**8. Prophylaxis**

An important chapter in the field of rickettsioses is related to prophylaxis. Since the majority of rickettsioses associated to travels are transmitted by ticks, the main preventive measure is to avoid tick-bites. Measures to avoid chiggers' attacks are the same as the ones used against ticks. Only fleas can be more difficult to avoid when cats and other pets are abundant. If there is risk of getting lice, hygiene measures such as changing clothing (they live in the seams of clothing) may be sufficient.

**How can we avoid tick-bites?** There are some rules that can be useful to avoid arthropodbites:


Stay in endemic area 2 Occurrence in May–October 2 Contact (certain or possible) with dog ticks 2

Fever > 39ºC 5 Eschar 5 Maculopapular or purpuric rash 5 Two of the above criteria 3 All three of the above criteria 5

Platelets < 150 GL 1 SGOT or SGPT > 50 UL 1

Blood culture positive for *Rickettsia conorii* 25 Detection of *Rickettsia conorii* in a skin biopsy 25

Single serum and IgG > 1 128 5 Single serum and IgG > 1 128 and IgM > 1 64 10 Four-fold increase in two sera obtained within a 2-week interval 10 SGOT, serum glutamate–oxaloacetate transaminase; SGPT, serum glutamate–pyruvate transaminase.

Table 5. Diagnostic criteria for Mediterranean spotted fever caused by *Rickettsia conorii* 

An important chapter in the field of rickettsioses is related to prophylaxis. Since the majority of rickettsioses associated to travels are transmitted by ticks, the main preventive measure is to avoid tick-bites. Measures to avoid chiggers' attacks are the same as the ones used against ticks. Only fleas can be more difficult to avoid when cats and other pets are abundant. If there is risk of getting lice, hygiene measures such as changing clothing (they live in the

**How can we avoid tick-bites?** There are some rules that can be useful to avoid arthropod-

1. You must not wear dark clothes to see the ticks and remove them before attaching. Curiously, dark clothes attract less arthropods than clear ones. But, in our opinion, to

3. Permethrin-based repellents can be used on clothing, although their effect is short in

4. A careful inspection of clothing and body looking for ticks after returning from outdoors activities in endemic areas as well as removing them correctly has been

look for the arthropods and remove them as soon as possible is more effective. 2. For outdoor activities (grass areas or mountains) you do not have to exposure your body to ticks. Thus, it is very useful to wear clothing that covers the majority of your body. The trousers must be tucked in your shocks with boots. Long sleeves shirt must

be tucked into trousers. You must also wear a cap (especially children).

time and the application should be repeated every few hours.

Epidemiological criteria

Non-specific laboratory findings

aA positive diagnosis is made when the overall score is ≥ 25.

Bacteriological criteria

Serological criteria

**8. Prophylaxis** 

bites:

seams of clothing) may be sufficient.

Clinical criteria

**CRITERIA SCOREa**

effective for the prevention of Lyme disease. The tick needs at least 24-48 hours for the transmission of *Borrelia burgdorferi.* This measure can be less efficient for *Rickettsia* spp. because these microorganisms can be transmitted since the first hours. But, anyway, the removal of the tick has to be done.

5. The contact with parasitized pets and wild animals must be avoided.

There are two questions that physicians have linked up with tick-bites: How must I remove the tick? Must I take prophylactic drugs after a tick-bite?

The first question is easy to answer. The most useful method to remove an attached tick is using forceps. Smooth forceps (without teeth) must be introduced between the tick's head and the skin in a 90º angle and then pull (Oteo et al., 1996). Other traditional methods as using oil, burning or freezing must be forgotten.

The other question is the use of prophylactic drugs after arthropod bites. There are no studies to answer this question. The transmission of rickettsias may be very quick, so we cannot extrapolate the recommendations for Lyme disease. Anyway, when people have been bitten by several ticks in an endemic area for a determinate disease (i.e.: Kruger National Park in South Africa and ATBF) and if the patient is anxious, we can offer doxycycline. It has been demonstrated that 3 doses of 100 mg. every 12 hours is safety and sufficient as treatment for the majority of rickettsioses. We must be cautious with the sun to avoid photo-sensibility. Children can take doxycycline for a short period of time. It is only contraindicated for pregnant women and in this case we can use macrolides (i.e. azythromycin).

Vaccine approaches for prevention of rickettsial diseases have been developed since the past century, but currently no vaccine is available. Major surface protein antigens (OmpA and OmpB) of *R. rickettsii* and *R. conorii* are candidate vaccine antigens. Molecular biology techniques such as selection, cloning and expression of genes encoding *R. prowazekii* virulence-associated proteins, offer the opportunity to develop new rickettsial vaccines against typhus group rickettsiae. Further research is needed to develop effective vaccines without undesirable toxic reactions (Azad & Radulovic, 2003; Walker, 2009).

#### **9. Treatment**

The treatment of rickettsiosis should be initiated as soon as possible. Antibiotics are very effective and may avoid severe complications and death. In all cases if rickettsiosis is suspected, samples should be sent for laboratory confirmation. In DEBONEL/TIBOLA, in which the clinical signs and symptoms are less severe, recovery without antimicrobials occurs but the use of antibiotics shortens the clinical course and improves the clinical picture (Ibarra et al., 2005).

Doxycycline is the most useful drug in children and adults. Doxycycline can be administered in short course (100 mg. every 12 hours for one day) for the treatment of typhus and scrub typhus. In the case of MSF, 2 doses of 200 mg./12 hous are also very effective (in children, 5 mg./kg./12hours); although most physicians use 100 mg. every 12 hours for 3-7 days after fever disappears. The same can be recommended for ATBF. This antibiotic regimen could probably be followed in other tick-borne rickettsioses but there are not good evidences (clinical assays) to support a recommendation. In RMSF the administration of doxycycline for 7 days is recommended. Other drugs that can be prescribed when not using doxycycline (allergy or pregnancy) are chloramphenicol (50-75 mg./kg./day given in 4 doses for 7-10 days) and azythromycin (500 mg./day for 5 days). Doxycycline for 7 days is the treatment of choice for rickettsialpox. Although there is *in vitro*

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