**4. Prevention of ehrlichiosis and rickettsiosis**

Studies in Cameroon indicate that one risk factor for contracting *E. chaffeensis* infection and ATBF appears to be exposure to potential tick vectors. Many reports involving acquisition of rickettsial diseases have also indicated that exposure to ticks during safari tours and visit to parks constitute an important risk factor. Therefore, an important method of preventing ehrlichiosis and rickettsiosis is by reducing contact with infected ticks. Personal protective measures are quite important, including wearing light colored clothes when walking in tick infested areas, using insect repellents and examination of clothing after a visit to a tick infested area, and prompt removal of attached tick can all reduce the risk of infection. Companion animals and other domesticated animals should be taken care of and tick infestation controlled.

#### **4.1 Conclusions**

34 Current Topics in Tropical Medicine

al., 2004a). These results were further confirmed by detection of *R. africae* DNA in about 6% of acutely ill febrile patients (Ndip et al., 2004b). Human infections or the agent has been detected in all regions of southern Cameroon where epidemiologic investigations have been made (Figure 3). According to these studies, age appeared to be a risk factor of acquiring the disease, and it is suggested that activities such as game hunting usually constitutes a risk factor (Ndip et al., 2011). Other activities which could predispose to infection include cattle

Cameroon is a sub-saharan tropical country with a vast equatorial forest providing a good habitat for ticks (especially *A. variegatum* ticks). Individuals residing in lowland rainforest habitats have a higher risk of acquiring ATBF probably because these habitats are ideal for *A. variegatum* ticks because of their moderate canopy cover, providing microclimates favoring tick survival (Ndip et al., 2011). Although ATBF has been shown to be prevalent in the southern part of Cameroon (Figure 2), the actual epidemiology of the disease through

Diagnosis of ATBF can be achieved by either serological analysis of acute and convalescent serum samples or molecular detection of the DNA of the bacterium by real-time or conventional PCR. Target genes that have been utilized include the rickettsial *gltA* and *ompA*  genes. For serological diagnosis, the indirect immunofluorescent test has been used in conjunction with western blot assay to detect antibodies reactive with whole cells or specific proteins of cell lysates of *R. africae*. However, these tests are not very reliable in distinguishing species because cross-reactivity may be observed among the SFG rickettsiae. However, some authors have proposed that a fourfold or greater titer for *R. africae* compared to other species is confirmatory (Raoult et al., 2001; Ndip et al., 2004a). The western immunoblot assay can also be used to detect antibodies against species-specific

The drug of choice for the treatment of ATBF is doxycycline (100 mg twice daily) for 3-7 days. *In-vitro* studies also indicate that *R. africae* is susceptible to tetracyclines, fluoroquinolones, some macrolides and chloramphenicol (Rolain et al., 1998). Mild cases of

Studies in Cameroon indicate that one risk factor for contracting *E. chaffeensis* infection and ATBF appears to be exposure to potential tick vectors. Many reports involving acquisition of rickettsial diseases have also indicated that exposure to ticks during safari tours and visit to parks constitute an important risk factor. Therefore, an important method of preventing ehrlichiosis and rickettsiosis is by reducing contact with infected ticks. Personal protective measures are quite important, including wearing light colored clothes when walking in tick infested areas, using insect repellents and examination of clothing after a visit to a tick infested area, and prompt removal of attached tick can all reduce the risk of infection. Companion animals and other domesticated animals should be taken care of and tick

ATBF have also been shown to recover naturally (Jensenius et al., 1999).

**4. Prevention of ehrlichiosis and rickettsiosis** 

rearing and exposure to tick habitats.

**3.6 Diagnosis** 

OmpA and OmpB proteins.

**3.7 Treatment** 

infestation controlled.

wider disease surveillance needs to be documented.

These data emphasize the importance of ehrlichiosis and ATBF as prevalent diseases in an indigenous Cameroonian population. Although these diseases present as febrile illnesses, they are rarely considered when evaluating patients with acute, undifferentiated febrile illnesses. This situation can be attributed in part to lack of adequate knowledge of the epidemiology and ecology of the disease to prompt diagnosis; unavailability of specific laboratory tests, equipment, and expertise and also the limited economic resources. Sharing new knowledge on these diseases and techniques to facilitate diagnosis are important factors that can change the types and frequencies of diseases diagnosed in febrile patients and necessitate surveillance for these diseases. Future efforts will attempt to address other issues requiring investigations such as the full description of the clinical spectrum of these diseases in African patients and risk factors for severe illness.

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**3** 

*Brazil* 

Marcia Marinho

**Leptospirosis: Epidemiologic Factors,** 

**Pathophysiological and Immunopathogenic** 

Leptospirosis is a disease of worldwide distribution present on all continents except Antarctica (Adler & Montezuma, 2010) affecting wildlife, domestic and man. Leading consequently serious socio-economic and public health. It is currently the highest incidence of zoonosis in the world, also considers as an occupational disease, and reemerging infectious disease, occurring endemic and epidemic in developing countries with tropical and subtropical (Levett, 2001; Bharti et al., 2003, Ko et al , 2009). more frequently in tropical and developing countries (Bharti et al, 2003), acarrretando with this serious social and economic problems. The disease is an acute infection caused by a spirochete *Leptospiraceae* family, consisting of two genera, *Leptospira* and *Leptonema*. Recently, the genus *Leptospira* was divided into 17 species based on molecular classification (DNA), saprophytic and pathogenic species (Brazil 2002; Bharti et al. 2003). The pathogenic species are: *L. interrogans, L. alexanderi, L. fanei, L. inadai, L. kirschineri, L. meyeri, L. borgetersenii, L. weil, L. noguchi, L. santarosai,* Genomospecie 1, Genomospecie 4, 5 Genomospecie. The serotypes of *Leptospira*  are interrogans Australis, Bratislava, Bataviae, Canicola, Hebdomadis, Icterohaemorrhagiae Copenhageni, Lai, Pomonoa, Pyrogenes, Hardjo and divided into serogroups (Ribeiro, 2006). The reservoir animals, mainly rats, are the most frequent disseminators, by eliminating spirochetes in the urine. *Leptospira* spp. can enter the body through intact skin or not, the oral mucosa, nasal and conjunctival (Kobayashi, 2001). The clinical manifestations of leptospirosis vary according to species, individual susceptibility, the pathogenicity and virulence of the serovar involved (Venugopal, 1990, Macedo 1991). After penetration of the bacteria likely, the organism spreads to the bloodstream to all organs (Hüttner et al, 2002). The incubation period is usually around 5-14 days, but have been described as short or long periods in some cases, such as 72 hours a month or more (Jezior, 2005). Leptospirosis is characterized by a vasculitis. The damage to capillary endothelial cells to the underlying cause of clinical manifestations such as renal tubular dysfunction, liver disease, myocarditis

The clinical features are: a) kidneys: interstitial nephritis, tubular necrosis, decreased capillary permeability, and the combination of hypovolemia resulting in renal failure, b) in the liver: necrosis with central lobular proliferation of Kupffer cells and hepatocellular dysfunction c) in the lung, the lesions were secondary to vascular damage resulting in interstitial hemorrhage d) in the skin, the lesions occur as a result of vascular epithelial

**1. Introduction** 

and pulmonary hemorrhage (Hill, 1997).

*Laboratory of Microbiology, Department of Support, Animal Production and Health Course for Veterinary Medicine of UNESP, Campus Araçatuba, São Paulo* 

description of Mediterranean spotted fever, in Tunisia. *Clinical Microbiology & Infection.* 15(S2):309-310 .

