Chemotherapy of porcine cysticercosis with albendazole sulphoxide.

Cysticercosis is a zoonotic disease of humans produced by the larval stage of swine parasite, Taenia solium. Chemotherapy of infected pigs is a possible strategy for avoiding disease transmission and improving health programs in endemic areas of cysticercosis. In this preliminary study, seven naturally infected pigs from 6 to 12 months of age were allotted to treated (n = 4) and control groups (n = 3). The treated animals received a subcutaneous injection in their forelegs and thighs of 15 mg/kg per body weight of albendazole sulphoxide (ABZSO; Pisa, Mexico) once per day for 8 days. At the same time, the control group received a subcutaneous injection of saline solution (9% NaCl). After 12 weeks, all the animals were slaughtered and at least 200 metacestodes were isolated from the muscles and brain of each animal. Using histology and the metacestode viability criteria described in this study, treated animals had no viable cysts in their muscle (0/200), while 7 of 17 (41.1%) viable cysts were observed in those isolated from their brains. In the control group, 183/200 (91.5%) muscle metacestodes were viable and from brain, 22/29 (75.8%) metacestodes were viable. The 15 mg/kg per body weight dosage of ABZSO was 100% effective against muscular cysticercosis as shown by the lack of viable cysts and the micro-calcifications in meat from the treated pigs.

Taenia solium metacestode viability in infected pork after preparation with salt pickling or cooking methods common in Yucatán, Mexico.

The cestode parasite Taenia solium is an important cause of foodborne infection throughout tropical and subtropical regions. Ingestion of pork meat infected with T. solium larvae can lead to taeniasis infection in humans. With tourism and the consumption of native food increasing, it is important to investigate potential risks of transmission associated with food preparation methods. In this study, traditional Mexican salt pickling and two methods of pork preparation (as roast pork [cochinita pibil] and in pork and beans [frijol con puerco]) were evaluated in order to determine their effects on T. solium cyst viability in infected tissue. In the control groups, all metacestodes isolated were 100% viable, and only small changes in pH (from 6.0 to 5.9) and temperature (29 to 30 degrees C) were recorded. No viable cysts were detected after 12 and 24 h of salt pickling. The pH of the meat during salting dropped from 6.0 to 5.3. Osmotic changes and dehydration from the salting, rather than a change in pH, could be considered the main cause of cyst death. Temperatures of >65 degrees C damaged T. solium metacestodes in roast pork and in pork and beans. The results of this study indicate that if traditional pork dishes are prepared properly, T. solium cysts are destroyed. The criteria used in this study to evaluate the viability of tissue cysts are discussed.

Epidemiological study of Taenia solium taeniasis/cysticercosis in a rural village in Yucatan state, Mexico.

A survey to detect human taeniasis and cysticercosis was conducted in a community in Yucatan state, Mexico, an area endemic for Taenia solium. Information on the environmental, demographic and risk factors associated with transmission of T. solium within the community was recorded on questionnaires. Although no Taenia eggs or proglottides were found in the initial faecal samples collected from each of the 475 subjects, the results of a capture-ELISA for T. solium coproantigen were positive for 10 of the subjects (of both genders and various ages). After treatment with niclosamide, proglottides were detected in purge samples from seven of these 10 subjects. The prevalence of parasitologically confirmed taeniasis was therefore 1.5% (seven in 475). The other three ELISA-positive cases delayed supplying faecal material post-treatment, and it is nuclear whether they had expelled proglottides before providing the samples. All 10 ELISA-positive subjects became ELISA-negative after treatment. Seroprevalence of human cysticercosis, based on the detection in immunoblots of antibodies to antigens of 8- and 26-kDa from a crude saline extract of T. solium metacestodes, was 3.7% (i.e. five positives out of 134 subjects). None of the seropositive cases demonstrated clinical symptoms of infection. Again, the positive cases were of both genders and various ages. Although tongue palpation indicated that 17 (23%) of 75 pigs kept within the community had T. solium cysticercosis, the results of immunoblotting demonstrated antibodies to the 8- and/or 26-kDa antigens of T. solium in 26 (35%). The pigs allowed to roam throughout the community were far more likely to have cysticercosis than those kept in pens (odds ratio = 42, with a 95% confidence interval of 5.05-920.2; P < 0.00001). Not surprisingly, the risk factors associated with human taeniasis and cysticercosis included the eating of infected pork and close proximity to a carrier of T. solium. The main risk factor identified for porcine cysticercosis was free-range husbandry, permitting access to human faeces. This is the first comprehensive report of taeniasis and cysticercosis in a rural population from the Yucatan peninsula of Mexico.

Papillomatous digital dermatitis on a commercial dairy farm in Mexicali, Mexico: incidence and effect on reproduction and milk production.

This retrospective study of papillomatous digital dermatitis (PDD) was performed using data for cows that calved between July 1993 and June 1994 on a Mexicali, Mexico, dairy farm in order to calculate incidence rates, and to compare milk yield and reproduction data between affected and nonaffected dairy cows. A total of 190 out of 577 (33%) cows were affected during lactation and six (1%) during the dry period. Fifty-two of 77 (68%) cows that had lesions in the previous lactation and were also present on the farm in the current lactation had lesions in the current lactation. The highest risk for PDD occurred during the first month of lactation (9%). The yearly estimated cumulative incidence risk was 35% and the incidence density rate was 44.6 cases per 1000 cow-months. More animals were affected in summer and fall than in winter and spring. Purchased animals were 3.4 times more likely to be affected than animals born on the farm. Survival analyses indicated healthy cows conceived 93 days after calving (median), but affected cows conceived 113 days after calving (median) (P < 0.01). PDD-affected animals produced less milk than healthy cows, but the difference was not statistically significant in the multiple regression.