Printer Friendly

Borrelia crocidurae infection in acutely febrile patients, Senegal.

As malaria cases decrease, the need for programs to study the roles of other causes of febrile syndromes in Africa increases (1). Other causes of fever in outpatients include typhoid and paratyphoid fevers; pneumococcal bacteremia; and a spectrum of viral infections, including influenza, yellow fever, dengue, chikungunya, and Rift Valley fever (2). In preliminary studies, we detected the DNA of Borrelia crocidurae, Rickettsia spp., Tropheryma whipplei, and Coxiella burnetii in environmental samples and blood specimens from febrile patients in Senegal (3-6).

In western Africa, tick-borne relapsing fever (TBRF) is caused by B. crocidurae; this acute febrile illness produces multiple recurrences of nonspecific signs and symptoms, including fever, headache, myalgia, and arthralgia. After decades of neglect, TBRF has again been detected (7) and is thought to be one of the major causes of fever in Africa. The reported incidence rate for TBRF in western Africa is high, reaching 25 cases per 100 person-years or accounting for 13% of febrile illnesses treated at rural dispensaries (4,8). This incidence rate is even higher than that for TBRF caused by B. duttonii in eastern Africa (9). A study from Tanzania found B. duttonii DNA in 3.9% of blood samples (10).

In 2008, we began to create a network of rural dispensaries from which to recruit patients (Table; Figure 1). The 5 study sites covered several ecosystems, ranging from dry Sahelian in northern Senegal (Keur Momar Sarr, Niakhar, and Sine-Saloum) to humid sub-Guinean in southern Senegal (Casamance and Kedougou). Two seasons are typical: dry (November-May) and rainy (June-October). The National Ethics Committee of Senegal approved the study (11,12). Since 2010, the populations of both villages in Sine-Saloum (Dielmo and Ndiop) have benefited from routine rapid point-of-care laboratory diagnostics (12).

The Study

From June 2010 through October 2011, fingerstick blood samples (200 mL) were collected from 1,549 febrile patients (axillary temperature >37.5[degrees]C) at 14 dispensaries and 91 randomly selected healthy villagers in Senegal. Samples were subjected to DNA extraction. Digesting, binding, and washing were performed directly in the village dispensaries by use of the QIAamp kit (QIAGEN, Hilden, Germany) as previously reported (6). DNA elution was performed at Aix-Marseille Universite in Marseille, France. Quantitative PCR (qPCR) was performed by using primers and probes specific for the genus Borrelia. All samples positive for Borrelia spp. were subjected to standard PCR (flaB gene) (4). To determine the quality of the extracted DNA, we also measured the human actin gene (5). The samples were considered positive only if qPCR and flaB-based PCR results were positive; the sequencing of all flaB amplicons demonstrated that they belonged to B. crocidurae.

Isolation of borreliae involved intraperitoneal inoculation of laboratory BALB/c mice with 100 mL of patient capillary blood. Borreliae in mice were detected by microscopic examination of Giemsa-stained peripheral blood smears followed by qPCR of blood samples.

The sex ratio for the 1,549 patients did not differ significantly among sites (772 male and 777 female patients). An analysis of 6 age groups (<12 months, 1-3 years, 4-6 years, 7-15 years, 16-29 years, and [greater than or equal to] 30 years) showed no differences among sites. All tested samples from clinically healthy persons had negative qPCR results for borreliae.

The incidence rate was calculated as the number of febrile episodes divided by the person-time multiplied by 1,000 (data available only for the Sine-Saloum site). The incidence rate of febrile episodes was 0.80 in Dielmo and 0.36 in Ndiop (p<0.05). Among the 1,566 samples tested, 115 (7.3%) were positive for B. crocidurae. The incidence rate for TBRF was 9.7 cases/100 persons in Dielmo and 2.4 cases/100 persons in Ndiop. The first autochthonous cases in Ndiop, which was previously considered borreliosis free, were observed in October 2010; incidence was significantly lower in Ndiop than in Dielmo (p<0.05). All cases registered in Ndiop before October 2010 were included in the epidemiologic investigation and considered to be imported. The proportion of the Borrelia-positive samples was significantly higher for northern sites with a drier Sudanian climate; positivity reached 19.1% (33/173) in Niakhar (Table). By analyzing the epidemiologic questionnaires completed by families of ill persons, we determined that the 2 TBRF cases in Casamance were imported from the northern regions of Senegal by seasonal workers.

Patients most frequently infected were 7-15 years of age (13.5 %, 43/318), unlike in eastern Africa where younger persons are more frequently infected (9). No positive results were found among the 155 children <12 months of age, but positive results were found for 16 (4.8%) of the 352 children 1-3 years of age (p<0.05). Unlike in other northern regions, in Sine-Saloum, the proportion of Borrelia-positive samples was significantly higher for samples collected during the dry (16.9%, 40/237) than the rainy season (6.9%, 30/432); p<0.0001 (Figure 1).

We identified 20 patients (49 samples) for whom 2-4 samples were positive for B. crocidurae. The interval between the sample collections was short (5-30 days) for 13 persons, average (30-66 days) for 4 persons, and long (102-381 days) for 3 persons. Two Borrelia isolates (no. 03-02 from Ndiop and no. 19/31 from Dielmo) were recovered from the peripheral blood of 2 febrile patients. The bacteria had a morphologic appearance that was typical for borreliae (Figure 2). A BLAST ( Blast.cgi) search for the sequenced flaB gene (JX119098) demonstrated that the isolates were nearly identical with the type Achema strain of B. crocidurae (CP003426).


We detected an alarmingly high proportion of Borrelia DNA in the blood of febrile patients in Senegal. The presence of this DNA is strongly and specifically linked to the fever because no Borrelia DNA was identified among the 90 control participants. In Tanzania, however, borreliae have been identified in up to 33% of blood samples obtained from asymptomatic blood donors who lived in similar conditions as ill persons (13).

The geographic repartition of TBRF is linked to drier climates (9). We observed autochthonous cases only in northern Senegal, roughly north of the 13[degrees]30' parallel. We noted the recent extension of B. crocidurae into the village of Ndiop, which had been free of B. crocidurae. This extension might be linked to recent climate changes (14). The person-year incidence of borreliosis in our study (6.1 cases/100 population) is similar to that reported by Vial et al. (4 cases/100 population) for the interepidemic period (8).

We report a unique series of cases in which Borrelia DNA was identified several times consecutively in the blood of the same patient. For 17 patients for whom the time between positive samples was short or average (up to 66 days), repeated detection of Borrelia DNA during repeated episodes of fever could be explained by relapses. However, reinfection is strongly suspected in 3 patients because the interval between 2 positive samples was >100 days. To the best of our knowledge, reinfection with relapsing fever borreliae has not been previously reported in Africa. The phenomenon of easy reinfection after treatment with tetracycline has been reported for the relapsing-fever group B. hermsii in vervet monkeys, which could be reinfected 12-36 weeks after primary infection (15).

In conclusion, the incidence of TBRF and the proportion of borreliosis cases among febrile patients in Senegal is very high and, in at least 1 region (Niakhar), exceeds that of malaria. This considerably high incidence rate should lead to the development of new therapeutic strategies that could be based on treating febrile patients in Senegal with doxycycline.


We thank the Agence National de Recherche, grant MALEMAF (Research of Emergent Pathogens in Africa) and La Fondation Mediterranee Infection for financial support; all villagers who participated in the study; Annick Bernard, Aliou Diallo, Denis Piak, and Khadim Mbacke Leye for technical support; and Pascal Weber for photography.

Dr Mediannikov is a researcher in epidemiology and microbiology in Dakar, Senegal. His scientific interests include vector-borne diseases and other causes of nonmalarial fever in Africa.


(1.) Gwer S, Newton CR, Berkley JA. Over-diagnosis and co-morbidity of severe malaria in African children: a guide for clinicians. Am J Trop Med Hyg. 2007;77(Suppl):6-13.

(2.) Hotez PJ, Kamath A. Neglected tropical diseases in sub-Saharan Africa: review of their prevalence, distribution, and disease burden. PLoS Negl Trop Dis. 2009;3:e412. journal.pntd.0000412

(3.) Mediannikov O, Fenollar F, Socolovschi C, Diatta G, Bassene H, Molez JF, et al. Coxiella burnetii in humans and ticks in rural Senegal. PLoS Negl Trop Dis. 2010;4:e654. http://dx.doi. org/10.1371/journal.pntd.0000654

(4.) Parola P, Diatta G, Socolovschi C, Mediannikov O, Tall A, Bassene H, et al. Tick-borne relapsing fever borreliosis, rural Senegal. Emerg Infect Dis. 2011;17:883-5. http://dx.doi. org/10.3201/eid1705.100573

(5.) Fenollar F, Mediannikov O, Socolovschi C, Bassene H, Diatta G, Richet H, et al. Tropheryma whipplei bacteremia during fever in rural West Africa. Clin Infect Dis. 2010;51:515-21. http://dx.doi. org/10.1086/655677

(6.) Mediannikov O, Diatta G, Fenollar F, Sokhna C, Trape JF, Raoult D. Tick-borne rickettsioses, neglected emerging diseases in rural Senegal. PLoS Negl Trop Dis. 2010;4. pii: e821. http://dx.doi. org/10.1371/journal.pntd.0000821

(7.) Bergeret C, Raoult A. Notes sur les formes nerveuses de la fievre recurrente--fievre recurrente a tiques en Afrique Occidentale Fran9aise. Bul Med Afrique Occidentale Fran9aise 1934;27:593-8.

(8.) Vial L, Diatta G, Tall A, Ba el H, Bouganali H, Durand P, et al. Incidence of tick-borne relapsing fever in West Africa: longitudinal study. Lancet. 2006;368:37-43.

(9.) Cutler SJ. Possibilities for relapsing fever reemergence. Emerg Infect Dis. 2006;12:369-74.

(10.) Reller ME, Clemens EG, Schachterle SE, Mtove GA, Sullivan DJ, Dumler JS. Multiplex 5' nuclease-quantitative PCR for diagnosis of relapsing fever in a large Tanzanian cohort. J Clin Microbiol. 2011;49:3245-9.

(11.) Trape JF, Rogier C, Konate L, Diagne N, Bouganali H, Canque B, et al. The Dielmo project: a longitudinal study of natural malaria infection and the mechanisms of protective immunity in a community living in a holoendemic area of Senegal. Am J Trop Med Hyg. 1994;51:123-37.

(12.) Sokhna C, Mediannikov O, Fenollar F, Bassene H, Diatta G, Tall A, et al. Point-of-care laboratory of pathogen diagnosis in rural Senegal. PLoS Negl Trop Dis. 2013;7: e1999. doi: 10.1371/journal. pntd.0001999.

(13.) Cutler SJ, Bonilla EM, Singh RJ. Population structure of East African relapsing fever Borrelia spp. Emerg Infect Dis. 2010;16:1076-80.

(14.) Trape JF, Godeluck B, Diatta G, Rogier C, Legros F, Albergel J, et al. The spread of tick-borne borreliosis in West Africa and its relationship to sub-Saharan drought. Am J Trop Med Hyg. 1996;54:289-93.

(15.) Felsenfeld O, Wolf RH. Reinfection of vervet monkeys (Cercopithecus aethiops) with Borrelia hermsii. Res Commun Chem Pathol Pharmacol. 1975;11:147-50.

Address for correspondence: Didier Raoult, URMITE, IRD 198, UM63, CNRS 7278, INSERM 1095, Aix-Marseille Universite, 13005 Marseille, France; email:

Oleg Mediannikov, [1] Cristina Socolovschi, [1] Hubert Bassene, Georges Diatta, Pavel Ratmanov, Florence Fenollar, Cheikh Sokhna, and Didier Raoult

[1] These authors contributed equally to this article.

Author affiliations: Aix-Marseille Universite, Marseille, France, and Dakar, Senegal (O. Mediannikov, C. Socolovschi, H. Bassene, G. Diatta, P. Ratmanov, F. Fenollar, C. Sokhna, D. Raoult); and Far Eastern State Medical University, Khabarovsk, Russia (P. Ratmanov)


Table. Rural health centers and laboratories participating
in study of Borrelia crocidurae infection in acutely febrile
patients, Senegal, June 2010-October 2011 *

Study site   District/dept/   District pop         Climate/
                 region                           vegetation

Sine-         Toubacouta/       120,554        Sudanian/wooded
              Foundiougne/                         savannah
Niakhar         Niakhar/         69,446            Sahelo-

               Fatick and                      Sudanian/wooded

                Niakhar/                            steppe


Casamance    Loudia-Oulof/       57,505              Sub-
               Oussouye/                     Guinean/primary and
               Ziguinchor                     secondary gallery


Kedougou      Bandafassi/        20,021            Sudano-
               Kedougou/                      Guinean/woodland,
                Kedougou                       wooded savannah

Keur           Keur Momar        70,743      Sahelian/steppe type
Momar Sarr    Sarr/Louga/

Study site   Precip,      Health           Coord
              mm/y        center

Sine-          939        Dielmo      13[degrees]43'N,
Saloum                                 16[degrees]24W
                          Ndiop       13[degrees]41N,
Niakhar        757        Toucar      14[degrees]32'N,
                         Diohine      14[degrees]30'N,
                        Ngayokheme    14[degrees]32'N,
                         Niakharf     14[degrees]28'N,
Casamance     1,432       Mlomp       12[degrees]33'N,
                         Kagnout      12[degrees]33'N,
                         Elinkine     12[degrees]30'N,
Kedougou      1,189     Bandafassi    12[degrees]32'N,
                           Ibel       12[degrees]30'N,
                         Tiabeji      12[degrees]38'N,
Keur           400      Keur Momar    15[degrees]55'N,
Momar Sarr                 Sarr        15[degrees]58W
                         Loboudou     15[degrees]57'N,
                       Ganket Balla   15[degrees]58'N,

Study site     Other         IR

Sine-           POC         10.5

Niakhar                     19.1


Casamance       DNA         0.6
             extraction   (2/315)

Kedougou        DNA         0.4
             extraction   (1/246)

Keur            DNA         5.5
Momar Sarr   extraction   (9/163)

* Climate information obtained from;
demographic data obtained from the National Agency of
Statistics and Demography of Senegal (
Dept, department; pop, population; precip, precipitation;
coord, coordinates; IR, B. crocidurae incidence rate,
% (no. tested/no. positive); POC, point-of-care laboratory.

([dagger]) No patient recruitment at this site.
COPYRIGHT 2014 U.S. National Center for Infectious Diseases
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2014 Gale, Cengage Learning. All rights reserved.

Article Details
Printer friendly Cite/link Email Feedback
Title Annotation:DISPATCHES
Author:Mediannikov, Oleg; Socolovschi, Cristina; Bassene, Hubert; Diatta, Georges; Ratmanov, Pavel; Fenolla
Publication:Emerging Infectious Diseases
Geographic Code:4EUFR
Date:Aug 1, 2014
Previous Article:Role of migratory birds in spreading Crimean-Congo hemorrhagic fever, Turkey.
Next Article:Isolation of MERS coronavirus from dromedary camel, Qatar, 2014.

Terms of use | Privacy policy | Copyright © 2022 Farlex, Inc. | Feedback | For webmasters |