Following the resolution of diarrhea, symptoms can reoccur after several days or weeks due to reinfection. The likelihood of re-infection is high in immunocompromised adults, and low in those with normal immune systems.In immunocompetent individuals, cryptosporidiosis is primarily localized to the distal small intestine and sometimes the respiratory tract as well. In immunocompromised persons, cryptosporidiosis may disseminate to other organs, including the hepatobiliary system, pancreas, upper gastrointestinal tract, and urinary bladder; pancreatic and biliary infection can involve acalculous cholecystitis, sclerosing cholangitis, papillary stenosis, or pancreatitis. Intestinal cryptosporidiosis
Common signs and symptoms of intestinal cryptosporidiosis include:

Moderate to severe watery diarrhea, sometimes contains mucus and rarely contains blood or leukocytesIn very severe cases, diarrhea may be profuse and cholera-like with malabsorption and hypovolemia
Low-grade fever
Crampy abdominal pain
Dehydration
Weight loss
Fatigue
Nausea and vomiting – suggests upper GI tract involvement and may lead to respiratory cryptosporidiosis
Epigastric or right upper quadrant tendernessLess common or rare signs and symptoms include:

Reactive arthritis (may affect the hands, knees, ankles, and feet)
Jaundice – suggests hepatobiliary involvement
Ascites – suggests pancreatic involvement

Respiratory cryptosporidiosis
Symptoms of upper respiratory cryptosporidiosis include:

Inflammation of the nasal mucosa, sinuses, larynx, or trachea
Nasal discharge
Voice change (e.g., hoarseness)Symptoms of lower respiratory cryptosporidiosis include:

Cough
Shortness of breath
Fever
Hypoxemia

Reason
Cryptosporidium is a genus of protozoan pathogens which is categorized under the phylum Apicomplexa. Other apicomplexan pathogens include the malaria parasite Plasmodium, and Toxoplasma, the causative agent of toxoplasmosis. A number of Cryptosporidium infect mammals. In humans, the main causes of disease are C. parvum and C. hominis (previously C. parvum genotype 1).
Diffuse unilateral subacute neuroretinitis (DUSN) is a rare condition that occurs in otherwise healthy, often young patients and is due to the presence of a subretinal nematode. Signs and symptoms
The clinical findings in this disease can be divided into acute and end-stage manifestations:
In the acute phase, patients often present with decreased visual acuity, vitritis, papillitis, and crops of gray-white or yellow-white outer retinal lesions. The clustering of the retinal lesions is important because this often helps to localize the causative nematode. If left untreated, patients ultimately develop late sequel, which may include optic atrophy, retinal arterial narrowing, diffuse retinal pigment epithelial changes, and an abnormal electroretinogram. The late findings of this condition are often misinterpreted as unilateral retinitis pigmentosa. Cause
DUSN may be caused by a helminthic infection with Toxocara canis, Baylisascaris procyonis, or Ancylostoma caninum. The characteristic lesions are believed to result from a single nematode migrating within the subretinal space. Although previously thought to be endemic in some areas, that belief was likely due to under awareness. DUSN has been diagnosed in patients in many countries and climates including America, Brazil, China and India. Diagnosis
Treatment
If the nematode can be seen by an ophthalmologist, which occurs in less than half of cases, it should be treated with photocoagulation for extramacular location and surgical removal in case the larva is lying in the macula. After the worm is killed, visual acuity loss usually does not progress. Alternatively, Antihelminthic treatment such as high dose oral Albendazole and prednisolone may be used. References


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