Cryptosporidium is a pathogen of significant public health issue especially in developing countries where water filtration and treatment is not up to the standards.
Worthy commandant, respected teachers and my fellow colleagues. The topic for today CPC is “Cryptosporidiosis in an immunocompromised patient”
A case presentation will be followed by case discussion.
The patient is an 12year old male , resident of Peshawar
My patient a young boy 12 years of age, resident of Peshawar presented on 28th August, 2009 at AFBMTC Rwp
This young boy, a known case of Fanconi’s anemia underwent allogenic bone marrow transplant in Armed Forces Bone Marrow Transplant Center (AFBMTC) Rawalpindi on Aug 10 2009. He was discharged after two weeks with uneventful recovery but was re-admitted on Aug 28, with symptoms of acute GVHD involving gut, liver and skin.
He developed acute watery diarrhea with 20-25 stools per day along with a low grade fever.
He was started with increasing dose of cyclosporine, steroids and intravenous immunoglobulins under cover of Inj. Ciproxin 500mg x 12 hourly, Inj. Metronidazole 250mg x 8 hourly and Inj. Amphotericin B 25mg in 250 ml of 5% Dextrose saline x OD with fluid and electrolyte replacement therapy
There is no history of major illness or hospitalization in the past except for the current illness of FANCONI’S Anemia for which he remained admitted off and on during the last 6 months.He belongs to a well off family and his personal and family history is not contributory.
There is no history of similar complaints in the past.He belongs to a well off family and his personal and family history was not contributory.
On GPE conducted at AFBMTC he was a young boy of average built lying in bed conscious and oriented. His temp was 99o F, BP was 100/70 mm Hg and pulse 94 bpm.
He was pale and mildly jaundiced. Rest of the GPE was unremarkable.
Systemic examination was also unremarkable except for mild hepatosplenomegaly.
Repeated blood cultures did not yield any growthCXR was normalUSG abdomen showed mild splenomegaly
Stool RE showed loose watery stools with numerous pus cells but no ova or cystStool culture did not yield any growth of salmonella, shigella or Vibrio choleraeSputum for AFB was negative and culture showed only presence of normal throat flora.
Modified ZN stain was performed on stool specimen sent to microbiology lab on sep 3, 2009 which revealed cysts of cryptosporidium parvum on microscopic examination.Modified ZN staining of sputum also revealed similar cyst.
Here you can see the bright red cysts of cryptosporidium in stool specimen
And this is the photograph of sputum under microscope. Acid fast cysts of cryptosporidium can be seen.
He was started with combination of syrup Azithromycin (Azomax) 5ml x 12 hourly and tab. Sulfamethoxazole/Trimethoprim (Septran) 1tablet x 8hourly.With combination therapy, his frequency of diarrhea reduced to 5-6 stools per day and pulmonary symptoms improved a
His repeat stool and sputum samples was taken for cryptosporidial cysts , two weeks after the start of anti-cryptosporidial therapy and they did not show any cystsAfter slow improvement his general condition started deteriorating again. His blood sample was sent for CMV PCR which was positive. He was put on Gancyclovir 250mg x 8hourly along with intravenous immunoglobulins in therapeutic doses. His condition remained stable for the next few days.But unfortunately on oct 7, he had episode of epileptic fit with tongue bite. His emergency X-ray showed bilateral bronchopneumonia. And a couple of days later he suddenly went into respiratory failure and died , most probably because of CMV pneumonia.
Now the case discussion
The word cryptosporidium is Greek for hidden spores.Cryptosporidium is a coccidian protozoan pathogen of the Phylum Apicomplexa.Many species of Cryptosporidium exist that infect humans and a wide range of animals. The most common species infecting humans are C. hominis and C. parvum.The pathogenic form of C. parvum is the oocyst which is 3 um in diameter Cryptosporidium can infect several different hosts, can survive most environments for long periods of time due to its "hardy cyst" and inhabits all climates and locales.
Cryptosporidium was discovered byE.E. Tyzzer of Harvard university. He,in 1907, described a cell-associated organism in the gastric mucosa of mice. For several decades, Cryptosporidium was thought to be a rare, opportunistic animal pathogen. The first case of human cryptosporidiosis in 1976 involved a 3-year-old girl from rural Tennessee who suffered severe gastroenteritis for two weeks. In the early 1980s, the strong association between cases of cryptosporidiosis and immunodeficient individuals (such as those with AIDS) brought Cryptosporidium to the forefront as an important human pathogen. Unlike other intestinal pathogens, Cryptosporidium can infect several different hosts, can survive most environments for long periods of time due to its "hardy cyst" and inhabits all climates and locales.
Cryptosporidiosis is an important cause of persistent diarrhea in developed as well as developing countries. Infection by C. parvum has been reported in six continents and identified in patients aged 3 days to 95 years old. The frequency of cryptosporidiosis has not been well-defined as most laboratories do not routinely test for this organism. About 30% of the adult population of the United States is seropositive.A Local Prospective Study was conducted at AFIP fromMay to September 2005 Cryptosporidium Oocysts were found in (8.3%) children with watery diarrhea (n=300)
Themajor impact of cryptospridiosis is among those with weakened immune systems, including:Pts on immunosuppressantPeople with HIV AIDS andTransplant recipients
In recent years there has been increasing recognition of outbreaks of cryptosporidiosis arising from contamination of water supplies.The 1993 Milwaukee Cryptosporidium outbreak was the largest waterborne disease outbreak in documented history. In a span of two weeks, over 400,000residents in the Milwaukee area became ill. Over 54 deaths were attributed to this outbreak, mostly among the elderly and immunocompromised people, such as AIDS patients.The number of nonoutbreak cryptosporidiosis cases reported increased from 3,411 cases in 20042 to nearly 8,300 in 2007 (CDC, unpublished data, 2008). This substantial increase (143%)
The life cycle of Cryptosporidium parvum consists of an asexual stage and a sexual stage.[1] After being ingested, the oocystsexcyst in the small intestine. They release sporozoites that attach to the microvilli of the epithelial cells of the small intestine. From there they become trophozoites that reproduce asexually by multiple fission, a process known as schizogony. The trophozoites develop into Type 1 meronts that contain 8 daughter cells.[9] These daughter cells are Type 1 merozoites, which get released by the meronts. Some of these merozoites can cause autoinfection by attaching to epithelial cells. Others of these merozoites become Type II meronts [12], which contain 4 Type II merozoites.[9] These merozoites get released and they attach to the epithelial cells. From there they become either macrogamonts or microgamonts. These are the female and male sexual forms, respectively.[9] This stage, when sexual forms arise, is called gametogony.[14] Zygotes are formed by microgametes from the microgamont penetrating the macrogamonts. The zygotes develop into oocysts of two types.[12] 20% of oocysts have thin walls and so can reinfect the host by rupturing and releasing sporozoites that start the process over again.[9] The thick-walled oocysts are excreted into the environment.[12] The oocysts are mature and infective upon being excreted.[9] They can survive in the environment for months.[15]
Cryptosporidial infections are transmitted from fecally contaminated food and water, from animal-person contact, and via person-person contact.Swimming pools and water park wave pools have been associated with outbreaks of cryptosporidiosis. Also, untreated groundwater or wellwater public drinking water supplies can be sources of contamination.
Food can be a source of transmission, when either an infected person or an asymptomatic carrier contaminates a food supply.The oocysts do not survive cooking, but food contamination can occur in beverages, salads, or other foods not heated or cooked after handling.Cryptosporidium transmission occurs at a high frequency in day-care centers, where infants or younger children are clustered within classrooms, share toilets or necessitate frequent diaper-changing.Nosocomial settings are also a major forum for cryptosporidial transmission. There have been several reports of both transmission from patients to health care staff and patient-to-patient transmission
Cryptosporidium oocysts are highly infectious, requiring only 101 -103 oocysts to cause human disease (50% infectious dose, 102)Upon oocyst excystation, four sporozoites are released which adhere their apical ends to the surface of the intestinal mucosaAfter sporozoite attachment, it has been hypothesized that the epithelial mucosa cells release cytokines that activate resident phagocytesThese activated cells release soluble factors that increase intestinal secretion of water and chloride and also inhibit absorption
Consequently, epithelial cells are damagedEither by direct result of parasite invasion, multiplication, and extrusion ORthrough T cell-mediated inflammation, producing villus atrophy and crypt hyperplasia
Symptoms usually appear 3 to 10 days after ingestion of the oocyst. The various symptoms of cryptosporidiosis differ between immunocompetent and immunocompromised individuals. In immunocompetent patients, cryptosporidiosis is an acute, yet self-limiting diarrheal illness (1-2 week duration), and symptoms include (Juranek, 1995):Frequent, watery diarrheaNauseaVomitingAbdominal crampsLow-grade fever
For immunocompromised persons, the illness is much more severe There is profuse, debilitating, cholera-like diarrhea (up to 20 liters of fluid may be lost per day)Other features include:Severe abdominal crampsMalaiseLow-grade feverWeight lossAnorexiaThe result is progressively severe dehydration, electrolyte imbalances, malnutrition, wasting, and eventual death. Cryptosporidium infection has also been identified in the biliary tract (causing thickening of the gallbladder wall)Pulmonary involvement is a rare complication of intestinal cryptosporidiosis7,8,9. Chronic cough, fever and dyspnea are major symptoms of pulomary cryptosporidiosis.
Cryptosporidium can be diagnosed in the lab by direct microscopic examination of the specimen, serological investigations and molecular methods
Microscopic examination is most reliable and specific but it is less sensitive.The modified Z-N ( kinyon stain) stain is traditionally used to reliably detect the presence of cysts in the stool. Red-stained round oocysts against a blue-green background is seen as in this image
AURAMINE PHENOL flouroscent stain can also be used in which cysts appear as small round and bright yellow.However there are chances of false positive results with this method.
Various serological methods can be used to detect cryptosporidium. ELISA can be used to detect specific cryptosporidialIgG, IgM, and IgA antibodies. It can differntiate between active and past infection and is higly sensitive
Immunoflourascence assays are more specific and sensitive as well but they are costly.
Cryptosporidium antigen can be detected in stool specimen by rapid immunochromatographic detection strips. They have high sensitivity but are costly.
PCR is used mainly for speciation and epidemiological studies. It is expensive and is not used routinely. Intestinal biopsy can be done to detect the pathogen and associated villous changes butit gives false negative results due to the "patchy" nature of the intestinal parasitic infection.
No safe and effective therapy for cryptosporodiosis has been successfully developed as yet. The majority of immunocompetent individuals suffer a short (less than 2 weeks) self-limiting course that requires supportive care. Oral or intravenous rehydration may be necessary for particularly voluminous, watery diarrhea. Drugs such as paromomycin, nitazoxanide,and azithromycin shortens the duration of diarrhea and can decrease the risk of mortality in malnourished children
In immunocompromised individuals, cryptosporidiosis resolves slowly or not at all. Spiramycin can help treat diarrhea in patients who are in the early stages of AIDS.[14] The mortality rate for infected AIDS patients is generally based on CD4+ marker counts; patients with CD4+ counts over 180 cells/mm³ generally recover with supportive hospital care and medication, but in patients with CD4+ counts below 50 cells/mm³, the effects are usually fatal within three to six months. During the Milwaukee cryptosporidiosis epidemic (the largest of its kind), 73% of AIDS patients with CD4+ counts lower than 50 cells/mm³ and 36% of those with counts between 50 and 200 cells/mm³ died within the first year of contracting the infection.[17]. In one AIDS patient from Iran, who had pulmonary cryptosporidiosis in addition to intestinal cryptosporidiosis, azithromycin and paromomycin helped to clear the infection
Cryptosporidiosis is a public health issue The World Health Organization’sguideline for drinking water classifies Cryptosporidiumas a pathogen of significant public health importance and Good personal hygiene , use of boiled or filtered water, healthy swimming and proper food sanitations are the keys to its prevention.