Iahtasham Khan

Brucellosis in camels

Camels are highly susceptible to brucellosis caused by Brucella melitensis and Brucella abortus. Difficulties can arise in diagnosis of camel brucellosis, especially as this disease provokes only few clinical signs in contrast to its clinical course in cattle. Because none of the commonly used serological test can be perceived as a perfect test for Brucella diagnosis in camel and most serological tests used for camels have been directly transposed from cattle without adequate validation, an incorrect diagnosis may occur when diagnosis is based on serology alone. Of imminent concern is the fact that brucellosis can be easily transmitted from animals or their products to humans mainly via milk. In many developing countries in the arid areas of Asia and Africa, camels are still the most important productive livestock for nomadic populations. Therefore, we reviewed the literatures on camel brucellosis to highlight the epidemiologic, economic and public health impact of camel brucellosis as a basis for designing effective control strategies.

Comparison of diagnostic tests for the detection of Brucella spp. in camel sera

BackgroundBrucellosis in livestock causes enormous losses for economies of developing countries and poses a severe health risk to consumers of dairy products. Little information is known especially on camel brucellosis and its impact on human health. For surveillance and control of the disease, sensitive and reliable detection methods are needed. Although serological tests are the mainstay of diagnosis in camel brucellosis, these tests have been directly transposed from cattle without adequate validation. To date, little information on application of real-time PCR for detection of Brucella in camel serum is available. Therefore, this study was performed to compare the diagnostic efficiency of different serological tests and real-time PCR in order to identify the most sensitive, rapid and simple combination of tests for detecting Brucella infection in camels.FindingsA total of 895 serum samples collected from apparently healthy Sudanese camels was investigated. Sudan is a well documented endemic region for brucellosis with cases in humans, ruminants, and camels. Rose Bengal Test (RBT), Complement Fixation Test (CFT), Slow Agglutination Test (SAT), Competitive Enzyme Linked Immunosorbant Assay (cELISA) and Fluorescence Polarization Assay (FPA) as well as real-time PCR were used. Our findings revealed that bcsp31 kDa real-time PCR detected Brucella DNA in 84.8% (759/895) of the examined samples, of which 15.5% (118/759) were serologically negative. Our results show no relevant difference in sensitivity between the different serological tests. FPA detected the highest number of positive cases (79.3%) followed by CFT (71.4%), RBT (70.7%), SAT (70.6%) and cELISA (68.8%). A combination of real-time PCR with one of the used serological tests identified brucellosis in more than 99% of the infected animals. 59.7% of the examined samples were positive in all serological tests and real-time PCR. A subpopulation of 6.8% of animals was positive in all serological tests but negative in real-time PCR assays. The high percentage of positive cases in this study does not necessarily reflect the seroprevalence of the disease in the country but might be caused by the fact that the camels were imported from brucellosis infected herds of Sudan, accidentally. Seroprevalence of brucellosis in camels should be examined in confirmatory studies to evaluate the importance of brucellosis in this animal species.ConclusionWe suggest combining bcsp31 real-time PCR with either FPA, CFT, RBT or SAT to screen camels for brucellosis.

Seroprevalence and Risk Factors Associated with Brucellosis as a Professional Hazard in Pakistan

The present study was conducted to determine the seroprevalence and identify risk factors associated with brucellosis in humans at high risk in the Potohar plateau of northeastern Pakistan. A total of 262 serum samples were collected from persons of different occupational groups: veterinary personnel, milkers, abattoir workers, livestock farmers, and others (drivers, security guards, housewives). Data related to gender, age, occupation, contact with animals, brucellosis-related symptoms, consumption of raw milk, and geographical region were collected. The Rose Bengal plate test and the serum agglutination test were performed to determine the seroprevalence of brucellosis. The overall seroprevalence was found to be 6.9% (95% confidence interval [CI]: 4.1, 10.6). Real-time polymerase chain reaction assay showed that all cases were affected by Brucella abortus. Individuals who consumed raw milk had higher odds of brucellosis seropositivity. This is the first report of human brucellosis related to B. abortus in high-risk professionals from Pakistan by the combined use of serological and molecular methods.

Q fever in cattle in some Egyptian Governorates: a preliminary study

BackgroundQ fever, caused by Coxiella burnetii, is a zoonosis with great public health significance and can cause financial losses to animal owners. The knowledge of the epidemiology of Q fever in Egypt is limited. Reports on this disease are scarce. In 2012 and 2013, we carried out this investigation to estimate the seroprevalence of antibodies to Coxiella burnetii in dairy cows of nine farms located in the lower Egyptian Governorates of Dakahlia, Damietta and Port Said. 1,194 blood sera were randomly collected from apparently healthy Holstein Friesian dairy cows. The collected sera were tested by ELISA for Coxiella burnetii antibodies.ResultsAll farms tested positive with seroprevalences ranging from 2.9 to 26.7% on farms with less than 200 animals and 9.8 to 20.0% in farms with more than 500 animals. 158 cows (13.2%) had anti-Coxiella antibodies.ConclusionQ fever may be enzootic in the cattle herds investigated in Damietta, Port Said, and Dakahlia Governorates of the Nile delta in both smaller and larger herds. There is a need for further research on the impact of Q fever on both veterinary and public health. The results of this study should trigger more detailed epidemiological studies in ruminants as well as investigations into the etiology of atypical pneumonia and fever of unknown origin in humans.

Performance of complement fixation test and confirmatory immunoblot as two-cascade testing approach for serodiagnosis of glanders in an endemic region of South East Asia.

Various serological tests were used for the diagnosis of glanders in the past but still complement fixation test (CFT) is the internationally prescribed test for trading equines. A new immunoblot (IB) technique has recently been introduced to overcome the well known shortcomings of CFT i. e. a considerable number of false positive and negative results and anticomplementary effects of sera. The objective of this study was the comparative evaluation of two glanders CFT antigens commercially available at Central Veterinary Institute ofWageningen UR, Lelystad, NL (CIDC) and at c.c.pro GmbH, Oberdorla, DE (c.c.pro) in a glanders endemic area regarding specificity and sensitivity. A total of 1678 serum samples from the endemic region (Province Punjab, Pakistan) and a non-endemic area (Germany) were analysed. All sera tested positive or suspicious with CFT were analysed by the confirmatory IB to exclude CFT false positive results. Both CFT antigens showed 100% sensitivity. The use of CIDC or c.c.pro antigen resulted in specificities of 77.45% or 75.71% for sera from endemic area and 93.75% or 94.79% for sera from non-endemic areas, respectively. The results demonstrate the different performances of identical tests in different epidemiologically settings. Based on these results, the combined use of CFT and IB is highly suggestive for the serodiagnosis of glanders. Good agreement was calculated between CFT (using either c.c.pro or CIDC antigen) and immunoblot.

Serological, cultural, and molecular evidence of Brucella infection in small ruminants in Pakistan

INTRODUCTION The objectives of the present study were to determine the seroprevalence and identify the causative agent of brucellosis in small ruminants in Pakistan. METHODOLOGY A total of 278 serum and 212 milk samples were collected from sheep and goats that had close contact with seropositive bovine herds. Data related to age, sex, location, and breed were collected on the sampling day. Serum and milk samples were initially screened using two different Rose Bengal plate test (RBPT) antigens and a milk ring test (MRT). Seropositive samples were subjected to bacterial isolation and PCR analysis using Brucella genus-specific (bcsp31) and Brucella species-specific (IS711 for Brucella abortus and Brucella melitensis) quantitative real-time polymerase chain reactions (qRT-PCR). RESULTS Twenty-four (8.6%) serum samples were positive by RBPT. Twenty (9.4%) animals were positive for Brucella antibodies using MRT. No Brucella isolates were obtained from the examined blood and milk samples. Of the 24 seropositive serum samples, 18 (75%) were positive in the Brucella genus-specific (bcsp31) and Brucella abortus-specific (IS711) qRT-PCR, respectively. CONCLUSIONS Brucella abortus was identified as causative agent of ovine and caprine brucellosis in Pakistan. Results of this study can be used for the development of an effective control and eradication strategy for brucellosis in livestock, especially small ruminants.

Effectiveness of an antimicrobial treatment scheme in a confined glanders outbreak

BackgroundGlanders is a contagious and fatal zoonotic disease of solipeds caused by the Gram-negative bacterium Burkholderia (B.) mallei. Although regulations call for culling of diseased animals, certain situations e.g. wild life conservation, highly valuable breeding stock, could benefit from effective treatment schemes and post-exposure prophylaxis.ResultsTwenty three culture positive glanderous horses were successfully treated during a confined outbreak by applying a treatment protocol of 12 weeks duration based on the parenteral administration of enrofloxacin and trimethoprim plus sulfadiazine, followed by the oral administration of doxycycline. Induction of immunosupression in six randomly chosen horses after completion of treatment did not lead to recrudescence of disease.ConclusionThis study demonstrates that long term treatment of glanderous horses with a combination of various antibiotics seems to eliminate the agent from the organism. However, more studies are needed to test the effectiveness of this treatment regime on B. mallei strains from different endemic regions. Due to its cost and duration, this treatment can only be an option in certain situations and should not replace the current “testing and culling” policy, in conjunction with adequate compensation to prevent spreading of disease.

Q Fever: A Re-Emerging Disease?

Q fever is a mainly airborne zoonosis with public health concern throughout the world caused by the highly contagious, obligate intracellular bacteria Coxiella burnetii. It is an important occupational zoonosis since its discovery in 1935; it has been shown to infect a wide range of hosts, including humans. Although Q fever is a disease closely related to occupations such as handling livestock, most of the previous studies concerned with general population. A recent outbreak in Europe reminds us that this is still a significant pathogen of concern, very transmissible with a very low infectious dose. For these reasons it has also featured regularly on various threat lists, as it may be considered to be used as a bio-weapon. Therefore, we reviewed the literatures on Q fever to highlight the epidemiologic, economic and public health impact of Q fever as a basis for designing effective control strategies.

Seroprevalence and risk factors associated with bovine brucellosis in the Potohar Plateau, Pakistan

BackgroundThe seroprevalence and risk factors of bovine brucellosis were studied at animal and herd level using a combination of culture, serological and molecular methods. The study was conducted in 253 randomly selected cattle herds of the Potohar plateau, Pakistan from which a total of 2709 serum (1462 cattle and 1247 buffaloes) and 2330 milk (1168 cattle and 1162 buffaloes) samples were collected. Data on risk factors associated with seroprevalence of brucellosis were collected through interviews using questionnaires. Univariable and multivariable random effects logistic regression models were used for identifying important risk factors at animal and herd levels.ResultsOne hundred and seventy (6.3%) samples and 47 (18.6%) herds were seropositive for brucellosis by Rose Bengal Plate test. Variations in seroprevalence were observed across the different sampling sites. At animal level, sex, species and stock replacement were found to be potential risk factors for brucellosis. At herd level, herd size (≥9 animals) and insemination method used were important risk factors. The presence of Brucella DNA was confirmed with a real-time polymerase chain reaction assay (qRT-PCR) in 52.4% out of 170 serological positive samples. In total, 156 (6.7%) milk samples were positive by milk ring test. B. abortus biovar 1 was cultured from 5 positive milk samples.ConclusionThis study shows that the seroprevalence of bovine brucellosis is high in some regions in Pakistan. Prevalence was associated with herd size, abortion history, insemination methods used, age, sex and stock replacement methods. The infected animal may act as source of infection for other animals and for humans. The development of control strategies for bovine brucellosis through implementation of continuous surveillance and education programs in Pakistan is warranted.