Piña R, Gutiérrez AH, Gilman RH
… +7 more, Rueda D, Sifuentes C, Flores M, Sheen P, Rodriguez S, García HH, Zimic M
Ann Trop Med Parasitol
· 2011 Jun · PMID 21871167
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Human neurocysticercosis (NCC), caused by the cestode Taenia solium, is responsible for a significant amount of neurological morbidity and epilepsy in developing countries. The disease remains highly endemic in many area...Human neurocysticercosis (NCC), caused by the cestode Taenia solium, is responsible for a significant amount of neurological morbidity and epilepsy in developing countries. The disease remains highly endemic in many areas, despite several efforts and interventions to control it. A simple, cheap and fast diagnostic assay that is suitable for use in field conditions is highly desired. In immunodiagnostics based on western immunoblots or standard ELISA, a cathepsin-L-like protein purified from the cysticercus fluid has previously performed well as an antigen. In a recent study in Peru, the same 53/25-kDa antigen was therefore used in the development of a dot-ELISA that could be employed for mass screenings under field conditions. The assay was standardized and tested not only against sera from a large group of NCC cases but also against sera from patients with other common parasitic infections, so that sensitivity and specificity could be assessed. For NCC, the assay gave better sensitivity in the detection of individuals with extraparenchymal cysts (94·4%-100%) or multiple parenchymal cysts (74·6%-80·0%) than in the detection of individuals with single parenchymal cysts (29·4%-45·1%). The assay also showed a high specificity for NCC (99·0%-100%), with a very low level of cross-reactivity with other parasitic infections. The dot-ELISA developed in this study is a highly specific, simple, cheap and rapid test for NCC that could be used under field conditions, even in the low-resource settings that are common in developing countries.
Molina N, Minvielle M, Grenóvero S
… +2 more, Salomón C, Basualdo J
Ann Trop Med Parasitol
· 2011 Jun · PMID 21871166
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The protozoan parasite most frequently associated with diarrhoea worldwide is Giardia intestinalis. In 2005, a study was initiated to identify the genotypes of this parasite infecting children in the Argentinian province...The protozoan parasite most frequently associated with diarrhoea worldwide is Giardia intestinalis. In 2005, a study was initiated to identify the genotypes of this parasite infecting children in the Argentinian provinces of Buenos Aires, Mendoza and Chaco, and to explore the associations between the genotype detected in a child, the characteristics of the child's household and the child's clinical presentation. Overall, 998 children (504 boys and 494 girls) aged between 2-14 years, with or without symptoms, were enrolled. The G. intestinalis in 94 of the 117 stool samples found positive for the parasite by microscopy were successfully genotyped by PCR. Seventy-seven of the children were found to be infected with genotype B only and 14 with genotype AII only, three children being found to have mixed (AII and B) infections. Only genotype B was detected in children from rural areas (P<0·05) and most Giardia detected in children from households with a piped water supply were also of this genotype (P<0·05). The other household characteristics investigated (quality of building, history of flooding, type of sanitation, level of overcrowding, and presence/absence of pet dogs) had no significant effect on the genotype distribution. Children infected with genotype AII were significantly younger than those infected with genotype B (P<0·05) and there was a significant positive association between infection with genotype B and abdominal pain (P<0·05). Diarrhoea was not, however, found to be significantly associated with genotype-AII or genotype-B infection. This is the first published report on the Giardia genotypes circulating in the provinces of Mendoza and Chaco. The results indicate the importance of asymptomatic children in the transmission of Giardia among the young.
Post RJ, Onyenwe E, Somiari SA
… +3 more, Mafuyai HB, Crainey JL, Ubachukwu PO
Ann Trop Med Parasitol
· 2011 Jun · PMID 21871165
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Although approximately 40% of all the people blinded by Onchocerca volvulus are Nigerians, almost nothing was known about the various cytospecies of the blackfly vectors present in Nigeria until 1981. The activation of t...Although approximately 40% of all the people blinded by Onchocerca volvulus are Nigerians, almost nothing was known about the various cytospecies of the blackfly vectors present in Nigeria until 1981. The activation of the Nigerian National Onchocerciasis Control Programme in 1986 (and that programme's initiation of mass distributions of ivermectin in 1991) provided a significant stimulus to understand the biology of the Nigerian vectors but the exploration of any possible differences between the cytospecies has been hampered by a lack of accessible taxonomic information. This review attempts to satisfy that need. There are nine different cytoforms reliably recorded from Nigeria (Simulium damnosum s.s. Nile form, S. damnosum s.s. Volta form, S. sirbanum Sirba form, S. sirbanum Sudanense form, S. soubrense Beffa form, S. squamosum A, S. squamosum B, S. squamosum C and S. yahense typical form), and three more are known from surrounding countries and might be reasonably expected to occur in Nigeria. All of these cytospecies are presumed to be vectors, although there have been almost no identifications of the vectors of O. volvulus in Nigeria. The biogeographical distribution of the cytoforms is broadly similar to that known in other parts of West Africa (although many of the cytoforms remain insufficiently studied). The physico-chemical hydrology of the Nigerian breeding sites of the cytospecies does not, however, correspond to that seen elsewhere in West Africa, and it is not clear whether this might be related to differences in the cytoforms. An illustrated cytotaxonomic key is presented to facilitate and encourage future studies.
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801504
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Helicobacter pylori has been incriminated in human diseases, such as peptic ulcer, gastritis and gastric malignancy. Although modern triple-drug regimens are usually highly effective in the treatment of H. pylori infecti...Helicobacter pylori has been incriminated in human diseases, such as peptic ulcer, gastritis and gastric malignancy. Although modern triple-drug regimens are usually highly effective in the treatment of H. pylori infection, the emergence of resistance to two of the most used antibiotics, metronidazole (Mtz) and clarithromycin (Cla), is a serious and increasing problem. Truncations in the rdxA and frxA genes of H. pylori are thought to be associated with Mtz resistance whereas mutations in the pathogen's 23S-ribosomal-RNA (23S-rRNA) genes are associated with Cla resistance. In a recent study, PCR and sequence analysis of the rdxA, frxA and 23S-rRNA genes were used to explore the genetic basis of resistance to Mtz and Cla in H. pylori. When 200 isolates of H. pylori from the Eastern Cape province of South Africa were tested for antibiotic susceptibility, almost all (95·5%) were found resistant to Mtz and 20·0% were found resistant to Cla. Only the Mtz-resistant isolates showed rdxA and frxA truncation. Two point mutations were detected in the 23S-rRNA genes of the Cla-resistant isolates. Many significant changes (resulting in 13 amino-acid substitutions in nine loci and truncated proteins in 14 loci) were observed in the rdxA genes of the Mtz-resistant isolates, and it appears that, compared with the rarer changes detected in frxA, such mutations may contribute more significantly to the high prevalence of Mtz resistance. To guide empiric treatment, the genotypes and antibiotic susceptibility of H. pylori in the Eastern Cape province of South Africa need to be monitored regularly.
Sejdini A, Mahmud R, Lim YA
… +5 more, Mahdy M, Sejdini F, Gjoni V, Xhaferraj K, Kasmi G
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801503
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Although intestinal parasitic infections (IPI) among children remain a global issue, the current information on such infections in Albanian children is very limited. A cross-sectional study of the IPI in 321 children liv...Although intestinal parasitic infections (IPI) among children remain a global issue, the current information on such infections in Albanian children is very limited. A cross-sectional study of the IPI in 321 children living in the Albanian counties of Tirana (152) and Elbasan (169) was therefore conducted in 2008, with a pre-tested standard questionnaire employed to gather the relevant personal and clinical data. Using formalin-ether concentration and permanent stains, stool samples were examined microscopically for the ova, cysts and oocysts of any parasites. The overall prevalence of IPI was 19% (61 of 321), with protozoan infections (11·5%) apparently more common than infections with soil-transmitted helminths (STH; 8·1%). Giardia duodenalis was the parasite most frequently detected (10·9%), followed by hookworm (5·6%), Ascaris lumbricoides (1·9%), Trichuris trichiura (0·6%), Cryptosporidium (0·3%) and Entamoeba histolytica/dispar (0·3%). The results of a univariate analysis indicated that the children from Tirana county were significantly more likely to be found infected with STH compared with the children from Elbasan county (12·5% v. 4·1%; P=0·006). Children sampled in the community were also more likely to be found STH-positive than the children sampled as they attended hospitals and health clinics (10·5% v. 6·0%) but this difference did not reach statistical significance. The children found STH-positive were five times more likely to be suffering from diarrhoea than the other children checked in clinical settings (P=0·004) and were also more likely to be suffering from abdominal pain (P=0·054) and/or diminished appetite (P=0·016).
Silva CC, Domingues AL, Lopes EP
… +5 more, Morais CN, Santos RB, Luna CF, Nader HB, Martins JR
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801502
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Schistosomiasis mansoni is a fibrogenic liver disease that constitutes a major health problem in north-eastern Brazil. Although one common manifestation of the disease, periportal fibrosis (PPF), can be assessed by ultra...Schistosomiasis mansoni is a fibrogenic liver disease that constitutes a major health problem in north-eastern Brazil. Although one common manifestation of the disease, periportal fibrosis (PPF), can be assessed by ultrasonography by well-trained physicians, the necessary equipment and personnel are not always readily available. Serum markers, including hyaluronic acid (HA), have been used as alternative means of measuring fibrosis. Recently serum concentrations of HA have been evaluated in 77 Brazilians (61 cases of schistosomiasis mansoni and 16 healthy controls) and compared against the ultrasound-evaluated PPF in the same subjects. The HA was measured using a non-competitive fluorescence-based assay, while the PPF was explored using a portable ultrasound scanner (SSD-500; Aloka, Tokyo) and graded, as patterns A-F, according to the World Health Organization's 'Niamey protocol'. In general, the serum concentrations of HA were found to be positively correlated with the severity of the PPF. The mean concentration of HA in the sera of the 16 controls was significantly lower than that recorded in the schistosomiasis cases who showed PPF of patterns D or E (P<0·001 for each). The cases who showed pattern-C PPF also had significantly less HA in their sera than the cases with PPF of patterns D or E (P<0·001 for each), and the cases with pattern-D fibrosis had significantly lower HA concentrations in their sera than the cases with PPF of pattern E (P<0·001). In an analysis based on a receiver-operating-characteristic (ROC) curve, an HA concentration of 20·2 μg/litre of serum was identified as a threshold that could be used to distinguish moderate cases of PPF (i.e. patterns C or D) from the more advanced cases (i.e. patterns E or F), with a sensitivity of 60% and specificity of 65%. In conclusion, it appears that serum concentrations of hyaluronic acid could be used as markers for periportal fibrosis in patients with schistosomiasis mansoni.
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801501
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Although the expression of matrix metalloproteinase-12 (MMP-12) appears to be increased in most inflammatory diseases, the role of this enzyme in the pathogenesis of toxoplasmosis in pregnant women, if any, is unknown. I...Although the expression of matrix metalloproteinase-12 (MMP-12) appears to be increased in most inflammatory diseases, the role of this enzyme in the pathogenesis of toxoplasmosis in pregnant women, if any, is unknown. In a recent study in Taiwan, the serum concentrations of MMP-12 and its substrate elastin were evaluated in pregnant women with Toxoplasma gondii infection. Compared with the healthy pregnant and non-pregnant women used as controls, the pregnant women with toxoplasmosis had significantly higher serum concentrations of MMP-12 and significantly higher levels of elastin synthesis and degradation. Interaction between MMP-12 and elastin in the serum samples was confirmed by co-immunoprecipitation. It seems possible that MMP-12 may contribute to elastin degradation occurring during the pathogenesis of toxoplasmosis in pregnant women.
Fakoorziba MR, Baseri A, Eghbal F
… +3 more, Rezaee S, Azizi K, Moemenbellah-Fard MD
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801500
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Human cutaneous leishmaniasis (CL) is of increasing public-health importance in Iran. On 10 July 2003, two mild earthquakes struck the rural town of Zarindasht in the southern Iranian province of Fars. The results of pas...Human cutaneous leishmaniasis (CL) is of increasing public-health importance in Iran. On 10 July 2003, two mild earthquakes struck the rural town of Zarindasht in the southern Iranian province of Fars. The results of passive detection of CL cases in this town (in which patients with any skin lesions were evaluated) from April 2002 to April 2004 indicated that the earthquakes may have led to an outbreak of the disease; annual incidence increased from 58·6 detected cases/100,000 in the 12 months before the earthquakes to (an outbreak peak of) 864 detected cases/100,000 in the following 12 months. In addition, the incidence of detected CL in the town that was struck by the earthquakes in 2003 was significantly higher in the 12 months after the earthquakes than that recorded, over the same 12 months, for Fars province as a whole (P<0·05). Most (70%) of the cases detected in the town were aged ≤10 years, about half (50·4%) of the detected skin lesions were on the face, and most (89·7%) of the skin lesions were caused by Leishmania major. Incidence over the study period showed marked seasonality, with most (79·5%) of the detected cases occurring between November and February. In areas where the disease is endemic, CL may need to be considered among the health threats posed by natural disasters such as earthquakes, and increased surveillance for CL after future earthquakes may be justified.
Ghasemian M, Maraghi S, Samarbafzadeh AR
… +2 more, Jelowdar A, Kalantari M
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801499
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In Iran, Leishmania major or L. tropica cause almost all of the human cutaneous leishmaniasis (CL). Unfortunately, the detection methods frequently used for CL (the microscopical examination of direct smears or the cultu...In Iran, Leishmania major or L. tropica cause almost all of the human cutaneous leishmaniasis (CL). Unfortunately, the detection methods frequently used for CL (the microscopical examination of direct smears or the culture of biopsies) are not very sensitive and the Leishmania species causing each case of CL in Iran is usually only tentatively identified from extrinsic factors, such as the case's clinical manifestations and region of residence. Recently, however, a nested PCR that targets the parasites' kinetoplast DNA has been used in the city of Ahvaz (the capital of the province of Khouzestan, in south-western Iran) to confirm the microscopical diagnosis of CL and to identify the causative parasites, to species level. Smears from the lesions on 100 suspected cases of CL were fixed, stained with Wright's eosin-methylene blue, and checked for amastigotes under a light microscope. Scrapings from the same smears were then tested for leishmanial DNA, using a nested PCR that allows the DNA from L. tropica to be identified and distinguished from that of L. major. The 100 smears investigated were all found amastigote-positive by microscopy and PCR-positive for either L. major DNA (97 smears) or L. tropica DNA (three smears). The predominant species causing CL in Ahvaz is therefore L. major.
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801498
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India is among the countries that are worse affected by human malaria, one of the major vector-borne diseases that continue to affect vast populations across the world. In a recent household survey in the Terai region of...India is among the countries that are worse affected by human malaria, one of the major vector-borne diseases that continue to affect vast populations across the world. In a recent household survey in the Terai region of eastern India, the factors that might explain the occurrence and clustering of human malaria and the consequent healthcare-seeking behaviour of the human population were explored. The topography and geo-climatic conditions in Terai appear to intensify the risks of malaria but some socio-economic attributes, such as engagement in agricultural occupations, poor economic status and congested household environments, were also identified as significant risk factors for the disease. In the study area, public health facilities predominate as sources of medical care for malaria, although, at least in the early stages of treatment seeking, informal providers and pharmacies are also often involved. Unfortunately, despite the high frequency of malarial outbreaks, the local public health facilities were found to be ill-equipped to tackle and contain the spread of malaria. Preventive public-health measures, health education on malaria and malaria-awareness exercises were found to be scarce and irregular. The reliance on a reactive strategy of offering curative care to the affected led to overcrowding in healthcare facilities and shortages of medicines and diagnostic procedures. Along with a more efficient and reliable emergency system to deal with major outbreaks of malaria, more effective convergent interventions, by the local government and other stakeholders, should be developed to help prevent the disease.
Al-Mekhlafi AM, Al-Mekhlafi HM, Mahdy MA
… +2 more, Azazy AA, Fong MY
Ann Trop Med Parasitol
· 2011 Apr · PMID 21801497
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<title/> Between June 2008 and March 2009, a cross-sectional study of human malaria was carried out in four governorates of Yemen, two (Taiz and Hodiedah) representing the country's highlands and the others (Dhamar and R...<title/> Between June 2008 and March 2009, a cross-sectional study of human malaria was carried out in four governorates of Yemen, two (Taiz and Hodiedah) representing the country's highlands and the others (Dhamar and Raymah) the country's coastal plains/foothills. The main aims were to determine the prevalences of Plasmodium infection among 455 febrile patients presenting for care at participating health facilities and to investigate the potential risk factors for such infection. Malarial infection was detected in 78 (17·1%) of the investigated patients and was more likely to be detected among the febrile patients from the highlands than among those presenting in the coastal plains/foothills (22·6% v.13·9%; χ(2)=10·102; P=0·018). Binary logistic-regression models identified low household income [odds ratio (OR)=13·52; 95% confidence interval (CI)=2·62-69·67; P=0·002], living in a household with access to a water pump (OR=4·18; CI=1·60-10·96; P=0·004) and living in a household near a stream (OR=4·43; CI=1·35-14·56; P=0·014) as significant risk factors for malarial infection in the highlands. Low household income was the only significant risk factor identified for such infection in the coastal plains and foothills (OR = 8·20; CI=1·80-37·45; P=0·007). It is unclear why febrile patients in the highlands of Yemen are much more likely to be found to have malarial infection than their counterparts from the coastal plains and foothills. Although it is possible that malarial transmission is relatively intense in the highlands, it seems more likely that, compared with those who live at lower altitudes, those who live in the highlands are less immune to malaria, and therefore more likely to develop febrile illness following malarial infection. Whatever the cause of the symptomatic malarial infection commonly found in the highlands of Yemen, it is a matter of serious concern that should be addressed in the national strategy to control malaria.
Ann Trop Med Parasitol
· 2011 Mar · PMID 21396252
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As part of a continuous, standardized programme of monitoring the Leishmania vectors in German military camps in northern Afghanistan between 2007 and 2009, a detailed taxonomic analysis of the endemic sandfly fauna, as...As part of a continuous, standardized programme of monitoring the Leishmania vectors in German military camps in northern Afghanistan between 2007 and 2009, a detailed taxonomic analysis of the endemic sandfly fauna, as sampled using light and odour-baited traps, was conducted. Of the 10 sandfly species that were recorded, six may serve as enzootic and/or zooanthroponotic vectors of parasites causing human leishmaniasis. The use of a simple DNA-'barcoding' technique based on the mitochondrial cyt b gene, to identify the collected sandflies to species level, revealed (1) a clear discrimination between the potential vector species, (2) clustering of species within most subgenera, and (3) particularly high heterogeneity within the subgenus Paraphlebotomus (Phlebotomus alexandri being grouped with Ph. papatasi rather than with other Paraphlebotomus species). The data also indicate a high level of genetic heterogeneity within the subgenus Sergentomyia but close similarity between Sergentomyia sintoni and Sergentomyia murgabiensis. The morphological similarity of many medically important sandflies can make species identification difficult, if not impossible. The new DNA-barcoding techniques may provide powerful discriminatory tools in the future.
Ann Trop Med Parasitol
· 2011 Mar · PMID 21396251
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Identification of wild animals that harbour the causative leptospires, and the identification of the most important of these 'wild reservoirs' (in terms of threat to human health), are key factors in the epidemiology of...Identification of wild animals that harbour the causative leptospires, and the identification of the most important of these 'wild reservoirs' (in terms of threat to human health), are key factors in the epidemiology of human leptospirosis. In an epidemiological investigation in the Australian state of Queensland, in 2007-2008, samples were collected from fruit bats (Pteropus conspicillatus) and rodents (to investigate the potential role of fruit bats in the maintenance and transmission of leptospires to ground-dwelling rodents) and checked for pathogenic leptospires. The results of these studies have now been carefully analysed in attempts to see which method of detection and type of test sample were best. The effects of pentobarbitone sodium used to euthanize wild mammals before collection of necropsy samples, on the survival and detection of leptospires in vitro, were also explored. In the earlier field investigation, serum, renal tissue and urine were collected from wild mammals, for the detection of pathogenic leptospires by culture, the microscopic agglutination test (MAT), real-time PCR and silver impregnation of smears. Although 27.6% of the rodents investigated were found leptospire-positive, culture only yielded four isolates, probably because many cultures were contaminated. The main aims of the present study were to quantify the performance of the individual diagnostic tests and examine the reasons behind the high incidence of culture contamination. The results of sensitivity and specificity analyses for the different diagnostic tests indicated that isolation by culture (the definitive diagnostic test for leptospiral shedding) had perfect (100%) sensitivity when compared with the results of the PCR but a low specificity (40%). The MAT performed poorly, with a sensitivity of 50% when compared against the results of culture. The prevalence of leptospiral carriage revealed by the PCR-based investigation of kidney and urine samples (59.2%) was higher than that revealed using any other method and far higher than the 2.0% revealed by culture. The results of the culture of renal tissue agreed fairly well with those of the PCR-based investigation of such tissue, with a Cohen's unweighted kappa coefficient (κ) of 0.5 (P = 0.04). The levels of agreement between other pairs of tests were generally poor. The presence of pentobarbitone sodium, at final concentrations of 27.8 or 167 mg/ml, did not affect the viability or the detection of leptospires in culture, and is therefore unlikely to reduce the chances of isolating leptospires from an animal that has been euthanized with the compound. It appears that collecting multiple samples from each mammal being checked will improve the chances of detecting leptospires (and reduce the chances of reporting an inconclusive result for any of the mammals). For the identification of a leptospiral carrier, however, the use of just two detection methods (culture and PCR) and one type of sample (renal tissue) may give adequate sensitivity and specificity. Given the robustness of PCR to contamination and its high sensitivity (it can give a positive result when DNA from just two leptospiral cells is present in the sample), a PCR-based serotyping method, to allow the combined detection and characterisation of leptospires from field isolates, would be extremely useful.
Al-Mekhlafi HM, Mahdy MA, 'Azlin MY
… +2 more, Fatmah MS, Norhayati M
Ann Trop Med Parasitol
· 2011 Mar · PMID 21396250
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Cryptosporidium is a coccidian parasite that is prevalent worldwide, some species of which cause morbidity in both immunocompromised and immunocompetent individuals. The prevalence and predictors of Cryptosporidium infec...Cryptosporidium is a coccidian parasite that is prevalent worldwide, some species of which cause morbidity in both immunocompromised and immunocompetent individuals. The prevalence and predictors of Cryptosporidium infection, and its effect on nutritional status, have recently been explored among 276 children (141 boys and 135 girls, aged 2-15 years) in aboriginal (Orang Asli) villages in the Malaysian state of Selangor. Faecal smears were examined by the modified Ziehl-Neelsen staining technique while socio-economic data were collected using a standardized questionnaire. Nutritional status was assessed by anthropometric measurements. Cryptosporidium infection, which was detected in 7.2% of the aboriginal children, was found to be significantly associated with low birthweight (≤2.5 kg), being part of a large household (with more than seven members) and prolonged breast feeding (>2 years). The output of a binary logistic regression confirmed that large household size was a significant predictor of Cryptosporidium infection (giving an odds ratio of 2.15, with a 95% confidence interval of 1.25-5.02). Cryptosporidium infection is clearly a public-health problem among the aboriginal children of Selangor, with person-to-person the most likely mode of transmission.