Presence of Toxoplasma gondii in Drinking Water from an Endemic Region in Southern Mexico.

Toxoplasmosis can be acquired through the ingestion of contaminated drinking water with oocysts of Toxoplasma gondii, highly resistant to the routinely disinfection processes; based on chlorination commonly used in the water supply industry. The aim of this study was to determine the presence of T. gondii DNA in samples of public drinking water from an endemic region of southern Mexico. In total 74 samples of water (5 L each) were collected from the three well fields (I, II, and III) and 71 independent wells, distributing public drinking water to the city of Merida Yucatan, after passing through the chlorination process. Water samples were filtered and concentrated by a sucrose solution, then DNA was extracted and evaluated through a nested-PCR (nPCR) specific for T. gondii. Positive samples were detected in 5.4% (4/74) of the water samples. This is the first report of the presence of T. gondii DNA in public drinking water from a large city in southern Mexico, where their consumption without any postpurification treatment could pose a risk for acquiring the infection in the urban population.

Presence of Toxoplasma gondii in Pork Intended for Human Consumption in Tropical Southern Mexico.

BACKGROUND: Toxoplasmosis is caused by the protozoon Toxoplasma gondii, which is one of the most widespread parasites that infect animals and humans worldwide. One of the main routes of infection for humans is through the consumption of infected meat containing bradyzoites in tissue cysts. Pork is one of the foremost meat types associated with outbreaks of acute toxoplasmosis in humans. MATERIALS AND METHODS: Sixty blood samples were collected from finished pigs at slaughter and their sera was evaluated by an indirect-IgG ELISA. Matched muscle samples were obtained from the tongue and loin. Whole blood and tissue samples were evaluated to search for T. gondii DNA using a nested-polymerase chain reaction. RESULTS: Seroprevalence of T. gondii was 96.6% (58/60) of sampled pigs. Meanwhile, T. gondii DNA was present in 23.21% of tongue tissue samples (13/56), 7% of loin tissues (4/57), and 0% in blood samples (0/44), respectively. Two pigs were serologically indeterminate. CONCLUSION: This is the first report of the presence of T. gondii DNA in tissue samples obtained from finalized pigs. Results from the present study suggest a high exposure to T. gondii in pigs intended for human consumption from the tropical region of Mexico. Thus, the consumption of some undercooked pork meat meals typical from the southern region of Mexico could represent a significant risk for acquiring infection for the human population.

Combined use of real-time PCR and serological techniques for improved surveillance of chronic and acute American trypanosomiasis in dogs and their owners from an endemic rural area of Neotropical Mexico.

In this study, the prevalence of T. cruzi infection was estimated in dogs and their owners from a rural community in Mexico using serological techniques for chronic infection cases, qPCR for acute phase cases, and a combination of both techniques to detect chronic and acute infections. Eighty-nine blood samples were collected from owners and their dogs for obtaining serum and parasite DNA. Prevalence was calculated using (i) positive cases detected in a serological test (ELISA and Western blot), (ii) positive cases detected in a qPCR test, and (iii) positive cases detected by both techniques. Sensitivity, specificity, and predictive values were determined individually for serology, qPCR and for both techniques used simultaneously. The prevalence observed varied: for serology, 25.8% of the dogs and 7.9% of the owners were seropositive, while for qPCR 29.2% of the dogs and 10.1% of the owners were identified as positive. Combination of serological and molecular techniques resulted in a prevalence of 38.2% for dogs and 12.4% for their owners. The sensitivity, specificity and predictive values calculated for both techniques improved when both techniques were used simultaneously (sensitivity of 92.4% and specificity of 100% for infected dogs and sensitivity of 93.4% and specificity of 100% for infected owners). Combined use of serological tests and qPCR allowed identifying a greater number of positive cases in dogs and their owners. This strategy may help implement adequate and timely epidemiological surveillance of American trypanosomiasis in order to prevent the appearance of new cases of Trypanosoma cruzi infections in endemic zones.

Quantification of Osteoprotegerin Plasma Levels in Patients with Periodontitis.

OBJECTIVE: Periodontitis (POD) is an infectious process directed at the structures supporting the teeth. Destruction of alveolar bone is considered one of the main causes of tooth loss in humans and is mediated by the host immune response. Osteoprotegerin (OPG), a protein that inhibits bone resorption by binding to the RANK ligand (RANKL), prevents osteoclastic differentiation. The aim of the study was to determine the plasma levels of OPG in patients with POD. METHODS: a case-control study with forty-nine patients with POD and 49 healthy controls were included in the study. OPG levels were determined by an ELISA test in plasma samples. RESULTS: OPG values (1.6203 ng/mL) were higher in the POD group compared with control group (1.2824 ng/mL). Among the studied groups, we detected significant differences in age, glycosylated haemoglobin (HbA1C), and plasma concentration of OPG (p < 0.05). CONCLUSION: plasma OPG levels are associated with bone formation and destruction processes, suggesting that OPG acts in a protective manner.

Screening of Zoonotic Parasites in Playground Sandboxes of Public Parks from Subtropical Mexico.

The pathological agents Toxoplasma gondii, Ancylostoma caninum, and Toxocara canis are widely distributed zoonotic parasites with high prevalence in tropical and subtropical regions of the world. The aim of the present study was to determine the presence of DNA from these parasites in sand samples from the sand playgrounds in the southeastern region of Mexico. Samples of sand were collected from 68 playgrounds in public parks in the city of Merida, Yucatan, which is the main urban area in the southeast of Mexico. The samples were examined using nested PCR to detect the SAG1 gene from Toxoplasma gondii, and endpoint PCR for the amplification of ITS-2 and rRNA-ITS2 genes from Toxocara canis and Ancylostoma caninum, respectively. The presence of T. gondii DNA was detected in 11.8% (8/68) samples, DNA from A. caninum and T. canis was not detected. Results indicate that playgrounds from the studied sandboxes are contaminated with T. gondii oocysts and may represent a risk of infection for people in contact with the sand, especially for preschoolers.

Toxoplasma gondii in Captive Wild Felids of Mexico: Its Frequency and Capability to Eliminate Oocysts.

There is little information about Toxoplasma gondii in wild felids, even when these species have been associated with cases of toxoplasmosis in humans. In this study, samples of serum and whole blood were collected from 42 felids from 10 different species, in 4 Mexican zoos. Stool samples from 36 animals were also collected, corresponding to 82% of the felids included in the study. Stool samples were used for the search of oocysts by light field microscopy and PCR. Serum samples were analyzed by indirect immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA) and indirect fluorescent antibody test (IFAT). DNA samples were purified from whole blood and stool for the amplification of a fragment of the SAG1 gene of T. gondii by a nested PCR (nPCR). The seroprevalence of IgG anti-T. gondii-specific antibodies by means of the ELISA was 100% (42/42) and 52.4% (22/42) by IFAT. The titers obtained varied from 1:80 to 1:2560. DNA of T. gondii was detected in 9.5% (4/42) of the blood samples by using nPCR. No oocysts were observed in the stool samples analyzed by light field microscopy. However, the DNA of the parasite was identified in 14.3% (5/35) of the stool samples evaluated. These results indicate a high prevalence of T. gondii in the studied populations of wild felids in captivity, with evidence of parasitemia and elimination of few oocysts even in adult hosts.

Frequency of Trypanosoma cruzi Infection in Synanthropic and Wild Rodents Captured in a Rural Community in Southeast of Mexico.

The protozoan parasite Trypanosoma cruzi is the causative agent of the Chagas disease, which is endemic in southeastern Mexico and is transmitted by the vector Triatoma dimidiata (triatomide). T. cruzi infect a great variety of domestic and wild mammals; rodents are considered one of the most important reservoirs of the parasite in the transmission cycles of T. cruzi. The objective of this study was to determine the frequency of T. cruzi infection and to determine the parasitic load in synanthropic and wild rodents from the rural community of southern Mexico. A total of 41 blood samples and 68 heart tissue samples were collected from various species of synanthropic (n= 48 in 2 species) and wild rodents (n= 35 in 5 species). DNA was extracted from samples to detect the presence of T. cruzi through quantitative PCR (qPCR). T. cruzi DNA was detected in the 9.75% of the blood samples of the synanthropic species (4/41) (14.28%) for Rattus rattus samples and 25% for Ototylomys phyllotis samples, with an average of parasitic load of 4.80 ± 1.17 parasites/µL. In the case of heart tissue samples, 10.29% were positive for T. cruzi (7/68) (8.7% for Rattus rattus, 40% for Peromyscus yucatanicus, and 42.8% for Ototylomys phyllotis) with an average parasite load of 3.15 ± 1.98 eq-parasites/mg. The active and chronic infection of T. cruzi in synanthropic or wild rodents of the rural community of southern Mexico evidences the natural infection in these reservoirs which contribute to maintaining the agent in the wild and domestic environments and can represent a risk of infection for the human population when the vector is present.

Toxoplasmosis in Mexico: epidemiological situation in humans and animals.

Toxoplasmosis is a parasitic disease widely distributed throughout the world, infecting a wide variety of animal species including humans. In Mexico, this parasite has been detected in different parts of the country, particularly in the tropical areas where the parasite can remain infective for long periods of time due to the environmental conditions (i.e. high temperature and humidity over the whole year). Several epidemiological studies have been conducted in both human and animal populations, but despite the wide distribution of the agent in the country, there is a significant lack of knowledge on the parasite transmission, treatment alternatives and control measures. The lack of feral cat populations and control measures in sites of meat production for human consumption are playing a role that has led to the wide spread of the disease in the country, particularly in tropical areas of Southeastern Mexico. For these reasons, this manuscript aims to review the published information on relevant epidemiological aspects of infection with T. gondii in humans and animals from Mexico.

Toxoplasmosis i Mexico: epidemiological situation in humans and animals / Toxoplasmosis en México: situación epidemiológica en humanos y animales

Toxoplasmosis is a parasitic disease widely distributed throughout the world, infecting a wide variety of animal species including humans. In Mexico, this parasite has been detected in different parts of the country, particularly in the tropical areas where the parasite can remain infective for long periods of time due to the environmental conditions (i.e. high temperature and humidity over the whole year). Several epidemiological studies have been conducted in both human and animal populations, but despite the wide distribution of the agent in the country, there is a significant lack of knowledge on the parasite transmission, treatment alternatives and control measures. The lack of feral cat populations and control measures in sites of meat production for human consumption are playing a role that has led to the wide spread of the disease in the country, particularly in tropical areas of Southeastern Mexico. For these reasons, this manuscript aims to review the published information on relevant epidemiological aspects of infection with T. gondii in humans and animals from Mexico.

La toxoplasmosis es una enfermedad parasitaria ampliamente distribuida en todo el mundo y puede infectar a una gran diversidad de especies animales y a los humanos. En México, esta parasitosis ha sido detectada en diferentes partes del país, en particular en las zonas tropicales en donde debido a las condiciones ambientales (ej. alta temperatura y humedad a lo largo todo el año), el parásito puede mantenerse infectante por largos períodos de tiempo en el medio ambiente. Se han realizado diversos estudios epidemiológicos tanto en poblaciones humanas como en animales y se observa que a pesar de la amplia distribución y buen establecimiento del agente en el país, existe un importante desconocimiento desde la epidemiologia, tratamientos alternativos o las medidas de control. La falta de control de las poblaciones ferales de felinos así como el establecimiento de medidas de control en unidades de producción de carne de diferentes especies para consumo humano están jugando un papel primordial que ha favorecido la amplia diseminación de la enfermedad en el país, principalmente en las zonas tropicales del sureste mexicano. Por lo que este manuscrito tiene como objetivo revisar la información publicada hasta ahora que nos describe aspectos epidemiológicos relevantes de la infección por T. gondii en humanos y animales de México.

Efficacy of a topical combination of fipronil-permethrin against Rhodnius prolixus on dogs

A controlled clinical trial was carried out to assess the mortality and repellency of a new topical combination of f ipronil-permethrin (Effitix® Virbac, Mexico) against Rhodnius prolixus in dogs. Ten medium-size dogs (10−15kg) with short hair were used. The dogs were exposed to 8 adult triatomines once weekly for 7 weeks. On the control day (D0), the dogs were exposed to the insects without treatment. On D7, the dogs were immediately treated with a spot-on 2.2ml pipette containing 134mg of fipronil and 1200mg permethrin after exposure to the insects. The dose was repeated after 4 weeks following the manufacturer's instructions. Repellency at D0 was, 0 % and the insects had a high blood content. After 12h post-contact, repellency was 86.3 % and slowly decrease though D21 and D28. On D7, none of the insects survived after 3h of feeding on the treated dogs. On D14, D35 and D42, all insects died within 12h post-feeding, whereas no mortality was observed in the control D0 (P < 0.05). The results of this study indicated that administration of the product following the manufacturer's instructions was efficacious at inducing rapid mortality of R. prolixus and therefore could be useful to prevent the transmission of American trypanosomiasis in dogs.