RESUMEN
This study aimed to analyze how meteorological conditions such as temperature, humidity and rainfall can affect the spread of COVID-19 in five Brazilian (São Paulo, Rio de Janeiro, Brasília, Manaus and Fortaleza) cities. The cities selected were those with the largest number of confirmed cases considering data of April 13. Variables such as number of cumulative cases, new daily cases and contamination rate were employed for this study. Our results showed that higher mean temperatures and average relative humidity favored the COVID-19 transmission, differently from reports from coldest countries or periods of time under cool temperatures. Thus, considering the results obtained, intersectoral policies and actions are necessary, mainly in cities where the contamination rate is increasing rapidly. Thus, prevention and protection measures should be adopted in these cities aiming to reduce transmission and the possible collapse of the health system.
Asunto(s)
Betacoronavirus , Infecciones por Coronavirus , Pandemias , Neumonía Viral , Clima Tropical , Brasil , COVID-19 , Ciudades , Humanos , Humedad , SARS-CoV-2 , TemperaturaRESUMEN
Naturally exposed dogs of an endemic area were vaccinated with the fucose mannose ligand (FML) antigen of Leishmania donovani in formulation with QuilA saponin. The 100% of vaccinees were seropositive to FML and showed intradermal reaction to L. donovani lysate, 2 months after vaccination. The absorbency values and size of intradermal reaction were both significantly higher in vaccinees than in controls along a 3.5 years period (ANOVA, P<0.0001). The 25% of the control animals (two dogs on the first year and six dogs on the fourth year, respectively) and 5% of the vaccinees (one dog during the fourth year) developed clinical and fatal disease until the end of experiment. This difference was significant (chi(2)=3.93, P<0.05). This means that 95% protection against kala-azar was achieved in vaccinees, after FML-QuilA vaccination (80% of vaccine efficacy (VE)). Leishmania infection was also confirmed, 3.5 years after vaccination, in saline controls that showed positive polymerase chain reaction (PCR) for Leishmania DNA and FML-serology with no intradermal reaction. Higher seropositivities and intradermal reactions with no Leishmanial DNA were detected in vaccinees. The FML-QuilA vaccine induced a significant, long lasting and strong protective effect against canine kala-azar in the field.
Asunto(s)
Enfermedades de los Perros/prevención & control , Leishmaniasis Visceral/veterinaria , Vacunas Antiprotozoos/administración & dosificación , Adyuvantes Inmunológicos/administración & dosificación , Animales , Anticuerpos Antiprotozoarios/sangre , Brasil , ADN Protozoario/genética , ADN Protozoario/aislamiento & purificación , Enfermedades de los Perros/inmunología , Enfermedades de los Perros/parasitología , Perros , Humanos , Inmunidad Celular , Lectinas/administración & dosificación , Lectinas/inmunología , Leishmania donovani/genética , Leishmania donovani/inmunología , Leishmaniasis Visceral/inmunología , Leishmaniasis Visceral/parasitología , Leishmaniasis Visceral/prevención & control , Proteínas Protozoarias/administración & dosificación , Proteínas Protozoarias/inmunología , Saponinas de Quillaja , Saponinas/administración & dosificaciónRESUMEN
Human visceral leishmaniasis (kala-azar) transmitted by blood transfusion has been described in previous reports. Seroprevalence of antibodies to Leishmania donovani was shown to be related to prior blood transfusions in multiply transfused hemodialysis patients in Natal, Rio Grande do Norte, Brazil. In this study, a possible correlation between seroreactivity and the presence of L. donovani DNA was investigated in asymptomatic healthy blood donors. Sera were tested using the fucose mannose ligand (FML) ELISA, which was shown to have a sensitivity of 100%, a specificity of 96-100%, reliability, and diagnostic and prognostic potential for the detection of human and canine kala-azar, respectively. Leishmanial DNA was assessed by the polymerase chain reaction (PCR) and dot-blot hybridization techniques in blood and bone marrow samples. Among 21 FML-seroreactive asymptomatic blood donors, 5 (24%) were positive by the PCR and 9 (43%) were positive in a dot-blot assay of blood samples, showing a significant correlation (chi2 = 14.24, P < 0.01). No Leishmania DNA was detected in 20 FML non-reactive blood donors. Our results point to the need for control of transmission of kala-azar by blood transfusion in areas endemic for this disease.
Asunto(s)
Donantes de Sangre , Leishmania donovani/aislamiento & purificación , Leishmaniasis Visceral/diagnóstico , Animales , Anticuerpos Antiprotozoarios/análisis , Anticuerpos Antiprotozoarios/sangre , Médula Ósea/parasitología , Brasil/epidemiología , Cartilla de ADN/química , ADN Protozoario/sangre , ADN Protozoario/química , ADN Protozoario/aislamiento & purificación , Electroforesis en Gel de Agar , Ensayo de Inmunoadsorción Enzimática , Humanos , Lectinas/sangre , Leishmania donovani/genética , Leishmania donovani/inmunología , Leishmaniasis Visceral/sangre , Leishmaniasis Visceral/epidemiología , Hibridación de Ácido Nucleico , Reacción en Cadena de la Polimerasa , Sensibilidad y Especificidad , Estudios Seroepidemiológicos , Reacción a la TransfusiónRESUMEN
Protection against canine kala-azar was investigated in naturally exposed dogs of an endemic area, vaccinated with the fucose mannose ligand (FML)-vaccine of Leishmania donovani. A total of 97% of vaccinees were seropositive to FML and 100% showed intradermal reaction to L. donovani lysate, 7 months after vaccination. The absorbency values and size of intradermal reaction were both significantly higher in vaccinees than in controls (ANOVA, P<0.0001). After 2 years, 92% (chi(2)=6.996; P<0.0025) protection was achieved: only 8% of vaccinees showed mild signs of kala-azar with no deaths while 33% of controls developed clinical or fatal disease. The FML-vaccine induced a significant, long-lasting and strong protective effect against canine kala-azar in the field.
Asunto(s)
Lectinas/inmunología , Leishmania donovani/inmunología , Leishmaniasis Visceral/prevención & control , Vacunas Antiprotozoos/inmunología , Animales , Brasil , Perros , Vacunación , ZoonosisRESUMEN
The fucose-mannose ligand (FML)-ELISA assay showed a sensitivity of 100% and a specificity of 100% in diagnosis of canine visceral leishmaniasis (CVL) (kala-azar) in sera from naturally infected dogs from São Gonçalo do Amaranto, Rio Grande de Norte, Brazil. The overall prevalence of antibodies to Leishmania in the endemic area was 23% (79 of 343). Seroreactivity detected by a Leishmania chagasi immunofluorescent (IF) assay was much lower (2.9%) and similar to the percentage of dogs with kala-azar symptoms (2.6%). Twenty-one of 21 asymptomatic, FML-seropositive animals died of kala-azar in a period ranging from 0 to 6 months after diagnosis. The predictive value was 100% for the FML-ELISA, 43% for an L. mexicana ELISA, and 24% for the L. mexicana and L. chagasi IF assays, respectively. In experimentally infected dogs, all assays detected seropositivity between 90 and 120 days after infection. Since the current strategy for control of CVL is based on detection and destruction of infected dogs, the highly predictive, sensitive, and specific FML-ELISA represents a useful tool for field control of the disease.
Asunto(s)
Lectinas , Leishmaniasis Visceral/diagnóstico , Animales , Antígenos de Protozoos/aislamiento & purificación , Brasil , Perros , Ensayo de Inmunoadsorción Enzimática/métodos , Técnica del Anticuerpo Fluorescente , Lectinas/sangre , Leishmania mexicana/inmunología , Leishmania mexicana/aislamiento & purificación , Leishmaniasis Visceral/sangre , Leishmaniasis Visceral/fisiopatología , Valor Predictivo de las Pruebas , Pronóstico , Sensibilidad y EspecificidadRESUMEN
The prevalence of anti-Leishmania donovani antibodies was investigated in 1,500 Brazilian blood donors and multiply transfused hemodialysis patients. Sera were tested using the fucose-mannose ligand (FML) ELISA, which was shown to have 100% sensitivity and 96% specificity for kala-azar. Among 1,194 volunteer blood donors, seroreactivity was 9%, increasing to 25% in a periurban kala-azar focus. However, higher positivity (37%) was found in multiply transfused hemodialysis patients from Natal, where kala-azar is constantly present in low numbers (endemic), with sporadic outbreaks in localized regions (endemic and epidemic). Risk factors included blood transfusion, which was significantly associated with the presence of anti-Leishmania antibodies (chi2 = 8.567, P < 0.005), but did not include potential exposure to sandfly bites (chi2 = 0.033, P > 0.1). The prevalence significantly decreased to 7% in hemodialysis patients from Rio de Janeiro, where kala-azar is only occasionally seen, and was 0% in patients undergoing continuous ambulatorial peritoneal dialysis. The prospective analysis of 27 FML-seroreactive donors from Natal revealed amastigotes of Leishmania in the bone marrow of one subject while four had clinical complaints, including splenomegaly and hepatosplenomegaly. Our results point to the need for control of blood transfusion as a possible route for transmission of kala-azar in endemic areas.