Patterns of brucellosis infection symptoms in azerbaijan: a latent class cluster analysis.

Rita Ismayilova,Emilya Nasirova,Colleen Hanou,Robert G Rivard,Christian T Bautista

doi:10.1155/2014/593873

Abstract

Brucellosis infection is a multisystem disease, with a broad spectrum of symptoms. We investigated the existence of clusters of infected patients according to their clinical presentation. Using national surveillance data from the Electronic-Integrated Disease Surveillance System, we applied a latent class cluster (LCC) analysis on symptoms to determine clusters of brucellosis cases. A total of 454 cases reported between July 2011 and July 2013 were analyzed. LCC identified a two-cluster model and the Vuong-Lo-Mendell-Rubin likelihood ratio supported the cluster model. Brucellosis cases in the second cluster (19%) reported higher percentages of poly-lymphadenopathy, hepatomegaly, arthritis, myositis, and neuritis and changes in liver function tests compared to cases of the first cluster. Patients in the second cluster had a severe brucellosis disease course and were associated with longer delay in seeking medical attention. Moreover, most of them were from Beylagan, a region focused on sheep and goat livestock production in south-central Azerbaijan. Patients in cluster 2 accounted for one-quarter of brucellosis cases and had a more severe clinical presentation. Delay in seeking medical care may explain severe illness. Future work needs to determine the factors that influence brucellosis case seeking and identify brucellosis species, particularly among cases from Beylagan.

Highlights

Brucellosis is a contagious bacterial disease among humans and usually presents as an acute febrile infection with nonspecific flu-like symptoms such as fever, headache, back pain, malaise, and night sweats [1, 2]
We investigated the existence of clusters of brucellosis infected patients according to clinical presentation in Azerbaijan
In total 454 brucellosis cases were included in the analysis

Summary

Introduction

Brucellosis is a contagious bacterial disease among humans and usually presents as an acute febrile infection with nonspecific flu-like symptoms such as fever, headache, back pain, malaise, and night sweats [1, 2]. Brucellosis is endemic in Azerbaijan, with the first case reported in 1922. Azerbaijan’s population of 9.6 million is evenly split between urban and rural residents, with almost 40% of the labor force employed in the agricultural or livestock industry, including raising cattle, sheep, and goats [3]. Between 1995 and 2009, 7,983 brucellosis cases were reported, with an average of 300–400 cases per year [1, 4]. We investigated the existence of clusters of brucellosis infected patients according to clinical presentation in Azerbaijan Brucella infection is diagnosed by using the Huddleston test and confirmed by the Wright test [5, 6].

Methods

Results

Conclusion