Cryptosporidiosis in Kuwaiti children: seasonality and endemicity

Waterborne Cryptosporidium species and Giardia duodenalis in resources of MENA: A systematic review and meta-analysis

This review explores our understanding of Cryptosporidium species and Giardia duodenalis distribution in Middle East and North African (MENA) water resources. Results emphasize that Cryptosporidium species (sp.) and G. duodenalis (oo)cysts are present in distinct categories of water in ten MENA countries. Cryptosporidium sp. proportional prevalence in the MENA region was 24.5% (95% CI 16.3-33.8), while G. duodenalis prevalence was 37.7% (95% CI 21.9-55.1). Raw wastewater and surface water were the water categories most significantly impacted. Both parasites were reported in the various types of MENA drinking waters. The most frequent species/genotypes reported were C. hominis, C. parvum, and G. duodenalis assemblage A. Despite the high prevalence of (oo)cysts reported, we should consider the absence of waterborne outbreaks. This indicates significant underestimation and underreporting of both parasites in MENA. Stakeholders should apply water contamination legislation to eradicate Cryptosporidium sp. and G. duodenalis (oo)cysts from water resources/categories.

Clinical and Laboratory Diagnosis of Cryptosporidiosis among Children with Acute Gastroenteritis at a Tertiary Hospital, Cairo, Egypt

BACKGROUND

Most studies on gastroenteritis have focused on viral and bacterial infections, while gastroenteritis where intestinal protozoan parasites may have played a role has not been well studied. This study was therefore, designed to assess the frequency and several potential risk factors for Cryptosporidium infection among children suffering from acute gastroenteritis and presented to a tertiary hospital in Cairo, Egypt. Effectiveness of modified Ziehl-Neelsen (MZN) and nested polymerase chain reaction (nPCR) for Cryptosporidium detection were evaluated as well.

METHODS

A cross-sectional study was performed during the period from July 2018 to December 2018, where 100 human diarrheic stool samples were collected from children aged 3 months up to 12 years old presented to Ain Shams University Pediatrics Hospital, Cairo, Egypt with acute gastroenteritis. Demographic and clinical data were obtained from the participants. Initial parasite screening was done using the MZN staining method, and microscopically examined for Cryptosporidium infection, while genotyping was based on molecular diagnostic assays using nPCR and sequencing for selected samples.

RESULTS

The overall frequency of Cryptosporidium infection was 5% using light microscopy, while 19% of samples were positive by nPCR. Cryptosporidium hominis was the only detected genotype. Clinical picture among cases were not significant in comparison to patients with other causes of gastroenteritis.

CONCLUSION

Cryptosporidium infection is more common below 5 years of age; however, clinical data are not enough for suspicion of infection. Nucleic acid-based methods are more sensitive and specific despite the high cost in developing countries. However, real estimation of Cryptosporidium disease burden is of an outmost importance to achieve prevention and detection of the Cryptosporidium species genetic diversity. Lay summaryCryptosporidium is a protozoan, which causes gastroenteritis in humans. It is most common below 5 years of age; however, diarrhea and vomiting characteristics are not different from other causes of gastroenteritis. General diagnostic methods are inadequate for detection of these infections. Nested polymerase chain reaction (nPCR) and sequencing are accurate methods for pathogen detection and species verification. Our study included 100 Egyptian children with acute gastroenteritis. The overall frequency of Cryptosporidium infection was 5% using light microscopy, while 19% of samples were positive by nPCR. The clinical picture of the children presenting with this disease was not significantly different from those presenting with gastroenteritis due to other causes. This emphasizes the importance of proper diagnosis to know the true burden of the disease.

Cryptosporidium and Cryptosporidiosis: The Perspective from the Gulf Countries

The present review discusses the burden of cryptosporidiosis in the Gulf Cooperation Council (GCC), which is underreported and underestimated. It emphasizes that the Cryptosporidium parasite is infecting inhabitants and expatriates in the Gulf countries. Children under 5 years are a vulnerable group that is particularly affected by this parasitic disease and can act as carriers, who contribute to the epidemiology of the disease most probably via recreational swimming pools. Various risk factors for cryptosporidiosis in the GCC countries are present, including expatriates, predisposing populations to the infection. Water contamination, imported food, animal contact, and air transmission are also discussed in detail, to address their significant role as a source of infection and, thus, their impact on disease epidemiology in the Gulf countries' populations.

Molecular Analysis of the Enteric Protozoa Associated with Acute Diarrhea in Hospitalized Children

Pediatric diarrhea is a common cause of death among children under 5 years of age. In the current study, we investigated the frequency of intestinal parasites among 580 pediatric patients with chronic diarrhea. Parasitic protozoa (all species combined) were detected by molecular tools in 22.9% of the children and the most common parasite was Cryptosporidium spp. (15.1%). Blastocystis hominis was detected in 4.7%, Dientamoeba fragilis in 4%, Giardia duodenalis in 1.7%, and Entamoeba histolytica in 0.17%. Protozoan infections were observed among all regional groups, but prevalence was highest among Qatari subjects and during the winter season. Typing of Cryptosporidium spp. revealed a predominance of Cryptosporidium parvum in 92% of cases with mostly the IIdA20G1 subtype. Subtypes IIdA19G2, IIdA18G2, IIdA18G1, IIdA17G1, IIdA16G1, and IIdA14G1 were also detected. For Cryptosporidium hominis, IbA10G2 and IbA9G3 subtypes were identified. This study provides supplementary information for implementing prevention and control strategies to reduce the burden of these pediatric protozoan infections. Further analyses are required to better understand the local epidemiology and transmission of Cryptosporidium spp. in Qatar.

Molecular epidemiology of blastocystosis in Malaysia: does seasonal variation play an important role in determining the distribution and risk factors of Blastocystis subtype infections in the Aboriginal community?

BACKGROUND

Alternating wet and dry seasons may play an important role in the acquisition and distribution of Blastocystis subtype infection in the tropics. This cross-sectional study was therefore conducted to provide the prevalence of Blastocystis and to determine the potential risk factors associated with each subtype during the wet and dry seasons in the Aboriginal community, Pahang, Malaysia.

METHODS

A total of 473 faecal samples were collected: 256 (54.1%) and 217 (45.9%) samples were obtained during the wet (October-November 2014) and the dry season (June 2015), respectively. All fresh faecal samples were subjected to molecular analysis for subtype and allele identification.

RESULTS

Of the 473 samples, 42.6% and 37.8% were positive for Blastocystis ST1, ST2, ST3 and ST4 during wet and dry seasons, respectively. Prevalence of Blastocystis ST1 was significantly higher during the wet season compared to the dry season (Z = 2.146, P < 0.05). Analysis of the association of each Blastocystis subtype with socioeconomic characteristics showed the presence of other family members infected with Blastocystis ST3 and the use of stored river water for domestic activities were the significant risk factors for Blastocystis ST3 infections during both seasons. Untreated water supply and low monthly household income (less or equal to RM 500) were the other significant risk factors for Blastocystis ST3 infections during wet and dry season, respectively. The presence of other family members with Blastocystis ST1 and ST2 was the only significant risk factor associated with ST1 and ST2 infections during both seasons. We hypothesise that transmission of Blastocystis ST1, ST2 and ST3 occurred from person to person during both seasons. The waterborne transmission was also identified as a mode of transmission of Blastocystis ST3.

CONCLUSION

The significant risk factors identified in this study were important in the dynamic transmission of Blastocystis infections during both seasons. Provision of treated water supply and health education are affirmative actions to be taken to control Blastocystis infections in this community.

Human cryptosporidiosis in Iran: a systematic review and meta-analysis

Cryptosporidiosis caused by Cryptosporidium spp. is an important parasitic disease that can be life-threatening for children and immunocompromised patients. This systematic review and meta-analysis was designed to determine the prevalence rate of Cryptosporidium infection and related risk factors among the Iranian general population. We searched electronic databases including Google Scholar, PubMed, Science Direct, Scopus and Proquest for articles in English and SID, Magiran, IranMedex, and IranDoc for articles in Persian. Out of 4816 studies identified in the electronic search, 94 articles were eligible for inclusion in the systematic review and meta-analysis. The prevalence rate of cryptosporidiosis by using the random effect model among children, healthy people, and gastroenteritis and immunocompromised patients in Iran was estimated as 3.65, 2.94, 1.29, and 4.54%, respectively. Findings of a phylogenetic analysis inferred by gp60 and 18S ribosomal RNA markers indicated that most of the infection rate belonged to C. parvum (particularly subtype IIaA15G2R1) and C. hominis among understudied groups. The present study is the first systematic review and meta-analysis providing a comprehensive view of the prevalence of human cryptosporidiosis and its related risk factors in Iran. It seems that the awareness of Cryptosporidium prevalence, risk factors, and disease complications may be required for developing effective strategies to prevent infection.

Molecular characterization of cryptosporidium in children aged 0- 5 years with diarrhea in Jos, Nigeria

Introduction

Cryptosporidium is an important cause of diarrhea in children and immune-compromised individuals. Recent advances in molecular diagnostics have led to the discovery of subtype families that are thought to be more commonly associated with diarrhea. We aimed to isolate and characterize Cryptosporidium spp among children with diarrhea in Jos, Nigeria.

Methods

Stool samples were collected from165 children aged 0-5 years with diarrhea. Cryptosporidium oocysts were examined by wet mount preparation, using formalin ether and a modified acid fast staining method. DNA was extracted from positive samples using QIAamp DNA stool mini kit and PCR-RFLP assay was carried out after quantification. Genotyping and phylogenetic analysis were done to determine the subtype families and their relatedness.

Results

From the 165 children studied, 8 (4.8%) were infected with Cryptosporidium. PCR-RFLP assay and genotype characterization found the following Cryptosporidium species: C. hominis 6 (75%) and C. parvum 2 (25.0%), with family subtypes Id-5, Ie-1 and IIa-1, IId-1 respectively.The most common species was C. hominis and the frequent subtype was C. hominis-Id 5 (62.5%).

Conclusion

Cryptosporidium is not an uncommon cause of diarrhea in children, with C. hominis being the dominant species. Also C. hominis Id is the commonest sub-family subtype. Put together, zoonotic species may be an important cause of diarrhea in children aged 0-5 years in Jos, Nigeria.

Systematic review on Endolimax nana: A less well studied intestinal ameba

Of the so-called nonpathogenic intestinal protozoa, Endolimax nana belongs to the ones least well described. Most data on E. nana have emerged from general surveys of intestinal parasites in selected cohorts and mostly in the absence of any particular focus on Endolimax. Hence, the genus of Endolimax remains largely unexplored in terms of morphology, taxonomy, genetic diversity, host specificity, and epidemiology. In this review, we seek to provide an overview of the work that has been performed on the parasite since the genus Endolimax was described by Kuenen and Swellengrebel in 1917 and suggest activities that may pave the way for a better understanding of E. nana in a clinical and public health context.

Evaluation of the xTAG Gastrointestinal Pathogen Panel Assay for the Detection of Enteric Pathogens in Kuwait

OBJECTIVE

To evaluate the utility of the Luminex xTAG gastrointestinal pathogen panel (GPP) assay in the detection of enteric pathogens from diarrheal stool samples in Kuwait.

MATERIALS AND METHODS

The Luminex xTAG GPP assay was used according to the manufacturer's instructions to evaluate single diarrheal stool samples from 109 hospitalized patients at Mubarak Al-Kabeer Hospital, Kuwait, from March 2014 to June 2015. The assay procedure involved nucleic acid extraction from stool samples, amplification of the target by reverse transcriptase polymerase chain reaction, hybridization of the amplified target by probe, detection of the target by the Luminex instrument and computerized data analysis. Conventional microbiological assays were used as the gold standard for comparison.

RESULTS

From the 109 diarrheal stool samples, 20 (18.4%) pathogens were detected by the xTAG GPP assay compared to 10 (9.2%) pathogens using conventional assays. Both methods detected 3 Salmonella spp., 3 Clostridium difficile, 2 rotavirus and 2 norovirus. In addition, the xTAG GPP assay detected 1 Shigella sp., 6 Campylobacter spp., 1 Cryptosporidium sp. and 2 Giardia lamblia which were missed by conventional assays.

CONCLUSIONS

In this study, xTAG GPP detected twice as many pathogens as the conventional assays. We recommend the introduction of this assay in routine diagnostic laboratories for a rapid and better diagnosis and treatment of diarrheal disease.

Prevalence of Cryptosporidium Infection among Inhabitants of 2 Rural Areas in White Nile State, Sudan

Cryptosporidium , a protozoan parasite that causes watery diarrhea, is found worldwide and is common in areas with low water hygiene. In February 2014, 866 stool samples were collected from the inhabitants of 2 rural areas in White Nile State, Sudan. These stool samples were assessed by performing modified acid-fast staining, followed by examination under a light microscope. The overall positive rate of Cryptosporidium oocysts was 13.3%. Cryptosporidium oocysts were detected in 8.6% stool samples obtained from inhabitants living in the area having water purification systems and in 14.6% stool samples obtained from inhabitants living in the area not having water purification systems. No significant difference was observed in the prevalence of Cryptosporidium infection between men and women (14.7% and 14.1%, respectively). The positive rate of oocysts by age was the highest among inhabitants in their 60s (40.0%). These findings suggest that the use of water purification systems is important for preventing Cryptosporidium infection among inhabitants of these rural areas in Sudan.

Social determinants associated with Giardia duodenalis infection in southern Côte d'Ivoire

The purpose of this investigation was to analyze the association between different social determinants of health at the local scale and Giardia duodenalis infection in diverse settlements in southern Côte d'Ivoire. Stool samples from 306 individuals aged 1-16 years were collected from six rural villages and a small town. Five variables were categorized to classify the increasing risk levels of acquiring intestinal parasites. Giardia prevalences (%) and odds ratios (ORs) were evaluated. Correlation and regression analyses were conducted to determine the correlation coefficients and to propose predictive models based on social determinants to forecast the risk of giardiasis. The overall observed prevalence of Giardia was 21.6 %. When the analysis was conducted at the local level, the percentage of infected people varied from a minimum of 12.7 up to 36.4 %. A significant association (p < 0.001) was found between the selected social determinants and G. duodenalis prevalence in the different localities. Correlation and regression analyses allowed us to describe two predictive models to estimate the OR of Giardia transmission. This study helps to clarify the possible impact of different social determinants of health on the risk of giardiasis at the local scale. Both predictive models could be suitable in order to assess the likelihood of the transmission of intestinal parasitic infection in developing countries.

Blastocystis hominis and Endolimax nana Co-Infection Resulting in Chronic Diarrhea in an Immunocompetent Male

Blastocystis hominis and Endolimax nana exist as two separate parasitic organisms; however co-infection with the two individual parasites has been well documented. Although often symptomatic in immunocompromised individuals, the pathogenicity of the organisms in immunocompetent subjects causing gastrointestinal symptoms has been debated, with studies revealing mixed results. Clinically, both B. hominis and E. nana infection may result in acute or chronic diarrhea, generalized abdominal pain, nausea, vomiting, flatulence and anorexia. We report the case of a 24-year-old immunocompetent male presenting with chronic diarrhea and abdominal pain secondary to B. hominis and E. nana treated with metronidazole, resulting in symptom resolution and eradication of the organisms. Our case illustrates that clinicians should be cognizant of both B. hominis and E. nana infection as a cause of chronic diarrhea in an immunocompetent host. Such awareness will aid in a timely diagnosis and possible parasitic eradication with resolution of gastrointestinal symptoms.

Cryptosporidiosis in Kuwaiti children: association of clinical characteristics with Cryptosporidium species and subtypes

To determine the association of clinical characteristics with Cryptosporidium types and subtypes, faecal specimens from 2548 children with diarrhoea were screened by microscopy for Cryptosporidium spp., and positive specimens were genotyped and subtyped by PCR-RFLP. A total of 87 of the 2548 children (3.4 %) had cryptosporidial diarrhoea by microscopy and the majority (41.4 %) of the infected children were in the 4-8-year-old age group. Molecular characterization of the 83 children studied further (4 had mixed infections and were not subtyped) showed that Cryptosporidium parvum was the most commonly identified species (73.5 %) and consisted of three subtypes: IIa and IId were the most common (80.3 %), followed by IIc. Twenty-two (26.5 %) of the children had Cryptosporidium hominis and showed three subtypes: Id was the most common (54.5 %), followed by Ia (36.4 %) and Ie. Associated clinical manifestations varied between C. parvum and C. hominis. Diarrhoea associated with subtype Id, the most commonly identified C. hominis subtype, was more severe than that associated with other subtypes. In conclusion, this study confirmed a very different Cryptosporidium genotype and subtype distribution compared with other tropical countries among Kuwaiti children with diarrhoea, with a predominance of C. parvum IIa and IId. In addition, subtype Id of C. hominis was associated with more diverse and severe clinical manifestations in infected children, suggesting that parasite genetics may play an important role in the clinical manifestations of human cryptosporidiosis.

Global distribution, public health and clinical impact of the protozoan pathogen cryptosporidium

Cryptosporidium spp. are coccidians, oocysts-forming apicomplexan protozoa, which complete their life cycle both in humans and animals, through zoonotic and anthroponotic transmission, causing cryptosporidiosis. The global burden of this disease is still underascertained, due to a conundrum transmission modality, only partially unveiled, and on a plethora of detection systems still inadequate or only partially applied for worldwide surveillance. In children, cryptosporidiosis encumber is even less recorded and often misidentified due to physiological reasons such as early-age unpaired immunological response. Furthermore, malnutrition in underdeveloped countries or clinical underestimation of protozoan etiology in developed countries contribute to the underestimation of the worldwide burden. Principal key indicators of the parasite distribution were associated to environmental (e.g., geographic and temporal clusters, etc.) and host determinants of the infection (e.g., age, immunological status, travels, community behaviours). The distribution was geographically mapped to provide an updated picture of the global parasite ecosystems. The present paper aims to provide, by a critical analysis of existing literature, a link between observational epidemiological records and new insights on public health, and diagnostic and clinical impact of cryptosporidiosis.

Seasonality of cryptosporidiosis: A meta-analysis approach

OBJECTIVES

We developed methodology for and conducted a meta-analysis to examine how seasonal patterns of cryptosporidiosis, a primarily waterborne diarrheal illness, relate to precipitation and temperature fluctuations worldwide.

METHODS

Monthly cryptosporidiosis data were abstracted from 61 published epidemiological studies that cover various climate regions based on the Köppen Climate Classification. Outcome data were supplemented with monthly aggregated ambient temperature and precipitation for each study location. We applied a linear mixed-effect model to relate the monthly normalized cryptosporidiosis incidence with normalized location-specific temperature and precipitation data. We also conducted a sub-analysis of associations between the Normalized Difference Vegetation Index (NDVI), a remote sensing measure for the combined effect of temperature and precipitation on vegetation, and cryptosporidiosis in Sub-Saharan Africa.

RESULTS

Overall, and after adjusting for distance from the equator, increases in temperature and precipitation predict an increase in cryptosporidiosis; the strengths of relationship vary by climate subcategory. In moist tropical locations, precipitation is a strong seasonal driver for cryptosporidiosis whereas temperature is in mid-latitude and temperate climates. When assessing lagged relationships, temperature and precipitation remain strong predictors. In Sub-Saharan Africa, after adjusting for distance from the equator, low NDVI values are predictive of an increase in cryptosporidiosis in the following month.

DISCUSSION

In this study we propose novel methodology to assess relationships between disease outcomes and meteorological data on a global scale. Our findings demonstrate that while climatic conditions typically define a pathogen habitat area, meteorological factors affect timing and intensity of seasonal outbreaks. Therefore, meteorological forecasts can be utilized to develop focused prevention programs for waterborne cryptosporidiosis.

Cryptosporidium and Giardia infection and drinking water sources among children in Lege Dini, Ethiopia

We assessed the prevalence of Cryptosporidium and Giardia infections among children using protected and unprotected water sources in the Lege Dini watershed, Eastern Ethiopia, in November 2005 and May 2006. Of 655 children examined, 80 (12.2%) were infected with Cryptosporidium and 231 (35.3%) with Giardia. No difference was observed in the prevalence of cryptosporidiosis and giardiasis (P > 0.05) between children drinking water from protected and unprotected sources.

Cryptosporidiosis in Saudi Arabia and neighboring countries

Cryptosporidium is a coccidian protozoan parasite of the intestinal tract that causes severe and sometimes fatal watery diarrhea in immunocompromised patients, and self-limiting but prolonged diarrheal disease in immunocompetent individuals. It exists naturally in animals and can be zoonotic. Although cryptosporidiosis is a significant cause of diarrheal diseases in both developing and developed countries, it is more prevalent in developing countries and in tropical environments. We examined the epidemiology and disease burden of Cryptosporidium in Saudi Arabia and neighboring countries by reviewing 23 published studies of Cryptosporidium and the etiology of diarrhea between 1986 and 2006. The prevalence of Cryptosporidium infection in humans ranged from 1% to 37% with a median of 4%, while in animals it was different for different species of animals and geographic locations of the studies. Most cases of cryptosporidiosis occurred among children less than 7 years of age, and particularly in the first two years of life. The seasonality of Cryptosporidium varied depending on the geographic locations of the studies, but it was generally most prevalent in the rainy season. The most commonly identified species was Cryptosporidium parvum while C. hominis was detected in only one study from Kuwait. The cumulative experience from Saudi Arabia and four neighboring countries (Kuwait, Oman, Jordan and Iraq) suggest that Cryptosporidium is an important cause of diarrhea in humans and cattle. However, the findings of this review also demonstrate the limitations of the available data regarding Cryptosporidium species and strains in circulation in these countries.

The association of Blastocystis hominis and Endolimax nana with diarrheal stools in Zambian school-age children

To determine the prevalence of endoparasites and their association with diarrhea, a survey was conducted in the Southern Province of Zambia that used conventional and molecular techniques applied to stool and urine samples from school-age children (n = 93). Almost half of the stools (49.5%) were diarrhetic. The overall prevalence of Endolimax nana, Schistosoma haematobium, Blastocystis hominis, Giardia lamblia, Cryptosporidium parvum, Encephalitozoon intestinalis, and Strongyloides stercoralis was 64.3, 59.1, 53.8, 19.4, 8.6, 8.6, and 1.1%, respectively. Only the associations between infection with B. hominis and E. nana with diarrhea were statistically significant. Although B. hominis and E. nana are considered to be nonpathogenic organisms, this study demonstrated that they can be associated with diarrhea in children when they occur at high prevalence and intensity. This survey supports the recent evidence that B. hominis and E. nana infections are associated with deficient sanitation and low hygiene standards and can contribute to diarrhea in children in developing countries.

Unique endemicity of cryptosporidiosis in children in Kuwait

To understand the transmission of Cryptosporidium infection in children, fecal specimens from 62 Kuwaiti children with gastrointestinal symptoms found to be positive by microscopy were genotyped and subtyped with a small subunit rRNA-based PCR-restriction fragment length polymorphism analysis and a 60-kDa glycoprotein-based DNA sequencing tool. The median age of infected children was 4.5 years, and 77% of infections occurred during the cool season of November to April. Fifty-eight of the children (94%) had Cryptosporidium parvum, three (5%) had Cryptosporidium hominis, and one (1%) had both C. parvum and C. hominis. Altogether, 13 subtypes of C. parvum (belonging to four subtype allele families) and C. hominis (belonging to three subtype allele families) were observed, with 92% of specimens belonging to the common allele family IIa and the unusual allele family IId. Thus, the transmission of cryptosporidiosis in Kuwaiti children differed significantly from other tropical countries.

Molecular Epidemiology of Cryptosporidiosis in Children in Malawi

Few studies have examined the molecular epidemiology of cryptosporidiosis in developing countries. In this study, DNA of 69 microscopy-positive human fecal samples collected from Malawi were examined by multilocus genetic analyses. From 43, 27 and 28 of the samples, the SSU rRNA, 70 kDa heat shock protein (HSP70) and 60 kDa glycoprotein (GP60) genes, respectively, were successfully PCR-amplified. Restriction analysis of the SSU PCR products showed that 41 of the 43 PCR-positive samples had C. hominis and 2 had C. parvum. Sequence analysis of the HSP70 and GP60 gene confirmed the species identification by SSU rRNA PCR-RFLP analysis, but also revealed high intraspecific variations. Altogether, six HSP70 subtypes and six GP60 subtypes (belonging to four subtype alleles) of C. hominis were found. Linkage disequilibrum analysis of the two genetic loci showed possible intraspecific recombination. Thus, cryptosporidiosis in the study area was largely caused by anthroponotic transmission. The high intraspecific variation and existence of genetic recombination were probably results of high transmission of cryptosporidiosis in this area.

Detection of Cryptosporidium amongst diarrhoeic and asymptomatic children in Jeddah, Saudi Arabia

Between the March and May of 2000, stool specimens were collected from children aged <5 in six pre-school crèches and clinics in the Jeddah area of Saudi Arabia. Sixty-three (25%) of the children had diarrhoeal disease but the other 190 were asymptomatic. When the stool samples were stained and examined for the oocysts of Cryptosporidium spp. and other enteric protozoa, 20 (32%) of the symptomatic children but only nine (4.7%) of the asymptomatic were found to be excreting Cryptosporidium oocysts. Similarly, Cyclospora cayetanensis was found, always as a co-infection with Cryptosporidium sp., in seven (11%) of the children with diarrhoeal disease but only eight (4.2%) of the asymptomatics. One asymptomatic child was found to be co-infected with Isospora belli and Cryptosporidium. Giardia intestinalis and cysts of Entamoeba histolytica/dispar were detected in 18 (29%) and nine (14%) of the children with diarrhoeal disease and in eight (4.2%) and 13 (6.8%) of the asymptomatic children, respectively. This appears to be the first report of Cy. cayetanensis from Saudi Arabia and the highest prevalence of Cryptosporidium infection ever described.

Epidemiological survey of Blastocystis hominis in Huainan City, Anhui Province, China

AIM: To provide scientific evidence for prevention and controlling of blastocystosis, the infection of Blastocystis homonis and to study its clinical significance in Huainan City, Anhui Province, China.

METHODS: Blastocystis homonis in fresh stools taken from 100 infants, 100 pupils, 100 middle school students and 403 patients with diarrhea was smeared and detected with method of iodine staining and hematoxylin staining. After preliminary direct microscopy, the shape and size of Blastocystis homonis were observed with high power lens. The cellular immune function of the patients with blastocystosis was detected with biotin-streptavidin (BSA).

RESULTS: The positive rates of Blastocystis homonis in fresh stools taken from the infants, pupils, middle school students and the patients with diarrhea, were 1.0% (1/100), 1.0% (1/100), 0% (0/100) and 5.96% (24/403) respectively. Furthermore, the positive rates of Blastocystis homonis in the stool samples taken from the patients with mild diarrhea, intermediate diarrhea, severe diarrhea and obstinate diarrhea were 6.03% (14/232), 2.25% (2/89), 0% (0/17) and 12.31% (8/65) respectively. The positive rates of Blastocystis homonis in fresh stools of male and female patients with diarrhea were 7.52% (17/226) and 3.95% (7/177) respectively, and those of patients in urban and rural areas were 4.56% (11/241) and 8.02% (13/162) respectively. There was no significant difference between them (P > 0.05). The positive rates of CD₃⁺, CD₄⁺, CD₈⁺ in serum of Blastocystis homonis-positive and-negative individuals were 0.64 ± 0.06, 0.44 ± 0.06, 0.28 ± 0.04 and 0.60 ± 0.05, 0.40 ± 0.05 and 0.30 ± 0.05 respectively, and the ratio of CD₄⁺/CD₈⁺ of the two groups were 1.53 ± 0.34 and 1.27 ± 0.22. There was significant difference between the two groups (P < 0.05, P < 0.01).

CONCLUSION: The prevalence of Blastocystis hominis as an enteric pathogen in human seems not to be associated with gender and living environment, and that Blastocystis hominis is more common in stool samples of the patients with diarrhea, especially with chronic diarrhea or obstinate diarrhea. When patients with diarrhea infected by Blastocystis hominis, their cellular immune function decreases, which make it more difficult to be cured.