Direct Wet Smear Research Articles

INTESTINAL PARASITIC INFECTIONS AMONG PRE-SCHOOL CHILDREN IN SANGKHLABURI, THAILAND

This study was conducted to investigate the presence of intestinal parasites among pre-school children (aged 3 months to 5 years) in Sangkhlaburi, a rural district in the west of Thailand along the Thai-Myanmar border. Stool specimens were collected from October 2001 through October 2002. A total of 472 pre-school children, 233 males and 239 females, 236 children with diarrhea and 236 asymptomatic children were recruited for the study. Each specimen was processed and examined by direct wet smear, modified acid fast stain, formalin-ethylacetate sedimentation concentration technique, and trichrome stain. In detecting Giardia lamblia and Cryptosporidium species ProSpecT Microplate assays (Alexon-Trend, Lenexa, KS) were performed. There were 107 individuals (22.7%), 41 diarrheal and 66 asymptomatic children, infected with intestinal parasites. The most frequent parasites identified in cases and controls were G. lamblia and Cryptosporidium spp. Eighteen specimens (3.8%) showed mixed parasite infections. Highest proportion of intestinal parasites occurred during the rainy season (June-October).

Prevalence Of Intestinal Helminthiasis In Parts Of Imo State, Nigeria

Three thousand and eighty seven (3,087) respondents comprising of 1994 females and 1093 males aged between 1 to 60 years were examined for intestinal helminthiasis in three Local Government Areas (Orlu urban; Orsu and Oru East) in Imo State. Direct wet smear and sedimentation techniques were used. Percentage infection was found to be 31.5% affecting 20.0% and 11.5% of female and male population respectively. Amongst the 972 infected respondents, 301(31%); 211(21.7%); 147(15.1%); 93(9.6%); 78(8.0%); 64(6.6%); 51(5.3%); and 25(2.6%), were infected by A. lumbricoides; N. americanus; A. duodonale; T. trichiura; T. saginata; S. stercoralis, E. vermiscularis, and T. solium respectively. Whereas 2(0.2%) were infected with both A. lumbricoides and N. americanus. Statistical analysis revealed no significant difference in the prevalence of infection between the two sexes (p >0.05). The prevalence of the infection was found to be highest among the younger age group than the older groups for all the helminths except for Taeniasis that was found to be higher among the older age group. This study reveals the prevalence and the relationship between intestinal helminthiasis and age groups in the area. KEY WORDS: Intestinal Helminthiasis Prevalence in Imo State Global Journal of Pure and Applied Sciences Vol.11(1) 2005: 17-21

Infectivity of Cryptosporidium parvum oocysts is retained upon intestinal passage through a migratory water-fowl species (Canada goose, Branta canadensis).

Summary Five Cryptosporidium‐free Canada geese (Branta canadensis) were individually orally dosed with 3–5 × 106 Cryptosporidium parvum oocysts infectious to neonatal BALB/c mice. After intestinal passage, inoculum‐derived oocysts extracted from goose faeces established severe infection in 14 neonatal BALB/c mice (inoculum dose 2.5 × 105/mouse). The inoculum‐derived oocysts were detected in goose faeces up to 9 days post‐inoculation (PI); the number of intact oocysts and oocyst shells shed during the first 3 days PI was significantly higher than for the remaining 6 days PI (P<0.01). Based on acid‐fast stained air‐dried direct wet smears, 62% of the oocysts in goose faeces were intact (oocyst shells constituted 38%) and conformed to morphological features of viable and infectious inoculum oocysts. The fluorescence scores of the inoculated oocysts, obtained by use of the MERIFLUOR test, were identical to those obtained for the faeces‐recovered oocysts (majority 3 + to 4 +). The dynamics of oocyst shedding showed that overall, the birds released a significantly higher number of intact oocysts than oocyst shells (P<0.01) Retention of the viability and infectivity of C. parvum oocysts following intestinal passage through a migratory water‐fowl species has serious epidemiological implications. Water‐fowl can serve as mechanical vectors for the water‐borne oocysts and can contaminate surface waters with C. parvum. As the concentration of Cryptosporidium oocysts in source waters is attributable to water‐shed management practices, water‐shed protection programme officials should consider water‐fowl as a potential factor enhancing contamination of the source water with Cryptosporidium.

Diagnosis of subclinical cryptosporidiosis in captive snakes based on stomach lavage and cloacal sampling

The applicability of stomach lavage and cloacal swab techniques for diagnosis of subclinical cryptosporidiosis were tested in eight captive snakes subclinically infected with Cryptosporidium serpentis. Two feeding regimes were employed. The snakes were first fed 7 days prior to stomach and cloaca sampling, and then 3 days prior to sampling, and the oocysts were detected by fluorescein labeled monoclonal antibody (mAb) and by acid-fast stained (AFS) direct wet smear (DWS). The overall sensitivity of AFS DWS was 95% for stomach samples and 57% for cloacal samples, with false-negativity of 5% and 43%, respectively. A significant relationship ( P<0.01) was found between stomach and cloacal samples when mAb were used for oocyst detection. Stomach sampling was diagnostically superior to cloacal sampling for identifying snake subclinical cryptosporidiosis. Based on gastric aspirates, cryptosporidial infection was diagnosed in all eight animals, and only in two or four snakes when cloacal swab material was processed by AFS or by mAb, respectively. Feeding snakes 3 days prior to sampling facilitated diagnosis based on stomach samples; however, it did not improve diagnosis when cloacal samples were used. The fraction of oocyst-positive stomach samples was significantly higher ( P<0.05) for snakes fed 3 days prior to gastric lavage when compared with the fraction of positive samples of snakes fed 7 days prior to lavage. If subclinical cryptosporidiosis is suspected in a non-eating snake patient, force-feeding and stomach lavage, 3 days after the meal, is recommended.

Viability and infectivity of Cryptosporidium parvum oocysts are retained upon intestinal passage through a refractory avian host.

Six Cryptosporidium-free Peking ducks (Anas platyrhynchos) were each orally inoculated with 2.0 x 10(6) Cryptosporidium parvum oocysts infectious to neonatal BALB/c mice. Histological examination of the stomachs jejunums, ilea, ceca, cloacae, larynges, tracheae, and lungs of the ducks euthanized on day 7 postinoculation (p.i.) revealed no life-cycle stages of C. parvum. However, inoculum-derived oocysts extracted from duck feces established severe infection in eight neonatal BALB/c mice (inoculum dose, 2.5 x 10(5) per mouse). On the basis of acid-fast stained direct wet smears, 73% of the oocysts in duck feces were intact (27% were oocyst shells), and their morphological features conformed to those of viable and infectious oocysts of the original inoculum. The fluorescence scores of the inoculated oocysts, obtained by use of the MERIFLUOR test, were identical to those obtained for the feces-recovered oocysts (the majority were 3+ to 4+). The dynamics of oocyst shedding showed that the birds released a significantly higher number of intact oocysts than the oocyst shells (P < 0.01). The number of intact oocysts shed (87%) during the first 2 days p.i. was significantly higher than the number shed during the remaining 5 days p.i. (P < 0.01) and significantly decreased from day 1 to day 2 p.i. (P < 0.01). The number of oocyst shells shed during 7 days p.i. did not vary significantly (P > 0.05). The retention of infectivity of C. parvum oocysts after intestinal passage through an aquatic bird has serious epidemiological and epizootiological implications. Waterfowl may serve as mechanical vectors for the waterborne oocysts and may enhance contamination of surface waters with C. parvum. As the concentration of Cryptosporidium oocysts in source waters is attributable to watershed management practices, the watershed protection program should consider waterfowl as a potential factor enhancing contamination of the source water with C. parvum.

Comparison of fresh versus sodium acetate acetic acid formalin preserved stool specimens for diagnosis of intestinal protozoal infections

The use of sodium acetate acetic acid formalin (SAF)-preserved stool specimens was compared with that of nonpreserved specimens for the recovery of intestinal protozoa. A total of 247 patients, 170 with diarrhea of more than one week's duration and 77 refugees, were asked to collect a stool specimen. Each specimen was placed into two vials, one empty, the other containing SAF fixative. Laboratory investigations included microscopic examination of the concentrated sediment and direct wet smears from both types of stool specimens and the microscopic examination of a permanent stained smear from the unsedimented, SAF-preserved stool specimens. Examination of SAF-preserved stool specimens revealed intestinal protozoa in 149 of the 247 patients. With the conventional procedure using unpreserved stool specimens, intestinal protozoa were found in 89 of the 247 patients. The results show that the examination of SAF-preserved stool specimens, consisting of the microscopic examination of both the concentrated sediment and the permanent stained smear from the unsedimented material, increases the chance of recovering intestinal protozoa as compared to the conventional procedure.