Query fever (Q. fever) is one of the most infectious diseases caused by the bacterium, Coxiella burnetii. It is primarily called Coxiellosis, a significant occupational zoonotic illness worldwide. It is one of 13 worldwide prioritized zoonoses (Sahu et al., 2021a; Ullah et al., 2022a), listed in the WOAH terrestrial animal health code. It is a highly contagious zoonosis prevalent in almost all mammals but predominantly humans, cattle, sheep, and goat. The infectious dosage of Coxiella burnetii can be as low as one bacterium (CDC, 2025; “Q Fever,” n.d.; Sahu et al., 2021b).
Coxiella burnetii is transmitted mainly through tick bites, but indirect transmission such as contaminated milk, feed, and environment, or by coming into close contact with diseased livestock while working on farms or airborne (Panth et al., 2017). Veterinary professionals, farm workers, and owners are more susceptible since they frequently handle small ruminants and contaminated materials (Clark & Soares Magalhães, 2018; Moreira et al., 2025). Q. fever is endemic in goat populations and responsible for abortion, along with infertility, subfertility, endometritis, necrotizing placentitis (Agerholm, 2013; Gache et al., 2017; Q Fever in Small Ruminants (Query Fever; Coxiella Burnetii; Coxiellosis) | Washington Animal Disease Diagnostic Laboratory | Washington State University, n.d.), dairy cattle are also affected (Yáñez et al., 2024). Clinical manifestations can vary and include self-limiting febrile infections with symptoms like exhaustion, irritation, general discomfort, myalgia, and arthiitis, or more serious complications like neurologic signs, pneumonia, hepatitis, and persistent fatigue (Peter et al., 2015; Q Fever: Causes, Symptoms & Prevention Explained, n.d.). About 60% of cases are asymptomatic (Ullah et al., 2022b).
C. burnetii lives and reproduces within the phagolysosomes of host monocytes and macrophages (Pérez-Arellano et al., 2025). There are currently two types known: the large cell variant, which is found inside infected host cells, and the small cell variants, which are extracellular and present in milk, urine, and excreta, with the majority occurring in reproductive and placental fluids (Mezouar et al., 2025). Human infection is generally asymptomatic for some interval, requiring sudden illness, hospitalization, and critical care, multiple diagnostic test is required for confirmation of the disease in humans (Eastwood et al., 2018). In Netherlands, over 4000 cases of human Q. fever have been reported from 2007 to 2010 (Van Der Hoek et al., 2012), South Korea also reported an increase in Q. fever infection after 2015 (Cho et al., 2023), clearly indicating its epidemic ability, and public health concern. This illness is most reported in areas with semi-urban habitat, where animals and humans live in proximity. The one health approach was applied to control the Q. fever outbreak in an Australian goat and sheep farm in 2014 (Bond et al., 2016; Tan et al., 2024). Animal husbandry, mainly goat rearing, is the main occupation in central region of Nepal. However, few studies report C. burnetii infection in animals in Nepal (Acharya & Phuyal, 2025; Panth et al., 2017; Paudyal et al., 2021). There for this study assesses the seroprevalence of C. burnetii and associated risk factors for epidemiological studies in this area.
2 Materials and methods:
2.1 Study Site:
A cross-sectional study was conducted between September and November 2022 at Nepal Agriculture Research Council, National Goat Research Program (NGRP), NARC Bandipur, Tanahun District, Gandaki Province, Nepal (Fig. 1). It is located in the hilly region at 27° 56' 21.83" North latitude and 84° 24' 3.22" East longitude, 141 km west of Kathmandu with an elevation of 812 M, annual rainfall is 2,447 mm, and an annual temperature is 16-27 °C.
Fig. 1. Map of study site (NARC, NGRP).
2.2 Flock selection and sampling methods:
Sample size was calculated using Epitools developed by AusVet (https://epitools.ausvet.com.au/), out of a population of 110, resulting in 86 (95% confidence level, 5% margin error, and 50% prevalence). We select 88 samples for more accuracy, using purposive sampling methods. Blood samples were collected from the jugular vein in an EDTA tube (MED-VAC, Sparsh Mediplus, India), and transported to the station laboratory at 4 °C. Serum was separated with a pipette after 10 minutes of centrifuging at 1500 rpm in a 1.5 mL Eppendorf tube, and stored at -20 °C.
2.3 Detection of C. burnetii
An ELISA test was performed to determine C. burnetii according to the manufacturer’s protocol (ID Screen® Q Fever Indirect Multispecies, Innovative Diagnostic, France). Initially, serum samples were diluted with dilution buffer at 1:400, and mixed properly, then 100 μL of diluted solution was added to each antigen-coated well, and 100 ul to the positive control and negative control wells each. Then incubated at 37 °C for 45 minutes. After that, the well was washed with buffer solvent, allowed to dry on absorbent paper. Later on, 100 μL of enzyme conjugate (Anti-ruminant IgG-HRP) was added to each well and incubated for 45 minutes at 37 °C. Repeated washing was carried out before the addition of 15 μL of TMB substrate solution to each well. Final incubation was done in a dark room for 15 minutes. At the last stage of test, 100 μl of 0.5 M H2SO4 (stop solution) was added. After 10 minutes, the yellow color stripe was read under 450nm light wavelength using ELISA plate reader at the National Animal Health Research Division, Khumaltar, Kathmandu, Nepal
2.4 Statistical analysis and interpretation:
The obtained results were entered into MS Excel. The prevalence rate and statistical significance according to age, physiological status, tick infestation, body condition score (BCS), abortion history, health condition, and stock source with lab results, were compared and analyzed with Chi-Square (χ2) using IBM Statistical Package for Social Science (SPSS) software version 25 with a significance level at 5% (p<0.05).
3 Results and Discussion:
This study shows a 2.27% prevalence (Table 1) in a blood sample of examined animals against C. burnetii. The prevalence rate of 2.27% is in contrast with the study, which found 6.52% in Kavre and lower than the prevalence rate in Makawanpur 28.57% as reported by a previous study in Nepal (Paudyal et al., 2021). It coincides with a study conducted on 184 cattle sera with 1.63% seropositivity from Rupandehi, Nepal (Panth et al., 2017). Researchers from Bangladesh also reported a similar prevalence level of 3.33% in goat, 3.57% in cattle, and 9.52% in sheep (Rahman et al., 2016). Serological investigation in Saudi Arabia shows 44.6% prevalence, followed by 36.8% prevalence in sheep (Alkenani et al., 2024). However, these finding was comparatively lower than 11.3% among 300 blood samples from small ruminants from Punjab, Pakistan (Amin et al., 2022).
Table 1: Overall prevalence results of C. burnetii.
|
Total case |
Positive case |
Negative Case |
Seropositivity |
|
88 |
2 |
86 |
2.27% |
There was no significant association between age, physiological status, tick infestation, body condition score (BCS), abortion history, health condition, and stock source. The prevalence of C. burnetii was higher (2.86%) (Table 2) in young animals when compared with adults (1.89%). Animals at young ages were more affected (3.85%) (Table 2) than adults (1.61%). The level of prevalence was higher (7.69%) (Table 2) in such animals that had tick infestation compared to those which hadn’t (1.33%). Similarly, prevalence was found to be higher in animals whose BCS score was higher (i.e., 2.5-3.5) (2.47%) (Table 2) than in animals with a low BCS (2.5) score. Animals with a history of previous abortion showed a higher prevalence (11.11%) (Table 2) when compared with no abortion history (1.27%). In addition to abortion history, animals with frequently sick and ill conditions had a higher prevalence (7.69%) (Table 2) when compared with healthy (1.33%) animals. Study found that animals purchased from outside of the research station have a higher prevalence (4.00%) (Table 2) than those that were born and reared (1.58%) within the research station.
The current study and other studies carried out in different parts of the world have shown variations in the prevalence rates of C. burnetii infection in animals. These variations have been attributed to several factors, including the quantity and type of sample collected, the season, the location, the type of essay, potential variations among laboratories, testing protocols, and the standards used to define positive results.
Table 2: Association between Coxiella burnetii and risk factors.
|
Risk factor |
Variable |
Positive Case |
Negative Case |
Seropositivity % |
p-value |
|
Age |
<3 Years |
1 |
34 |
2.86% |
0.64 (NS) |
|
>3 Years |
1 |
52 |
1.89 % |
||
|
Physiological status |
Adults |
1 |
61 |
1.61 % |
0.51 (NS) |
|
Young |
1 |
25 |
3.85 % |
||
|
Tick History |
Yes |
1 |
12 |
7.69 % |
0.28 (NS) |
|
No |
1 |
74 |
1.33 % |
||
|
Body count Score (BCS) |
2.5 |
0 |
7 |
0 |
0.85 (NS) |
|
2.5-3.5 |
2 |
79 |
2.47 % |
||
|
Abortion History |
Yes |
1 |
8 |
11.11 % |
0.20 (NS) |
|
No |
1 |
78 |
1.27 % |
||
|
Health status |
Healthy |
1 |
74 |
1.33 % |
0.28 (NS) |
|
Sick |
1 |
12 |
7.69 % |
||
|
Source of Stock |
Purchased |
1 |
24 |
4.00 % |
0.49 (NS) |
|
Reared |
1 |
62 |
1.58 % |
4 Conclusion
This research demonstrated the prevalence of Q. fever in small ruminants in the Mid-hill region of Nepal. This suggests that Nepal may be an important endemic site for Q. fever, although there is a non-significant association with risk factors, due to the small study size. This doesn’t mean that there is no biological link; it was outside of the reach of our study. However, further serological and PCR techniques are required for disease surveillance and monitoring. Governmental regulatory authorities and related stakeholders should raise proper awareness and provide information; repeated screening and investigation are essential. Safe animal trading for disease-free animals should be implemented to minimize financial loss, and the promotion of the one health approach for disease control is essential. Furthermore, studies and diagnoses of Q. fever in other livestock are crucial for understanding disease transmission, control, outbreaks, and preventing health problems in Nepal.
List of Abbreviations:
PCR, Polymerase Chain Reaction; WOAH, World Organization of Animal Health; BCS, Body Condition Score; NARC, Nepal Agriculture Research Council; NGRP, National Goat Research Program; EDTA, Ethylene diaminetetraacetic Acid.
Acknowledgment:
We would like to acknowledge all staff of National Goat Research Program, Bandipur, Tanahun, Nepal.
Author’s contribution:
Methodology, Investigation, RG, PBS; Writing Original Draft, data analysis, RS, SA; Funding acquisition, Supervision, PBS.
Funding:
This Cross-sectional study was supported by Nepal Agriculture Research Council, National Goat Research Program, NARC/Project/2080/81, Surveillance of common goat diseases in the outreach and research sites of NGRP, Bandipur, Tanahun. Unique Project Identifier (UPI): 4187681004 and Office LMBIS Code: 312413801.
Ethical approval:
Not applicable. This study is carried as routine examination of livestock within goat research program.
Informed consent
Not applicable.
Conflict of Interest
The authors declare that there are no conflicts of interest regarding this study.
Data availability
Data can be provided by corresponding author upon reasonable request.
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