Rickettsia typhi and R. felis are the etiological agents of murine typhus and flea-borne spotted fever, respectively. Both are emerging acute febrile zoonotic diseases for which fleas are vectors; they also have similar clinical characteristics and global distribution. In 2005, we identified the circulation of murine typhus in 6 towns within the mountainous coffee-growing area north of Caldas, Colombia. We now report the specific seroprevalence against R. typhi and R. felis, and associated risk factors in 7 towns of this province. The combined seroprevalence against the 2 flea-borne rickettsioses is the highest yet reported in the literature: 71.7% (17.8% for R. felis, 25.2% for R. typhi, and 28.7% for both). We also report a prospective analysis of 26 patients with a febrile illness compatible with rickettsioses, including murine typhus; 9 of these patients had a rickettsiosis. This supports our sero-epidemiological results and highlights the diagnostic complexity of febrile syndromes in this region.

Abstract. Rickettsioses caused by Rickettsia felis are an emergent global threat. Historically, the northern region of the province of Caldas in Colombia has reported murine typhus cases, and recently, serological studies confirmed high seroprevalence for both R. felis and R. typhi. In the present study, fleas from seven municipalities were collected from dogs, cats, and mice. DNA was extracted and amplified by polymerase chain reaction (PCR) to identify gltA, ompB, and 17kD genes. Positive samples were sequenced to identify the species of Rickettsia. Of 1,341 fleas, Ctenocephalides felis was the most prevalent (76.7%). Positive PCR results in the three genes were evidenced in C. felis (minimum infection rates; 5.3%), C. canis (9.2%), and Pulex irritans (10.0%). Basic Local Alignment Search Tool (BLAST) analyses of sequences showed high identity values ( 98%) with R. felis, and all were highly related by phylogenetic analyses. This work shows the first detection of R. felis in fleas collected from animals in Colombia.

BackgroundHuman Pegivirus (HPgV) may have a beneficial effect on HIV disease progression in co-infected patients; however, the virologic characteristics of this infection are not well defined. In this study, we determined HPgV viremia prevalence in Mexico and provide new insights to understand HPgV infection and HPgV/HIV co-infection.MethodsWe analyzed and quantified 7,890 serum samples for HPgV viremia by One-Step RT-Real-Time PCR, 6,484 from healthy blood donors and 1,406 from HIV-infected patients. Data on HIV progression were obtained from patients’ records. HPgV genotyping was performed in 445 samples by nested PCR of the 5’URT region. Finite Mixture Models were used to identify clustering patterns of HPgV viremia in blood donors and co-infected antiretroviral (ART)-naïve patients.ResultsHPgV was detected in 2.98% of blood donors and 33% of HIV patients, with a wide range of viral loads. The most prevalent genotypes were 3 (58.6%)and 2 (33.7%). HPgV viral loads from healthy blood donors and HPgV/HIV+ ART-naïve co-infected patients were clustered into two component distributions, low and high, with a cut-off point of 5.07log10 and 5.06log10, respectively. High HPgV viremia was associated with improved surrogate markers of HIV infection, independent of the estimated duration of HIV infection or HIV treatment.ConclusionsHPgV prevalence in Mexico was similar to that reported for other countries. The prevalent genotypes could be related to Mexico’s geographic location and ethnicity, since genotype 2 is frequent in the United States and Europe and genotype 3 in Asia and Amerindian populations. HPgV viral load demonstrated two patterns of replication, low and high. The more pronounced beneficial response observed in co-infected patients with high HPgV viremia may explain discrepancies found between other studies. Mechanisms explaining high and low HPgV replication should be explored to determine whether the persistently elevated replication depends on host or viral factors.

Introducción: Las rickettsiosis son enfermedades zoonóticas, algunos artrópodos cumplen el papel de vectores. la inespecificidad de los síntomas hace que su diagnóstico clínico sea difícil. La Inmunofluorescencia indirecta (IFI), se usa en el diagnóstico. En Colombia, a partir del 2003, ha resurgido el interés por realizar estudios en búsqueda de dicha patología. Objetivo: Caracterizar epidemiológicamente los casos humanos compatibles con rickettsiosis que consultan a las instituciones de salud del departamento de Caldas-Colombia, durante el periodo de tiempo comprendido en los años 2016- 2019. Métodos: Se realizó un estudio de diseño cuantitativo, observacional, descriptivo, con una muestra no probabilística constituida por 175 pacientes con síntomas compatibles con rickettsiosis que consultaron en diferentes municipios de Caldas- Colombia; se les realizo IFI para la detección de anticuerpos en fase aguda y convaleciente frente a Rickettsia rickettsii, Rickettsia typhi y Rickettsia felis. Resultados: El promedio de edad fue de 31 años, Los municipios con mayor proporción de casos son Belalcázar, Chinchiná, Filadelfia, La Dorada, La Merced, Manizales. El 66 % tenían mascotas, frecuentemente perros; el 12% manifiestan picaduras por artrópodos. Los signos y síntomas más frecuentes fueron: cefalea 69,7%, artromialgia 60%, fiebre 58,2%. La seroprevalencia por IgG fue del 60%, 47,9% y 24% para R. rickettsii, R. typhi y R. felis respectivamente. Cinco pacientes presentaron seroconversión frente a R. rickettsii y R. felis y uno frente a R. typhi. Conclusión: Hay evidencia de enfermedad rickettsial en el departamento, predominantemente asociada con rickettsias del grupo de las fiebres manchadas.

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