<i>Cryptosporidium</i> and <i>Microsporidia</i> Infections in Children with Cancer: Epidemiology, Diagnosis and Treatment Strategies

Cryptosporidium spp. and Microsporidia spp., intracellular protozoan parasites, represent significant etiologic agents of opportunistic infections in immunocompromised pediatric cancer patients. These pathogens cause severe gastrointestinal symptoms including persistent diarrhea, abdominal pain, and weight loss which may be fatal in advanced stages. In developing countries with suboptimal sanitation, co-infections exacerbate morbidity among children with cancer. With the global incidence of childhood cancer increasing, immunosuppressive chemotherapy markedly heightens susceptibility to these infections. This review evaluates their epidemiology, clinical manifestations, diagnostic methodologies, and the pivotal role of early detection. The severity of infections hinges on immune competence, nutritional status, and parasite species. Although self-limiting in immunocompetent hosts, these infections persist in immunocompromised children, precipitating dehydration, malnutrition, and delays in cancer therapy. Early diagnosis is imperative to mitigate complications and enhance outcomes through prompt supportive care and infection control measures. Diagnostic techniques, such as modified acid-fast staining for Cryptosporidium spp., modified trichrome staining for Microsporidia spp., and polymerase chain reaction (PCR), exhibit variable sensitivity; however, challenges in consistent detection and therapeutic resistance persist, particularly in resource-constrained settings. In such regions, low-cost diagnostics frequently fail to detect low burden infections, and treatment options beyond rehydration and nutritional support remain limited. Advances in molecular epidemiology have deepened insights into these infections, yet practical obstacles endure in pediatric oncology. Future investigations should prioritize the development of accessible high precision diagnostics such as next generation sequencing and targeted therapeutic strategies to reduce morbidity and improve survival and quality of life in this vulnerable cohort.