practices, and hygiene, can influence infection risk and severity.^1,6 Medication like nitazoxanide and fluoroquinolones is available, but the optimal management strategy for Cryptosporidium in RTRs remains unclear.⁶ This study aims to assess the prevalence, risk factors, and treatment options for cryptosporidiosis among RTRs, with a particular focus on the role of food handlers in transmission.

Materials and Methods

This retrospective study was conducted at Osmania General hospital in South India from January 2022 to January 2023. We identified RTRs with diarrhea who required evaluation and hospitalization. Inclusion criteria encompassed all RTRs presenting to the hospital with diarrhea (both OPD and IPD patients). All underwent stool analysis for Cryptosporidium, along with the food-handlers, routinely. This protocol ensured that both patient and food handler data were systematically documented in the medical records. Cryptosporidium was detected through stool microscopy using acid-fast staining and confirmed with fluorescent microscopy. Data were extracted from medical records using a standardized data collection form. Patient's consent was taken stating that all data would be anonymized. Ethics committee approval was not required as it was retrospective data collection.

Information collected included patient demographics, including age, sex, education status, dietary habits (vegetarian or non-vegetarian), source of drinking water, and native kidney disease. Transplant data, including type of transplant (live or deceased donor), type of induction therapy, maintenance immunosuppressive regimen, history of recent rejection episodes (within the last 6 months) treated with either anti-thymocyte globulin (ATG) or pulse steroids, and the time gap between Cryptosporidiosis and induction or recent rejection treatment, were collected. Clinical details including extra-gastrointestinal presentations, co-infections (e.g., Cytomegalovirus-CMV, Parvovirus B19, Tuberculosis-TB, Salmonella), hospitalization requirement, graft dysfunction, treatment regimens (monotherapy with nitazoxanide or combination therapy with nitazoxanide plus macrolides &/ fluoroquinolones), modifications in immunosuppression, and treatment duration were noted. Food handlers of all patients were subjected to stool microscopy with acid-fast staining and fluorescent microscopy. Treatment protocols and modifications in immunosuppression have been elaborated in Figure 1. Treatment response was assessed by clinical symptom resolution and/or oocyte clearance, as determined by twice-repeat microscopy. Remission was defined as the resolution of symptoms combined with oocyte clearance. If oocyte clearance was achieved but symptoms persisted, patients were evaluated for other causes, such as CMV, Clostridium, or malabsorption syndrome. Tacrolimus levels were measured during diarrheal episodes in case of renal dysfunction or features suggestive of tacrolimus toxicity. Doses were adjusted according to their levels. Follow-up was conducted to monitor for relapse in patients who achieved remission, evaluate recovery in those with graft dysfunction, and adjust immunosuppressive medications once remission was attained. Food handlers were referred to family members for living with and preparing meals for RTRs throughout their illness. Due to close contact with the patients, stool samples from them were assessed for potential transmission. When Cryptosporidium was detected in the food handlers, they were educated on proper hygiene practices, but no treatment was administered as all remained asymptomatic. The study used comprehensive electronic medical records with minimal missing data, primarily related to follow-up information for patients who passed away during the study. These cases were excluded from follow-up analyses to ensure they did not affect the overall findings.

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Figure 1:

Management protocols followed in RTRs visiting hospital with diarrhea. RTR: Renal transplant recipient, CMV: Cytomegalovirus, MMF: Mycophenolate mofetil, MPS: Mycophenolate mofetil sodium, AFB: Acd fast bacilli, BD: Twice in a day.

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Results

A total of 96 RTRs were followed up, with 60 experiencing diarrhea. Among these, 18 (30%) were diagnosed with Cryptosporidium infection. The mean age of the participants was 36.7 ± 7.9 years; a majority were male (66.7%). The main causes of kidney disease were chronic glomerulonephritis (CGN) (n=9, 50%), chronic interstitial nephritis (CIN) (n=5, 27.8%), CKD-unknown (n=3, 16.7%), and other causes (n=1, 5.6%). Regarding educational status, 22.2% had no formal education, 22.2% had primary schooling (10^th grade), 33.3% had secondary/ higher secondary education (12^th grade), and 22.3% were graduates [Table 1]. Around 83.3% of participants were non-vegetarians. Approximately 83.3% used municipal (chlorinated) water, while 27.8% relied on groundwater (boiled). Thirteen (72.2%) and five (27.8%) transplants were from living and deceased donors, respectively. Induction therapy with ATG was administered to 66.7% of participants, while 33.3% did not receive it. All patients (100%) were maintained on triple immunosuppression therapy with mycophenolate mofetil (MMF), tacrolimus, and prednisolone. Infections developed in 72.2% of participants, either within 6 months post-transplant or following treatment for rejection with ATG/pulse steroids. The remaining 27.8% were >6 months posttransplant at infection onset. Hospitalization was required for 88.9% of patients diagnosed with Cryptosporidiosis. Co-infections were observed in 27.8% of patients and included Parvovirus B19 (5.6%), tuberculous meningitis (5.6%), CMV (11.1%), and sporotrichosis (5.6%). The most common extra-gastrointestinal symptom reported was weight loss, affecting 44.7% of patients [Figure 2]. Graft dysfunction occurred in 38.9% of cases, most commonly due to hypotension and dehydration. Among these, 86% (6/7 patients) recovered without requiring dialysis, while one (14%) died before evaluation due to co-infection with tuberculous meningitis. The treatment approaches and responses to various therapies have been listed in Figure 1 and Tables 2 and 3, respectively. Immunosuppressive modification was done to achieve the response mentioned in Figure 3. Half the patients (50%) were treated for 4 weeks, while 27.8% received treatment for 2 weeks and 22.2% for >6 weeks. Relapse was observed in 12% of the patients. Food handler testing revealed that 55.6% of patients with Cryptosporidiosis tested positive for the infection, while 44.4% tested negative. Among non-Cryptosporidium cases, 94.4% food handlers tested negative, indicating that transmission from food handlers primarily affected those with Cryptosporidium infections.

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Figure 2:

Extra-gastro-intestinal presentations in RTRs with cryptosporidiosis. RTR: Renal transplant recipient.

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Figure 3:

Immunosuppressive modification done in RTRs with Cryptosporidiosis to achieve response. MMF: Mycophenolate mofetil, MPS: Mycophenolate mofetil sodium, RTR: Renal transplant recipient

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Statistical analysis showed significant associations between Cryptosporidium infection and several factors. Patients without formal education had higher Cryptosporidium infection rates (p=0.015). Around 83.3% of Cryptosporidium-positive individuals reported a nonvegetarian diet, compared with 47.6% in those without the infection (p=0.010). Induction therapy with ATG was common among those with the infection (66.7% vs. 38.1%, p=0.042). Hospitalization needs were higher in the Cryptosporidium-positive group, with 88.9% requiring hospital care vs. 38.1% in the non-Cryptosporidium group (p<0.001). Co-infections were more frequent among those with Cryptosporidium vs. 11.9% in the non-Cryptosporidium group (p=0.014). Additionally, 66.7% of Cryptosporidium-positive patients required changes to their immunosuppressive treatment (p<0.001), and graft-related complications were seen in 38.9% of these patients, compared with only 7.1% in the non-Cryptosporidium group (p=0.002). Food handling appeared to be an important factor, as 56% of food handlers tested positive for Cryptosporidium, compared to only 5% in the non-Cryptosporidium group (p<0.01, odds ratio=25). A detailed analysis has been provided in Table 1 and Table 2.

Discussion

The study on Cryptosporidiosis in RTRs offers important insights into the risks, treatments, and outcomes of this infection in immunocompromised patients. One key finding is the high Cryptosporidiosis frequency among RTRs. Age and sex distribution of patients in this study matches earlier studies.⁵ The study saw a 30% prevalence of Cryptosporidium infection. Bhadauria et al.¹ state that a significant number (34/119, 28.5%) of RTRs with diarrhea may be affected, highlighting the need for routine screening in post-transplant diarrhea patients. Our study identified municipal water as the primary source in >70% of patients. This is significant because Cryptosporidium is often transmitted via water,⁷ particularly non-boiled water. This is because boiling, not chlorination, kills the oocytes. This highlights the need for careful monitoring of water safety. About 83.3% of RTRs had a non-vegetarian diet, which can be a Cryptosporidium source. Chalmers et al.⁸ also determined food-borne transmission as a concern for immunosuppressed populations. The fact that 55.6% of patients had positive food handler status reinforces the potential risk of contaminated food. This emphasizes the need for strict food safety practices. RTRs without formal education had a higher infection, likely due to limited awareness of hygiene practices and preventive measures. This aligns with research by Checkley et al.,⁷ which emphasized that lower education levels can correlate with poorer hygiene practices, increasing the infection risk in immunocompromised populations. Induction therapy, hospitalization, and co-infections also played a significant role in Cryptosporidium infection status. This study found that patients on ATG induction therapy had a higher infection rate, consistent with findings by Kapel et al.,⁹ who reported that intensive immunosuppression increases susceptibility to opportunistic infections like Cryptosporidiosis. The need for hospitalization in 88.3% of Cryptosporidium-infected patients further illustrates the infection's severity, as Kapel et al.⁹ similarly observed high morbidity rates in RTRs with Cryptosporidium. This suggests that infections in RTRs can result in severe complications, necessitating close monitoring and prompt medical intervention. Co-infections were significant, with 27.8% of patients having other infections like Parvovirus B-19 and CMV. This aligns with findings from other studies showing the risk for multiple infections in immunocompromised patients. Research by Kotloff et al.¹⁰ highlights the need for comprehensive care in RTRs, as these co-infections can worsen Cryptosporidiosis and complicate treatment.

Another important finding was the impact of Cryptosporidiosis on graft function, as shown in earlier studies,⁹ which showed that Cryptosporidiosis can cause graft failure.

The treatment strategies primarily involved nitazoxanide, either alone or with azithromycin. This is consistent with existing literature. However, Cabada et al.¹¹ noted that nitazoxanide might not be effective in severely immunosuppressed individuals, necessitating the use of combination therapies. Adapting therapy to each patient's condition is crucial for better outcomes and effective infection control. Relapse occurred in 12% of the patients; in all of them food handlers were positive for Cryptosporidium, indicating the importance of repeating stool microscopy even in food handlers and educating them regarding good hygiene practices.

Our study contributes important insights into several risk factors associated with Cryptosporidiosis in RTRs. It emphasizes how dietary habits, education status, and water sources can inform targeted prevention strategies. Additionally, the impact of induction therapy as a risk factor emphasizes the need for judicious immunosuppression. The study highlights that a high index of suspicion, monitoring, and timely intervention can prevent graft dysfunction. Lastly, the high positivity rate among food handlers underscores the necessity for enhanced food safety measures to protect RTRs from potential infections.

The findings may have limited generalizability as the study was conducted at a single center with a small sample size. The retrospective design and dependence on existing records could introduce potential biases. Additionally, the study lacked molecular characterization of Cryptosporidium species, which may limit the depth of its conclusions. This study does not establish causality but highlights the need for further investigation into transmission dynamics.

To conclude, this study reinforces the importance of safe water and food practices, early detection of infection, and tailored treatment regimens. The study highlights the complexity of managing infections in an immunocompromised population, where the interplay between infection control and immunosuppressive therapy must be carefully managed to protect both the patient and the transplanted organ. Further research is needed to refine treatment protocols and preventive strategies, particularly in regions with limited access to clean water and robust healthcare infrastructure.