Karla Y. Acosta-Viana

American Trypanosomiasis in Dogs from an Urban and Rural Area of Yucatan, Mexico

American trypanosomiasis in dogs is reported from South of the United States to Argentina and Chile. It is transmitted through the contact of dogs with reduviid insects when they feed; reduviid insects are well established in the southern state of Yucatan, Mexico. However, there are no reports available about trypanosomiasis prevalence in dogs of urban and rural areas. A cross-sectional study was performed in 345 stray dogs, 102 from a rural community of Yucatan (Tunkas) and 243 from Merida, capital city of the Yucatan state. Serum samples were obtained for detection of immunoglobulin G antibodies against Trypanosoma cruzi by indirect immunofluorescence assay and Western blot. DNA was extracted from whole blood of urban dogs for polymerase chain reaction (PCR) assay. Prevalence was determined and the risk to become infected in both urban and rural dogs was evaluated using a 2 x 2 contingency table. In addition to the effect of body condition score (BCS), the age and sex of dogs were also evaluated to determine the risk of infection. Antibody prevalence against T. cruzi in rural areas was 9.8%, whereas in urban dogs was 14.4%. When PCR results were included, prevalence in dogs from the urban area increased to 17.3%. PCR allowed the detection of active asymptomatic acute-phase disease. The risk to become infected was not different between urban and rural areas, suggesting that the vector is well adapted both to rural areas and urban sprawling. Dogs with poor BCS tended to have a higher probability of seroreactivity to T. cruzi proteins than dogs with regular or good BCS (p = 0.05).

Stray dogs as reservoirs of the zoonotic agents Leptospira interrogans, Trypanosoma cruzi, and Aspergillus spp. in an urban area of Chiapas in southern Mexico.

This investigation determined the presence and prevalence of the zoonotic agents Leptospira interrogans, Trypanosoma cruzi, and Aspergillus spp. in the stray dog population (a total of 224 stray dogs) in an urban area of Southern Mexico. Blood serum samples were taken from all dogs, and root hair samples were taken from dogs with skin lesions and partial alopecia. IgG antibodies for L. interrogans from 10 serovars were detected using the microscopic agglutination test. Immunofluorescence antibody test and Western blot assay were used for serologic diagnosis of T. cruzi. The Sabouraud medium was used to isolate Aspergillus spp. Prevalence of L. interrogans was 4.9%, which was determined by identifying only serovars Pyrogenes, which accounted for 3.6%, and Tarassovi, which constituted 1.3%, with titers from 1:100 to 1:800. Additionally, T. cruzi antibodies were detected in 4.5% of the dogs. Skin lesions were found in 43% of the dogs (98/224), and 35 cultures were positive for Aspergillus spp. (35.7%, p < 0.05, 95% confidence interval 2.45-3.67), identified as A. niger (82.8%), A. flavus (14.3%), and A. terreus (2.9%). This study demonstrates the presence of certain zoonotic agents (bacteria, protozoa, and fungi) in stray dogs living within the studied area. Dogs play an important role in the transmission of diseases that are potentially harmful to humans. Although the prevalence of canine leptospirosis and trypanosomiasis is not high in Southern Mexico compared with other tropical regions of Mexico, the presence of these zoonotic agents in the stray dog population demonstrates that the stray dog population in this region is a significant reservoir and potential source of infection in humans. Special care should be taken when handling stray dogs that exhibit skin lesions with partial alopecia, since a pathological Aspergillus sp. fungus may be present.

Infection dynamic of Toxoplasma gondii in two fattening pig farms exposed to high and low cat density in an endemic region

The presence of cats in the farms is considered a risk factor for the infection of pigs with Toxoplasma gondii (T. gondii). Cats eliminate oocysts that contaminate food, water and promote the infection of host reservoir such as rodents and birds among others that are also involved in the infection of pigs. The objective of this study was to assess the dynamic of infection of T. gondii in seronegative weaned pigs from weaning to 20 weeks of age from two farms from an endemic region, one with high and low density of cats. A cohort study was performed in 64 pigs, 31 newly weaned pigs on a farm with a high density of cats (FA) and 33 newly-weaned pigs on a farm with a low density of cats (FB). Blood samples were collected every 14 days to determine the presence of IgG antibodies against T. gondii in the serum using an indirect ELISA test. True incidence rate (TIV), cumulative incidence (AI) and relative risk (RR) was calculated. The age of seroconversion was determined by using survival tables; both farms were compared with Long-Rank test. In FA 97.5% of the pigs seroconverted at the second sampling and 100% at the third sampling, while in the FB all pigs seroconverted to the fourth sampling. The TIV was 0.67 and 0.43 for FA and FB respectively, during the first four weeks at risk. A RR of 1.5 (1.04-2.39) was obtained (p<0.05). Animals of the FA had a higher risk of infection compared with the FB, however, all animals included in the study had contact with the agent. Infection with T. gondii was rapidly distributed in both farms, regardless of the relative density of cats observed during the study. These results suggest a high environmental contamination with oocysts in the facilities of both farms probably due to the fact that T. gondii infection is endemic in the area where the farms are located, allow proper establishment of the etiological agent. The points of prevention and control strategies to avoid exposure of pigs to T. gondii in an endemic area should focus on the control of cats and rodents.

Synergistic Effect of Lupenone and Caryophyllene Oxide against Trypanosoma cruzi

The in vitro trypanocidal activity of a 1 : 4 mixture of lupenone and caryophyllene oxide confirmed a synergistic effect of the terpenoids against epimastigotes forms of T. cruzi (IC50 = 10.4 μg/mL, FIC = 0.46). In addition, testing of the terpenoid mixture for its capacity to reduce the number of amastigote nests in cardiac tissue and skeletal muscle of infected mice showed a reduction of more than 80% at a dose level of 20.8 mg·kg−1·day−1.

Stage specific kinetoplast DNA-binding proteins in Trypanosoma cruzi

Knowledge regarding kinetoplast DNA organization in all members of the Trypanosomatid family is incomplete. Recently, the presence of kinetoplast-associated proteins in condensing kDNA networks in Crithidia fasciculata has been described and a role for these proteins in the maintenance of these complex structures was suggested. To investigate the presence of protein components in Trypanosoma cruzi kinetoplast, we previously described seven epimastigote kinetoplast-associated proteins. We report here the existence of kinetoplast binding proteins in amastigote and trypomastigote stages of T. cruzi, which could bind both mini and maxicircles components with a stage specific elements for every infective form of the parasite. We propose three major classes of kinetoplast-associated proteins related to the basic processes of this intricate disc structure and suggest a possible function of these binding proteins in the T. cruzi mitochondrial DNA organization.

Immunological Status Against Toxoplasma gondii in Non-Cat Owners from an Endemic Region of Mexico

A cross-sectional study was developed to determine anti-Toxoplasma gondii immunoglobulin G (IgG) and IgM antibodies from 80 persons aged 18-21 years without a history of previous contact with cats. Individuals who consented to take part in the survey were served with a questionnaire to obtain response on their eating habits. Blood samples were taken and specific IgM and IgG antibodies against T. gondii were measured by indirect enzyme-linked immunoassay. Seropositivity was found in 29 (37%) and 20 (25%) of 80 persons for IgM and IgG, respectively. Of the cases, 14 (18%) of 80 were positive to both IgM and IgG T. gondii antibodies. A significant association of IgM seropositivity was found in people consuming pork (p-value = 0.04) and wildlife meat (odds ratio = 4.5; confidence intervals = 1.47-14.25; p-value = 0.009). The presence of specific IgG and IgM antibodies in the studied population indicate previous contact and/or recent infections with T. gondii despite avoiding direct contact with cats. Ingestion of pork and meat from wild animals appears to be playing a key role in transmitting the parasite.

Seroprevalence of feline leukemia virus, feline immunodeficiency virus and heartworm infection among owned cats in tropical Mexico

Several infectious agents may be distributed within a healthy population of cats where diverse risk factors predispose them to come into contact with pathogens. Blood samples from 227 owned cats in Merida, Mexico, were collected with the objective of determining the seroprevalence and associated risk factors of feline leukemia virus (FeLV) and Dirofilaria immitis antigen, and feline immunodeficiency virus (FIV) antibody. Serological detection of FeLV and D immitis antigens, and FIV antibodies was performed using the commercial kit SNAP Feline Triple Test. The prevalence was found to be 7.5% for FeLV, 2.5% for FIV and 0% for D immitis. Adult cats were at a higher risk of coming into contact with FeLV (P <0.01) than younger cats. Owing to its low prevalence, a risk factor analysis was not performed for FIV. The prevalence of retroviral infections found in this study was low, but within the limits reported in the different geographical areas of the world. Cases of filariosis in the domestic cats of Merida, Mexico, may be absent or very low; however, the low sample size may have influenced these results.

Epidemiological Survey of Trypanosoma cruzi Infection in Domestic Owned Cats from the Tropical Southeast of Mexico

American trypanosomiasis is an infectious disease of importance for public health and caused by the protozoa Trypanosoma cruzi mainly transmitted by triatomine bugs. The precise role of cats in the peridomestic transmission of T. cruzi and the mechanism by which cats become infected remain uncertain. The objective of this work was to determine the prevalence of T. cruzi infection in domestic cats from an urban area of tropical Mexico by serological and molecular methods and evaluate associated risk factors. A total of 220 domestic cats from Merida Yucatan, Mexico, were studied. Animals older than 3 months were blood sampled. Serum and DNA were obtained. Specific T. cruzi IgG antibodies were detected using a commercial indirect ELISA with an anti‐cat antibody HRP labelled. Positive cases were confirmed by Western blot (WB). Polymerase chain reaction (PCR) was also performed using the primers TC1 and TC2. From the 220 cats, 8.6% had antibodies against T. cruzi using ELISA test and later confirmed by WB. In 75 cats (34%), the sequence of ADNk of T. cruzi was amplified. The bad–regular body condition was the only risk factor associated with PCR positive to T.cruzi (P < 0.001). In Mexico, there are no previous epidemiological reports that demonstrate the importance of the cat as a reservoir of T. cruzi. Few individuals were identified with a serological response because they were probably at an early stage of infection or antibodies were not detected because they could be immunocompromised (FIV, FeLV or others). It is necessary to monitor PCR‐positive patients and conduct further studies for better understanding of the epidemiology and pathogenesis of Chagas disease in domestic cats.

Anti-trypanosomal activity of (8-hydroxymethylen)-trieicosanyl acetate against infective forms of Trypanosoma cruzi.

The activity of an (8-hydroxymethylen)-trieicosanyl acetate compound obtained from chloroform extracts of Senna villosa (Mill.) H.S. Irwin & Barneby (Leguminosae) against Trypanosoma cruzi was evaluated in vivo. Oral doses of 2.1, 8.4, and 33.6 µg/g were tested for 28 days in BALB/c mice infected with T. cruzi. Reduced parasitemia levels of 70.5%, 73.8%, and 80.9%, respectively, were observed. A significant reduction in amastigote nests was detected in the cardiac tissue of treated animals at doses of 8.4 and 33.6 µg/g. The LD50 of (8-hydroxymethylen)-trieicosanyl acetate was impossible to determine because none of the animals died, even at oral doses of 5000 µg/g; consequently, it was impossible to determine the acute oral toxicity in vivo.

Parasitic Zoonoses in Humans and Their Dogs from a Rural Community of Tropical Mexico

A cross-sectional study was made on 89 inhabitants and their dogs from a rural community of Yucatan, Mexico, to determine the serological prevalence of some zoonotic parasitic agents. Samples were taken to monitor the presence and intensity of infection with gastrointestinal parasites in dogs. In humans, the serological prevalence of T. canis, T. gondii, and T. spiralis was 29.2%, 91.0%, and 6.7%, respectively. No associations were found between positive cases and studied variables. From the total of blood samples taken from dogs, 87 (97.6%) were seropositive to T. gondii; only 52 viable fecal samples were collected from dogs of which 46.2% had the presence of gastrointestinal parasites with low to moderate intensity; from those, 12% had the presence of T. canis. This study demonstrates the presence of the studied zoonotic agents in the area particularly T. gondii which suggest a common source of infection in dogs and humans and a high number of oocyts present in the environment. Preventive measures must be designed towards good prophylactic practices in domestic and backyard animals (T. canis and T. spiralis). Contaminated sources with T. gondii (food and water) should be further investigated in order to design effective control measures.