**12. References**


susceptibility to quinolones, the use of these drugs has been associated with worse clinical

In conclusion, rickettsioses are a worldwide threat that must be suspected in travellers returning from endemic areas. Most cases are caused by tick-bites, although in some areas of the world old diseases as typhus are present, and the risk exists. Rickettsiosis must be suspected in all patients with fever, exanthema with or without rash. Starting treatment with doxycycline when possible may be essential to rapidly recover and avoid complications. ATBF along with malaria is the leading cause of fever after returning from

We are grateful to all members from the Centre of Rickettsiosis and Arthropod-Borne Diseases,

Financial support was provided in part by a grant from 'Instituto de Salud Carlos III' (EMER

Althaus, F., Greub, G., Raoult, D. & Genton, B. (2010). African tick-bite fever: a new entity in

*Diseases*, Vol.14, Suppl.3 (September 2010), pp. e274-276, ISSN 1201-9712 Angelakis, E., Botelho, E., Socolovschi, C., Sobas, C.R., Piketty, C., Parola, P. & Raoult, D.

Angel-Moreno, A., Bolaños, M., Santana, E., Pérez-Arellano, J.L. (2006). Murine typhus

*Diseases*, Vol.15, No.11, (November 2009), pp. 1805-1808, ISSN 1080-6059 Azad, A.F. & Radulovic, S. (2003). Pathogenic rickettsiae as bioterrorism agents. *Annals of the New York Academy of Sciences*, Vol.990 (June 2003), pp. 734-8, ISSN 0077-8923 Azuma, M., Nishioka, Y., Ogawa, M., Takasaki, T., Sone, S. & Uchiyama, T. (2006). Murine

Bernabeu-Wittel, M., Pachón, J., Alarcón, A., López-Cortés, L.F., Viciana, P., Jiménez-Mejías,

No.9, (September 2006), pp. 1466-1468, ISSN 1080-6059

the differential diagnosis of multiple eschars in travelers. Description of five cases imported from South Africa to Switzerland. *International Journal of Infectious* 

(2010). Murine typhus as a cause of fever in travelers from Tunisia and Mediterranean areas. *Journal of Travel Medicine*, Vol.17, No.5, (September 2010), pp.

imported from Senegal in a travelling immigrant. *Enfermedades Infecciosas y Microbiología Clínica*, Vol.24, No.6, (June-July 2006), pp. 406-407, ISSN 0213-005X Askling, H.H., Lesko, B., Vene, S., Berndtson, A., Björkman, P., Bläckberg, J., Bronner, U.,

Follin, P., Hellgren, U., Palmerus, M., Ekdahl, K., Tegnell, A. & Struwe J. (2009). Serologic analysis of returned travelers with fever, Sweden. *Emerging Infectious* 

typhus from Vietnam, imported into Japan. *Emerging Infectious Diseases*, Vol.12,

M.E., Villanueva, J.L., Torronteras, R. & Caballero-Granado, F.J. (1999). Murine typhus as a common cause of fever of intermediate duration: a 17-year study in the south of Spain. *Archives of Internal Medicine*, Vol.159, No.8, (April 1999), pp. 872-876,

Hospital San Pedro-Centre of Biomedical Research (CIBIR), Logroño (La Rioja), Spain.

course (Botelho-Nevers et al., 2011).

**10. Conclusion** 

Sub-Saharan Africa.

**12. References** 

**11. Acknowledgment** 

07 033), Ministerio de Ciencia e Innovación (Spain).

310-315, ISSN 1195-1982

ISSN 0003-9926


Rickettsiosis as Threat for the Traveller 23

Oteo, J.A., Martínez de Artola, V., Gómez-Cadiñanos, R., Casas, J.M., Blanco, J.R. & Rosel, L.

Oteo, J.A., Portillo, A., Santibáñez, S., Blanco, J.R., Pérez-Martínez, L. & Ibarra, V. (2006).

Paddock, C.D., Zaki, S.R., Koss, T., Singleton, J. Jr., Sumner, J.W., Comer, J.A., Eremeeva,

Pages F., Faulde M., Orlandi-Pradines E. & Parola P. (2010). The past and present threat of

Pérez-Arellano, J.L., Fenollar, F., Angel-Moreno, A., Bolaños, M., Hernández, M., Santana,

Raoult D. (2010b). *Rickettsia akari* (Rickettsialpox), In: *Mandell, Douglas, and Bennett´s* 

Raoult, D. (2010a). Introduction to Rickettsioses, Ehrlichioses, and Anaplasmosis, In:

Raoult, D., Fournier, P.E., Fenollar, F., Jensenius, M., Prioe, T., de Pina, J.J., Caruso, G., Jones,

Raoult, D., Ndihokubwayo, J.B., Tissot-Dupont, H., Roux, V., Faugere, B., Abegbinni, R. &

Santibáñez, S., Portillo, A., Santibáñez, P., Ibarra, V., Palomar, A., Oteo, J.A. (2011). Utility of

*Española* Vol.196, No.9, (September 1996), pp. 584-587, ISSN 0014-2565 Oteo, J.A., Portillo, A., Blanco, J.R., Ibarra, V. & Santibáñez, S. (2004a). Medicina Clínica,

*Microbiology and Infection,* Vol.10, pp. 327-331, ISSN 1198-743X

Vol.122, No.20, (May 2004), pp. 786-788, ISSN 0025-7753

2669-2671, ISSN 0095- 1137

Philadelphia-USA.

ISSN 1058-4838

Greece, June 2011.

2003), pp. 36-44, ISSN 1749-6632

No.3, (March 2010), pp. 209-224, ISSN 1198-743X

(December 2005), pp. 1961-1964, ISSN 1080-6059

ISBN 978-0-4430-6839-3, Philadelphia-USA.

Vol.344, No.20, (May 2001), pp. 1504-1510, ISSN 0028-4793

Clinical and epidemiological features of a new tick-borne disease. *Clinical* 

(1996). Evaluation of methods of tick removal in human ixodidiasis. *Revista Clínica* 

Cluster of cases of human *Rickettsia felis* infection from southern Europe (Spain) diagnosed by PCR. *Journal of Clinical Microbiology*, Vol.44, No.7, (July 2006), pp.

M.E., Dasch, G.A., Cherry, B. & Childs, J.E. Rickettsialpox in New York City: a persistent urban zoonosis. *Annals of the New York Academy of Sciences*, Vol.990, (June

vector-borne diseases in deployed troops. *Clinical Microbiology and Infection*, Vol.16,

E., Hemmersbach-Miller, M., Martín, A.M. & Raoult, D. (2005). Human *Rickettsia felis* infection, Canary Islands, Spain. *Emerging Infectious Diseases*, Vol.11, No.12,

*Principles and Practice of Infectious Diseases*, Mandell G.L., Bennett J.E., Dolin R. (Eds.), pp. 2509-2510, Churchill Livingstone Elsevier, ISBN 978-0-4430-6839-3,

*Mandell, Douglas, and Bennett´s Principles and Practice of Infectious Diseases*, Mandell G.L., Bennett J.E., Dolin R. (Eds.), pp. 2495-2498, Churchill Livingstone Elsevier,

N., Laferl, H., Rosenblatt, J.E. & Marrie, T.J. (2001). *Rickettsia africae*, a tick-borne pathogen in travelers to sub-Saharan Africa. *The New England Journal of Medicine*,

Birtles, R.J. (1998). Outbreak of epidemic typhus associated with trench fever in Burundi. *Lancet*, Vol.352, No.9125, (August 1998), pp. 353-358, ISSN 0140-6736 Roch, N., Epaulard, O., Pelloux, I., Pavese, P., Brion, J.P., Raoult, D. & Maurin M. (2008).

African tick bite fever in elderly patients: 8 cases in French tourists returning from South Africa. *Clinical Infectious Diseases*, Vol.47, No.3, (August 2008), pp. e28-35,

five PCR targets for molecular diagnosis of human rickettsioses, *Proceedings of the 6th International Meeting on Rickettsiae and Rickettsial Diseases*, Heraklion, Crete,

(2006). Spectrum of disease and relation to place of exposure among ill returned travelers. *The New England Journal of Medicine*, Vol.354, No.2, (January 2006), pp. 119-130, ISSN 0028-4793


Gikas, A., Kokkini, S., Tsioutis, C., Athenessopoulos, D., Balomenaki, E., Blasak, S.,

*and Infection*, Vol.15, Suppl. 2 (December 2009), pp. 211-212, ISSN 1198-743X Hechemy, K.E., Oteo, J.A., Raoult, D., Silverman, D.J. & Blanco, J.R. (2006). A century of

Ibarra, V., Blanco, J.R., Portillo, A., Santibáñez, S., Metola, L., Oteo, J.A. (2005). Effect of

*Academy of Sciences*, Vol.1063 (December 2005), pp. 257-258, ISSN 0077-8923 Jensenius, M., Davis, X., von Sonnenburg, F., Schwartz, E., Keystone, J.S., Leder, K., Lopéz-

Jensenius, M., Fournier, P.E. & Raoult, D. (2004). Rickettsioses and the international traveler.

Jensenius, M., Fournier, P.E., Vene, S., Hoel, T., Hasle, G., Henriksen, A.Z., Hellum, K.B.,

Jensenius, M., Montelius, R., Berild, D. & Vene, S. (2006). Scrub typhus imported to

Kelly, D.J., Richards, A.L., Temenak, J., Strickman, D., Dasch, G.A. (2002). The past and

Laurent, M., Voet, A., Libeer, C., Lambrechts, M., Van Wijngaerden, E. (2009).

Niang, M., Brouqui, P., Raoult, D. (1999). Epidemic typhus imported from Algeria. *Emerging* 

Oteo, J.A., Ibarra, V., Blanco, J.R., Martínez de Artola, V., Márquez, F.J., Portillo, A., Raoult,

*Diseases*, Vol.36, No.11, (June 2003), pp. 1411-1417, ISSN 1058-4838

(November 2009), pp. 1791-1798, ISSN 1080-6059

119-130, ISSN 0028-4793

0077-8923

1058-4838

ISSN 0036-5548

1988), pp. 799-805, ISSN 0002-9343

1058-4838

6059

(2006). Spectrum of disease and relation to place of exposure among ill returned travelers. *The New England Journal of Medicine*, Vol.354, No.2, (January 2006), pp.

Matheou, C., Tselentis, Y. & Psaroulaki, A. (2009). Murine typhus in children: clinical and laboratory features from 41 cases in Crete, Greece. *Clinical Microbiology* 

rickettsiology: emerging, reemerging rickettsioses, clinical, epidemiologic, and molecular diagnostic aspects and emerging veterinary rickettsioses: an overview. *Annals of the New York Academy of Sciences*, Vol.1078 (October 2006), pp. 1-14, ISSN

antibiotic treatment in patients with DEBONEL/TIBOLA. *Annals of the New York* 

Véléz, R., Caumes, E., Cramer, J.P., Chen, L. & Parola, P.; GeoSentinel Surveillance Network. (2009). Multicenter GeoSentinel analysis of rickettsial diseases in international travelers, 1996-2008. *Emerging Infectious Diseases*, Vol.15, No.11,

*Clinical Infectious Diseases*, Vol.39, No.10, (November 2004), pp. 1493-1499, ISSN

Raoult, D. & Myrvang, B.; Norwegian African Tick Bite Fever Study Group. (2003). African tick bite fever in travelers to rural sub-Equatorial Africa. *Clinical Infectious* 

Scandinavia. *Scandinavian Journal of Infectious Diseases*, Vol.38, No.3, pp. 200-202,

present threat of rickettsial diseases to military medicine and international public health. *Clinical Infectious Diseases*, Vol.34, Suppl.4, (June 2002), pp. S145-169, ISSN

Mediterranean spotted fever, a diagnostic challenge in travellers. *Acta Clinica Belgica*, Vol.64, No.6, (November-December 2009), pp. 513-516, ISSN 0001-5512 McDonald, J.C., MacLean, J.D. & McDade, J.E. (1988). Imported rickettsial disease: clinical

and epidemiologic features. *American Journal of Medicine*, Vol.85, No.6, (December

*Infectious Diseases*, Vol.5, No.5, (September-October 1999), pp. 716-718, ISSN 1080-

D., Anda, P (2004b). *Dermacentor*-borne Necrosis Erythema and Lymphadenopathy:

Clinical and epidemiological features of a new tick-borne disease. *Clinical Microbiology and Infection,* Vol.10, pp. 327-331, ISSN 1198-743X


**2** 

*1University of Buea* 

*1Cameroon 2USA* 

**Human Ehrlichioses and** 

**Rickettsioses in Cameroon** 

*2University of Texas Medical Branch, Galveston* 

Lucy Ndip1, Roland Ndip1, David Walker2 and Jere McBride2

Human ehrlichioses and rickettsioses are important arthropod borne infectious diseases which are transmitted by ticks, mites, lice and fleas. Infections result in mild to fatal outcomes, with clinical presentations that resemble other tropical infectious diseases such as malaria making clinical diagnosis difficult. Despite recognition as important causes of lifethreatening diseases in the United States, the geographic distribution of these diseases worldwide remains undefined due to their recent emergence, challenges in diagnosis and lack of comprehensive epidemiological studies needed to determine incidence in developing countries. Recently, the transfer of technological developments to other parts of the world especially developing countries has encouraged basic epidemiological inquiry and generated scientific interest in understanding the epidemiology of these tick borne diseases and their role as causes of undifferentiated febrile illnesses. In this chapter, we review the current knowledge of human monocytotropic ehrlichiosis (HME) and spotted fever

Ehrlichioses are diseases caused by small (approximately 0.4–1.5 μm diameter) Gram negative, obligately intracellular bacteria belonging to the genus *Ehrlichia* of the family Anaplasmataceae, Order Rickettsiales and the alpha sub-division Proteobacteria (Dumler et al., 2001). Although they have a characteristic Gram negative cell wall structure, they lack the necessary enzymes to synthesize cell membrane components such as lipopolysaccharide and peptidoglycan (Lin & Rikihisa, 2003). As intracellular pathogens, *Ehrlichia* reside in cytoplasmic membrane-bound vacuoles inside host cells (granulocytes or monocytes) forming microcolonies called morulae, derived from the Latin word "morus" for mulberry (Popov et al., 1995; Paddock et al., 1997; Ismail et al., 2010). These morulae (ranging in size from 1.0 to 6.0 µm in diameter) may contain 1 to >40 organisms of uniform or mixed cell

Organisms in the family *Anaplasmataceae* were first described in 1910 when Theiler described *Anaplasma marginale*, the etiologic agent of an economically important and severe disease of

**1. Introduction** 

**2. Ehrlichiosis** 

**2.1 Etiologic agents** 

rickettsiosis (African tick bite fever) in Cameroon.

types (Popov et al., 1995; Rikihisa, 1999).

