Lillian F. Mayberry

Population-based survey of taeniasis along the United States–Mexico border

Abstract Taenia solium and T. saginata are zoonotic tapeworms of substantial medical and economic importance. Although human taeniasis is widely recognised as an endemic problem in Mexico, its presence in the United States is poorly understood. The first population-based study to estimate the prevalence of human infection with Taenia tapeworms along the Texas–Mexico border has recently been conducted. Households were interviewed in the Texan city of El Paso and in the neighbouring Ciudad Juárez, in Mexico. Faecal samples from household members were then checked for Taenia eggs by flotation and/or for Taenia copro-antigens in an ELISA. The overall prevalence of taeniasis in this border region was found to be 3% but, compared with the residents of Juárez, El Paso residents were 8.6-fold more likely to be tapeworm carriers. The interviews revealed some important differences between the two study sites, particularly the more frequent use of anthelminthic drugs on the Mexican side of the border. These findings have implications in terms of the planning of effective health-education campaigns to decrease the prevalence of taeniasis in the human populations along the Texas–Mexico border.

GENETIC DEPENDENT TRANSMISSION OF EIMERIA SEPARATA FROM RATTUS TO THREE STRAINS OF MUS MUSCULUS, AN ABNORMAL HOST

We examined susceptibility of several strains of mice to Eimeria separata. Mice of the following coat-color genotypes were inoculated with 2 X 10(4) sporulated oocysts of E. separata isolated from Rattus norvegicus: random-bred (aabbCC and A-bbCC), Balb/C (AAbbcc), Balb/Gw (AABBcc), Z/Gw (aaBBcc), and Swiss NLW (cc). Allele designations are A = agouti, a = nonagouti, B = black, b = brown, C, c = albino. Eimeria separata completed its life cycle with oocyst production in all male and female random-bred (aabbCC), Balb/Gw and G/Gw mice. The reproductive index of E. separata in Balb/Gw mice was significantly lower (P less than or equal to 0.05) than that of the other mouse strains. Among the random-bred mice, E. separata had a significantly lower (P less than or equal to 0.05) mean reproductive index in male than in female hosts. Patent period and oocyst length/width indices remained constant irrespective of host genus. This is the first documentation that genetic factors play a role in susceptibility of mice to the rat coccidium, E. separata.

INTERSPECIFIC INTERACTIONS BETWEEN NIPPOSTRONGYLUS BRASILIENSIS AND EIMERIA NIESCHULZI IN THE RAT

Interspecific interactions between Nippostrongylus brasiliensis and Eimeria nieschulzi were studied by measuring parasite fecundity and patency in rats concurrently infected with both species. Nine groups of five rats each were inoculated with either 4 x 10(3) N. brasiliensis larvae or 2.6 x 10(5) E. nieschulzi sporulated oocysts or both. Groups 1 and 2 served as singly-infected controls. Group 3 rats were infected simultaneously with both parasites. Rats in Groups 4 to 8 were infected first with N. brasiliensis and later with E. nieschulzi on days 3, 4, 8, 9, and 14 PI. Rats in Group 9 were infected with E. nieschulzi and then with N. brasiliensis 2 days later. Patency of N. brasiliensis infections was extended significantly (P less than or equal to 0.05) beyond singly-infected controls in all groups with concurrent infections except Group 3, whereas ova production was significantly greater than that in singly-infected controls only when both parasites were administered simultaneously (Group 3). Patency of E. nieschulzi was significantly shorter in Group 7 rats and longer in Group 9 rats compared to that of singly-infected controls. Total oocyst production was unaltered except for Groups 5 and 7 in which there was a significant reduction. These results demonstrate that the endogenous stages of E. nieschulzi increased N. brasiliensis longevity.

Suppression of peripheral eosinophilia by the coccidium Eimeria nieschulzi (Apicomplexa: Eimeriidae) in experimentally infected rats.

Four groups of 60 rats each were used to examine interspecific interactions between Eimeria nieschulzi and Nippostrongylus brasiliensis. Rats in group 1 served as uninoculated controls. Group 2 rats were each injected subcutaneously with 2.0 X 10(3) L3 larvae of N. brasiliensis. Group 3 rats were each inoculated per os with 2.5 X 10(5) sporulated oocysts of E. nieschulzi. Rats in group 4 were first infected with 2.0 X 10(3) larvae of N. brasiliensis and, at 8 days postinoculation, with 2.5 X 10(5) oocysts of E. nieschulzi. Ten animals from groups 1-3 were sacrificed at 4-day intervals postinoculation and group 4 rats were sacrificed at 4-day intervals beginning after the secondary infection. Blood smears were prepared from each animal to determine differential blood cell counts, bone marrow was examined at the times of peak infection for absolute and relative numbers of eosinophils, portions of the duodenum and jejunum were examined histologically for mast cells, and feces obtained from the cecum and large intestine were examined for ova/gram of feces. Results revealed that relative numbers of peripheral neutrophils and monocytes became elevated during the course of infection for all infected animals, and rats infected with the helminth only also had elevated eosinophil levels. However, rats infected singly with E. nieschulzi, or concurrently with the coccidium and helminth, had peripheral eosinophil levels that were not significantly different from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

Hyperendemic H. pylori and tapeworm infections in a U.S.-Mexico border population

Objective. A higher incidence of infectious disease has been documented in U.S. regions bordering Mexico compared with non-border areas. We assessed the prevalence of important gastrointestinal infections in Ciudad Juarez, Mexico, and El Paso, Texas, the largest binational community along the U.S.-Mexico border. Methods. Fecal specimens from a sample of the asymptomatic population representing all ages were tested for Helicobacter pylori (H. pylori), Cryptosporidium spp., Giardia spp., and other intestinal parasitic pathogens using flotation, immunoassays, and/or polymerase chain reaction. We also measured indicators of microbiological contamination of drinking water, hands of food preparers, and kitchen surfaces. Results. Overall, of the 386 participants, H. pylori was present in 38.2%, Taenia spp. in 3.3%, Giardia spp. in 2.7%, Cryptosporidium spp. in 1.9%, Entamoeba dispar in 1.3%, and Ascaris lumbricoides and Necator americanus in 0.3% of the study subjects; Cyclospora spp. and Entamoeba histolytica were not found. H. pylori infection was associated with handwashing (prevalence ratio [PR] = 1.3, 95% confidence interval [CI] 1.0, 1.8). Taenia spp. was found more often on the U.S. side (PR=8.6, 95% CI 2.3, 30.8). We did not find an association between these infections and the occurrence of total coliforms or fecal coliforms on kitchen surfaces. In addition, Escherichia coli was not found in any drinking water sample. Conclusion. The study results indicated that H. pylori and Taenia spp. infections may be highly prevalent along the U.S.-Mexico border. Additional research is necessary to adequately characterize the prevalence, as well as determine whether interventions that reduce these infections are warranted.

Occurrence of faecal contamination in households along the US–Mexico border

Aims:  The study aim was to determine the presence of total and faecal coliforms on kitchen surfaces, in tap water and on the hands of caregivers in households on both sides of the US–Mexico border.

Nippostrongylus brasiliensis: Malabsorption in experimentally infected rats

Glucose absorption and net small intestinal water movement were examined in rats infected with Nippostrongylus brasiliensis at Days 4, 6, 9, 13, and 19 after inoculation. Rats were infected with 4 X 10(3) N. brasiliensis third stage larvae. The entire small intestine was divided into three segments and each segment perfused simultaneously in vivo with Krebs-Ringer phosphate buffer containing 80 mM glucose, 6 X 10(5) dpm/ml [3H]glucose, and 6.2 X 10(3) dpm/ml [14C]polyethylene glycol. Rats perfused on Days 6, 9, 13, and 19 after inoculation showed a significant (P less than 0.05) decrease in glucose absorption rates from all three segments of the small intestine when compared to uninfected controls. In the three segments of uninfected rat small intestine and those perfused on Days 4, 13, and 19 after inoculation, net absorption of water occurred. However, in the proximal and distal segments perfused on Day 6 and the proximal segment perfused on Day 9, net water movement into the lumen occurred. This is the first report of depressed glucose absorption along the entire length of the small intestine during nippostrongylosis and contradicts previous reports of unaltered net glucose absorption in response to this parasite.

Suppression of Nippostrongylus brasiliensis (Nematoda)-induced lysophospholipase activity and peripheral eosinophilia by Eimeria nieschulzi (Apicomplexa).

Interspecific interactions between Nippostrongylus brasiliensis and Eimeria nieschulzi were studied by measuring fecal lysophospholipase (LYPH) activity and relative numbers of peripheral eosinophils in rats singly or concurrently infected with one or both parasite species. Three groups of 10 rats each were inoculated with 2 X 10(3) N. brasiliensis L3 larvae and/or 5 X 10(5) E. nieschulzi sporulated oocysts. Groups 1 and 2 were infected with E. nieschulzi or N. brasiliensis, respectively. Group 3 rats were infected first with N. brasiliensis, followed on day 8 postinoculation (PI) with E. nieschulzi. Each rat served as its own control. Results revealed LYPH levels rose steadily in Group 2 rats, reaching significant peaks on days 10 and 12 PI before decreasing to control levels. Lysophospholipase activity in Groups 1 and 3, however, did not differ from control values. Group 2 rats also demonstrated peripheral eosinophilia, with peak values occurring on days 10, 12, 14, and 16 PI, while rats in Groups 1 and 3 exhibited no eosinophilia. These results demonstrate that E. nieschulzi suppressed intestinal LYPH activity and relative peripheral eosinophilia and demonstrate that a hosts immune response to a single parasite may be significantly altered when a second parasite species is present.

Small intestinal sucrase activity during experimental infections withNippostrongylus brasiliensis and/orEimeria nieschulzi in rats

Conflicting results have been reported in the literature over the years as to whether or not malabsorption of glucose occurs in rats with nippostrongylosis that had been given single large inocula (Symons 1960, Aust J Biol Sci 13: 180-187; Symons 1961, Aust J Biol Sci 14: 165-171; Scofield 1977, Int J Parasitol 7: 159-161; Scofield 1980, Int J Parasitol 10: 375-380; Nolla et al. 1985, Exp Parasitol 59: 180-184). In all cases, glucose was introduced and its disappearance or transport measured. In a normal diet, however, carbohydrates are not usually ingested as monosaccharides but as polysaccharides which must be digested to monosaccharides prior to being absorbed by enterocytes. If a parasite were to interfere with enzymes catalyzing the digestion of disaccharides or more complex carbohydrates to monosaccharides, it is possible that the host would suffer from a glucose deficiency even if the transport systems are not affected. Brush border enzyme activity has been measured in a variety of hostparasite systems and those involved with digestion have been found to be depressed during helminth infections (Castro 1981, Physiol Gastroenterol Tract, Johnson (ed), p 1381). Symons and Fairbairn (1963, Exp Parasitol 13:284-304) reported that at 10 days postinoculation (pi) with Nippostrongylus brasiliensis, in vitro jejunal maltase activity was reduced by 70 percent. These authors also reported that at 5 days p.i., activity was unaffected while during recovery (21 days p.i.) activity remained depressed. Depressed activity would result in decreased maltose digestion and, thus, decreased availability of glucose for absorption. The present study was designed to determine if the activity of sucrase, a brush border enzyme that catalyzes the conversion of sucrose to glucose and fructose, is affected at various days p.i. by the nematode, N. brasiliensis. In addition, we were interested

Suppression of phytohemagglutinin induced splenocyte proliferation during concurrent infection withEimeria nieschulzi andNippostrongylus brasiliensis

Results suggest that infection withEimeria nieschulzi (Protozoa) interferes with splenocyte proliferation induced by infection withNippostrongylus brasiliensis (Nematoda).