Effect of climatic factors on the seasonal fluctuation of human brucellosis in Yulin, northern China

Abstract

Background: Brucellosis is a serious public health problem primarily affecting livestock workers. The strong seasonality of the disease indicates that climatic factors may play important roles in the transmission of the disease. However, the associations between climatic variability and human brucellosis are still poorly understood. Methods: Data for a 14-year series of human brucellosis cases and seven climatic factors were collected in Yulin City from 2005 to 2018, one of the most endemic areas in northern China. Using cross-correlation analysis, the Granger causality test, and a distributed lag non-linear model (DLNM), we assessed the quantitative relationships and exposure-lag-response effects between monthly climatic factors and human brucellosis. Results: A total of 7103 cases of human brucellosis were reported from 2005 to 2018 in Yulin City with a distinct peak between April and July each year. Seasonal fluctuations in the transmission of human brucellosis were significantly affected by temperature, sunshine duration, and evaporation. The effects of climatic factors were nonlinear over the 6-month period, and higher values of these factors usually increased disease incidence. The maximum separate relative risk (RR) was 1.36 (95% confidence interval [CI], 1.03-1.81) at a temperature of 17.4°C, 1.12 (95% CI, 1.03-1.22) with 311 h of sunshine, and 1.18 (95% CI, 0.94-1.48) with 314 mm of evaporation. In addition, the effects of these three climatic factors were cumulative, with the highest RRs of 2.27 (95% CI, 1.09-4.57), 1.54 (95% CI, 1.10-2.18), and 1.27 (95% CI, 0.73-2.14), respectively. Conclusions: In Yulin, northern China, variations in climatic factors, especially temperature, sunshine duration, and evaporation, contributed significantly to seasonal fluctuations of human brucellosis within 6 months. The key determinants of brucellosis transmission and the identified complex associations are useful references for developing strategies to reduce the disease burden.

Brucella spp. Contamination in Artisanal Unpasteurized Dairy Products: An Emerging Foodborne Threat in Tunisia

“…The transmission and persistence of Brucella spp. may be enhanced in warmer conditions [ 27 ]. Data on the prevalence of animal brucellosis in Tunisia are scarce and fragmented, and the absence of specific and continuous surveillance programs and specialized diagnostic laboratories with adequate biosecurity conditions and sensitive diagnostic tools impeded the evaluation of the real and accurate extension of brucellosis infection in animals.…”

Transmission dynamics of brucellosis: Mathematical modelling and applications in China

“…It should be pointed out that this review is mainly based on deterministic models of brucellosis transmission. However, the mechanisms of transmission may be affected by precipitation amount, temperature change, and other climatic factors [68] , [69] , [70] . Under these circumstances, stochastic models are the better methods to portray the propagation mechanism of the spread of brucellosis.…”

Exploring risk transfer of human brucellosis in the context of livestock agriculture transition: A case study in Shaanxi, China

“…some transactions that evade regulation and insufficient quarantine of animal production in rapidly developed animal husbandry industrialization are also partially responsible for HB emergence and transfer particularly caused by foodborne infection (36). In spite of some environmental factors such as rainfall, temperature, and vegetation that can also impact the transmission mechanism of brucellosis (37,38), it should come as no surprise that anthropogenic activities play a key role in determining the emergence and transfer of HB. Because different study areas have diverse driving factors of HB transfer concerning their own specific livestock agricultural policies and geographical circumstances, it must be recognized that quantitative analysis conducted to examine brucellosis risk transmission in one place may not be appropriate for applying directly to another area.…”