Prevalence and risk factors associated with Haemophilus ducreyi cutaneous ulcers in Cameroon

Epidemics of yaws-like cutaneous ulcers are regularly documented in children in the tropics. They occur mainly in poor and remote communities without access to health facilities. The integration of molecular tools into yaws control efforts has made it possible to describe Haemophilus ducreyi (HD) as a major cause of cutaneous ulcers. The objective of this work was to determine the prevalence of HD as cause of cutaneous ulcers, as asymptomatic carriage and the risk factors associated. A cross-sectional study was conducted in yaws endemic districts of Cameroon. Participants included people presenting yaws-like ulcers and asymptomatic individuals. Swab samples were collected from each participant and tested for HD and Treponema pallidum (TP) using established qPCR method. Additionally, demographic, habitat, proximity, and hygiene characteristics were collected using a structured questionnaire. A total of 443 individuals, including 271 ulcer cases and 172 asymptomatic contacts, were enrolled in this study. The prevalence of HD in ulcers was 30.3% (Confidence Interval (CI) 95% [24.8 - 35.7]) and the prevalence of asymptomatic HD carriage was 8.6% (CI95% [4.5 - 12.9]). TP was also detected in our sample among ulcer cases but in lower proportion (5.2% CI95% [2.5 - 7.8]) compared to HD. The adjusted logistic regression model showed that women were as much at risk of having HD cutaneous ulcer as men regardless of age; physical proximity to a confirmed ulcer case was the major factor favouring HD transmission. HD ulcers were more likely to be present on Bantu individuals compare to Baka as well as HD colonization. Data from this study highlight HD as the most common cause of cutaneous ulcers in yaws-endemic communities in Cameroon. The real issues of HD detection on intact skin are not yet clear. Further studies are needed to elucidate the implications of this carriage in the spread dynamics of the disease. Author summaryCutaneous ulcers are commonly found affecting children in low-income countries of Africa and the South Pacific. In rural and remote communities of Cameroon the limited access to health care and shortage of sanitation is associated with a high morbidity of cutaneous ulcers. The latter represent an important cause of suffering and stigmatization in children. HD is commonly known as the causative agent of the sexually transmitted infection chancroid and has been recently described as a leading cause of cutaneous ulcers in yaws-endemic regions. In this study, we investigated the presence of HD and the associated risk factors. Our findings indicate a prevalence of HD associated with cutaneous ulcers of 30.3% and a prevalence of asymptomatic HD carriage of 5.2%. Physical proximity to a confirmed ulcer case, Bantu ethnicity, and the use of traditional latrines were the main risk factors associated with HD ulcers. TP DNA was detected in some cutaneous ulcer samples but in lower proportion compared to HD. This study confirms that HD is a leading cause of cutaneous ulcer in yaws endemic areas in Cameroon. National control programmes in endemic countries should therefore consider this pathogen in their strategies for controlling and eliminating skin neglected tropical diseases (NTDs).