Boutonneuse Fever and Climate Variability

Abstract

Researchers have long appreciated the role of climate in vector-borne diseases, including the resurgence of boutonneuse fever (BF). Portugal usually is classified as having temperate Mediterranean climate. In this new century, in analyzing the data from the Meteorology Institute, this pattern has changed and an accentuated variability in climate is being observed. BF (febre escaro nodular) is endemic and high season is from late spring and summer. The brown dog tick Rhipicephalus sanguineus. is the vector and reservoir of Rickettsia conorii complex strains: R. conorii Malish and Israeli spotted fever strain. To assess the influence of climate change in BF seasonality our aim was to compare the human sera samples received at CEVDI-INSA for laboratory diagnosis of MSF for 5 months per year from October to February, ("off-season") from 2000 to 2005. Of 1,299 sera samples in persons with suspected clinical diagnosis of MSF, 45 (3.4%) were considered positive cases and the number of positive cases has doubled in the last 2 years. BF epidemiology clearly appears to be associated with climate change, especially with low precipitation values. Physicians should be aware of increasing off-season BF cases.

The hard-tick fauna of mainland Portugal (Acari: Ixodidae): an update on geographical distribution and known associations with hosts and pathogens

“…This includes recently collected data, which have led to the modification of earlier opinions and interpretations. Also, human activities such as land management and pest control strategies, extensive habitat destruction by fires and, possibly, the first effects of climatic change have altered the ecology in many areas of the country and consequently led to changes in the distribution of tick populations Casimiro et al 2006;Pereira et al 2006;Sousa et al 2006b). The important role that ticks play in maintaining and transmitting tick-borne pathogens in Portugal, reinforces the need to offer a summary of the present-day information on ticks, their biology, ecology, associations with vertebrate hosts, relationship with pathogens, and taxonomy.…”

Update on Tick-Borne Rickettsioses around the World: a Geographic Approach

“…The MSF incidence may increase with higher temperatures, lower rainfall, and a decrease in the number of days of frost during the preceding year (177,216,217). Particularly, this higher incidence during warmer months seems to be related to a warming-mediated increase in the aggressiveness of R. sanguineus ticks to bite humans (177).…”

Climate change and the epidemiology of selected tick‐borne and mosquito‐borne diseases: update from the International Society of Dermatology Climate Change Task Force

“…The annual incidence of MSF in Marseille, southern France, was positively associated with the average temperature of the preceding year and was negatively correlated with number of days with frost . In Spain and Portugal as well, the epidemiology of MSF appears to be associated with climate change, particularly with higher temperatures and low precipitation . (Table summarizes these data.…”