Date Published: March 29, 2017
Publisher: Public Library of Science
Author(s): Zaida Herrador, Amalia Fernandez-Martinez, Diana Gomez-Barroso, Inmaculada León, Carmen Vieira, Antonio Muro, Agustín Benito, Ulrike Gertrud Munderloh.
Mediterranean spotted fever (MSF) is a zoonotic disease caused by Rickettsia conorii. In Spain, deficiencies in the official reporting result in misreporting of this disease. This study aims to describe the clinical and temporal-spatial characteristics of MSF hospitalizations between 1997 and 2014.
We performed a retrospective descriptive study using the Hospitalization Minimum Data Set (CMBD). All CMBD’s hospital discharges with ICD-9 CM code 082.1 were analyzed. Hospitalization rates were calculated and clinical characteristics were described. Spatial distribution of cases and their temporal behavior were also assessed.
A total of 4,735 hospitalizations with MSF diagnosis were recorded during the study period, out of which 62.2% were male, mean age of 48. Diabetes mellitus, alcohol dependence syndrome, and chronic liver disease occurred in 10.8%, 2.4% and 2.8% hospitalizations, respectively. The median annual hospitalization rate showed a decreasing trend from a maximum of 12.9 in 1997 to a minimum rate of 3.1 in 2014. Most admissions occurred during the summer, showing a significant annual seasonal behavior. Important regional differences were found.
Although MSF hospitalization rates have decreased considerably, it remains a public health problem due to its severity and economic impact. Therefore, it would be desirable to improve its oversight and surveillance.
Mediterranean spotted fever (MSF), or ‘boutonneuse’ fever, is caused by Rickettsia conorii and is transmitted by the brown dog tick Rhipicephalus sanguineus. This tick is relatively host-specific, and rarely feeds on people unless its preferred host—the dog—is not available . It was first described in 1910 as a disease that caused high fever and spots . In Europe, it is endemic in the Mediterranean area, where most cases are encountered in the summer when the tick vectors are highly active. In Southern Europe many cases can also occurred in spring, especially if this season is particularly warm and, thus the abundance and activity of these ticks is high .
Our study indicates that most of the MSF hospitalizations were males aged over 45 years old. In most affected countries, rickettsioses cases commonly occurred among young males . According to the CMBD database, MSF hospitalizations in Spain occurred more frequently in those above 45 years old. In a study carried out in Portugal, the highest incidence rate was observed in children (1–4 years old), though it was the elderly patients who had higher complication and mortality rates . As the CMBD database included hospitalized patients (and not those treated at ambulatory level), we might have a selection bias for the most complicated forms of this disease.
There are some aspects that need to be considered when interpreting the findings from this research. Our study only included cases of MSF requiring hospitalization, which is not equivalent to the true MSF incidence in the population. Even if the CMBD provide information from a network of hospitals that covers more than 99% of the population living in Spain , hospital discharge records do not include cases managed in an outpatient setting or asymptomatic cases, thus hospital records are still underestimating the real burden of MSF in Spain.