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Patterns and risks of trichinella infection in humans and pigs in northern Laos.

ABSTRACT: Several outbreaks of trichinellosis associated with the consumption of raw pork have occurred in Laos since 2004. This cross-sectional study was conducted in four provinces of northern Laos to investigate the seroepidemiology of trichinellosis in the human population and determine the prevalence and species of Trichinella infection in the domestic pig population. Serum samples and questionnaire data were obtained from 1419 individuals. Serum samples were tested for Trichinella antibodies by ELISA using larval excretory-secretory (ES) antigens and a subset of 68 positive samples were tested by western blot. The seroprevalence of Trichinella antibodies was 19.1% (95% confidence interval (CI)?=?17.1-21.1%). The risk of having antibodies detected by ELISA using ES antigens increased with age, being of Lao-Tai ethnicity, living in Oudomxay province and being male. Tongue and diaphragm muscle samples were collected from 728 pigs and tested for Trichinella larvae by the artificial digestion method. Trichinella larvae were isolated from 15 pigs (2.1%) of which 13 were identified as T. spiralis by molecular typing; the species of the two remaining isolates could not be determined due to DNA degradation. Trichinella spp. are endemic in the domestic environment of northern Laos and targeted preventative health measures should be initiated to reduce the risk of further outbreaks occurring.

SUBMITTER: Conlan JV

PROVIDER: S-EPMC4117436 | biostudies-other | 2014

REPOSITORIES: biostudies-other

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Patterns and risks of trichinella infection in humans and pigs in northern Laos.

Conlan James V JV Vongxay Khamphouth K Khamlome Boualam B Gomez-Morales Maria Angeles MA Pozio Edoardo E Blacksell Stuart D SD Fenwick Stanley S Thompson R C A RC

PLoS neglected tropical diseases 20140731 7

Several outbreaks of trichinellosis associated with the consumption of raw pork have occurred in Laos since 2004. This cross-sectional study was conducted in four provinces of northern Laos to investigate the seroepidemiology of trichinellosis in the human population and determine the prevalence and species of Trichinella infection in the domestic pig population. Serum samples and questionnaire data were obtained from 1419 individuals. Serum samples were tested for Trichinella antibodies by ELIS ...[more]

PMID: 25078088

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Project description:BACKGROUND:Domesticated and wild swine play an important role as reservoir hosts of Trichinella spp. and a source of infection for humans. Little is known about the survival of Trichinella larvae in muscles and the duration of anti-Trichinella antibodies in pigs with long-lasting infections. METHODS:Sixty pigs were divided into three groups of 20 animals and infected with 10,000 larvae of Trichinella spiralis, Trichinella britovi or Trichinella pseudospiralis. Four pigs from each group were sacrificed at 2, 6, 12, 18 and 24 months post-infection (p.i.) and the number of larvae per gram (LPG) of muscles was calculated. Serum samples were tested by ELISA and western blot using excretory/secretory (ES) and crude antigens. RESULTS:Trichinella spiralis showed the highest infectivity and immunogenicity in pigs and larvae survived in pig muscles for up to 2 years p.i. In these pigs, the IgG level significantly increased at 30 days p.i. and reached a peak at about 60 days p.i., remaining stable until the end of the experiment. In T. britovi-infected pigs, LPG was about 70 times lower than for T. spiralis at 2 months p.i. and only very few infecting larvae were detected at 6 months p.i., whereas no larvae were detected at 12, 18 and 24 months p.i. At 6 months p.i., degenerated/calcified larvae and cysts were detected in the muscles by trichinoscopy and histology. The IgG pattern showed by T. britovi-infected pigs was similar to that of T. spiralis-infected pigs, although seroconversion occurred some days later. The larval burden of T. pseudospiralis was slightly greater than for T. britovi at 2 months p.i., but no larvae were detected at 6 and 12 months p.i. In T. pseudospiralis-infected pigs, seroconversion occurred slowly, as in T. britovi-infected pigs. The IgG level showed a significant drop at 6 months p.i. and declining to the cut-off value at 12 months p.i. CONCLUSIONS:The longer survival of T. spiralis in pigs in comparison with the other two species highlights its exceptional dissemination potential. These results provide an explanation of the controversial data collected by parasitological and serological tools in the course of epidemiological investigations.

Project description:The present study compares the immunogenic patterns of muscle larvae excretory-secretory proteins (ML E-S) from T. spiralis and T. britovi recognized by Trichinella-infected human sera. Samples were analyzed using two-dimensional electrophoresis (2-DE) coupled with 2D-immunoblot and liquid chromatography-tandem mass spectrometry LC-MS/MS analysis, two ELISA procedures and a confirmatory 1D-immunoblot test. Sera were obtained from nine patients with a history of ingestion of raw or undercooked meat who presented typical clinical manifestations of trichinellosis and from eleven healthy people. Specific anti-Trichinella IgG antibodies were detected in all samples tested with the Home-ELISA kits, but in only four samples for the commercially-available kit. The 1D-immunoblot results indicated that all nine serum samples were positive for T. spiralis ML E-S antigens, expressed as the presence of specific bands. In contrast, eight of the serum samples with T. britovi E-S ML antigens were positive, with one serum sample taken from a patient at 33dpi (days post infection) being negative. To identify immunoreactive proteins that are specifically recognized by host antibodies, both species of ML E-S proteins were subjected to 2D-immunoblotting with human serum taken at 49 dpi. The sera recognized 22 protein spots for T. spiralis and 18 for T. britovi in 2D-immunoblot analysis. Their molecular weights (MW) ranged from 50 to 60 kDa. LC-MS/MS analysis identified both common and specifically-recognized immunoreactive proteins: transmembrane serine protease 9, serine protease, antigen targeted by protective antibodies and Actin-1 partial were shared for both Trichinella species; hypothetical protein T01_7775 and P49 antigen, partial those specific to T. spiralis; deoxyribonuclease-2-alpha and hypothetical protein T03_17187/T12_7360 were specific to T. britovi. Our results demonstrate the value of 2-DE and 2D-immunblot as versatile tools for pinpointing factors contributing to the parasite-host relationship by comparing the secretomes of different Trichinella species.

Project description:BackgroundInfantile beriberi (thiamine deficiency) occurs mainly in infants breastfed by mothers with inadequate intake of thiamine, typically among vulnerable populations. We describe possible and probable cases of infantile thiamine deficiency in northern Laos.Methodology/principal findingsThree surveys were conducted in Luang Namtha Province. First, we performed a retrospective survey of all infants with a diagnosis of thiamine deficiency admitted to the 5 hospitals in the province (2007-2009). Second, we prospectively recorded all infants with cardiac failure at Luang Namtha Hospital. Third, we further investigated all mothers with infants (1-6 months) living in 22 villages of the thiamine deficiency patients' origin. We performed a cross-sectional survey of all mothers and infants using a pre-tested questionnaire, physical examination and squat test. Infant mortality was estimated by verbal autopsy. From March to June 2010, four suspected infants with thiamine deficiency were admitted to Luang Namtha Provincial hospital. All recovered after parenteral thiamine injection. Between 2007 and 2009, 54 infants with possible/probable thiamine deficiency were diagnosed with acute severe cardiac failure, 49 (90.2%) were cured after parenteral thiamine; three died (5.6%). In the 22 villages, of 468 live born infants, 50 (10.6%, 95% CI: 8.0-13.8) died during the first year. A peak of mortality (36 deaths) was reported between 1 and 3 months. Verbal autopsy suggested that 17 deaths (3.6%) were due to suspected infantile thiamine deficiency. Of 127 mothers, 60 (47.2%) reported edema and paresthesia as well as a positive squat test during pregnancy; 125 (98.4%) respected post-partum food avoidance and all ate polished rice. Of 127 infants, 2 (1.6%) had probable thiamine deficiency, and 8 (6.8%) possible thiamine deficiency.ConclusionThiamine deficiency may be a major cause of infant mortality among ethnic groups in northern Laos. Mothers' and children's symptoms are compatible with thiamine deficiency. The severity of this nutritional situation requires urgent attention in Laos.

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Patterns and risks of trichinella infection in humans and pigs in northern Laos.

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Patterns and risks of trichinella infection in humans and pigs in northern Laos.

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