Updates on the worldwide burden of amoebiasis: A case series and literature review

BACKGROUND

Amoebiasis is an intestinal and tissue parasitic infection caused by the protozoan Entamoeba histolytica. Despite significant medical importance and worldwide dispersion, little is known about the epidemiology and distinct geographical distribution of various clinical forms of amoebiasis in the world. In this study, we present an amoebiasis case series referred to Avicenne Hospital (Bobigny, France) from 2010 to 2022 followed by an overview of the released literature to explore diverse clinico-pathology of amoebiasis and to update the actual epidemiological situation of this parasitosis worldwide.

METHODS

The referred patients underwent a combination of clinical and parasitological examinations and imaging. The study was followed by an overview of released literature performed based on PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guideline.

RESULTS

A total of 15 patients with amoebiasis were diagnosed with an average age of 48.5 years old at the occurrence time of infection. Men (78%) were the most affected patients. Most of the cases were reported following a trip to endemic regions, such as Mali, India, Nepal, Algeria, Cameroon or Congo. All of the processed patients exhibited a hepatic amoebiasis. Amoebic abscess was observed in all cases with an average size of 6.3 cm. Of these patients, seven cases (46.7%) benefited from drainage following a risk of rupture or superinfection of the abscess. A compilation of findings extracted from 390 scientific publications via seven major medical databases, allowed us to update the main epidemiological and clinical events that has led to the current worldwide expansion of amoebiasis. We presented a clinical and epidemiological overview of the amoebiasis accompanied with a worldwide illustrative map displaying the current distribution of known amoebiasis foci in each geographical ecozone of Asia, Europe, Africa, Americas, and Australia.

CONCLUSIONS

Although Metropolitan France is not known as an endemic region of amoebiasis, amoebic liver abscess was the most frequent clinical form observed among our 15 patients processed. Most of infected patients had a history of travel to or lived-in endemic areas before arriving in France.

Intestinal amoebiasis: 160 years of its first detection and still remains as a health problem in developing countries

Amoebiasis is a parasitic disease caused by Entamoeba histolytica (E. histolytica), an extracellular enteric protozoan. This infection mainly affects people from developing countries with limited hygiene conditions, where it is endemic. Infective cysts are transmitted by the fecal-oral route, excysting in the terminal ileum and producing invasive trophozoites (amoebae). E. histolytica mainly lives in the large intestine without causing symptoms; however, possibly as a result of so far unknown signals, the amoebae invade the mucosa and epithelium causing intestinal amoebiasis. E. histolytica possesses different mechanisms of pathogenicity for the adherence to the intestinal epithelium and for degrading extracellular matrix proteins, producing tissue lesions that progress to abscesses and a host acute inflammatory response. Much information has been obtained regarding the virulence factors, metabolism, mechanisms of pathogenicity, and the host immune response against this parasite; in addition, alternative treatments to metronidazole are continually emerging. An accesible and low-cost diagnostic method that can distinguish E. histolytica from the most nonpathogenic amoebae and an effective vaccine are necessary for protecting against amoebiasis. However, research about the disease and its prevention has been a challenge due to the relationship between E. histolytica and the host during the distinct stages of the disease is multifaceted. In this review, we analyze the interaction between the parasite, the human host, and the colon microbiota or pathogenic microorganisms, which together give rise to intestinal amoebiasis.

Approach to amoebic colitis: Epidemiological, clinical and diagnostic considerations in a non-endemic context (Barcelona, 2007-2017)

Background

Amoebic colitis is the most frequent clinical manifestation of invasive intestinal infection due to Entamoeba histolytica and a common cause of diarrhoea worldwide. Since higher transmission rates are usually related to poor health and exposure to unhygienic conditions, cases reported in Europe usually involve immigrants and international travellers. The goal of this study was to characterise both the clinical and the epidemiological features of a European population diagnosed with amoebic colitis and then to evaluate the diagnostic tools and therapeutic options applied.

Methods and results

This was a retrospective observational study in which data from all patients diagnosed with amoebic colitis attending at the International Health Units of two tertiary referral hospitals, Germans Trias i Pujol University Hospital (Badalona, North Barcelona Metropolitan Area) and Vall d’Hebron University Hospital (Barcelona city) between 2007 and 2017 were analysed. During the study period 50 patients were diagnosed with amoebic colitis. Thirty-six (72%) were men, and immigrants accounted for 46% of all cases. Antecedents of any international travel were reported for 28 (56%), the most frequent destinations having been the Indian subcontinent, South and Central America and sub-Saharan Africa. Preexisting pathological conditions or any kind of immunosuppression were identified in 29 (58%) patients; of these, 13 (26%) had HIV infection—all of them men who have sex with men—and 5 (10%) had inflammatory bowel disease. Diarrhoea, abdominal pain and dysentery were the most frequently recorded symptoms of invasive amoebae. Diagnosis was made through microbiological study in 45 (90%) and/or histological identification of amoebae in colon biopsies in 10 (20%). After treatment with metronidazole (82%) or tinidazole (8%), all patients had good outcomes. Post-acute intraluminal treatment was indicated in 28 (56%).

Conclusions

Amoebic colitis should be suspected in patients with diarrhoea and compatible epidemiological risk factors (immigration, travelling abroad or men who have sex with men), especially if some degree of immunosuppression concurs. These risk factors must be taken into account in any diagnostic approach to inflammatory bowel disease (IBD), and active searches for stool parasites should be performed in such cases to rule out misdiagnosis or simultaneous amoebic infection. Treatment should include intraluminal anti-amoebic treatment in order to avoid relapse and prevent further spread of the disease.

Prevalence of Entamoeba spp. in Stool Samples of Patients with Amebiasis Suspect by Native-Lugol and ELISA

OBJECTIVE

This study aimed to determine the prevalence of Entamoeba spp. in suspected stool samples submitted to our laboratory.

METHODS

In this retrospective study, stool samples of 998 patients with suspected amebiasis were sent from various clinics and services to our laboratory and were investigated by native-Lugol and enzyme-linked immunosorbent assay (ELISA) [for Entamoeba spp. antigen (Ridascreen® Entamoeba)] between January 2010 and December 2014.

RESULTS

By the end of the study, it was shown that 8.5% (85) of 997 patients, 7.45% (39) of males and 9.8% (46) of females whom amoeba antigen inspected in their stool samples, were positive. No parasite was identified by the saline-Lugol method. The highest antigen positivity was detected in the 25-44-year-old group with 11% positivity, and a high positivity of 23.2% was seen in March.

CONCLUSION

These results demonstrate that amebiasis is still a major health concern for our region. Although no parasite was detected during microscopic examinations, the detection of antigen positivity by ELISA reveals that microscopic examinations require experience and utilizing only microscopic examinations may lead to overlooks. To obtain more reliable results in diagnosis, ELISA analyses that use E. histolytica-specific monoclonal antibodies should be applied in addition to microscopic methods.

Impacts of different grades of tropical cyclones on infectious diarrhea in Guangdong, 2005-2011

Objective

Guangdong province is one of the most vulnerable provinces to tropical cyclones in China. Most prior studies concentrated on the relationship between tropical cyclones and injuries and mortality. This study aimed to explore the impacts of different grades of tropical cyclones on infectious diarrhea incidence in Guangdong province, from 2005 to 2011.

Methods

Mann-Whitney U test was firstly used to examine if infectious diarrhea were sensitive to tropical cyclone. Then unidirectional 1:1 case-crossover design was performed to quantitatively evaluate the relationship between daily number of infectious diarrhea and tropical cyclone from 2005 to 2011 in Guangdong, China. Principal component analysis (PCA) was applied to eliminate multicollinearity. Multivariate logistic regression model was used to estimate the hazard ratios (HRs) and the 95% confidence intervals (CI).

Results

There were no significant relationships between tropical cyclone and bacillary dysentery, amebic dysentery, typhoid, and paratyphoid cases. Infectious diarrhea other than cholera, dysentery, typhoid and paratyphoid significantly increased after tropical cyclones. The strongest effect were shown on lag 1 day (HRs = 1.95, 95%CI = 1.22, 3.12) and no lagged effect was detected for tropical depression, tropical storm, severe tropical storm and typhoon, with the largest HRs (95%CI) of 2.16 (95%CI = 1.69, 2.76), 2.43 (95%CI = 1.65, 3.58) and 2.21 (95%CI = 1.65, 2.69), respectively. Among children below 5 years old, the impacts of all grades of tropical cyclones were strongest at lag 0 day. And HRs were 2.67 (95%CI = 1.10, 6.48), 2.49 (95%CI = 1.80, 3.44), 4.89 (95%CI = 2.37, 7.37) and 3.18 (95%CI = 2.10, 4.81), respectively.

Conclusion

All grades of tropical cyclones could increase risk of other infectious diarrhea. Severe tropical storm has the strongest influence on other infectious diarrhea. The impacts of tropical cyclones on children under 5 years old were higher than total population.

Epidemiological features of intestinal infection with Entamoeba histolytica in Taiwan, 2002-2010

Amebiasis remains an important public health problem worldwide, and immigration and an increase in international travel have affected the incident cases of the disease. The purpose of this study was to assess the prevalence of Entamoeba histolytica in Taiwan between 2002 and 2010. We analyzed data from surveillance programs run by the Centers for Disease Control, Taiwan (Taiwan CDC), and only laboratory-confirmed cases were analyzed. In total, 1796 cases with E. histolytica infections were included in our analysis. Among them, 788 (44%) of the cases were imported, and 1008 (56%) were locally acquired. The average annual incidence rate of E. histolytica infections was 0.49 and 9.26 per 100,000 for local patients and immigrants/foreign workers from endemic countries, respectively. The annual incidence of E. histolytica infections among immigrants/foreign workers was significantly higher than among Taiwanese who had not traveled abroad (P < 0.0001). Travelers to E. histolytica-endemic areas (e.g., Southeast countries) had a higher risk acquiring an E. histolytica infection. This study emphasized that E. histolytica infection is an important intestinal infectious disease in Taiwan. The risk of infection with E. histolytica for travelers was higher for those with destinations in South and Southeast Asia. To control E. histolytica infections in Taiwan, a sensitive surveillance system needs to be established, and the amebiasis-screening program for immigrants/foreign workers from endemic countries should be enforced.

Amoebic dysentery

INTRODUCTION

Amoebic dysentery is caused by the protozoan parasite Entamoeba histolytica. It is transmitted in areas where poor sanitation allows contamination of drinking water and food with faeces. In these areas, up to 40% of people with diarrhoea may have amoebic dysentery.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of drug treatments for amoebic dysentery in endemic areas? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 6 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review, we present information relating to the effectiveness and safety of the following interventions: diiodohydroxyquinoline (iodoquinol), diloxanide, emetine, metronidazole, nitazoxanide, ornidazole, paromomycin, secnidazole, and tinidazole.

[Disentery and hepatic abscess in the colonial and republican Chile. Doctor Miguel Claro Vásquez]

The frequency and severity of dysentery and hepatic abscess during the colonial and republican era in Chile are reviewed. The amebian etiology was confirmed in both clinical entities. Also, Miguel Claro Vásquez, physician and later priest and bishop of the Catholic Church, was distinguished for his contribution to hepatic abscess surgery.

A ten year (1999-2008) retrospective study of amoebiasis in University Malaya Medical Centre (UMMC), Kuala Lumpur, Malaysia

This is a ten year (1999-2008) retrospective study of amebiasis in patients admitted to UMMC. A total of 34 cases were analyzed. The most common were amebic liver abscess 22(65%) and the rest were amoebic dysentery 12(35%). Majority of the cases occurred among Malaysians 29(85%), with Chinese 14(41%), followed by the Malays 9(26%) and the Indians 6(18%). Foreigners made up of one Indonesian, one Pakistani and three Myanmarese and constituted 5(15%) of the total cases. Males 24(71%) were more commonly affected. Most of the cases occurred between the age group of 40-49 years, 8(23%) and 60 years and above, 8(23%). Age group of 20-50 years constituted 20(60%) of the cases. The most common clinical presentations were fever with chills and rigors 26(76%), diarrhoea 20 (59%), right hypochondrium pain 17(50%), abdominal pain 17(50%), hepatomegaly 16 (47%) and jaundice 7(20%). All were discharged well after treatment except for one case of death in a 69-year-old Chinese male with amebic liver abscess.

Presence and diagnosis of amebic infestation in Turkish patients with active ulcerative colitis

BACKGROUND

It is difficult to definitively diagnose acute amebiasis, particularly when this condition is superimposed on inflammatory bowel disease. Our goals in this study were to determine the prevalence of amebiasis in individuals with active ulcerative colitis, and to identify clinical and laboratory parameters that are of value for diagnosing amebiasis in this patient group.

METHODS

The subjects were 111 patients (76 women, 35 men) with confirmed active ulcerative colitis who attended our hospital's Inflammatory Bowel Disease Outpatient Clinic between May 2002 and March 2006. In each case, a detailed medical history was collected, blood samples were tested for inflammatory markers, and stool samples were evaluated for presence of amebae using an Enzyme-Linked Immunosorbent Assay (ELISA) for detection of Entamoeba histolytica antigen. The clinical and laboratory variables for the ELISA-positive and ELISA-negative groups were compared.

RESULTS

Amebiasis was detected in 35 (31.5%) of the subjects. Patient age, disease duration, endoscopic activity index, serum C-reactive protein level, and white blood cell count were not useful for diagnosing amebiasis in this patient group.

CONCLUSIONS

Given the high rate of amebiasis observed in our patients with active ulcerative colitis, we recommend that, in Turkey any individual with ulcerative colitis who presents with symptoms of disease activation should be tested for ameba using antigen detection kits. A high index of suspicion is especially important in any region where E. histolytica is endemic.

Identification of Entamoeba histolytica and Entamoeba dispar by PCR assay of fecal specimens obtained from Thai/Myanmar border region

Due to the indistinguishable morphology between Entamoeba histolytica (pathogenic) and Entamoeba dispar (non pathogenic), PCR-based assays were conducted. Based on microscopy, suspected Entamoeba cells were detected in 30 out of 455 fecal samples obtained from individuals residing at Thai/Myanmar border region. The target genes for PCR amplification included genes encoding small subunit rRNA (SSU-rRNA), chitinase and serine rich Entamoeba protein. PCR primers derived from SSU-rRNA gene amplified both E. histolytica and E. dispar genes producing an amplicon of 1,080 bp, and detected 3 out of 30 samples. PCR primers derived from chitinase gene of E. histolytica generating amplicons of 500 and 1,260 bp, samples were positive in 12 out of 30 samples. Due the large difference of gene encoding serine rich protein between E. histolytica and E. dispar, two specific sets of primers were designed. SREH-primer set, specific for E. histolytica, generated amplicons of 550 and 700 bp and detected 22 out of 30 samples. SED-primer set, specific to E. dispar, produced an amplicon of 550 bp, and together with a nested primer pair generating an amplicon of 477 bp, detected 16 out of 30 samples. Thus, detection of single and mixed infections of the two Entamoeba species could be effectively achieved directly from DNA extracted from feces without the need to culture the parasites.

[Epidemiological investigation on an outbreak of amoebic dysentery in Jiangshan City of Zhejiang Province]

The investigation was carried out from 15 May to 10 June 2006 among diarrhea patients of two schools and periphery residents in Hecun Town, Jiangshan City. Stool samples were examined for Entamoeba histolytica. Water samples were taken for microbial analysis. 31 cases with E. histolytica were found,with 74.2% (23 cases) of students and preschool children. 9 cases were found in Liuyi kindergarten and 8 cases in Hecun central primary school with a prevalence of 7.4% and 0.65%, respectively. Among 594 asymptomatic close contactors, 9 cases (1.5%) were carriers of cysts. Of the 31 cases, 22 were found with no habit of handwashing before eating or after defecation, and 14 cases had a close contact to the patients. No amoebic cysts or trophozoites were found from 12 water samples collected from schools or patient's houses, but the Escherichia coli level exceeded the national standard in 7 samples.

[Epidemiologic and molecular study of Entamoeba histolytica and Entamoeba dispar strains in pacients with diarrhea in Cumana, Sucre state, Venezuela]

An epidemiological and molecular study on E. histolytica and E. dispar was carried out in 428 patients with gastrointestinal symptomatology of diarrhea from different health centers in Cumana, Sucre state. The samples were processed through: direct examination with 0.85% physiological saline solution, temporal lugol staining, trichromic staining and the Ritchie method of concentration; a sucrose gradient was used for cyst isolation. The small subunit of the 16S RNA was amplified by nested, multiplex PCR for the molecular detection. The E. histolytica/E. dispar prevalences according to the direct, Ritchie and trichromic staining methods were 20.09, 13.79 and 12.15%, respectively; while prevalences according to PCR for E. histolytica and E. dispar were 6.31% and 4.44%, respectively, also detecting four cases of mixed infection. Sequencing of the amplified fragments of E. histolytica showed 100% homology with the sequences with strains from Merida (Venezuela), USA, Brazil, Mexico and GenBank. The infections by E. histolytica and E. dispar were statistically associated with age but not with sex. The presence of mucus, blood and abdominal pain were only associated to E. histolytica infection. The moderate prevalence of E. histolytica shows the endemic status of this population and warns about the potential problem as a morbidity and mortality in Sucre state. The frequency of E. dispar in this population suggests the existence of an overestimation problem in the diagnosis of amoebiasis with its clinical and epidemiological implications, and shows the poor knowledge about the true prevalences of this protozoan. The PCR allowed for the differential identification of E. histolytica and E. dispar, as well as the presence of mixed infections, making a great tool for epidemiological amoebiasis studies.

Seroprevalence of Entamoeba histolytica infection in HIV-infected patients in China

Seroprevalence of Entamoeba histolytica infection in HIV-infected individuals from Shanghai city, Anhui province, and Henan province, China, was examined by enzyme-linked immunosorbent assay using crude antigen and a recombinant surface antigen, C-Igl, of the parasite. In 215 HIV-infected individuals, the positive rates for these antigens were 12.1% and 7.9%, respectively; these rates were significantly higher than the rates of 3.1% and 0.5%, respectively, in 191 patients with gastrointestinal symptoms who were not infected with HIV. There was no significant difference in seropositivity to E. histolytica between men and women. Seropositivity in HIV-infected individuals was higher in patients with a CD4(+) T cell count of < 200/microL. This is the first report showing a higher seroprevalence of E. histolytica infection in HIV-infected patients in China. Our results also suggest that HIV infection is a risk factor for infection with E. histolytica.

PCR detection of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from Sydney, Australia

This study investigated the presence of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from a patient population in Sydney, Australia. Stool samples were tested by microscopy and PCR. Five patients were found with E. histolytica infections, while E. dispar and E. moshkovskii were observed in 63 (70.8%) and 55 (61.8%) patients, respectively, by PCR. This is the first study in Australia using molecular techniques to determine the presence of E. histolytica, E. dispar, and E. moshkovskii.

Amoebic dysentery

INTRODUCTION

Amoebic dysentery is caused by the protozoan parasite Entamoeba histolytica. It is transmitted in areas where poor sanitation allows contamination of drinking water and food with faeces. In these areas, up to 40% of people with diarrhoea may have amoebic dysentery.

METHODS AND OUTCOMES

We conducted a systematic review and aimed to answer the following clinical question: What are the effects of drug treatments for amoebic dysentery in endemic areas? We searched: Medline, Embase, The Cochrane Library and other important databases up to July 2006 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS

We found 11 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS

In this systematic review we present information relating to the effectiveness and safety of the following interventions: emetine, metronidazole, ornidazole, paromomycin, secnidazole, and tinidazole.

Frequency of Giardia lamblia among children in Dohuk, northern Iraq

Out of 1261 stool specimens collected from children in Dohuk city, northern Iraq, the prevalence of Giardia lamblia infection was 38.5%. The highest rate of infection was in orphan care centres (48.1%) and the lowest in the paediatric hospital (31.3%). The age group 10-12 years had the highest rate (81.2%) and 7-9 years the lowest (22.9%); boys had a higher rate than girls. Some infected samples (70/486) showed double or triple infections and G. lamblia was combined with Hymenolepis nana, Blastocystis hominis, Entamoeba histolytica and Iodamoeba buetschlii.

Patients with gastrointestinal complains due to enteric parasites, with reference to Entamoeba histolytica/dispar as dected by ELISA E. histolytica adhesion in stool

A total of 210 patients with gastrointestinal troubles, of both sex and a mean age of 32 +/- 6.1 years, selected from the outpatient's clinics of Al-Azhar University Hospitals. 115 (54.76%) had dysentery, 95 (45.23%) did not have dysentery, 15 (14%) suffered flatulence, 20 (9.52%) had epi-gastric pain, 19 (9.05%) had vague abdominal pain, 5 vomiting (5.2%) and 10 (4.9%) had fever. Two symptoms were in 29 (13.81%) patients and three symptoms in 12 (5.71%). Of the 210 patients, 20 (9.9%) had helminthes infection, 121 (57.6%) had intestinal protozoa and 69 (32.9%) had no parasitic infection. Of these parasite-free patients, 16 had Shigella sp. and nine had Campylobacter sp. Of the patients with intestinal protozoa, 34 (16.2%) had E. histolytica/dispar by stool examination of stained smears. By using ELISA for detection of E. histolytica adhesion in stool samples of 115 with diarrhea only 18 had true E. histolytica infection and of 3 without diarrhea only one had E. histolytica infection. Mean-while, ELISA did not cross-reacted E. coli, Giardia lamblia, Cryptosporidium parvum, Endolimax nana or Blastocystis hominis. So, ELISA for detection of E. histolytica adhesion in stool samples was more specific than microscopy and safe direction to the E. histolytica treatment. Apart from intestinal protozoan and bacteria, helminthes were seen in stool analysis. These were Schistosoma mansoni (0.95%), Capillaria sp. (0.95%), Enterobius vermicularis (1.90%) macroscopically, Hymenolepis nana (4.3%) and Ascaris lumbricoides (1.43%).

Entamoeba histolytica infection in children and protection from subsequent amebiasis

The contribution of amebiasis to the burden of diarrheal disease in children and the degree to which immunity is acquired from natural infection were assessed in a 4-year prospective observational study of 289 preschool children in an urban slum in Dhaka, Bangladesh. Entamoeba histolytica infection was detected at least once in 80%, and repeat infection in 53%, of the children who completed 4 years of observation. Annually there were 0.09 episodes/child of E. histolytica-associated diarrhea and 0.03 episodes/child of E. histolytica-associated dysentery. Fecal immunoglobulin A (IgA) anti-parasite Gal/GalNAc lectin carbohydrate recognition domain (anti-CRD) was detected in 91% (183/202) of the children at least once and was associated with a lower incidence of infection and disease. We concluded that amebiasis was a substantial burden on the overall health of the cohort children. Protection from amebiasis was associated with a stool anti-CRD IgA response. The challenge of producing an effective vaccine will be to improve upon naturally acquired immunity, which does not provide absolute protection from reinfection.

[Incidence of intestinal parasites in municipal sanitary workers in Malatya]

The incidence of intestinal parasites is closely related to such factors as the socio-economic level of the society, nutritional and hygienic habits, climate, environmental conditions, infrastructure and degree of literacy. In this study, the municipal sanitary workers who are regarded as a high risk group in Malatya were examined for intestinal parasites. Cellophane slides and fecal samples from 241 workers were examined and intestinal parasites were found in 93 (39.0%). The most common parasite was Entamoeba coli (34). Other parasites detected include Enterobius vermicularis (32), Giardia intestinalis (22), Blastocystis hominis (8), Iodamoeba butschlii (5), Entamoeba histolytica (2), Taenia sp. (2), Chilomastix mesnili (2), Dientamoeba fragilis (2), Entamoeba hartmanni (1), Trichomonas intestinalis (1) Hymenolepis nana (1), and Ascaris lumbricoides (1). A training seminary was conducted in order to inform all the workers about means of protection. The workers were given suitable treatment and were called for control after a month. The examinations revealed a significant decrease in the incidence rate of parasites (qui-square test in dependent samples P<0.05). It was concluded that offering training seminaries for certain occupational groups under risk is efficient in terms of protection.

Risk of cancer onset in sub-Saharan Africans affected with chronic gastrointestinal parasitic diseases

Gastrointestinal Schistosomiasis and Amebiasis are uncommon in the western world, while such infections are frequent in the African community. In addition to the problems associated with the clinical symptoms of these parasitic infections, it is important to stress the increase in cancer of the Gastro-Intestinal (GI) tract. In this study we evaluate the prevalence of cancer in patients affected by chronic inflammatory diseases caused by the above named parasites. In three years, from January 2000 to December 2003, we observed a total of 1199 subject. Of these, 950 presented with complaints of diarrhoea, vomiting, abdominal pain, melena, hematemesis, rectal discharges and alteration of bowel habits. A total of 818 patients were evaluated in Uganda (Mulago and Arua hospitals) and 381 at Luisa Guidotti Hospital in Zimbabwe. An exhaustive clinical history was collected for each patient and then physical and laboratory examinations were performed. The clinical files of all patients previously admitted to the respective hospitals were obtained and the information taken from these files was then integrated with our clinical findings. Subjects who were found free of gastro-intestinal disease after examinations and did not have a clinical history of infective GI disease but presented with other pathologies, were regarded as control group. The control group was composed of 249 subjects. The subjects who were positive on examination underwent further investigations. The number of patients affected by schistosomiasis and amebiasis were 221 and 224 respectively. The number of patients who suffered from aspecific enterocolitis was 454, intestinal tuberculosis was present in 21 patients and we found 30 patients with esophageal candidiasis. Patients who had the above mentioned GI diseases were then divided into 3 groups. First group was composed of patients who had a clinical history of infective GI diseases and were re-admitted for similar symptoms, and on examination were positive for the presence of the same infective GI diseases. Such patients were placed in the Chronic group. The second group was formed of patients who had previously undergone treatment for infective GI diseases but on readmission were found free of infective GI disease, and this group was described as the Cured group. They had symptoms associated with other pathologies. A third group, which we described as the Acute group was composed of patients who did not have any previous case of GI infection and were admitted for the first time. Such patients were found positive on examination for infective GI diseases. In the 950 patients, we found a total of 45 tumors. The tumors were prevalent (42 tumors) in the chronic group. In 34 patients the tumor was in the colo-rectal region, in 3 patients in the stomach, in 4 patients in the esophagus and 1 patient had cancer in the small bowel. Our results show a strong association between the chronic infection of the GI tract and the likelihood to develop tumors. However, it is not clear which biological mechanisms are implicated in such transformations. They may depend on the chronic inflammation of the GI mucous which permits the entrance of carcinogenic materials or on the effects of mutagenic products produced by the parasites or both.

Etiology of childhood diarrhea in Zliten, Libya

OBJECTIVE

To determine the etiological agents of diarrhea in children from a small semi-urban city in Libya and the association of age, gender, seasonal variation, breast-feeding, source of water for drinking, or antibiotic use with the isolation of enteropathogens and whether such agents are community or hospital acquired.

METHODS

Using standard microbiological techniques we examined stool samples from 169 children (70 females) aged a few days to 12 years with acute diarrhea for viral, bacterial and parasitological agents. We used the disc diffusion method to determine the susceptibility of bacterial pathogens to antimicrobial agents. We carried out the study between April 2000 to March 2001.

RESULTS

We detected a single agent in 44.4%, rotavirus in 26.6%, Salmonella in 13.6%, and Cryptosporidium in 13% of patients and other enteric pathogens, Shigella in 3.6%, Aeromonas in 5.5%, Entamoeba histolytica/dispar in 11.8, and Giardia lamblia in 1.2%. Serotyping of isolated Salmonella resulted in 21 being Salmonella enteric serotype heidelberg and 3 Salmonella enteritidis. We detected both serotypes in one child. More than 75% of the isolated Salmonella were resistant to 6 different commonly used antimicrobial agents.

CONCLUSION

We found rotavirus, non-typhoid Salmonella and Cryptosporidium to be the most important enteric agents associated with childhood diarrhea in Zliten. The isolated bacterial pathogens showed high resistant rates, particularly among the Salmonella, to the commonly used antimicrobial agents. The ease of which one can obtain these drugs in Zliten may play a role in such resistance.

Entamoeba histolytica and Entamoeba dispar infections in cynomolgus monkeys imported into Japan for research

Three hundred and three stool samples of cynomolgus monkeys (Macaca fascicularis) imported from China and the Philippines were examined for Entamoeba histolytica/Entamoeba dispar infections. Microscopy detected E. histolytica/E. dispar cysts in 41 samples. Positive rates were higher in the monkeys from China (37.5%) than in the monkeys from the Philippines (3.7%). PCR analysis of 25 samples successfully cultured from the cysts demonstrated that 24 were E. dispar, one of the samples from China was E. histolytica. The one sample was also identified as E. histolytica by an antigen detection kit, although the monkey was asymptomatic and serology was negative. To our knowledge, this is the first report of E. histolytica isolation from cynomolgus monkeys based on the discrimination between E. histolytica and E. dispar.

High prevalence rate of Entamoeba histolytica asymptomatic infection in a rural Mexican community

The frequency of Entamoeba histolytica and Entamoeba dispar infection was analyzed in a rural community in the state of Morelos, Mexico, using polymerase chain reaction (PCR). Sociodemographic variables as risk factors for the infection were assessed. Results highlighted the number of individuals with intestinal parasites (43.1%) in the community, indicating extensive fecalism. A high frequency of E. histolytica asymptomatic infection, higher than E. dispar infection (13.8% versus 9.6%), was detected by PCR. Anti-amebic antibody levels (IgG) in serum and saliva (IgA) samples were not associated with E. histolytica intestinal infection. These findings suggest a predominant distribution of E. histolytica strains of low invasive potential in this community.

Prevalence of intestinal parasitic infections in the Islamic Republic of Iran

A national survey of the prevalence of intestinal parasitic infections in the Islamic Republic of Iran was made on a random sample of families covered by local health centres affiliated to the medical universities. Out of 53,995 people aged 2+ years, from 12,495 families (0.1% of all families in 1999), 45,128 stool samples were analysed by formalin-ether precipitation. Intestinal parasitic infections were found in 19.3% of the study population (19.7% male, 19.1% female). Giardia lamblia (10.9%), Ascaris lumbricoides (1.5%), Entamoeba histolytica (1.0%) and Enterobius vermicularis (0.5%) were the most common infections. The infection rate was highest in the 2-14 years age group (25.5%) and in rural residents (23.7%).

Genetic characterization of Entamoeba dispar isolates in Northeast Brazil

The genetic variability of Entamoeba dispar strains was investigated in 39 positive isolates on a survey of 1783 individuals from two different cities of Northeast Brazil (Recife and Macaparana) using two polymorphic species-specific loci (loci 1-2 and 5-6). A combinatory clustering analysis revealed no geographical correlation and remarkable genetic polymorphism among all the isolates examined. Nevertheless, a comparison of the frequency of eight individual PCR products, shared by both Recife and Macaparana populations, for the two loci, showed that only one product of locus 5-6 was significantly different between the two cities. These results suggested that the Macaparana population is infected by similar strains and that locus 5-6 shows potential in assaying questions related to the molecular epidemiology of this region.

Comparison of two methods (microscopy and enzyme-linked immunosorbent assay) for the diagnosis of amebiasis

Diagnosis of amebiasis is usually performed on a clinical basis alone in most endemic countries having limited economic resources. This epidemiological study was conducted using modern diagnostic tests for amebiasis in the southeastern region of Turkey, an endemic area for amebiasis. The population of this study included patients with symptomatic diarrhea/dysentery attending both Yuzuncu Yil University, Van and Harran University, Sanliurfa, Turkey. A total of 380 stool specimens were collected and examined for Entamoeba by light microscopy (fresh, lugol, and trichrome staining) and stool antigen detection based- enzyme-linked immunosorbent assay (EIA) test (TechLab Entamoeba histolytica II). 24% (91/380) of stool specimens were positive for E. histolytica/Entamoeba dispar trophozoites/cysts microscopically using trichrome staining. 13% (51/380) of the stool specimens were found to be positive for E. histolytica by the EIA test, including 15% (14/91) of microscopy (+) stool specimens and 13% (37/289) of microscopy (-) stool specimens. Enteric parasites were common in these populations with 66% (251/380) of the study population harboring more than one parasite. In addition to the 13% (51/380) of patients determined to have E. histolytica by EIA, eighty-six patients (22.6%) had Blastocystis hominis, 54 (14.2%) Entamoeba coli, 44 (11.5%) Giardia lamblia, 16 (4.2%) Chilomastix mesnili, 15 (3.9%) Iodamoeba bütschlii, 12 (3.1%) Hymenolepis nana, 9 (2.3%) Endolimax nana, 9 (2.3%) Dientamoeba fragilis, and 8 (2.1%) had Ascaris lumbricoides. We concluded that E. histolytica infection was found in 13% of the patients presenting with diarrhea in Van and Sanliurfa Turkey.

[Cryptosporidiosis and isosporiasis in children suffering from diarrhoea in Abidjan]

A parasitological survey on intestinal coccidia, Cryptosporidium sp and Isospora belli, has been carried out in paediatric service of an teaching hospital in the district of Abidjan (Côte d'Ivoire). 130 children under 5 years old suffering from diarrhoea have been enrolled. Direct stools examination method, simplified Ritchie technique and Ziehl Neelsen modified coloration were used for analysis. Moreover, the AIDS serological status of the patients has been determined. The results show that Cryptosporidium sp and Isospora belli were found respectively with a prevalence of 7.7% and 3.9%. Only one case of mixed infestation between theses two parasites has been found. Coccidia were the most recurrent parasites found in diarrhoea after flagellates. Parasitism by coccidia was not related to AIDS serological status of the children. These results point out the necessity to make common coccidian parasitical diagnosis in children under 5 years old suffering from diarrhoea.

[Outbreak of amoebiasis in a Dutch family; tropics unexpectedly nearby]

An amoebic liver abscess, amoebic dysentery and asymptomatic cyst passage were diagnosed in a father, a mother and one of their three children, respectively. One of the other children had been in the tropics, but only after the father's symptoms had begun. All three family members were infected with the same strain of Entamoeba histolytica as determined by polymerase chain reaction (PCR)-based DNA typing. The source of infection was most probably in Southern Italy where the family regularly spent their summer holidays. All three infected patients recovered after drug treatment. In a patient with a liver abscess or colitis, amoebiasis should be considered even in the absence of a history of a stay in the tropics. Stool samples should be examined for amoebic cysts and trophozoites. PCR analysis of parasite DNA extracted directly from stool samples makes differentiation between the morphologically identical cysts of E. histolytica and the non-pathogenic Entamoeba dispar possible. In addition, serum antibodies to E. histolytica are almost always present in symptomatic patients. Invasive infections with E. histolytica require treatment with a tissue amoebicidal drug, followed by a contact amoebicide to prevent recurrence. Currently, paromomycin is considered to be the first-line luminal amoebicide because of its efficacy and safety.

Évolution de la prévalence des parasitoses digestives au CHU de Fort-de-France (Martinique)

OBJECTIVE

Determine the prevalence of intestinal parasitosis between January 1, 1997 and December 31, 1999 in the microbiology laboratory of the Fort de France University Hospital.

METHOD

Retrospective study of the results of 4684 parasitological examinations of stools performed in 2704 patients between January 1, 1997 and December 31, 1999 in this laboratory.

RESULTS

This survey showed the high prevalence of anguillulosis, found in 51.69% of infested patients and in 4.56% of the population studied, the ever high prevalence of non or scarcely pathogenic amoebas (Endolimax nanus, Dientamoeba fragilis, Entamoeba coli) found in 27.19% of infested patients and 1.88% of the population studied, together with that of hookworms (12.80% of infested patients and 1.13% of the population), and the persistence of lambliasis. This study also revealed the presence of cryptosporidies (7 cases) and microsporidies (4 cases) in the patients infected by the human immunodeficiency virus.

DISCUSSION

These results confirm the trend of the past twenty Years and the results of surveys initiated by the national statistics board (INSERM) in 1978, 1988 and 1995-1995, with the regression of bilharziosis and the persistence of anguillulosis and hookworms.

CONCLUSION

The improvement in living conditions and hygiene, the combined efforts of the health care workers and Authorities in Martinique over the past 30 Years in the fight against parasites have led to a great reduction in the prevalence of classical intestinal parasitosis. However, new parasites associated with HIV infection have appeared.

[Prevalence of infection by intestinal parasites in north Lebanon: 1997-2001]

We determined the prevalence of intestinal parasites in the north of Lebanon between 1997 and 2001. We analysed the parasitology records of 17126 patients and evidence of parasitic infections was found in 5 713 (33.35%) cases. There was no significant difference in prevalence for males or females for any of the parasites. The most prevalent parasites were Entamoeba coli (38.45%), Ascaris lumbricoides (37.14%), Giardia lamblia (15.39%), Ent. histolytica (4.57%) and Taenia sp. (3.3%). A comparison between our data and results of previous studies in Lebanon in 1937, 1939, 1956, 1967 and 1993 showed an increase in the prevalence of A. lumbricoides and G. lamblia in the period 1997-2001, with less marked changes in the prevalence of the other parasites.

Bloody diarrhoea cases caused by Shigella and amoeba in Jordan

This study was done to evaluate the occurrence of bloody diarrhoea in Jordan in the period 1988-2000, with particular interest in Shigilla and amoeba cases in relation to the surveillance control system and hygiene policy. The cases were collected from various medical diagnostic laboratories. In addition to the clinical presentation, stool specimens or rectal swabs were collected and sub-cultured on the appropriate media. Shigella spp. and amoeba were identified using standard methods. Anti-microbial susceptibility tests were performed. One-way ANOVA and Least Significant Difference (LSD) were used for statistical analysis. The number of stool specimens tested for bloody diarrhoea was 34,529 in the study period. Positive stool samples were reported in 711 (2.1%) patients. Out of these 55% were males and 45 % were females. The highest number of cases 96 (13.5%) was reported in the year 1999. The highest incidence rate was (20.6) in the year 1996 and the lowest incidence rate (8.9) was in the year 2000. The highest number of cases during the period 1998-1992 was among age group 1-4 year. During the year 1993-1996 the highest number of cases was among group 5-14 year. The highest number of cases during the year 1997-2000 was among age group 15-24 year. There was a significant variation between numbers of bloody diarrhoeal cases and age groups (P < 0.001) as well as sex (P = 0.028). No significant variation (P = 0.06) was observed between number of bloody diarrhoea cases and seasons or months. The number of stool specimens tested for amoebiasis during the study period 1994-2000 was 229,040. Shigella was isolated from 304(0.13%) cases and amoeba was found in 24,211(10.6%) cases. The lowest incidence rate in bloody diarrhoeal cases in the year 2000 indicates good quality hygienic control. The increased resistance of Shigella to antibiotics may produce a future problem, which might require a further prescribing policy for treatment.

Epidemiologic and clinical characteristics of acute diarrhea with emphasis on Entamoeba histolytica infections in preschool children in an urban slum of Dhaka, Bangladesh

The epidemiology, clinical features, nutritional status, and causative agents of diarrhea were studied in 289 Bangladeshi children (147 boys and 142 girls) 2-5 years old. The use of improved diagnostic tests for amebiasis enabled for the first time analysis of the contribution of Entamoeba histolytica to total diarrheal illness in this community setting. The average incidence rate of diarrhea was 1.8/child-year, and the average number of diarrheal days was 3.7 days/child-year over an average observation period of 2.8 years/child. Seventy-five percent of the diarrheal episodes were < or = 2 days in duration. Persistent diarrhea was relatively uncommon (0.2% of the children) and chronic diarrhea was observed in only one episode. Compared with malnourished and/or stunted children, better-nourished children experienced significantly fewer diarrheal episodes. The diarrheal incidence rate for children with blood group A was significantly less that that of the children with blood groups O and AB. The most frequent bacterial enteropathogens isolated from diarrheal stool specimens were enterotoxigenic Escherichia coli (9%) and Aeromonas species (9%), followed by Plesimonas shigelloides (4%) and Shigella flexneri (3.8%). Rotavirus was the most common viral agent isolated from diarrheal stool samples (5%). Giardia lamblia, Cryptosporidium parvum, and E. histolytica were identified in 11%, 8.4%, and 8%, respectively, of the diarrheal stool specimens. Dysentery was observed in 7.7% of all diarrheal episodes. The most common pathogens isolated from dysenteric stool were S. flexneri (11.6%), Aeromonas sp. (10%), E. histolytica (8.7%), Campylobacter jejunii (5.8%), P. shigelloides (4.3%), and A. caviae (4.3%). The overall incidence rate of E. histolytica-associated diarrhea was 0.08/child-year. Visible blood and hemoccult test-detected blood loss was found in 7% and 25%, respectively, of cases of E. histolytica-associated diarrhea. Children who had recovered from a diarrheal episode with E. histolytica, but not E. dispar, had half the chance of developing subsequent E. histolytica-associated diarrhea, consistent with the development of species-specific acquired immunity. In conclusion, the use of modern diagnostic tests demonstrated that E. histolytica contributed to overall morbidity from diarrheal illness. Understanding the etiology, frequency, and consequences of acute diarrhea in children from a developing country should aid in the design of interventions to improve child health.

Geohelminth infections protect against severe inflammatory diarrhoea inchildren

We investigated the risk of severe inflammatory diarrhoea associated with geohelminth parasites in 1746 children attending a rural hospital in Ecuador from December 2000 to July 2002. Infections with geohelminths were strongly protective against the risk of severe inflammatory diarrhoea. Our findings suggest that geohelminth infections have important protective effects against enteroinvasive infections in young children.

Genotyping of Entamoeba species in South Africa: diversity, stability, and transmission patterns within families

Using a recently described polymerase chain reaction-based DNA typing method for Entamoeba histolytica and E. dispar, we investigated the genetic diversity of these species in a geographically restricted region of South Africa. Patterns were stable over time in the same infection, and, with few exceptions, infected family members carried the same strain. However, both species exhibited remarkable variation, with no 2 family groups being infected with the same strain of E. histolytica. Mixed infections were rare. The results indicate that this typing method will be useful in identifying epidemiological linkage between infections.

Symptomatic intestinal amoebiasis and climatic parameters

Symptomatic intestinal amoebiasis is an important problem, especially in the developing world. The relationships between climatic parameters and amoebic dysentery cases were evaluated in this study. Climatic data were obtained from the local meteorological department and the diagnosis of amoebic dysentery was established by clinical and laboratory investigation. Monthly mean temperature (r = 0.755, p = 0.005), monthly mean maximum temperature (r = 0.711, p = 0.01), monthly mean temperature at 100 cm underground (r = 0.818, p = 0.001) and monthly mean humidity values (r = -0.656, p = 0.02) correlated significantly with symptomatic disease. Although inverse relationships were found for humidity and atmospheric pressure, the monthly mean atmospheric pressure (r = -0.084) did not seem to have a significant effect on intestinal amoebiasis (p = 0.80). Thus, when the weather warmed up, the frequency of symptomatic intestinal amoebiasis increased significantly. To improve the ability to predict disease trends, it seems logical to assess the independent and interactive effects of climatic parameters on disease impact.

[Epidemiological, clinical and parasitological data concerning intestinal amebiasis in northern Tunisia]

In order to evaluate the principal characteristics of the intestinal amoebiasis in the north of Tunisia, one retrospective study review all cases diagnosed in principal gastroenterologic sections of the hospitals of Tunis. Twenty height cases of intestinal amoebiasis, 10 of which have an inflammatory bowel disease associated were included. Watery stools containing blood and mucus were the most important symptoms (25 cases). The endoscopic exam showed for all the cases non specific lesions. The diagnosis was based on histologic exam in 21 cases, on the positivity of serologic tests in 3 cases and on the presence of E. histolytica/dispar cysts in stools in 6 cases. In two cases, the diagnosis was made by therapeutic test.

Overdiagnosis of amoebiasis in the absence of Entamoeba histolytica among patients presenting with diarrhoea in Wonji and Akaki, Ethiopia

To confirm the high reported incidence of intestinal amoebiasis among study participants at 2 cohort sites in Ethiopia where an HIV/AIDS study is taking place, stool samples of 232 patients with complaints of diarrhoea were examined for the presence of Entamoeba histolytica and E. dispar DNA between April and December 2001. By microscopy, 91 (39%) of the study participants were reported to harbour Entamoeba trophozoites and/or four-nucleated cysts. Using specific E. histolytica and E. dispar DNA amplification and detection, none of the study participants were found to be infected with E. histolytica and only 21 (9%) with E. dispar. The consequences of the overdiagnosis of E. histolytica are briefly discussed.

Intestinal parasites in children with diarrhea in Delhi, India

The parasitic causes of diarrhea in children in Delhi were determined by the direct smear technique; stool specimens of 127 children were examined for intestinal parasites. In 59 cases (46.5%) intestinal helminths and protozoa were demonstrated. Ascaris lumbricoides was observed in 1 (0.8%) case, while Trichuris trichiura was the finding in 3 (2.4%). Protozoal parasites included Giardia intestinalis and Entamoeba histolytica in 14 (11%) cases each, Balantidium coli in 3 (2.4%) cases and Cryptosporidium spp in 24 (18.9%) patients. Mixed infection was not seen in any of the cases. Intestinal parasites may increase susceptibility to infection with other intestinal pathogens and therefore with the help of a simple technique, like direct fecal smear examination. rapid diagnosis can be made and specific therapy instituted.

Diagnosis of amoebic colitis by antigen capture ELISA in patients presenting with acute diarrhoea in Cairo, Egypt

We studied 84 consecutive patients presenting with acute diarrhoea (less than 1 week in duration) at an outpatient tropical medicine clinic in Cairo, Egypt. The diagnosis of amoebic colitis was established by the presence of Entamoeba histolytica galactose-inhibitable lectin antigen and the presence of occult blood in stool. Controls were 182 healthy regional people and 64 patients complaining of prolonged diarrhoea lasting more than 1 week. Entamoeba histolytica infection was found more frequently in patients with acute diarrhoea (57.1%) than in healthy controls (21.4%) or patients with prolonged diarrhoea (25%) (P < 0.001). There was a higher prevalence of Entamoeba dispar infection in the two control groups (24.2 and 20.3%, respectively, P=0.004 and 0.061) compared with those with acute diarrhoea (8.3%). Of the 84 patients with acute diarrhoea 32 had amoebic colitis (38%), and of these, 31 (97%) had at least one positive assay for serum amoebic antibodies (P < 0.001 compared with control groups). In summary, as determined by antigen-detection enzyme-linked immunosorbent assay, there is an unexpectedly high prevalence of amoebic colitis among patients presenting with acute diarrhoea to a tropical disease clinic in Cairo, Egypt.

Acute appendicitis caused by amebiasis

We report a case of appendicitis caused by amebiasis in a 45-year-old Japanese man. He presented to our hospital with bloody stools in June 1998. Sigmoidoscopy disclosed erosion, and a biopsy of the erosion showed colitis caused by Entamoeba histolytica infection. Four months later, he was admitted to our hospital with a small elastic mass and severe pain in the lower quadrant of the abdomen, which was diagnosed as acute appendicitis. He underwent appendectomy. Histopathological examination revealed numerous E. histolytica trophozoites, and we diagnosed acute appendicitis caused by E. histolytica. The patient has been free of symptoms, colonoscopy has revealed no erosion, and biopsy has revealed no E. histolytica for 12 months after the operation.