**Tropical Diseases Due to Bacteria and Viruses**

**1** 

*Spain* 

**Rickettsiosis as Threat for the Traveller** 

Over the past six decades, tourism has experienced continued expansion and diversification becoming one of the largest and fastest growing economic sectors in the world. Many new destinations have emerged alongside the traditional ones of Europe and North America. In the next years an increase of travelling is expected, and the number of related infections will also be higher (http://www.unwto.org/facts/menu.html). Rickettsioses are an important

Rickettsiae are small gram-negative intracellular bacteria (belonging to the alpha-1 proteobacteria) mainly transmitted by arthropods (lice, fleas, ticks and other acari) with two genera: *Orientia* with a unique specie (*Orientia tsutsugamushi*) and *Rickettsia* with several

Rickettsioses have been a threat all along the History and nowadays they are an important cause of morbi-mortality in some areas of the world. To know the distribution of the different diseases caused by these bacteria and how the clinical pictures are recognized may be essential for a quick diagnoses and starting the correct treatment. Some of these infections can be also easily prevented with basic rules. Main rickettsioses with their distribution area

In the 21st Century in most parts of the world hygienic conditions have improved and epidemic typhus is absent. To acquire this condition it is necessary to be in contact with body lice. Furthermore, if people have personal hygiene and change their clothing, body lice are removed. Nevertheless it is possible that if we travel for cooperation to catastrophic areas or other places with poverty, we may take body lice (refugees' camps) and may

There are a lot of references of rickettsioses acquired by travellers and considered imported diseases (McDonald et al., 1988; Bottieau et al. 2006; Freedman et al., 2006; Askling et al.

Nowadays ticks cause most travel-associated rickettsioses. Ticks are considered to be one of the most important vectors of infectious diseases in the world, preceded only by mosquitoes. Therefore, tick-borne rickettsioses are endemic all over the world (Hechemy et al., 2006). The majority of travel-associated rickettsioses refer to Sub-Saharan Africa tourists who develop African tick-bite fever (ATBF), mainly transmitted by *Amblyomma hebraeum* (Figure 1). In addition to malaria, ATBF is an important cause of fever in people returning from the tropic (Field et al., 2010). Other reports describe Mediterranean spotted fever (MSF) acquired by tourists bitten by *Rhipicephalus* spp. ticks (Figure 2) when visiting Europe, being

2009; Chen & Wilson, 2009; Jensenius et al., 2009; Stokes & Walters, 2009).

species. The clinical pictures that they cause are named rickettsioses (Raoult, 2010a).

**1. Introduction** 

chapter in the field of travel medicine.

are showed in the table 1.

develop exanthematic typhus.

Aránzazu Portillo and José A. Oteo

*Hospital San Pedro-Centre of Biomedical Research (CIBIR)* 
