Clinical and laboratory features of rickettsioses in Yucatan, Mexico
Karla Dzul-Rosado1, Candi Panti-Balam1, Dayana Lavín-Sánchez1
1Dr. Hideyo Noguchi Regional Research Center, Emerging and Re-emerging Disease Laboratory, Avenida Itzáes, No 490 x Calle 59, Col. Centro, CP 97000, Autonomous University of Yucatan, Merida, Yucatan 97000, Mexico.
Abstract:
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.
Insights
Rickettsial diseases, including typhus and spotted fever groups, are endemic in Yucatan, Mexico. Molecular diagnostics confirmed 22.7% of cases, highlighting the need for increased disease awareness and prevention strategies.
Area of Science:
- Medical Microbiology
- Infectious Diseases
- Molecular Diagnostics
Background:
- Rickettsia species cause a spectrum of human diseases, from mild to fatal febrile illnesses.
- Classification into four groups is based on phylogeny, clinical symptoms, and antigenic properties.
- Rickettsial infections depend on the specific species, host factors, and prompt medical intervention.
Purpose of the Study:
- To characterize rickettsial diseases in Yucatan, Mexico.
- To analyze clinical and laboratory features of confirmed Rickettsia infections.
- To evaluate the prevalence and distribution of Rickettsia species.
Main Methods:
- Retrospective analysis of 427 patient medical records from 2015-2018.
- Molecular diagnosis using genus-specific PCR for rickettsial 17kDa and ompB genes.
- Purification and sequencing of PCR amplicons for species identification.
Main Results:
- 22.7% (97/427) of samples tested positive for Rickettsia species.
- The majority of cases (75.2%) were identified in Merida during autumn.
- Pediatric (5-14 years) and adult (25-49 years) age groups showed the highest frequencies; six pediatric deaths occurred.
- Typhus group (60.8%) and Spotted Fever Group (32.9%) rickettsioses were identified.
Conclusions:
- Rickettsia species, including typhus and spotted fever groups, are endemic in Yucatan.
- Molecular identification enhances diagnostic accuracy and treatment outcomes.
- Public health initiatives focusing on Rickettsia disease awareness and prevention are crucial.
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