Impacto indirecto de COVID-19 en las tasas de incidencia de enfermedades transmitidas por vector en México / Indirect impact of COVID-19 on the incidence rates of vector-borne diseases in Mexico

Resumen Introducción: La distribución espacial y temporal de la infección por SARS-CoV-2 sobrepasa las áreas endémicas de enfermedades transmitidas por vector (ETV), cuya vigilancia en México ha cambiado sustancialmente a partir del primer caso confirmado de COVID-19. Objetivos: Estimar y comparar las tasas de incidencia de las ETV antes y después de la introducción del SARS-CoV-2 en México. Métodos: Estudio retrospectivo de casos de ETV de 2014 a 2021. Las tasas de incidencia de cada ETV en el periodo previo (2014-2019) y posterior (2020-2021) a la introducción del SARS-CoV-2 en México fueron calculadas y comparadas. Resultados: Antes de la introducción del SARS-CoV-2, las tasas de incidencia de las ETV fueron altas y posterior a la introducción del coronavirus hubo un descenso en los índices epidemiológicos; sin embargo, solo se identificó diferencia estadística significativa en la tasa de incidencia de la malaria (p ≤ 0.05) y otras rickettsias (p ≤ 0.05). Conclusiones: Algunas medidas para reducir los casos de COVID-19, como el distanciamiento social, el confinamiento domiciliario, la reducción en el aforo en el transporte público y el trabajo en casa, probablemente contribuyeron a disminuir temporalmente el número de casos de las ETV; sin embargo, puede haber rebrote de las ETV en el futuro cercano.

Abstract Introduction: SARS-CoV-2 infection spatial and temporal distribution overlaps with endemic areas of vector-borne diseases (VBD), whose surveillance in Mexico has substantially changed since the first COVID-19 confirmed case. Objectives: To estimate and compare the incidence rates of VBDs before and after the introduction of SARS-CoV-2 in Mexico. Methods: Retrospective study of VBD cases from 2014 to 2021. The incidence rates of each VBD in the period before (2014-2019) and after (2020-2021) the introduction of SARS-CoV-2 in Mexico were calculated and compared. Results: Before the introduction of SARS-CoV-2, the incidence rates of VBDs were high and after the introduction of coronavirus there was a decrease in epidemiological indices; however, there was only statistically significant difference in the incidence rate of malaria (p ≤ 0.05) and other rickettsiae (p ≤ 0.05). Conclusions: Some measures to reduce COVID-19 cases, such as social distancing, home confinement, reductions in public transport and working at home (home office), probably temporarily decreased the number of VBD cases; however, there may be a resurgence of VBDs in the near future.

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.

Quantification of sphingosine-1-phosphate (S1P) in patients with periodontitis stage II grade B / Cuantificación de esfingosina 1 fosfato en pacientes con periodontitis estadío II grado B

Abstract The aim of this study was the quantification of Sphingosine-1-phosphate (S1P) in periodontal pockets of patients with periodontitis. This is an observational, descriptive, case-control study. Thirty subjects were selected: 15 controls and 15 cases. A periodontal study was conducted following the parameters of AAP 2017 for the diagnosis of periodontal diseases. A sample of saliva and gingival crevicular fluid was obtained from each subject and then analyzed with the Human S1P Elisa kit (MyBioSource #MBS2516132) accordingly to the manufacturer's instructions, in order to verify the presence of S1P and quantify it´s concentration when founded. Results showed a significant difference (p=0.05) between cases and controls. In the case of saliva samples, the concentration of S1P was higher than the ones found in the control group (72.94 ng/mL and 45.12 ng/mL). For GCF, a higher amount of S1P was found in patients with POD (20.09 ng/mL and 15.20 ng/mL). This work raises a possible route of bone metabolism, inflammatory process, and identification of periodontitis through oral quantification of S1P, however, future studies are needed.

Resumen El propósito de este estudio fue la cuantificación de Esfingosina-1-Fosfato (S1P) en las bolsas periodontales de pacientes con periodontitis. Estudio observacional, descriptivo de casos y controles. 30 sujetos fueron seleccionados de los cuales 15 controles y 15 casos. Se realizó un estudio periodontal completo siguiendo los parámetros establecidos por la AAP en 2017 para el diagnóstico de las enfermedades periodontales. Se tomaron muestras de saliva y de líquido crevicular gingival de cada sujeto estudiado y se analizaron con el ELISA kit humano para S1P (MyBiosource #MBS2516132) y de acuerdo con las instrucciones del fabricante, se realizó para cuantificar la presencia d S1P en las muestras estudiadas. Los resultados mostraron diferencia significativa (p=0.05) entre casos y controles. En el caso de las muestras de saliva, la concentración de S1P en controles fue mayor (72.94 ng/mL y 45.12 ng/mL). Para Líquido crevicular gingival, se encontró mayor cantidad de S1P en los pacientes con periodontitis (20.09 ng/mL y 15.20 ng/mL). Este estudio plantea una posible ruta de metabolismo óseo, proceso inflamatorio e identificación de la Periodontitis a través de la cuantificación oral de S1P, sin embargo se necesitan estudios futuros.

Quantification of TNF-α in Patients with Periodontitis and Type 2 Diabetes.

OBJECTIVE: The present study aimed to compare variations in quantified tumor necrosis factor-alpha (TNF-α) levels in patients with periodontitis stage 2 grade B (POD2B) and/or type 2 diabetes (T2D) and to identify any relationships between this cytokine and these diseases. METHODS: Levels of the cytokine TNF-α in gingival crevicular fluid in patients with POD2B and/or T2D were evaluated. A total of 160 subjects were distributed into four groups: those with POD2B (n=44); those with T2D (n=37); those with POD2B/T2D (n=40); and healthy subjects (n=39). Glycosylated hemoglobin (HbA1c) and blood glucose (BG) levels were quantified in each subject. Data were collected on body mass index (BMI), loss of insertion (LI), and probe depth (PD). Gingival crevicular fluid samples were collected from the most acutely affected periodontal pocket and gingival sulcus in each subject, and TNF-α was quantified by multiplex analysis. RESULTS: Kruskal Wallis tests was used to identify differences in TNF-α levels, LI, PD, BMI, BG, and HbA1c by group. Differences (p<0.001) were found for LI, PD, BG, and HbA1c. A Spearman test was used to calculate possible correlations between TNF-α levels and LI or PD identified a weak but significant negative correlation of TNF-α with LI (Rho=-0199; p=0.012), and a moderately positive correlation of LI with PD (Rho=0.509; p < 0.001). CONCLUSIONS: No variation was found between TNF-α levels and the presence of POD2B, POD2B/T2D, or T2D, suggesting the absence of any direct relationship between progression of these diseases and TNF-α levels. However, a correlation was present between low TNF-α concentrations and greater LI.

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.

Stray Dog Population in a City of Southern Mexico and Its Impact on the Contamination of Public Areas.

To assess the risk of zoonotic pathogen transmission as function of stray dog presence and health status, a cross-sectional study was carried out in a large city of southern Mexico that lacks comprehensive strategies for the control of stray canine populations. The photographic capture-recapture method was used to estimate the density of dogs/km2. In the same way, dog feces from 14 public parks of the city were collected to determine the prevalence and intensity of infection with gastrointestinal parasites. The canine population was estimated between 65 and 80 thousand dogs, with a population density of 1,081 dogs/km2, mostly males (71.4%). A high proportion of dogs (72.3%) were found to be in good body condition score (BCS 3). The person:dog ratio was 2.3. The likelihood of being in the BCS 2 category was lower in areas with a higher density of dogs. All feces collected from the parks contained eggs of intestinal parasites, most of them with a medium (42.9%) to high (35.7%) infection intensity, notably Ancylostoma caninum. It was recorded that cases with a low-intensity of GI infection showed polyparasitism (35.7%) associated with A. caninum. There is a large population of stray dogs that roam freely in the streets of Campeche city with access to sources of food, which is reflected by their good BCS, and dogs do not have access to preventive medicine programs (de-worming) and thus contaminate public parks with feces with significant parasitic egg loads of zoonotic importance.

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.

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.

American trypanosomiasis and associated risk factors in owned dogs from the major city of Yucatan, Mexico

Background The American trypanosomiasis is a zoonosis caused by the protozoaTrypanosoma cruzi (T. cruzi). The disease is widely distributed throughout the American continent, affecting a wide range of hosts, including dogs. It is present in the canine population in the State of Yucatan, Mexico. However, no significant studies in owned dogs have been performed in the metropolitan area of Merida. A transversal study was conducted in 370 owned dogs from Merida, Yucatan, Mexico.Methods A cross-sectional study including 370 dogs was performed in a major city of Yucatan, Mexico, to detect IgG antibodies against T. cruzi. A commercial ELISA test kit was used and a chi-square test used to evaluate associated risk factors; odds ratio (OR) and 95 % confidence interval (CI) were also estimated.Results The indirect ELISA and western blot (WB) tests were used to detect specific immunoglobulin G antibodies against T. cruzi in serum samples. A prevalence of 12.2 % was found; age and area of residence were statistically associated with seropositivity in dogs (p<0.05).Conclusions Results from the present study suggests the presence and abundance of the vector in urban conditions where a high number of seropositive cases ofT. cruzi cases were found.(AU)

American trypanosomiasis and associated risk factors in owned dogs from the major city of Yucatan, Mexico

Background The American trypanosomiasis is a zoonosis caused by the protozoaTrypanosoma cruzi (T. cruzi). The disease is widely distributed throughout the American continent, affecting a wide range of hosts, including dogs. It is present in the canine population in the State of Yucatan, Mexico. However, no significant studies in owned dogs have been performed in the metropolitan area of Merida. A transversal study was conducted in 370 owned dogs from Merida, Yucatan, Mexico.Methods A cross-sectional study including 370 dogs was performed in a major city of Yucatan, Mexico, to detect IgG antibodies against T. cruzi. A commercial ELISA test kit was used and a chi-square test used to evaluate associated risk factors; odds ratio (OR) and 95 % confidence interval (CI) were also estimated.Results The indirect ELISA and western blot (WB) tests were used to detect specific immunoglobulin G antibodies against T. cruzi in serum samples. A prevalence of 12.2 % was found; age and area of residence were statistically associated with seropositivity in dogs (p 0.05).Conclusions Results from the present study suggests the presence and abundance of the vector in urban conditions where a high number of seropositive cases ofT. cruzi cases were found.

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.

Assessment of the anti-protozoal activity of crude Carica papaya seed extract against Trypanosoma cruzi.

In order to determine the in vivo activity against the protozoan Trypanosoma cruzi, two doses (50 and 75 mg/kg) of a chloroform extract of Carica papaya seeds were evaluated compared with a control group of allopurinol. The activity of a mixture of the three main compounds (oleic, palmitic and stearic acids in a proportion of 45.9% of oleic acid, 24.1% of palmitic and 8.52% of stearic acid previously identified in the crude extract of C. papaya was evaluated at doses of 100, 200 and 300 mg/kg. Both doses of the extracts were orally administered for 28 days. A significant reduction (p < 0.05) in the number of blood trypomastigotes was observed in animals treated with the evaluated doses of the C. papaya extract in comparison with the positive control group (allopurinol 8.5 mg/kg). Parasitemia in animals treated with the fatty acids mixture was also significantly reduced (p < 0.05), compared to negative control animals. These results demonstrate that the fatty acids identified in the seed extracts of C. papaya (from ripe fruit) are able to reduce the number of parasites from both parasite stages, blood trypomastigote and amastigote (intracellular stage).