Over the last 16 years, we reported at least 23 outbreaks with increased frequency of reporting among the 47 counties. The number of outbreaks reported highlights the complex public health landscape in Kenya, while the frequent occurrence of epidemic-prone diseases illustrates the vulnerability of the country to large disease outbreaks. We also detected diseases earmarked for elimination and eradication though these diseases were not associated with high caseloads. Our classification of diseases determined that VPDs such as COVID-19, malaria, cholera, and measles were the most frequent causes of morbidity and mortality.
Over time, there was an increase in the magnitude of outbreaks. The increase may be due to; (i) revision of the IDSR technical guidelines in 2012 and 2022 increased the number of priority diseases, conditions, and events for surveillance from 18 to 55, therefore increasing the number of outbreaks reported, (ii) improvements in surveillance activities across the country may have occurred after the transition to a devolved system of governance in 2013, and (iii) the government enforced regular reporting of COVID-19 and as a result counties, that had never previously reported any disease, reported cases of COVID-19. This suggests that improved surveillance rather than an increase in the occurrence of diseases led to the rise in reports over time.
We observed the highest burden in urban counties; Nairobi, Nakuru, and Mombasa, and the North-Eastern counties; Garissa, Wajir, and Mandera. Nairobi, Mombasa, and Nakuru host 3 of the 4 cities in Kenya. These cities are overcrowded areas which are characterized by inadequate water and sanitation infrastructure (6). Nairobi and Mombasa serve as border transit hubs, attracting a constant influx of people from countries experiencing active disease outbreaks. Garissa, Wajir, and Mandera are classified as arid lands, with inadequate water and sanitation infrastructure. Although Garissa is sparsely populated, it has overcrowded refugee camps (7), (8). The country’s susceptibility to frequent outbreaks is worsened by inadequate access to safe water and sanitation, internal conflicts, food insecurity, limited access to health services, poor socio-economic status, and environmental conditions (9). To strategically address the needs of high-burden counties, a regional disease response hub should be established for the high-risk counties to preposition commodities and enhance timely and effective response to epidemics.
Globally, the infectious diseases that have caused the highest number of outbreaks between 1996 to 2022, in order of magnitude, are COVID-19, pandemic influenza virus, cholera, acute poliomyelitis, and yellow fever (Torres Munguía et al., 2022). Nationally, we found that COVID-19, cholera, malaria, leishmaniasis, measles, and SARI were the most frequent causes of illness and death due to infectious diseases. Although in 2015, anthrax, trypanosomiasis, rabies, brucellosis, and RVF were identified as the top priority zoonotic diseases in Kenya (10), we found that influenza-A, dengue, and chikungunya were the more commonly occurring zoonotic diseases in the recent past.
Limitations
The use of routine surveillance data is affected by reporting rates, surveillance performance across counties, and the effect of long-term data archiving. Furthermore, the detection of diseases is limited by the availability of diagnostic tests which may affect reporting of some diseases.