Brucellosis is a known zoonotic disease occurring worldwide particularly in the Middle-East and the Mediterranean regions. Brucellosis is also endemic in Asia, sub-Saharan Africa, and some countries in South East Europe and Latin America, whereas it is rare in industrialized world thanks to the routine screening of domestic live stocks and implementation of animal vaccination program. Brucellosis is a bacterial disease caused by various Brucella species, which mainly infect cattle, swine, goats, sheep and dogs. Humans generally acquire the disease through direct contact with infected animals, by eating or drinking contaminated animal products, or by inhaling airborne agents. The majority of cases are caused by ingesting unpasteurized milk or cheese from infected goats or sheep. Person-to-person transmission is rare. The disease causes flu-like symptoms, including fever, weakness, malaise and weight loss.
Despite the continuous progress in brucellosis control measures, it still remains a major public health problem of great economic concern.
Bacteria, common zoonosis,
Transmission
Economic public health concern,
Epidemiology, survival incidence in Egypt
Brucellosis is a zoonotic infection caused
by bacteria of the genus Brucella; species
considered important agents of human disease
are B. melitensis, B. abortus and B. suis
[1]. Brucellosis has worldwide distribution;
but nowadays the disease is rare in the
United States of America and in many other
industrialized nations because of routine
screening of domestic livestock and animal
vaccination programmes [2-4]. This disease
is, however, still a leading zoonosis in
the countries of the Eastern Mediterranean
Region and a disease of economic importance
[5]. Additional losses result from
human infection (undulant fever) with its
prolonged misery, debility and generalized
aching, which may last for months or years
[5,6]. Sheep and goats and their products
are the main sources of infection. Consequently,
brucellosis has been an occupational
risk for farmers, veterinary surgeons
and employees in the meatpacking business
[1]. Non-occupational sources of infection
include consumption of fresh, unpasteurized
goat cheese and raw fresh (untreated)
milk [7].
In Egypt, the infection is mostly caused
by B. melitensis and B. abortus [2]. The
Epidemiology and Surveillance Unit of the
Egyptian Ministry of Health and Population
has recorded a substantial increase in the
number of patients with brucellosis in the
recent past, from 24 cases in 1988 to 1429 in
1998 [8]. An earlier report (1992) described
the distribution pattern of human cases of
brucellosis during the period 1982-91: the
infection rate was generally low except in
1987 and 1991, when there were marked
increases in numbers of cases. This was
clearly observed in Alexandria and Menofiya,
and also in Giza and Domiyat [9].
A full description of the epidemiology
of the disease is needed for planning of any
intervention for its control. Therefore, the
objectives of this study were to define the
trend of brucellosis in Alexandria governorate
over a 16-year period and to determine
the risk factors.
1st phase: Prevention of human infection
Data collection on human and animal infections to evaluate the need for a control program in animal populations
Retrospective study based on the epidemiological reports and official
data on brucellosis cases from the
Seasonal characteristics of the disease were expressed with the highest occurrence in May (15.9%),
June (16.3%) and July (15.1%)
Within the total number of 3,284 brucellosis cases in
the period 2001-2009, 2320 (70.6%) were from rural settlements and 964 (29.4%) from
urban areas. 385 of all cases of brucellosis (8.4%) reported in the period 1998-2009 were
from the ranks of professional staff.
Regions most heavily burdened by the disease include
Clinical signs and symptoms of the disease are usually acute and nonspecific, often mimicking other illnesses
been no known published efforts to map and describe the occurrence of the disease at a local level.
There were three primary objectives of this study: 1)
to describe the spatial and temporal distribution of
human brucellosis in Azerbaijan; 2) identify the potential
presence of clusters of the disease in space and time;
and 3) identify epidemiological characteristics of individuals
that were diagnosed with an infection.
No human subjects work was undertaken in this study,
human brucellosis case data were extracted from annual
government reports. These government reports
are prepared public reports, providing summarized
count data of patients diagnosed at government health
care facilities by category of disease and year. All data
were anonymised.
In this study a case was defined as any individual
with a confirmed positive serology test for Brucella spp.
Suspected cases of human brucellosis are confirmed by
laboratory testing with the Wright serum agglutination tests.
the locations of human brucellosis seropositives were aggregated to the 6 districts in the city
Cumulative incidences per 100,000 individuals were
mapped at the district level for each of the three 5-year
time periods to highlight any spatial changes in risk over
Cumulative incidences were calculated per district for each
of the three, 5-year periods with the total number of cases
during each period as the numerator and the median year
population of each 5-year period as the denominator.
Population estimates for incidence rates were obtained
from the RAPS and the Azeri State Statistical Committee
(http://www.azstat.org/ ).
Epidemiological data on the age and sex of seropositive cases were obtained from disease registries
and stratified by male and female sexes into the following age groups: 0-7, 8-11, 12-15, 16-19, 20-29, 30-39, 40-49,
50-59, and ≥60 years.
Since brucellosis infections can
have symptoms that mimic other diseases and may have
an unknown date of onset
Temporal analysis
Information on the month of diagnosis of the reported
cases was examined to identify the presence of a possible
seasonality in the reporting of cases. Monthly cases were
aggregated into seasons, defined as winter (December,
January, February), spring (March, April, May), summer
(June, July, August), and fall (September, October,
November). Additionally
During the study period 1995 to 2009 there were 7,983
reported cases of human brucellosis in Azerbaijan
(Figure 1).
Annual case totals ranged from 756 in the
year 1996 to 392 cases in the year 2009 with a median
number of reported cases per year of approximately
522.5 (95% CI: 429, 591).
There appears to be a distinct seasonality in the temporal
distribution of monthly human brucellosis cases
(Figure 6). Reporting of cases was highest in the month
of July with a total of 1045 cases (13.1%) during the fifteen
year period. The Summer season accounted for the
greatest number of cases 3,131 (39.2%) followed by
Spring 2,228 (27.9%) then Fall 1,624 (20.3%) and lastly Winter with 1,000 cases (12.5%).
Age and sex stratified case totals illustrated a disproportionate
number of cases reported among males, with
males more heavily burdened by the disease across all
age groups (Figure 8). There were a total of 5,730 cases
in males accounting for approximately 71.8% of all
reported infections. Among age groups for both sexes,
16 to 19 year olds accounted for 2,230 cases [27.9% (95%
CI: 27.7, 28.2)] while 20 to 29 year olds accounted for
3,431 cases [43.0% (95% CI: 42.6, 43.3)], with a combined
total of 5,661 cases [70.9% (95% CI: 70.6, 71.2)]
The data presented here were taken from historical
records that most likely represent an under reporting of
the disease. Analyzing cases obtained from government
health care facilities may have introduced biased since
individuals in more rural areas may not readily have access
to care. Additionally, those individuals in a lower
socio-economic strata (SES) may not be able to afford
care, medication, or travel to government facilities.
These populations within rural areas in a low SES are
also more likely to participate in an agricultural related
occupation, which may thereby have resulted in underreporting
of the burden of disease in this study. Since the
onset of brucellosis is often insidious the time of diagnosis
was used as the date of infection rather than the
onset of the disease. Furthermore, cases obtained from
healthcare facilities may not be representative of the
general population. This may have skewed the monthly
reporting of cases since the incubation period can be
greater > 1 month and an individual may not immediately
seek care [7]. However, most cases occurred during
the spring and summer months and most likely did not
dramatically impact cumulative or yearly incidence risk
estimates.
There are also limitations to the sensitivity of serological
tests for brucellosis and no data were available
on the percentage of human cases that were confirmed
on bacterial culture, the gold standard for Brucella
species. Spatial analyses were limited to district level
reporting and may not reflect localized areas of infection
inside of a given district. The age of individuals
also could not be tied back to their district of origin
and so no adjustments were made. While it was
hypothesized that food was not the main source of infection
in Azerbaijan there were limited epidemiological
data associated with cases in this study and the
data do not provide a definitive link to occupational
exposure. Furthermore, the dummy regions created to
improve the synthesis of reporting for the results do
not represent or delineate national recognizable zones.
This study represents the first attempts to map and describe
local (district level) patterns of human brucellosis
in Azerbaijan.
brucellosis persists annually throughout much of the
country, particularly the central region. These current
analyses affirm the notion that brucellosis has become
endemically established since the first documented
The results of this study indicated variation in the
spatial and temporal distribution of brucellosis reporting
in Azerbaijan.
The number of reported cases most likely represents a significant underestimation
of the actual disease burden across the country as
human brucellosis is often misdiagnosed or is unreported
[21].
Additionally, traditional serological tests,
like Rose Bengal can have relatively low sensitivity [22].
In Azerbaijan, these issues are likely confounded by the
underutilization of the nation's healthcare facilities [23].
However, temporal clustering also suggests
that the disease persisted through the more contemporary
time period This highlights the need
for continued surveillance, particularly in those districts
identified.
The seasonality of brucellosis can often be attributed
to the seasonal birthing of small ruminants (goats and
sheep) [24,25].
recent study in Greece indicated that
human cases were directly related to the parturition of
small ruminants [26]. In Azerbaijan the birthing of small
ruminants occurs in early spring and is often
demarcated by an increase in the incidence of livestock
brucellosis [11]. Reporting of brucellosis in this study
shows a concordance with the spring/summer birthing
of small ruminants, with a greater number of cases
reported during the summer and spring months (March -
August) with a peak in reporting in July. Similar findings
related to the seasonality of the disease were also reported
in Uzbekistan and Italy [27,28].
As brucellosis is not a contagious disease, spatial clusters
of human cases are most likely a result of shared
food sources, animal processing, more intensive agricultural
production zones, or similar socio-cultural practices
[6]. Clusters of disease in this case are also most
likely indicative of a larger underlying prevalence of the
disease in the local livestock population.
animal accommodation on farms may remain contaminated for
prolonged period, with survival of the pathogen for months, up to a year or
probably longer.
It takes from 5 to 90 days
(usually 14 days) from infection to the first sudden severe symptoms of the
disease [13, 15]
Aim. The aim of the study is to analyze available data and present the
frequency and distribution of brucellosis in humans in R. Macedonia in the period
1980-2009 by gender, age, place of residence, profession, and seasonal
distribution of the brucellosis cases. In addition, the study intends to review the
most important factors of the appearance and spread, and the approaches for
control and eradication of B. melitensis infection in animals and humans
Human brucellosis cases in R. Macedonia were recognized in both sexes
and all age categories.
veterinary control of imported livestock was not adequately performed Inadequate implementation of measures against epizootic disease in
affected municipalities contributed to the faster spread of this zoonosis to the
remaining parts of
has a major agrarian population
It has been estimated that the true incidence may be 25-times higher than the reported incidence due to misdiagnosis and underreporting, largely due to lack of proper laboratory facilities in remote areas as well as poor exchange of information between veterinary and public health services.
Most suspected brucellosis patients in Georgia are referred to
Currently many health services are becoming privatized,
and health insurance is not widely available.
However, diagnostics and treatment for brucellosis
remain subsidized
Examination of the epidemiology and clinical characteristics
of this infection was not systemically conducted
in the recent past in Georgia. It is important that health
care providers and public health leaders are aware of
current trends in brucellosis, because the scenarios in
which brucellosis is acquired, as well as the types of
patients exposed and duration of infection before presentation,
are influenced by multiple factors and may
change over time. Assumptions about brucellosis from
10-20 years ago may be incorrect, leading to inaccurate
clinical suspicion of infection and inappropriately targeted
public health surveillance efforts.
To address the lack of recent data on human brucellosis
in the region and explore changes in the epidemiology
and clinical presentation and course over time, we
conducted a medical chart review of suspected or confirmed
brucellosis patients at the IPTM in Tbilisi. The
purpose of the study was to better understand the
demographic distribution as well as clinical manifestations
and the patterns of response to treatment of the
disease. The review allowed for comparisons in management
strategies over three decades.
According to place of residence, only 20.5% of patients were from
urban areas and 79.5% from rural settlements where the population is generally
in close contact with animals potentially infected by brucellosis, or handles raw
animal products such as milk, meat (offals), etc. or consumes raw milk or homemade
dairy products from unheated milk, a common nutritional habit in some rural
communities in R.
limitation
Most of the data about the brucellosis cases within the observed period
from 1980 to 2009 are not available for individual cases but only as aggregated
data by year, month, gender and age groups,
preparation of a questionnaire for basic data collection
These results suggest that human brucellosis persisted annually in Azerbaijan across the study period.
The current situation necessitates the development of appropriate surveillance aimed at improving control and mitigation strategies in order to help alleviate the current burden of disease on the population. Areas of concern identified as clusters by the spatial-temporal statistical analyses can provide a starting point for implementing targeted intervention efforts.
WHO: Fact sheet N173. Geneva, Switzerland: World Health Organization;1997:7.
