Cryptosporidium spp., a frequent cause of diarrhea in Central Africa

Impact of co-infections with enteric pathogens on children suffering from acute diarrhea in southwest China

Background

Acute diarrhea is a global health problem, resulting in high morbidity and mortality in children. It has been suggested that enteric pathogen co-infections play an important role in gastroenteritis, but most research efforts have only focused on a small range of species belonging to a few pathogen groups. This study aimed to assess the impact of co-infections with a broad range of enteric pathogens on children aged below five years who suffer from acute diarrhea in southwest China.

Method

A total of 1020 subjects (850 diarrhea cases and 170 healthy controls) were selected from four sentinel hospitals in Kunming, Yunnan province, southwest China, from June 2014 to July 2015. Stool specimens were collected to detect five virus (rotavirus group A, RVA; norovirus, NoV; Sapovirus, SaV; astrovirus, As; and adenovirus, Ad), seven bacterial (diarrheagenic Escherichia coli, DEC; non-typhoidal Salmonella, NTS; Shigella spp.; Vibrio cholera; Vibrio parahaemolyticus; Aeromonas spp.; and Plesiomonas spp.), and three protozoan (Cryptosporidium spp., Giardia lamblia, and Blastocystis hominis, B. hominis) species using standard microbiologic and molecular methods. Data were analyzed using the partial least square regression technique and chi-square test.

Results

At least one enteric pathogen was detected in 46.7 % (n = 397) of acute gastroenteritis cases and 13.5 % (n = 23) of healthy controls (χ² = 64.4, P < 0.05). Single infection with RVA was associated with acute diarrhea (26.5 % vs. 5.8 %, P < 0.05). The prevalence of a single infection with B. hominis in diarrhea cases was higher than in healthy controls (3.1 % vs. 0.5 %, OR = 4.7, 95 % CI: 1.01–112.0). Single infection with NoV GII was not associated with diarrhea (4.4 % vs. 3.5 %, OR = 1.2, 95 % CI: 0.5–3.3). Single infections with bacterial species were not observed. The prevalence of co-infections with two enteric pathogens in diarrhea cases was higher than in asymptomatic children (20.1 % vs. 5.3 %, P < 0.05). RVA-NoV GII was the most common co-infection in symptomatic children (4.4 %), with it aggravating the severity of diarrhea.

Conclusions

Although it is clear that RVA has an overwhelming impact on diarrhea illnesses in children, co-infection with other enteric pathogens appears to also aggravate diarrhea severity. These findings should serve as evidence for public health services when planning and developing intervention programs.

Electronic supplementary material

The online version of this article (doi:10.1186/s40249-016-0157-2) contains supplementary material, which is available to authorized users.

Cryptosporidiosis, whether it is more prevalent in Southern India

Cryptosporidium species is identified as an important cause of morbidity in children and adults. Prevalence rate as reported from various studies in India is much lower when compared to developed word. Present study was designed to analyze the prevalence of cryptosporidiosis in West Godavari District, Andhra Pradesh. Stool samples from 306 patients suffering with gastrointestinal symptoms were examined for the presence of Cryptosporidium oocysts. A higher prevalence (25%) was found when compared to reports from north east and western India. Cryptosporidium was prevalent in 35-36% of adults, 17% of children and 20% of infants.

First report of cryptosporidiosis in paediatric patients in Swaziland

Diarrhoeal disease is a significant cause of morbidity and mortality in many African countries, especially among the immunocompromised and the under five population. Over the last decade, the protozoan parasite Cryptosporidum spp. has been shown to be a significant cause of gastro-enetritis in the immunocompetent and immunocompromised in both the developed and developing world. This study reports the first finding of Cryptosporidum spp. oocysts in 2 of 48 (4.2%) faecal samples obtained from Swazi paediatric outpatients (two year old male and three year old female), presenting with diarrhoea at Mbabane Government Hospital between the months July-August 2003. Oocysts were detected using a standard anti-Cryptosporidium immunofluorescence and nuclear staining technique (after formal-ether concentration). Oocysts ranged in size from 4-6 microm with between 1-4 oocysts per field of view (x 400). The precise species was not determined. Further studies are required to determine the public health significance of Cryptospoirdium in Swaziland.

Seven years' experience with Cryptosporidium parvum in Guinea-Bissau, West Africa

In community-based studies conducted from 1991 to 1997 in Guinea-Bissau, West Africa, stool specimens from children aged less than 5 years with diarrhoea were routinely examined for enteric parasites. Cryptosporidium parvum, found in 7.7% of 4,922 samples, was the second most common parasite, exceeded only by Giardia lamblia which was found in 14.8% of the samples. The highest prevalence of cryptosporidium was found in children aged 6-11 months, whereas the prevalence of other enteric parasites increased with age. Cryptosporidiosis showed a marked seasonal variation, with peak prevalences found consistently at the beginning of or just before the rainy seasons, May through July. By contrast, no seasonality was found for the enteric parasites Giardia lamblia or Entamoeba histolytica. We conclude that Cryptosporidium parvum is an important pathogen in children with diarrhoea.

Parasites and Diarrhea. I: Protozoans and Diarrhea

Intestinal parasitism is extremely common, with approximately 70% of all people harboring one or more intestinal parasite. Parasitism and diarrhea are both hyperendemic in areas where sanitation is suboptimal. Many clinicians assume that the identification of intestinal parasites in patients with diarrhea implies that the parasites are the cause. This approach is frequently misguided. Some intestinal parasites such as Giardia lamblia and Entamoeba histolytica certainly do cause diarrhea. Others, for example Entamoeba coli and Ascaris lumbricoides, almost certainly do not. In addition, there are a number of other organisms that have been associated with diarrheal illness in some cases, which may or may not be important pathogens. In this article, we will review the role of protozoans as definite and possible causes of diarrhea. In Part II, we review the role of helminths in diarrhea.

Cryptosporidiosis in Houston, Texas. A report of 95 cases

Cryptosporidiosis is an important cause of diarrhea. We identified 95 patients with cryptosporidiosis over a 6-year period in our county hospital system, including 9 children and 86 adults infected with the human immunodeficiency virus (HIV). Risk factors included male-to-male sexual practices and Hispanic race. Diarrhea, weight loss, and gastrointestinal complaints were the most common symptoms at presentation. Among the HIV-infected adults, 20 (23%) developed biliary tract disease. Biliary involvement was associated with low CD4 counts. Treatment with paromomycin and antimotility agents was effective in reducing diarrheal symptoms in 54 of 70 (77%) patients with the acquired immunodeficiency syndrome (AIDS), although there was a high rate of relapse. Paromomycin did not prevent the development of biliary disease. Biliary disease responded to cholecystectomy or sphincterotomy with stent placement. Though often a cause of morbidity, cryptosporidiosis was only rarely the cause of death, even among patients with HIV. Cryptosporidiosis continues to be an important medical problem even in developed-countries. Current methods of prevention and treatment are suboptimal.

Cryptosporidium sp. in children suffering from acute diarrhea at Uberlândia City, State of Minas Gerais, Brazil

This study's objective was to search for Cryptosporidium sp. in diarrheic feces from children aged zero to 12 years and cared for at medical units within Universidade Federal de Uberlândia or at a private practice in Uberlândia, State of Minas Gerais, Brazil, from September 1992 to August 1993. Three fecal samples preserved in 10% formalin, were collected from 94 children. Oocyst concentration was performed through Ritchie's (modified) method and staining of fecal smears for each sample (total of 1128 slides) was done by the "Safranin/Methylene Blue" and the "Kinyoun (modified)" techniques. The Hoffmann, Pons & Janer method was also employed to look for other enteroparasites. From 94 children, 4.26% excreted fecal Cryptosporidium oocysts. The infection seemed to vary according to age: 5.08% of patients aged zero to two years old; 33.33% of those aging eight to ten years (P > 0.05). Cryptosporidium appeared in November, December and March, during the rainy season. 20.21% of the children harbored at least one enteroparasite different from Cryptosporidium, mainly Giardia intestinalis (12.77%). From Cryptosporidium infected patients, two had only this kind, another harbored Giardia intestinalis; the last one hosted Strongyloides stercoralis.

Prevalence of Cryptosporidium in children with enteritis in southern Italy

Cryptosporidium parvum is a protozoan which causes self-limiting diarrhea in immunocompetent subjects, and severe life-threatening disease in immunocompromised patients. Cryptosporidiosis is more common in developing countries and in infants. In this paper we have evaluated the prevalence of C. parvum in 368 hospitalized children with enteritis, of whom 359 were immunocompetent and 9 HIV-infected. Stool specimens were concentrated by sedimentation and stained with a modified Ziehl-Neelsen method. Cryptosporidium parvum oocysts were found in 7 (1.90%) out of 368 subjects. Six of these were immunocompetent (with an infection rate in this population of 1.67%) and 1 HIV-infected, asymptomatic except for diarrhea. In all children symptoms of enteritis and oocyst excretion cleared within 10 days. These results indicate that the prevalence of C. parvum as a causative agent of diarrheal illness in hospitalized immunocompetent children is rather low in our region (Apulia, South Italy).

Influence of hydrogen peroxide on acid-fast staining of Cryptosporidium parvum oocysts

Infections by the protozoan parasite Cryptosporidium parvum are routinely diagnosed by modified Ziehl-Neelsen (acid-fast) staining of faecal preparations despite the counterstaining and ghost-like appearance of some oocysts. Quantitative studies demonstrated that only a small percentage of oocysts excreted by naturally infected newborn calves displayed acid-fast characteristics, but that percentage increased when the time between excretion and sample staining was increased. The treatment of faecal samples with hydrogen peroxide (10 min, 5 vol. final concentration) caused all oocysts to become acid-fast, with up to 40-fold increases in test sensitivity in samples treated and stained within 3 h of excretion. Flow-cytometry analysis of hydrogen peroxide-treated oocysts also demonstrated increased labelling of oocysts by a commercial monoclonal antibody preparation commonly used for diagnosis.

Prevalence of Cryptosporidium sp. in patients with neoplasia and diarrhea

The prevalence of Cryptosporidium sp. was investigated in fecal specimens from 106 patients with neoplasia and diarrhea (74 females, 32 males) by using Ziehl-Neelsen and Giemsa stains. Oocystic forms of Cryptosporidium sp. were found in 18 (17%) of these patients. No oocystic form of Cryptosporidium sp. was detected in the control group of 60 patients with neoplasia (37 females, 23 males) but without diarrhea. The frequent findings of Cryptosporidium sp. in patients with neoplasia and diarrhea who are undergoing chemotherapy indicates that a search for this organism is justified.

Prevalence of Cryptosporidium species in elementary school children

The project described here was conducted to study the prevalence of various parasites in elementary school children in northern Jordan. A single stool specimen was collected from each of 1,000 students in the 6- to 14-year-old age group. A questionnaire covering demographic information, health status, and other relevant information was filled out by one of the parents of each student. Fresh stool specimens were processed by using wet mount preparations, formalin-ether, and Sheather's sugar flotation techniques. Permanently stained slides were prepared by acid-fast, Giemsa, and trichrome staining. Cryptosporidium species was found in 40 specimens (4%); however, only 15 specimens had Cryptosporidium species alone, and these 15 specimens were from symptomatic children with diarrheic stools. The symptoms reported most often were abdominal pain, cramps, malaise, nausea, and headache. The number of cases of infection was higher in villages, where contact with animals was evident and where contaminated drinking water could have been a major source of the infections.

Detection of Cryptosporidium oocysts from out-patients of the Severance Hospital, Korea

A total of 230 randomly collected formalin-fixed fecal samples (submitted to the Severance Hospital, Yonsei University) were selected for tests for human cryptosporidiosis. The stool specimens were examined for Cryptosporidium oocysts by acid-fast (AF) stain, auramin-rhodamine (AR) stain, and monoclonal antibody (mAb) OW3 fluorescence method specific for oocyst wall. Of the 230 stool specimens, 21% were identified by the AF method, 22% were identified by the AR method, and 10% were identified by the mAb fluorescence method, indicating that human Cryptosporidium infections have been existing in Korea.

Parasitismo por Cryptosporidium sp. em crianças com diarréia aguda

No período de agosto de 1987 a julho de 1990, examinaram-se, na Seção de Enteroparasitoses do Instituto Adolfo Lutz, 241 amostras de fezes de crianças, com idade variável entre 1 e 48 meses, que apresentavam episódio agudo de diarréia e foram atendidas no Instituto da Criança do Hospital das Clínicas da Faculdade de Medicina da Universidade de São Paulo. Quarenta e duas (17,43%) amostras revelaram a presença de Cryptosporidium sp. após coloração por fucsina-carbólica. O achado de oocistos de Cryptosporidium sp. foi mais freqüente no período compreendido pelos meses de março a maio. Os autores discutem as associações entre Cryptosporidium sp. e outros agentes diarréicos.

Cryptosporidium infection and diarrhea in rural and urban areas of Jiangsu, People's Republic of China

Screening of infants and children under age 15 years for Cryptosporidium oocysts in their stools was carried out in the suburb of Xuzhou City and six rural areas of Jiangsu Province. The infection rate varied from 0.7 to 5.06%. Of the total of 5,089 children examined, 89 (1.75%) were oocyst positive. The incidence was evidently higher in the group of children under age 4 years than it was in children from 4 to 15 years (P less than 0.01). Routine blood examination and immunoassay performed on blood samples from some of the infected children indicated that more than half of them had anemia and lower cellular immunity. Diarrhea was the main symptom of cryptosporidiosis. It was intermittent or persistent and was present in 57 of the 89 children positive for Cryptosporidium oocysts, while the other 32 children were asymptomatic carriers. Examination of stool specimens of adult members and domestic animals of about half of the infected families showed that two mothers, one pig, and one dog were positive for Cryptosporidium oocysts.

Cryptosporidium parvum: investigation of sporozoite excystation in vivo and the association of merozoites with intestinal mucus

Enteric cryptosporidiosis was studied in the small intestine of five-day-old sucking mice after infection with 10(6) Cryptosporidium parvum oocysts. It was shown that excystation and the majority of subsequent endogenous stages occurred predominantly in the ileum. During the first three days of infection the number of merozoites collected in ileal washings increased over 100-fold to approximately 10(6) merozoites per mouse on the third day. In contrast to control mice, wash fluid from infected mice contained numerous strands of dislodged mucus. Estimates of mucus in the ileal washings of infected mice were similar to those made in controls until day 4 after infection when they increased and remained high throughout the remainder of the experiment. This study describes a method whereby ileal mucus washings from C parvum infected infant mice could be used as a rich source of merozoites.

Cryptosporidiosis

Before 1982, only eight case reports of human cryptosporidiosis and fewer than 30 papers on Cryptosporidium spp. appeared in the biomedical literature. At that time, cryptosporidiosis was thought to be an infrequent infection in animals and rarely an opportunistic infection in humans. The concept of Cryptosporidium spp. as pathogens has changed dramatically within the past 8 years because of improved diagnostic techniques, increased awareness within the biomedical community, and the development of basic research programs in numerous laboratories. Presently, greater than 1,000 publications including over 400 case reports in the biomedical literature address Cryptosporidium spp. and cryptosporidiosis. Cryptosporidium parvum is now thought to be one of the three most common enteropathogens causing diarrheal illness in humans worldwide, especially in developing countries. It is likely that cryptosporidiosis was previously included in the 25 to 35% of diarrheal illness with unknown etiology. Because of the severity and length of diarrheal illness and because no effective therapy has been identified, cryptosporidiosis is one of the most ominous infections associated with AIDS. The role of C. parvum as an enteropathogen is well established; documentation of its role as a cause of hepatobiliary and respiratory diseases is now appearing in the literature. Our present understanding of the natural history, epidemiology, biology, and immunology of Cryptosporidium spp. as well as the clinical features, pathogenicity, and treatment of cryptosporidiosis are reviewed here.

Epidemiological aspects of human cryptosporidiosis

The coccidian protozoan parasiteCryptosporidiumhas been described in many host species since its discovery in the early part of the century, but it remained obscure until the recognition by veterinary workers in the 1970s of its importance as a cause of scours in young livestock animals [1–4].

Aetiological factors of infantile diarrhoea: a community-based study

A community-based study was undertaken to compare the organisms responsible for diarrhoea in children living in formal housing with indoor water supply and sanitation with those from a deprived environment. The role of "home remedies" was also assessed. Among 373 children with diarrhoea, rotavirus was detected in 15% (in 371 symptom-free controls, 9%), and proved to be the single most common causative agent. Bacterial pathogens were found in 20% of patients, with enteropathogenic Escherichia coli (EPEC) being isolated most frequently (9%; controls 3%), followed by Shigella species (4%; controls 1%), Campylobacter jejuni (4%; controls 1%), Salmonella species (2%; controls 1%) and enterotoxigenic E. coli (ETEC) (2%; controls 1%). Giardia lamblia and cryptosporidium were detected in 6% (controls 6%) and 3% (controls 1%) of patients, respectively; 7% (controls 1%) harboured more than one enteropathogen and no pathogens were detected in 58% (controls 78%). The vast majority (greater than 90%) of both patients and controls received some form of "home remedy" which included disinfectants and traditional herbs. The findings of this study therefore confirm the extremely complex nature of diarrhoea in developing communities and indicate that environmental factors are compounded by other issues.

Cryptosporidium as a common cause of childhood diarrhoea in Italy

Cryptosporidium oocysts were observed in the stools of 9 (7.2%) of 124 Italian children with diarrhoea, examined during the period 1 January-31 December 1984. In two children, the parasite was associated with other enteric pathogens. The duration of diarrhoea was 2-30 days, with a median of 6 days. In all cases the infection was self limiting. The mean age of the Cryptosporidium-positive children was 34 months, and all cases occurred in the warm season. Cryptosporidium was found to be the third most common enteric pathogen after rotavirus and Salmonella spp.

Detection of Cryptosporidium oocysts in human fecal specimens by an indirect immunofluorescence assay with monoclonal antibodies

An indirect fluorescence assay (IFA) with monoclonal antibodies developed for the detection of Cryptosporidium oocysts in fecal smears (Meridian Diagnostics, Inc., Cincinnati, Ohio) was compared with the Zeihl-Neelsen-modified acid-fast stain (MAFS) in 119 human fecal specimens collected between 1984 and 1987. The sensitivity of the IFA was 100%; all 56 specimens positive by MAFS exhibited fluorescence. There were 63 specimens negative for Cryptosporidium sp. by MAFS; of these, 61 were negative by IFA (97% specificity). This discrepancy may reflect an increased sensitivity of the IFA to detect oocysts that were not visualized by MAFS because of faint staining or a paucity of organisms. On average, the IFA required less time than the MAFS (1 versus 5 min, respectively) when only rare or few oocysts were present. Cost comparison of reagents showed the IFA to be three times more expensive. The IFA offers a reasonable alternative to the MAFS because of its high sensitivity and specificity, the simplicity of performing it and interpreting results, and its capability of providing a definitive diagnosis of Cryptosporidium oocysts.

Cryptosporidium causing chronic diarrhea

The authors report a case of a child with chronic diarrhea due to Cryptosporidium. The child had also hemolytic uraemic syndrome. Cryptosporidium oocysts were identified by the modified Ziehl-Neelsen technique.

Cryptosporidiosis: clinical features and diagnosis

Cryptosporidiosis is an infectious disease caused by the coccidian parasite Cryptosporidium spp. that primarily infects the gastrointestinal tract of animals. Prior to late 1982, only 11 cases of human infection had been reported, with the first human case reported in 1976. During the 1980s, the number of human cases began to rise dramatically. Most of these patients were immunodeficient, many of whom had the acquired immune deficiency syndrome (AIDS). Immunocompetent individuals can also acquire the infection with mild-to-severe diarrhea lasting from several days to weeks. Immunocompromised patients develop severe, irreversible diarrhea, often thought to be a significant contributing factor leading to death. Although many therapeutic compounds have been tried, none have proven to be very successful. The incidence of this infection is worldwide, with many published reports of infection in both immunodeficient and immunocompetent individuals. The diagnostic approach has been expanded to include stool examinations using modified acid fast procedures and fluorescent monoclonal antibody reagents. Although histological methods are still routinely used for biopsy specimens, the examination of stool has proven to be a very effective, noninvasive procedure. In addition to the gastrointestinal tract, other areas of the body that have been found to be infected with this organism include the respiratory tract and the biliary tree and gall bladder epithelium. Screening for this organism may become very important in known risk groups (animal handlers; children, staff members, and contacts of those who attend day care centers; travelers; and those who are immunodeficient), particularly if an effective therapy is found. Some laboratories screen every specimen submitted for an ova and parasite examination, while others have limited their testing to specific requests, risk groups, and those patients who are symptomatic.

Cryptosporidium infections in humans with gastroenteritis in Zaria, Nigeria

The stool samples of 75 patients with gastroenteritis and/or loose and watery faeces at three hospitals and one clinic in Zaria were examined for Cryptosporidium. The stool samples were concentrated by the formol-ether method and stained with safranin-methylene blue. Sixteen (21%) samples were positive. The rate of detection was higher among females (27%) than males (17%) and among adults (29%) than children (8%). The study confirmed the presence and possible significance of Cryptosporidium, which is a known zoonotic protozoan, in the aetiology of human gastroenteritis in Zaria, Nigeria.

Cryptosporidiosis in perspective

In this review I have examined the vast literature which has accumulated on Cryptosporidium, particularly in the past 3 years, in an attempt to highlight areas in which progress has been made in relation to the organism and the disease, and to indicate areas in which knowledge is still lacking. Since 1982, a global effort by scientists and clinicians has been directed towards determining the nature of the disease in humans and the relative contribution of cryptosporidiosis to gastroenteritis. From published data, the incidence of diarrhoea is 1-5% in most developed countries, and 4-7% in less developed countries, when measured throughout the year and in all age groups. The frequency of cryptosporidiosis is highest in children aged between 6 months and 3 years, and in particular locations (e.g., day-care centres) and at particular times of the year. Although susceptibility to infection is life-long, one suspects that the lower prevalence among older children and adults is due to immunity acquired from frequent exposure. Other important factors contributing to higher prevalence are the season--it is more frequent in a wet, warm climate--association with travel to particular destinations, poor hygiene, intimate contact with certain animals, and congregation of large numbers of young previously unexposed children in day-care centres. The association between cryptosporidiosis and giardiasis presumably results from the existence of a common source of infection. The immune status of the host appears to be a major determinant of whether the infection is self-limiting or persistent. It is clear that both branches of the immune system are required for complete recovery, since T-lymphocyte dysfunction or hypogammaglobulinaemia can both lead to persistent illness. Chronic diarrhoea and malabsorption attributed to cryptosporidiosis also occur in the absence of evidence of immune defect. The importance of respiratory tract infection in humans, other than in the terminal stages of chronic illness, requires investigation. The infection has now been identified in all classes of vertebrates; it has been observed in all domestic animals including pets, and a wide range of wildlife including birds. Cryptosporidiosis seems to cause diarrhoea in young ruminants, less frequently in pets. In birds the parasite has been observed in the gastrointestinal tract, without ill effect, and in the respiratory tract, in which clinical symptoms of variable severity have been described. The mucosal response of the gastrointestinal tract to infection appears to vary among mammals and may be the key to the variable clinical manifestations observed.(ABSTRACT TRUNCATED AT 400 WORDS)

Infection and diarrhea caused by Cryptosporidium sp. among Guatemalan infants

During July 1985 to June 1986, fecal excretion of Cryptosporidium oocysts was determined prospectively in a cohort of 130 infants, aged 0 to 11 months, living in a marginal urban area of Guatemala City, Guatemala. A total of 1,280 stool specimens were examined; 158 of them were collected during episodes of diarrhea, and 1,122 were collected during symptom-free periods, every 2 to 3 weeks, from every child. Of the children, 20 (15.4%) excreted Cryptosporidium oocysts during the observation period. Of the diarrheal episodes, 13 (8.3%) were associated with Cryptosporidium sp. Of the control specimens, seven (0.6%) were positive for oocysts. Most of the infections were documented during the months of February to May, at the end of the dry season. Cryptosporidium infections are very common among Guatemalan infants and are an important cause of diarrhea and weight loss. The introduction of liquid or solid foods in the diets of the children, the presence of domestic animals (dogs, cats, or poultry), and the absence of toilet facilities in the house seem to be important risk factors for infection; also, deficient nutritional status may predispose the infected child to Cryptosporidium-associated illness.

Human cryptosporidiosis

Cryptosporidium is an enteric coccidial protozoan recognized in humans in 1976. Since its manifestation as an acquired immunodeficiency syndrome (AIDS)-related infection, new diagnostic techniques have improved recognition of Cryptosporidium oocysts, making apparent its true prevalence in human populations. Cryptosporidium represents 5 to 15% of all enteric pathogens in children in warm climate countries. It is responsible for both endemic and epidemic disease. Day-care center spread is well known, and evidence is strong for person-to-person transmission. The spectrum of illness caused by Cryptosporidium is broad, and while self-limited in immunocompetent individuals, gastrointestinal symptoms can be severe. Asymptomatic infection has been described in population surveys and outbreak investigations. Severe dehydration with malabsorption and failure-to-thrive in children from developing countries has been attributed to this organism. Intractable, incurable diarrhea can be fetal in immunosuppressed adults. Cryptosporidiosis in human immunodeficiency virus-infected individuals is declining in frequency in New York City, possibly reflecting changing sexual behaviors and comparatively low infectivity. No effective treatment for Cryptosporidium has been documented, but clinical trials are in progress.

The epidemiology of cryptosporidiosis and other intestinal parasitoses in children in southern Guinea-Bissau

In order to determine the prevalence of Cryptosporidium and other intestinal parasites, a household sample survey of children under 5 years old was carried out during the late dry season in 8 rural villages in southern Guinea-Bissau, West Africa. Cryptosporidium oocysts were found in 10 of 270 stool samples (3.7%), using a safranin-methylene blue staining method. Of these 10 children (age range 5-16 months), all non-Muslims, 6 had diarrhoea, giving a prevalence of 12.5% in 48 children with diarrhoea, compared with 1.8% in children without diarrhoea (P less than 0.001). The ethnic group with the highest prevalence (9.2%) also kept most domestic animals, and was the only group to keep cattle. Giardia lamblia was found in 16 children, and the overall prevalences of other enteric parasites were: hookworm, 21.7%; Strongyloides stercoralis, 7.4%; Ascaris lumbricoides, 6.9%; Trichuris trichiura, 4.4%; Entamoeba histolytica, 1.5%; and Taenia sp., 0.5%. The prevalence of cryptosporidiosis was highest in the age group 7-12 months, while for the other parasites it was highest in the oldest children. The prevalence of hookworm was highest (c. 50%) in the southernmost villages. No significant relationship was found between hookworm infection and anaemia.

Intestinal cryptosporidiosis. Association with Pneumocystis carinii, cytomegalovirus and Candida sp. infections

This is a case report of intestinal cryptosporidiosis diagnosed in histological specimen collected from autopsy. The patient was a child of 5 months admitted to the hospital with severe acute diarrhea associated with Pneumocystis carinii pneumonia, cytomegalic sialadenitis, oral and dermal candidiasis. The presence of multiple opportunistic infections in this case indicated immunodeficiency state. Cryptosporidium sp is a possible etiology of acute diarrhea in both immunodeficient and immunocompetent patients and has to be searched for at autopsy when diagnosis was not possible "in vivo".

Cryptosporidium species, a protean protozoan

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Cryptosporidiosis in well-nourished and malnourished children

During a 5-month period, 513 stool samples submitted to the enteric laboratory at the University Hospital of the West Indies were examined for Cryptosporidium. Oocysts were detected in 4.9% of all stools, 7.3% of diarrhoeal stools, 19.5% of stools from malnourished children and 23.7% of stools from malnourished children with diarrhoea. Cryptosporidium was the sole pathogen detected in all 25 positive stools, and was the second most frequent enteric isolate. All cases of cryptosporidiosis occurred in children less than 2.5 years of age. All 15 malnourished children were admitted to hospital where they presented with dehydration (87%), vomiting (93%), fever (100%) and diarrhoea which lasted an average of 15.3 days. Two of these children died. In contrast, dehydration (20%), vomiting (40%) and fever (50%) were less common and diarrhoea less protracted in well-nourished children, four of whom were admitted to hospital. This preliminary report suggests that cryptosporidial gastroenteritis presents with increased frequency and severity in malnourished compared with well-nourished Jamaican children.

Parasitic diseases of the small intestinal tract

The epidemiology, clinical aspects, and treatment of human intestinal infections with Giardia, Cryptosporidium, coccidia and Strongyloides in industrialized countries are reviewed. In well-nourished and immunocompetent persons, inapparent infections or mild, transitory gastrointestinal upsets caused by these parasites are quite common. Some patients develop severe symptoms, such as profuse diarrhoea, dehydration, stool irregularities for weeks or months followed by weight loss and malabsorption of fat, vitamins and iron. In patients receiving immunosuppressive treatment or with lymphotropic viral infections, Cryptosporidium and Strongyloides can cause life-threatening or debilitating disease. By autoinfection or external reinfection these parasites can persist in the intestine for years. Clinicians should consider such infections in immigrants, travellers and former servicemen, even long after their stay in endemic areas, and also in the handicapped and children in day-care centres.

Cryptosporidia in immunocompetent patients with gastroenteritis

In a prospective study Cryptosporidium spp. were detected in nine immunocompetent patients (0.6%). The frequency was remarkably higher in children in the 0 to 14 year age group (1.6%), surpassed only by Salmonella spp. and Campylobacter spp. The predominant clinical features were watery diarrhea, abdominal pain, and vomiting. Comparison of the epidemiological data of the patients with those of a control group showed that contact persons with enteritis and drinking of unpasteurized milk were significantly associated with cryptosporidiosis.

Timing of symptoms and oocyst excretion in human cryptosporidiosis

To determine the timing of symptoms and oocyst excretion after the acquisition of cryptosporidium infection, we used a screening parasitologic stool examination to identify patients and then contacted them for the collection of retrospective histories and follow-up stool specimens. The study included 68 otherwise healthy patients with an identifiable source and time of infection. All 68 had diarrhea, 61 had abdominal pain, most also had other gastrointestinal symptoms, 33 had fever, and all recovered spontaneously. Among the 50 patients who submitted follow-up stool samples, more than 90 percent of the 610 symptomatic days and of the 136 oocyst-positive stools occurred between days 7 and 28 of infection, the mean incubation period was 7.2 days (range, 1 to 12), and the mean duration of illness was 12.2 days (range, 2 to 26). During the oocyst-excretion period cryptosporidium was detected in 90 percent of Ziehl-Neelsen-stained fecal concentrates. The end of oocyst excretion could be accurately determined in 26 patients; 19 (73 percent) had positive stools after the cessation of symptoms for a mean period of 6.9 days (range, 1 to 15). Fourteen patients were studied for two or more months, and in three of them asymptomatic episodes of oocyst excretion were detected up to two months after clinical recovery. We conclude that many cases of symptomatic cryptosporidiosis occur among immunocompetent patients, some of whom may excrete oocysts even when they have become asymptomatic. Conversely, infected symptomatic patients may occasionally have intermittently negative stools.

Cryptosporidium spp. and cryptosporidiosis

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Immunofluorescence detection of Cryptosporidium oocysts in fecal smears

An indirect fluorescent antibody (IFA) procedure was developed for the detection of Cryptosporidium sp. oocysts in human, nonhuman primate, and bovine fecal smears. The procedure, which takes about 90 min to perform, involves the use of a rabbit antiserum against Cryptosporidium oocysts isolated from dairy cattle. Cross-specificity testing of the IFA method revealed no reactivity with yeasts, various amoebae, Giardia lamblia, Chilomastix sp., or Blastocystis sp. and only very weak cross-reactivity with coccidian oocysts of other genera. IFA detection of oocysts in human and nonhuman primate fecal smears was far more sensitive than was dimethyl sulfoxide-carbolfuchsin staining. Moreover, IFA detection was comparable in sensitivity to auramine O staining with samples of high oocyst concentration and somewhat more sensitive than auramine O with samples containing relatively few oocysts. The IFA procedure may be useful in the clinical diagnosis of human and animal cryptosporidiosis and also in the detection of oocysts in environmental samples.

Quantification of specific antibody response to Cryptosporidium antigens by laser densitometry

Cryptosporidium spp. is a protozoan parasite with worldwide distribution associated with diarrhea in immunocompromised patients (particularly those with acquired immunodeficiency syndrome [AIDS]) and in immunocompetent humans. Immunoglobulin M (IgM) and IgG antibody responses are readily detected by an enzyme-linked immunosorbent assay. To determine which Cryptosporidium antigens invoke antibody responses in humans, we performed polyacrylamide gel electrophoresis using purified oocysts, followed by Western blots with human sera from various populations. Of 40 sera from persons with cryptosporidiosis (24 AIDS and 16 non-AIDS patients), in 37 (93%) a 23,000-dalton antigen measured quantitatively by laser densitometry was recognized. Of 63 sera from IgM- or IgG-positive individuals, as determined by enzyme-linked immunosorbent assay, in 58 (92%) this same antigen was recognized. Up to three additional bands between 125,000 and 175,000 daltons were identified by some of these sera. These results suggest that most persons infected with Cryptosporidium spp. produce antibodies which recognize at least one common low-molecular-weight antigen. Isolation of this antigen will be useful in development of diagnostic tests and may be important in the study of immunity.

[Cryptosporidiosis in children]

Cryptosporidiosis in Children. During an 11-month survey, Cryptosporidium oocysts were found in the stools of 20 of 142 children admitted with gastroenteritis. Five of these 20 patients also excreted other enteropathogens. The clinical findings in 18 children infected with cryptosporidia could be analyzed. All patients were immunocompetent. Watery diarrhea, vomiting and anorexia were the most frequent symptoms. Differences in the clinical findings were observed between children aged one to two years and older children. The older children remained ill for 4.1 days compared to 19.9 days in the younger children. The younger children also presented a history of recurrent diarrhea. Problems of etiology and therapy are discussed. Cryptosporidia should be considered as a cause of diarrhea in children.

Cryptosporidiosis among black children in hospital in South Africa

Over a period of 3 months during the summer, 362 African children admitted to King Edward VIII Hospital, Durban, were screened for the faecal excretion of Cryptosporidium oocysts. Of 259 children with diarrhoea, oocysts were detected in 31 (11.9%), while none was found in the faeces of 103 children without diarrhoea (controls). All those children excreting Cryptosporidium were under 2 years of age, giving a prevalence of 15% for this group. Other potential enteric pathogens were detected in the faeces of 12 (38.7%) of these children. The case fatality rate for patients with Cryptosporidium was 22.6%, which may reflect the selection of patients in a study concentrating on hospital inpatients. Cryptosporidium was the second most common organism detected in diarrhoeal faeces, and the only one detected in 9.2% of diarrhoeal children aged less than two years. These findings indicate that Cryptosporidium should be regarded as a potential pathogen in children admitted to this hospital with severe diarrhoea. Such association of Cryptosporidium with diarrhoea in children accords with recent studies in other parts of the world.

Cryptosporidium spp., a frequent cause of diarrhea in Liberian children

This report presents results from a sample survey designed to investigate the possible role of Cryptosporidium spp. in childhood diarrhea in a developing country, Liberia, West Africa. During the four months of January to April 1983, a house-to-house study was carried out in two geographically and socially different communities--an urban slum and three rural villages. Stool samples from 374 children, aged 6 to 59 months, were tested for Cryptosporidium spp. Among the children with diarrhea 8.4% were Cryptosporidium spp. positive compared with a prevalence rate of 5.9% in asymptomatic children. Of the children living in a household with a Cryptosporidium spp.-positive index child, 8.6% had a positive stool sample. Of all children attending a clinic because of diarrhea, 14.6% were Cryptosporidium spp. positive. Cryptosporidiosis was more frequent in younger children; 24 of the total of 29 positive cases (83%) were below 2.5 years old. Actual or previous bottle feeding (formula) was a risk factor, particularly in children below 18 months old. Of the bottle-fed children, 28% were Cryptosporidium spp. positive versus 9.1% of children never bottle fed. Crowding is another possible risk factor. The prevalence of cryptosporidiosis was 13.5% in big urban households with more than 10 children, whereas the prevalence in the small urban households was 6.1%. Ethnic and religious differences were particularly evident in the rural area. No Muslim households had cryptosporidiosis, whereas the prevalence in non-Muslim tribes was 9%. The general belief that cryptosporidiosis is primarily a zoonosis is questioned in this study, partly because many carriers and asymptomatic household contacts were found.

Rapid immunoassay for detection of Cryptosporidium oocysts

A direct immunological method by means of latex agglutination (LX) reaction was applied to the demonstration of Cryptosporidium oocysts from stools and gut homogenates. The LX method gave a positive diagnosis for all the specimens judged positive by the modified Ziehl-Neelsen technique, which served as a reference method, The results of the study indicate that the LX method can be adopted as a diagnostic tool for cryptosporidiosis, but further study concerning the specificity and sensitivity of the method is clearly warranted.