Burden of Invasive NontyphoidalSalmonellaDisease in a Rural and Urban Site in Kenya, 2009–2014

Abstract

Background Invasive infections with non-typhoidal Salmonella (NTS) lead to bacteremia in children and adults and are an important cause of illness in Africa; however, few data on the burden of NTS bacteremia are available. We sought to determine the burden of invasive NTS disease in a rural and urban setting in Kenya. Methods We conducted the study in a population-based surveillance platform in a rural setting in western Kenya (Lwak), and an informal urban settlement in Nairobi (Kibera) from 2009 to 2014. We obtained blood culture specimens from participants presenting with acute lower respiratory tract illness, or acute febrile illness to a designated outpatient facility in each site, or any hospital admission for a potentially infectious cause (rural site only). Incidence was calculated using a defined catchment population and adjusting for specimen collection and healthcare seeking practices. Results A total of 12,683 and 9,524 blood cultures were analyzed from Lwak and Kibera, respectively. Of these, 428 (3.4%) and 533 (5.6%) grew a pathogen; among those 208 (48.6%) and 70 (13.1%) were positive for NTS in Lwak and Kibera, respectively. Overall, the adjusted incidence of invasive NTS disease was higher in Lwak (839.4 per 100,000 person-years observation [pyo]) compared with Kibera (202.5 per 100,000 pyo). The highest adjusted incidences were observed in children <5 years of age (Lwak 3,914.3 per 100,000 pyo and Kibera 997.9 per 100,000 pyo). In Lwak the highest adjusted annual incidence was 1,927.3 per 100,000 pyo (in 2010) and in Kibera 220.5 per 100,000 pyo (in 2011); the lowest incidences were 303.3 and 62.5 per 100,000 pyo respectively (in 2012). In both sites, invasive NTS disease incidence generally declined over the study period. Conclusion We observed an extremely high burden of invasive NTS disease in a rural area of Kenya and a lesser, but still substantial, burden in an urban slum. Although the incidences in both sites declined during the study period, invasive NTS infections remain an important cause of morbidity in these settings, particularly among children < 5 years old.

Invasive Nontyphoidal Salmonella Disease in Africa

“…iNTS disease in African populations primarily affects HIV-infected adults and young children. In the limited number of African studies with defined denominator populations (9)(10)(11)(12)(13)(14)(15), the median estimated incidence of iNTS disease in children is 195 cases (range 26 to 1,870) per 100,000 person-years of observation (Table 1). Among African adults, population-based surveillance data estimated the incidence of iNTS disease to be between 0 and 54 cases per 100,000 person-years of observation in 13 surveillance sites across sub-Saharan Africa (16).…”

Clinical and microbiological features of invasive nontyphoidal Salmonella associated with HIV-infected patients, Gauteng Province, South Africa

“…[3,5] Much work has also focused on microbiological aspects of iNTS, including serotype and multidrug resistance (MDR), [4,5] or iNTS disease burden. [7] Several have called for development of nontyphoidal Salmonella vaccines. [8] Although there have been reports of decreasing incidence of iNTS infections in some parts of Africa, [7,9] mortality rates among persons with iNTS infections remain high [4,5,9] and factors associated with mortality among persons infected with iNTS are not well understood.…”

“…[7] Several have called for development of nontyphoidal Salmonella vaccines. [8] Although there have been reports of decreasing incidence of iNTS infections in some parts of Africa, [7,9] mortality rates among persons with iNTS infections remain high [4,5,9] and factors associated with mortality among persons infected with iNTS are not well understood. A better understanding of disability and associated mortality of iNTS infections will inform decisions for control and prevention of iNTS infections.…”

The Application of Wearable Technologies to Improve Healthcare in the World’s Poorest People

“…However, waterborne fecal illnesses abound [20]. In Kibera, HIV is endemic although precise infection rates are not know because of HIV-associated stigma; HIV levels are at about 40% in those who agree to be tested and 14% among expectant mothers [24].…”

“…HIV treatment and prevention are sporadic and so HIV infection rates are expected to increase. HIV is not the only infectious disease of concern in Kibera; others include tuberculosis (TB), malaria, hepatitis and infection with soil borne pathogens [20] [25] [26] [27]. Wearable sensors have multiple potential roles in infectious disease.…”