Chronic kidney disease, which is a state of kidney damage or reduced kidney function lasting for three months or longer, is common in Sudan . Several conditions can cause chronic kidney disease including diabetes, hypertension, or glomerulonephritis . Leptospirosis is well known to be associated with kidney disease  but it has never been thoroughly investigated and is severely overlooked in most African countries, including Sudan. We believe this bacterium could be a major cause of chronic kidney disease in the country. In addition, symptoms of leptospirosis may mimic those of other endemic infections in Sudan such as malaria, typhoid, meningitis, hepatitis, or even dengue . We, therefore, intended to explore its existence in possibly suspected high risk patients in Khartoum via sero-screening random febrile patients and those undergoing renal dialysis. Interestingly, anti-leptospiral IgM antibodies were detected in 7% out of all our 119 screened patients. Similarly, clinical researchers in Vanuatu (Pacific Islands)  wanted to investigate leptospirosis as a cause of non-malarial acute febrile illness and found a high seroprevalence of 6%. Leptospira seroprevalence in a study in Western Uganda was 35% . They further reported a probable recent leptospirosis seroprevalence of 1.9% that was associated with having self-reported malaria within the past year . Other studies reported varied leptospiral seroprevalence of 8.4% among febrile inpatients in North-Eastern Malaysia , 24% among individuals at high-risk occupations in Morocco  and 38.5% among miners in India . Further, a study in Portugal revealed 46% of Sa˜o Miguel Island population has circulating anti-leptospiral antibodies .
A total of 9% out of all our 57 patients in renal dialysis and that of 6% out of the 47 patients with fever of unknown origin were seropositive for leptospiral specific IgM, indicating current or recent leptospirosis. Unfortunately, all patients undergoing dialysis were at end stage renal disease and those with fever of unknown origin were long term hospitalized. Knowing that the condition could have been easily reversed -if the highly antimicrobial susceptible bacterial cause was identified early and treated- is heartbreaking. Therefore, sero-screening of suspected febrile patients or those with kidney disease should be a must in hospitals and renal centres in Sudan. Since this lateral flow immunochromatographic test kit can provide reliable results and is easy to perform, rapid, can be easily available and is cost effective, we recommend introducing it in the routine diagnostic laboratories, outpatient clinics and rural health centers in Sudan.
The majority of human cases of leptospirosis worldwide result from occupational exposure to water (or flood waters) or soil contaminated with animals urine [20, 27]. People with relatively high incidence of infection –amongst others- are farmers, agricultural workers, animal handlers, and those exposed to flood waters [20, 27]. Therefore, we wanted to explore these risk factors that could possibly be associated with leptospirosis among our population. A total of 80% out of the seropositive patients with end stage renal disease in our study had a history of recurring episodes of fever, and were living with domestic animals or have contacted them at some point. Most of these patients were farmers and a contaminated food and drink with animals and rodents urine can never be ruled out. These factors indicate and support the diagnosis of leptospirosis. In addition, the source of drinking water was the Nile River for 60% of these patients and 20% used river canals. The original residence for 60% was Dongola and Rofaa and 20% lived in Juba. Considering the fact that people living in these areas rely on the mentioned natural water sources without prior treatment suggest another possible risk for acquiring the infection. Higher risk activities in the study from Western Uganda included skinning cattle and living in close proximity to monkeys  whereas most of the seropositive high-risk individuals in the study from Morocco  were involved in poultry (37%), market fish (26%) and meat slaughterhouse workers (15%).
Furthermore, the possibility that our sero-positive patients with fever of unknown origin might have consumed contaminated water by animal and rodents urine greatly arises since they were living in Aljazira and Dar Alsalam. The first area is known to be agricultural; facilitating a rich environment for the survival and spread of the disease, the second area has been urbanized by rural residents and the different water facilities have less quality control. All positive patients were middle aged or elderly. Many studies in the literature also reported a higher prevalence in this age group [20, 27, 28]. Male to female ratio was almost equivalent and this was also consistent with the findings of Rafizah et al (2012)  in their large scale study in North-Eastern Malaysia.
On the other hand, combined infections have been reported in literature [20, 27]; Chaudhry et al (2013)  reported hepatitis-E, malaria and dengue fever in 7% of patients with leptospirosis. In the present study, we identified co-infections in 25%; one was co-infected with malaria and one with hepatitis-C. However, we did not identify anti-leptospiral antibodies (0%) in the 15 patients with fever of known origin (i.e. malaria/typhoid).
Leptospirosis renal complications are present in our population indicated by a sero-positivity of approximately 2:1 among those with end stage renal disease (i.e. 62%) relative to those with fever of unknown origin (i.e. 38%). Yang et al (1997)  reported high prevalence of renal failure among patients with leptospirosis; they also reported fever and jaundice. Because of their finding, Yang and colleagues recommended that leptospirosis should be suspected in febrile patients with jaundice and renal failure, and we should do the same!