Malaria and typhoid fever (TF) are the endemic infectious diseases in tropical areas. Both diseases have been considered as poverty related diseases and cause high morbidity and mortality mainly in sub-Saharan Africa 12345. Malaria and TF coinfection has been described in the medical literature in the mid-19th century and named "typhomalaria" 6.

Malaria and TF, whose clinical sign dominating is the fever, are due to two distinct pathogens, with different transmission modes. In fact, human malaria is caused by 5 haematozoa parasite species, Plasmodium genus and transmitted actively by Anopheles female mosquito infecting bite 7. Salmonella TF is due to invasive enteric bacteria, Salmonella genus and transmitted through the oral route consuming water and food contaminated by infected faeces 8. Thus, malaria is vector borne diseases and TF food borne diseases.

Although TF and malaria are caused by distinct microorganisms (Gram-negative bacillus versus hematozoa protozoan parasite for malaria) and transmitted via different mechanisms. The two diseases have many similar clinical signs such as fever, headache and abdominal pain 1. Differential diagnosis between malaria and TF are essential for treatment and co-infection care management is a challenge for clinicians.

In the biological profile, the previous study has reported a false positive malaria rapid diagnostic test (RDT) (BinaxNOW® malaria) result for P. falciparum in Salmonellatyphi bacteremia case without rheumatoid or autoimmune factors due to an immunological disorder 9. In addition, it was also reported that Plasmodium infections increase, Salmonella spp infection susceptibility. In fact, haemolysis during malaria, releases heme oxygenase, which is an enzyme that demobilizes the granulocytes involved in anti-Salmonella cellular immunity 10.

In Africa, few epidemiology studies have shown that the prevalence of "typhomalaria" is not negligible. In Ethiopia, 6.5% of prevalence was reported 11 and 5% to 40% in Nigeria 101213. In Burkina Faso, to our best knowledge, no data on "typhomalaria" was published. We performed this study to analyze the epidemiological profile of co-infection malaria-typhoid fever at the University Hospital Sourô SANOU of Bobo-Dioulasso.

Malaria and typhoid fever are the major public health problem in sub-Saharan African countries including Burkina Faso. Here, we analyzed epidemiology of concomitant infection of these two diseases. The prevalence of "typhomalaria" was high (34.28%). Similar prevalence has been found in Cameroon (32.5%) and in Nigeria (20-40%) 1314. Our high prevalence could be explained by the conditions of sanitation, food hygiene and the rainy season favorable to these diseases. Our study has been carried out during the rainy season in Burkina Faso. The peak of malaria transmission in Burkina Faso was September to October 15. In addition many studies have indicated that the high prevalence of TF during rainy seasons 16.

The co-infection increased with age, but the difference between the age groups was not significant (p = 0.32). Identical observations had been made in Nigeria 1213141516. This result could be explained by the eating behavior. Usually, in our developing countries, adults eat in public restaurants where hygiene can be lacking 17. Any association was not found between male and female concerning "typhomalaria (p = 0.46). However, the "typhomalaria" prevalence was higher in women, according with one study in Ethiopia 11. Thus, women could be contaminated by Salmonella during food preparation and other maternal activities such childcare. Concerning blood parameters, hemoglobin rate was significantly associated to co-infection with the highest prevalence in non-anemic patient compared to anemic patient. The lack of anemia in malaria cases would be an indicator for co-infection exploration.

The major limitation of this study was the use of SDWF only for the TF diagnosis. The cross-reaction of SDWF with many non-pathogen Salmonella, Brucella and Proteus OX-19 have been notified 18. In addition, SDFW cannot be discriminated between Salmonella carriage and infection. Thus, TF false positive has been reported using SDWF 19. Accurate typhoid fever diagnosis needs to use hemoculture and/or coproculture. To limit the number of false positive, we have considered only titers of anti-agglutinin O antibodies higher than 1/400 and / or anti-agglutinin H higher than 1/800 positive for Salmonella sp. And also, Andualem et al, have shown a good negative predictive value of SDWF test indicating that negative SDWF results have a good indication for the absence of the disease 19.

Yet, our study has important implication for public health. The high prevalence of "typhomalaria "found in our study raises the question of malaria care management in Burkina Faso. The national malaria management guidelines did not mention other infectious diseases exploration in positive malaria cases using microscopy or RDT associated with clinical signs. Malaria concomitant infection with other infectious fever diseases having similar clinical signs could be omitted. It is important to mention in this national guideline to explore other fever diseases, mainly TF focused on non-anemia malaria cases almost clinical signs do not improve 48h after an adapted treatment.

For future research, it would important to determine the potential impact of "typhomalaria" on malaria RDT diagnosis performance in Burkina Faso.

Epidemiological profile of typhomalaria in Bobo-Dioulasso indicated that in 1/3 of malaria cases, we have a Salmonella concomitant infection. Typhomalaria is thus a serious public health problem in Burkina Faso and must be integrate in the malaria diagnosis algorithm therefore to non-anemic cases. Interesting research perspective of our study would be to explore the epidemiology of other fever diseases associated to malaria and or not in order to elaborate adapted recommendations for fever etiological diagnosis in Burkina Faso.