Clinical and laboratory features of rickettsioses in Yucatan, Mexico.

Rickettsia species are obligate intracellular bacteria that can cause mild to severe human disease. Based on phylogeny, clinical symptoms, and antigenic properties, rickettsiae are classified into four groups. Infections by these agents are characterized by clinical symptoms ranging from self-limited to severe and even fatal febrile illnesses, depending on the Rickettsia spp. involved, the patient's predisposition, and timely medical care. The present study aimed to characterize rickettsial diseases in Yucatan according to clinical and laboratory features appearing in medical records corresponding to 427 samples taken between 2015 and 2018. A study was conducted over the period 2015-2018 on 427 samples. Clinical and laboratory features were documented from the patients' medical records. For molecular diagnosis, blood was collected in 3.8 % sodium citrate as anticoagulant, and DNA was extracted. Single-step and nested PCR amplification was performed using genus-specific primers for the rickettsial 17kDa and ompB genes. The amplicons obtained were purified and sequenced. A total of 22.7 % (97/427) positive cases of Rickettsia spp. were identified by PCR from 14.15 % (15/106) of the municipalities in Yucatan. 75.2 % (73/97) of the cases were from the city of Merida during the autumn (September-December). The age groups with the highest frequency of confirmed cases were pediatric (5-14 years) (57.7 %) and adults (25-49 years) (42.2 %). There were six fatal cases in children, one associated with R. typhi and five with R. rickettsii. In non-fatal cases, 32.9 % (32/97) corresponded to the spotted fever group (SFG), and 60.8 % (59/97) to the typhus group (TG). Significant differences in signs, and laboratory data, were observed between the pediatric and adult populations. For the treatment of patients, oral and intravenous doxycycline was used in severe hospitalized cases. Typhus group and spotted fever group Rickettsiae are endemic pathological agents found in urban and rural areas of our region. Molecular identification allows for greater diagnostic accuracy and timely treatment and consequently a better prognosis. It is necessary to implement or reinforce measures focused on the dissemination of knowledge regarding rickettsial diseases and their prevention.

Molecular Detection of Leishmania (Leishmania) mexicana in Sandflies from the State of Yucatan, Mexico.

Background: Leishmaniases are a group of vector-borne zoonotic diseases of public health relevance within the tropical and subtropical regions of the world. The state of Yucatan is a vulnerable and receptive area to localized cutaneous leishmaniasis (LCL) due to its proximity to the high-transmission endemic states of Campeche and Quintana Roo. Autochthonous cases of LCL caused by Leishmania (Leishmania) mexicana have been documented in the state, showing a geographical expansion of the disease. Materials and Methods: Using CO2-supplemented Centers for Disease Control and Prevention light traps and Shannon traps, we captured anthropophilic sandflies in the surroundings of a locality with recent records of autochthonous cases of LCL. Sandflies carrying Leishmania DNA were evidenced using PCR. Results: A total of 140 Phlebotominae (Diptera: Psychodidae) females of four species were captured: Lutzomyia (Tricholateralis) cruciata (Coquillett), Psathyromyia (Psathyromyia) shannoni (Dyar), Lutzomyia (Lutzomyia) longipalpis (Lutz and Neiva), and Dampfomyia (Coromyia) deleoni (Fairchild and Hertig). Molecular results showed that 6.1% (95% confidence interval [CI] = 2.3-12.9%) of Lu. cruciata and 43.8% (95% CI = 19.8-70.1%) of Pa. shannoni showed evidence of carrying L. (L.) mexicana DNA. Conclusion: We provide evidence of anthropophilic sandflies carrying L. mexicana DNA in a municipality with recorded autochthonous cases of LCL caused by this parasite species in the state of Yucatan, suggesting the emergence of new focus of LCL in Mexico.

Report of autochthonous cases of localized cutaneous leishmaniasis caused by Leishmania (Leishmania) mexicana in vulnerable, susceptible areas of Southeastern Mexico.

Localized cutaneous leishmaniasis (LCL) is an endemic disease in several Mexican States with the main endemic areas located in the South-Southeast region of the country, where 90% of Leishmania (Leishmania) mexicana cases are registered. The Southeast region is located in the Yucatan Peninsula, including Campeche, Quintana Roo and Yucatan States. Campeche and Quintana Roo register more than 60% of the cases in the country each year, while in Yucatan the reports are of imported cases due to residents traveling to endemic areas. However, since 2015, autochthonous cases have been diagnosed by health authorities in municipalities with no previous transmission records. We aimed to identify Leishmania parasite species involved in autochthonous cases by means of the PCR technique. The present study included 13 autochthonous cases of LCL with clinical and parasitological diagnoses during 2018 and 2019 by health authorities, without specific identification of the causal agent. Tissue samples were taken by scraping the margins of active lesions and then they were spotted onto an FTATM Elute Microcard. Next, DNA was eluted and used for PCR amplification of specific Leishmania genus and L. (L.) mexicana species-specific fragments. Molecular analysis showed evidence that L. (L.) mexicana was the causal agent of LCL in 12 of the 13 patients; in one patient, PCR was not performed due to the patient's refusal to participate in the study. Identifying Leishmania species that cause LCL is necessary to define efficient treatment schemes and control strategies for the disease in vulnerable and susceptible areas of the Yucatan State's municipalities.

Report of autochthonous cases of localized cutaneous leishmaniasis caused by Leishmania (Leishmania) mexicana in vulnerable, susceptible areas of Southeastern Mexico

ABSTRACT Localized cutaneous leishmaniasis (LCL) is an endemic disease in several Mexican States with the main endemic areas located in the South-Southeast region of the country, where 90% of Leishmania (Leishmania) mexicana cases are registered. The Southeast region is located in the Yucatan Peninsula, including Campeche, Quintana Roo and Yucatan States. Campeche and Quintana Roo register more than 60% of the cases in the country each year, while in Yucatan the reports are of imported cases due to residents traveling to endemic areas. However, since 2015, autochthonous cases have been diagnosed by health authorities in municipalities with no previous transmission records. We aimed to identify Leishmania parasite species involved in autochthonous cases by means of the PCR technique. The present study included 13 autochthonous cases of LCL with clinical and parasitological diagnoses during 2018 and 2019 by health authorities, without specific identification of the causal agent. Tissue samples were taken by scraping the margins of active lesions and then they were spotted onto an FTATM Elute Microcard. Next, DNA was eluted and used for PCR amplification of specific Leishmania genus and L. (L.) mexicana species-specific fragments. Molecular analysis showed evidence that L. (L.) mexicana was the causal agent of LCL in 12 of the 13 patients; in one patient, PCR was not performed due to the patient's refusal to participate in the study. Identifying Leishmania species that cause LCL is necessary to define efficient treatment schemes and control strategies for the disease in vulnerable and susceptible areas of the Yucatan State's municipalities.

Urban ecology of hosts and vectors of Rickettsia in a rickettsiosis-endemic city of the Yucatan peninsula, Mexico.

Rickettsioses are vector-borne zoonotic diseases that occur in urban environments. Currently, they are associated with the presence of domestic and synanthropic animals, the ectoparasites that they harbor, and their local habitat. The implementation of prevention actions relies on the understanding of the local ecology of interactions between hosts, vector species, and the etiologic agents. In this context, this study aimed to explore and describe the occurrence of infected mammals and their ectoparasites in human urban dwellings, and those characteristics of urban dwellings associated to the presence of Rickettsia infected animals in groups of households where at least one human case of rickettsiosis has occurred in the previous year of the study. Briefly, blood-samples and ectoparasites from synanthropic and domestic animals, were obtained from groups of households from different areas of an urban settlement. Serologic and molecular diagnostics helped to identify Spotted Fever Group (SFG) and TG (Typhus Group) Rickettsia in animal and ectoparasite samples. A total of 99 mammals were sampled, 29 opossums (Didelphis virginiana), 13 house mice (Mus musculus), seven black rats (Rattus rattus) and 50 dogs. Infection occurrence in opossums was 8.3% of SFG, 50% for TG, and 4.2% of undetermined group. For house mice 46.2% for SFG and 30.8% were undetermined. Black rats 28.6% of SFG and 57.1% undetermined. Finally, dogs were 19.1% of SFG, 57.4% to TG, and 23.4% belonged to undetermined group. A total of 424 ectoparasites were collected from the mammals. In opossums occurred the ticks Ambyomma sp., Ornithodoros (Alecterobius) nr. talaje, and the flea Ctenocephalides felis. In dogs we found the ticks Rhipicephalus sanguineus s. l., Amblyomma sp., O. (A.) nr. talaje, and the flea Ct. felis. No ectoparasites were collected from rodents. The occurrence of infected animals was associated primarily with the material of the backyard floor, the type of sanitary system in the household, the presence of garbage in the backyard, presence of firewood storage, stored polyethylene terephthalate (PET) containers for sale to recyclers, and the store of construction supplies in the backyard. Nonetheless a generalized linear model showed that the household with a backyard with a dirt floor or other non-concrete material has more chances of harboring infected animals (RR= 1.74, 95% CI= 1.07-2.84 and RR= 1.03, 95% CI= 0.39-2.32 respectively). In contrast, when the house has a sanitary system of urban sewer system or a latrine outside de house, the chances of having infected animals decreased significantly (RR= 0.39, 95% CI= 0.12-0.94 and RR= 0.46, 95% CI= 0.03-2.22). We conclude that both SFG and TG rickettsioses occur in animals and their ectoparasites in peridomiciles of urban households were at least one human rickettsiosis case had occurred.

Personal and household factors involved in recent Rickettsia exposure in a rural population from Yucatán, Mexico.

The aim of the study was to describe the epidemiological factors associated with the risks of recent Rickettsia exposure in inhabitants of a rural population from Yucatán, Mexico. The study included 130 inhabitants from Maxcanú, Yucatán. Blood samples were collected to detect IgM and IgG antibodies against Rickettsia typhi and Rickettsia rickettsii by an indirect immunofluorescence antibody test. Additionally, nested polymerase chain reaction was performed to amplify fragments of the 17kDa and sca5 genes. Previously, an epidemiological questionnaire was applied focused on collecting information on personal and housing exposure variables related to the recent infection with Rickettsia to determine epidemiological associations. Results that exhibited a p-value < .25 were included in a generalized multinomial logistic linear model to determine the variables involved with the risk of contact or Rickettsia infection. In all, 76% (99/130) of the participants presented with immunoglobulin titres against the Rickettsia species evaluated, while rickettsial DNA was detected in 35.4% (46/130) of the participants. The association analysis with the personal exposure variables showed that the productive age group (OR = 0.32; 95% CI = 0.10-1.03) and the elders group (OR = 0.12; 95% CI = 0.01-0.83) were protective factors for recent infection with R. typhi, taking as reference the school group. The presence of a family orchard in the home (OR = 7.56; 95% CI = 1.62-35.29) was a risk factor for recent infection with R. rickettsii. Presumably, the presence of ectoparasites (OR = 2.71; 95% CI = 0.90-8.09) at home was a risk factor for recent infection with both Rickettsia species. Recent infection was demonstrated in inhabitants from Maxcanú, Yucatán. A high seropositive frequency was obtained. The results highlight the importance of the family garden and the presence of ectoparasites in the home as risk factors associated with recent infection with Rickettsia in inhabitants from Maxcanú.

Direct evidence of Rickettsia typhi infection in Rhipicephalus sanguineus ticks and their canine hosts.

Murine typhus is a rickettsiosis caused by Rickettsia typhi, whose transmission is carried out by rat fleas in urban settlements as classically known, but it also has been related to cat fleas in a sub-urban alternative cycle that has been suggested by recent reports. These studies remarks that in addition to rats, other animals like cats, opossums and dogs could be implied in the transmission of Rickettsia typhi as infected fleas obtained from serologically positive animals have been detected in samples from endemic areas. In Mexico, the higher number of murine typhus cases have been detected in the Yucatan peninsula, which includes a great southeastern region of Mexico that shows ecologic characteristics similar to the sub-urban alternative cycle recently described in Texas and California at the United States. To find out which are the particular ecologic characteristics of murine typhus transmission in this region, we analyzed blood and Rhipicephalus sanguineus ticks obtained from domestic dogs by molecular approaches, demonstrating that both samples were infected by Rickettsia typhi. Following this, we obtained isolates that were analyzed by genetic sequencing to corroborate this infection in 100% of the analyzed samples. This evidence suggests for the first time that ticks and dogs could be actively participating in the transmission of murine typhus, in a role that requires further studies for its precise description.

Caso fulminante de rickettsiosis (Rickettsia rickettsii) en una lactante del sureste de México / Fatal case of rickettsiosis in a toddler from southeastern Mexico

La fiebre manchada de las Montañas Rocosas es una enfermedad ocasionada por Rickettsia rickettsii, una bacteria transmitida por garrapatas infectadas, y que se caracteriza por fiebre, exantema, artralgias y mialgias, aunque, ocasionalmente, su presentación es inespecífica. Debido a que su evolución asemeja otras enfermedades exantemáticas, como dengue o chikungunya, su diagnóstico no es de primera intención, a pesar de que países como México tienen las características ecológicas y socioeconómicas propicias para su transmisión, con índices de mortalidad hasta de 30% en pacientes pediátricos. Esta elevada mortalidad se asocia a diagnósticos y terapia retrasados debido al desconocimiento médico acerca de la enfermedad, lo que propicia la aparición de formas atípicas y fulminantes de fiebre manchada de las Montañas Rocosas. El objetivo del presente trabajo es describir un caso clínico fulminante de fiebre manchada de las Montañas Rocosas para que sea considerada en el diagnóstico diferencial, lo cual impactaría directamente en los índices de mortalidad.

Rocky Mountain spotted fever is a disease caused by Rickettsia rickettsii, a bacteria transmitted by infected ticks. It is characterized by fever, exanthema, arthralgias and myalgias; but sometimes its clinical presentation is non specific. Due to its similarities with other exanthematic diseases like dengue or chikungunya, Rocky Mountain spotted fever is not a first line diagnosis, even though countries like Mexico show the ecologic and socioeconomic characteristics that favor its transmission, with a 30% mortality rate among pediatric patients. This mortality rate has been associated to a delayed diagnosis and therapy, due to a poor knowledge among physicians regarding this disease; this favors the occurrence of atypical and fulminant cases. The objective of this work is to describe a fulminant case of Rocky Mountain spotted fever, expecting that this disease could be later considered among the differential diagnosis which could directly impact its mortality rate.

[Fatal case of rickettsiosis in a toddler from southeastern Mexico]. / Caso fulminante de rickettsiosis (Rickettsia rickettsii) en una lactante del sureste de México.

Rocky Mountain spotted fever is a disease caused by Rickettsia rickettsii, a bacteria transmitted by infected ticks. It is characterized by fever, exanthema, arthralgias and myalgias; but sometimes its clinical presentation is non specific. Due to its similarities with other exanthematic diseases like dengue or chikungunya, Rocky Mountain spotted fever is not a first line diagnosis, even though countries like Mexico show the ecologic and socioeconomic characteristics that favor its transmission, with a 30% mortality rate among pediatric patients. This mortality rate has been associated to a delayed diagnosis and therapy, due to a poor knowledge among physicians regarding this disease; this favors the occurrence of atypical and fulminant cases. The objective of this work is to describe a fulminant case of Rocky Mountain spotted fever, expecting that this disease could be later considered among the differential diagnosis which could directly impact its mortality rate.

La fiebre manchada de las Montañas Rocosas es una enfermedad ocasionada por Rickettsia rickettsii, una bacteria transmitida por garrapatas infectadas, y que se caracteriza por fiebre, exantema, artralgias y mialgias, aunque, ocasionalmente, su presentación es inespecífica. Debido a que su evolución asemeja otras enfermedades exantemáticas, como dengue o chikungunya, su diagnóstico no es de primera intención, a pesar de que países como México tienen las características ecológicas y socioeconómicas propicias para su transmisión, con índices de mortalidad hasta de 30% en pacientes pediátricos. Esta elevada mortalidad se asocia a diagnósticos y terapia retrasados debido al desconocimiento médico acerca de la enfermedad, lo que propicia la aparición de formas atípicas y fulminantes de fiebre manchada de las Montañas Rocosas. El objetivo del presente trabajo es describir un caso clínico fulminante de fiebre manchada de las Montañas Rocosas para que sea considerada en el diagnóstico diferencial, lo cual impactaría directamente en los índices de mortalidad

Detection of Rickettsia felis in Wild Mammals from Three Municipalities in Yucatan, Mexico.

The aim of this study was to provide information of the occurrence of Rickettsia felis in wild mammals from three municipalities in Yucatan, Mexico. The reactivity of rodent serum to Rickettsia antigens was detected in 80.9% (17 of 21) samples using immunofluorescence assay. Polymerase chain reaction identified rickettsial DNA in spleens of 43.5% (10 of 23) rodents and 57.1% (4 of 7) opossums. The identification of the rickettsial DNA was confirmed as R. felis by restriction fragment length polymorphism and DNA sequencing. This study comprises the first report of R. felis detection in wild mammals in Yucatan.