Livestock Research

1. Introduction

Bovine mastitis, an inflammation of the mammary gland parenchyma most commonly triggered by microbial invasion through the teat canal, is widely regarded as the most economically damaging disease affecting the global dairy industry (Cobirka et al., 2020; Kour et al., 2023). In Bangladesh, where the livestock sector contributes nearly 1.5–1.8% of national GDP and sustains direct or partial employment for a large share of the rural population, dairy cattle are a cornerstone of household livelihoods and food security (Department of Livestock Services [DLS], 2025; Hossain et al., 2022). Despite a cattle population approaching 25 million head and rising annual milk production, the country still meets barely two-thirds of domestic demand, largely because smallholders with only one to three animals dominate production (Al Emon et al., 2024; Zaman Faruk et al., 2025). Within this fragile system, bovine mastitis is a principal biological constraint on productivity and on the national ambition of milk self-sufficiency (Ali et al., 2025; Bag et al., 2021).

Clinically, mastitis ranges from overt clinical disease marked by udder swelling, pain, and visibly abnormal milk to a far more insidious subclinical form that produces no outward symptoms yet substantially depresses yield and raises somatic cell counts (Cheng & Han, 2020; Stanek et al., 2024). Subclinical mastitis (SCM) is reported in the global literature to be fifteen to forty times more common than clinical disease (Kour et al., 2023; Sarker et al., 2013); the Bangladesh-specific prevalence figures compiled in this review suggest a comparatively narrower, though still substantial, gap, underscoring SCM as a genuine silent threat to Bangladeshi herds. Cow-level prevalence estimates vary widely from roughly 20% to nearly 72%, reflecting differences in geography, breed composition, management, and diagnostic method, while herd-level infection rates frequently exceed 70% (Aktaruzzaman et al., 2025; Bhuiyan et al., 2020; Hoque et al., 2015). Crossbred, high-yielding cattle such as Holstein Friesian crosses appear disproportionately vulnerable compared with indigenous zebu breeds, a pattern attributed to their greater metabolic demand and altered udder morphology (M. A. Islam et al., 2012; Singha et al., 2021).

Aetiologically, mastitis is a multifactorial disease associated with well over a hundred potential microbial agents, though bacteria, chiefly Staphylococcus aureus, Escherichia coli, and various Streptococcus species, remain the dominant organisms isolated from Bangladeshi dairy herds (Kabir et al., 2019; M. M. Islam et al., 2025). Compounding this microbial burden is a rapidly escalating pattern of antimicrobial resistance among mastitis-associated bacteria, with multidrug resistance reported in well over half, and in some studies nearly all, of the isolates examined (Bag et al., 2021; Salauddin et al., 2020). The detection of methicillin-resistant S. aureus carrying the mecA gene, alongside extended-spectrum β-lactamase producers, signals a resistance crisis with direct implications for both veterinary therapeutics and human medicine (Al Emon et al., 2024). This convergence of animal disease and antimicrobial resistance situates bovine mastitis squarely within a One Health framework, given the documented potential for resistant pathogens and antibiotic residues to move from infected udders into milk, the farm environment, and ultimately human consumers through the widespread practice of selling raw, unpasteurized milk (Abebe et al., 2016; Wani et al., 2022).

Although numerous regional investigations have documented mastitis prevalence, bacteriology, and resistance patterns across individual districts of Bangladesh, no comprehensive synthesis has yet integrated these disparate findings into a unified epidemiological and public health narrative spanning nearly two decades of research. Addressing this gap is essential for guiding evidence-based control interventions and for informing policy aimed at safeguarding both animal productivity and human health within a rapidly intensifying dairy sector (Ali et al., 2025; Tommasoni et al., 2023). Accordingly, this review pursues the following objectives: (i) to consolidate and critically appraise the existing literature on the prevalence and regional distribution of bovine mastitis in Bangladesh; (ii) to characterize its bacterial aetiology, risk factors, and diagnostic landscape; (iii) to evaluate the extent and public health significance of antimicrobial resistance among mastitis-associated pathogens within a One Health framework; and (iv) to identify critical knowledge gaps that should orient future research priorities in this economically vital sector.

2. Materials and Methods

Literature Search Strategy. As a narrative review, this paper does not follow a formal systematic-review protocol (e.g., PRISMA); rather, a structured search strategy was used to identify and organize the relevant literature. A literature search was conducted across six major databases and platforms: PubMed, ScienceDirect, Google Scholar, BanglaJOL, ResearchGate, and Scopus, covering publications from 2011 to 2025. This 15-year window was chosen to capture both foundational and the most recent research on the subject. The search combined key terms including “bovine mastitis,” “subclinical mastitis,” “clinical mastitis,” “dairy cattle,” “economic loss/impact,” “antimicrobial resistance,” and “Bangladesh,” applied individually and in Boolean combinations to maximize retrieval sensitivity and specificity. A supplementary manual search of the reference lists of retrieved articles and prior review papers was also conducted to capture studies not indexed by the primary search.

Inclusion and Exclusion Criteria. Studies were included if they were (a) peer-reviewed journal articles, postgraduate theses, or credible preprints; (b) reporting primary data or a review-level synthesis specifically on bovine mastitis in cattle reared within Bangladesh; (c) presenting data on prevalence, risk factors, bacteriology, antimicrobial susceptibility, or economic loss; and (d) published in English. Studies were excluded if they addressed mastitis in species other than cattle or in humans, were duplicate publications of the same dataset, were conference abstracts lacking extractable data, or were conducted outside Bangladesh except where an international study was used solely to provide comparative global context.

3. Bovine Mastitis: An Overview

Bovine mastitis is an inflammatory response of the mammary gland parenchyma, typically resulting from invasion of pathogenic microorganisms through the teat canal, and is characterized by physical, chemical, and bacteriological alterations in milk alongside pathological changes in glandular tissue (Ali et al., 2025; Cheng & Han, 2020). While primarily bacterial, inflammation can also follow physical trauma or irritation, and its severity reflects the interplay of host immune status, pathogen virulence, and management (Haxhiaj et al., 2022; Tommasoni et al., 2023).

Three principal clinical forms are recognized. Clinical mastitis (CM) presents with overt local signs redness, heat, pain, and swelling of the udder together with visibly abnormal milk (clots, flakes, watery consistency, or blood), and in peracute or acute cases, systemic signs such as fever, anorexia, and depression (Ali et al., 2025; Stanek et al., 2024). Subclinical mastitis (SCM), the “silent threat,” produces no visible abnormality in udder or milk yet reduces yield and elevates somatic cell count (SCC) above 200,000 cells/mL; it is reported globally to be 15–40 times more prevalent than CM, though Bangladesh-specific data suggest a narrower margin, and is detected only through screening tests such as the California Mastitis Test (CMT) or laboratory SCC (Cobirka et al., 2020; Hoque et al., 2015; Tommasoni et al., 2023). Chronic mastitis persists for months or an entire lactation, often with fibrosis, and because pathogens can survive within biofilms is difficult to cure and frequently causes permanent loss of productive quarters (Haxhiaj et al., 2022; Hoque et al., 2018).

Over 135–200 microorganisms have been implicated as potential causative agents, but bacteria dominate (Kabir et al., 2019; Kour et al., 2023). In Bangladeshi herds, the most frequently isolated pathogens are Staphylococcus aureus (a globally problematic Gram-positive pathogen often causing chronic or subclinical infection), Escherichia coli (a major Gram-negative environmental pathogen and leading cause of clinical disease), Streptococcus species particularly the contagious Strep. agalactiae and environmental Strep. uberis and Klebsiella pneumoniae, an environmental organism associated with severe clinical signs (Ali et al., 2025; Kour et al., 2023). Non-aureus staphylococci (NAS) have also emerged as important opportunistic pathogens driving elevated SCC (Al Emon et al., 2024; Farabi et al., 2025).

Pathogenesis begins with bacterial entry through the teat canal, whose keratin lining normally provides antimicrobial protection; damage from trauma or poor milking hygiene enables invasion (Cobirka et al., 2020; Haxhiaj et al., 2022). Once pathogens reach the teat cistern and alveoli, pattern-recognition receptors such as TLR4 trigger release of cytokines (IL-1, IL-6, TNF) and chemokines, recruiting neutrophils and sharply raising SCC (Haxhiaj et al., 2022; Hussein et al., 2018). S. aureus typically invades epithelial cells and forms protective biofilms, favoring chronicity, whereas E. coli provokes a rapid, severe response through endotoxin release that can cause systemic toxemia (Ali et al., 2025; Cheng & Han, 2020).

Epidemiologically, mastitis is classified as contagious reservoired in infected udders and spread via milkers’ hands, shared equipment, or biting flies or environmental, originating from bedding, feces, soil, and water and exploiting the exposed teat canal between milkings (Ali et al., 2025; Cobirka et al., 2020; Kour et al., 2023). In smallholder systems, unhygienic hand-milking and failure to milk infected cows last exacerbate contagious spread (Cobirka et al., 2020; Mia et al., 2025), while the sale of raw milk creates a route for zoonotic transmission of mastitis pathogens to consumers (Abebe et al., 2016; Kabir et al., 2019). Together, these biological and epidemiological features establish the backdrop against which the Bangladesh-specific evidence on prevalence, aetiology, and resistance is examined in the sections that follow.

4. Results and Discussion

4.1 The Bangladesh Dairy Sector and the Mastitis Burden

Livestock contribute approximately 1.54–1.82% of Bangladesh’s GDP and provide direct employment for about 20% of the population, with a further 50% partially or seasonally employed, particularly among youth, women, and landless farmers (DLS, 2025; Hossain et al., 2022). As of the 2024–2025 fiscal year, the national cattle population was estimated at 25.17 million, including about 3.53 million milking cows, and milk production reached 15.38 million metric tons meeting only about 69% of domestic demand (Singha et al., 2021; Zaman Faruk et al., 2025). This deficit is compounded by the predominance of smallholders, who manage 70–80% of the country’s dairy output with only one to three cows per farm (Al Emon et al., 2024). Against this backdrop, bovine mastitis represents one of the most significant threats to sector sustainability, with reported SCM prevalence ranging from 20% to 71.9% and crossbred cows exhibiting markedly higher infection rates (28.5–61.3%) than indigenous breeds (Ali et al., 2025; Al Emon et al., 2024; Singha et al., 2021). These figures set the scale of the challenge that the following sections examine in more granular, region-by-region detail.

4.2 Prevalence of Clinical and Subclinical Mastitis Across Bangladesh

SCM is the most pervasive form of mammary gland inflammation nationally; while global estimates put its incidence at 15–40 times that of CM (Kour et al., 2023; Sarker et al., 2013), the Bangladesh-specific animal-level figures below (20–71.9% SCM versus 7.4–15% CM) indicate a narrower gap of roughly five- to tenfold. Cow-level SCM prevalence has been reported to range from 20% to 71.9% depending on region and breed composition (Aktaruzzaman et al., 2025; Bag et al., 2021), while herd-level investigations find that 70.3–82.7% of farms have at least one affected cow (Al Emon et al., 2024; Farabi et al., 2025). Quarter-level prevalence typically falls between 21.7% and 32.3%, and clinical mastitis is comparatively rare, with animal-level rates of 7.4–15% (Ali et al., 2025; Zaman Faruk et al., 2025). Regional variation is considerable: Chattogram and the coastal belt report SCM up to 45.7% (animal level) and 76.8% (herd level), attributed to hot, humid conditions and poor floor hygiene (Hoque et al., 2015; Mia et al., 2025); the Sirajganj milk-shed shows 40.2–42.7% cow-level prevalence (Ali et al., 2025); Sylhet Division has recorded molecular SCM prevalence of 64.9% (herd level 82.7%) (Al Emon et al., 2024); and Northern Bangladesh (Rangpur–Dinajpur) reports an overall prevalence of 35.2% (Zaman Faruk et al., 2025). Detection rates also vary by screening tool, with laboratory SCC (71.9–85.2% sensitivity/accuracy) outperforming CMT, the White Side Test (WST), and the Surf Field Mastitis Test (SFMT) (Hoque et al., 2015). Table 1 summarizes prevalence data reported across representative regional studies.

4.3 Bacterial Aetiology

Staphylococcus aureus is consistently the leading aetiological agent in both clinical and subclinical mastitis in Bangladesh, with reported prevalence from 31.8% (SCM) to 46.7% (CM) (Al Emon et al., 2024; M. M. Islam et al., 2025). E. coli is the second major pathogen, particularly in clinical disease, with isolation rates around 35.8% nationally and up to 82.0% among SCM-positive animals in Sylhet (Bag et al., 2021; Al Emon et al., 2024). Streptococcus species, including S. agalactiae and S. dysgalactiae, also contribute substantially as contagious or environmental pathogens depending on species (Farabi et al., 2025; Singha et al., 2021), while non-aureus staphylococci notably S. chromogenes have emerged as a leading cause of SCM, accounting for up to 67.3% of isolates in some studies (Farabi et al., 2025). Klebsiella pneumoniae and Bacillus species are typically linked to environmental contamination and poor farm hygiene (Al Emon et al., 2024; Zaman Faruk et al., 2025). Table 2 summarizes the major bacterial pathogens and their reported antimicrobial resistance profiles.

4.4 Risk Factors

Occurrence of mastitis in Bangladesh reflects a complex interplay of host, management, and environmental factors (Ali et al., 2025; Zaman Faruk et al., 2025). Breed is a critical host factor: crossbred cows (e.g., Holstein Friesian × local) show significantly higher susceptibility than indigenous breeds, owing to higher yield and metabolic stress (Mia et al., 2025; Shikder et al., 2024). Higher parity (≥4) and older age are associated with markedly increased risk, likely reflecting chronic teat-end wear (Hoque et al., 2018; Zaman Faruk et al., 2025), and susceptibility peaks in early and late lactation (Al Emon et al., 2024; Shikder et al., 2024). Poor udder hygiene and absent post-milking teat disinfection are strongly linked to higher infection rates (Farabi et al., 2025; Hoque et al., 2018), and the absence of dry cow therapy and routine screening further compounds risk (Farabi et al., 2025; Hoque et al., 2018). Environmental factors such as concrete or muddy flooring and inadequate manure removal favor environmental pathogens (Singha et al., 2021; Zaman Faruk et al., 2025), and a history of prior clinical mastitis is among the strongest predictors of recurrent SCM (Sarker et al., 2013; Zaman Faruk et al., 2025). Lack of green grass feeding has also been identified as a nutritional risk factor, potentially reflecting inadequate vitamin and mineral intake (Sarker et al., 2013). Notably, most of these host, management, and environmental determinants are modifiable at low cost, putting meaningful risk reduction well within reach of smallholder farms provided the relevant practices are applied consistently.

4.5 Antimicrobial Resistance and Public Health Significance

AMR among mastitis-associated pathogens in Bangladesh has reached critical levels. Studies from Sylhet, Chattogram, and Northern Bangladesh report MDR bacteria in 64–84% of isolates, with SCM isolates from Sylhet reaching 98.2% MDR (Bag et al., 2021; Al Emon et al., 2024; M. M. Islam et al., 2025). This resistance is primarily attributed to indiscriminate antibiotic use without prior susceptibility testing, often at suboptimal doses (Bag et al., 2021; Salauddin et al., 2020). S. aureus, E. coli, and K. pneumoniae show extensive resistance to first-line antimicrobials: highest rates against amoxicillin (up to 94.5%), ampicillin (up to 89.5%), and penicillin G (up to 100%); tetracycline/oxytetracycline resistance of 66–89.5%; and near-complete resistance to cefixime and rising resistance to azithromycin and cephalosporins (Bag et al., 2021; Farabi et al., 2025; Zaman Faruk et al., 2025). Molecular studies have identified the tetA gene in up to 100% of resistant isolates, β-lactam resistance mediated by blaTEM-1 and blaZ, MRSA (mecA-positive) in 20–21.4% of isolates, and ESBL genes (blaTEM, blaOXA, blaCTX-M) among Enterobacteriaceae (Bag et al., 2021; Al Emon et al., 2024; Hoque et al., 2018).

These findings carry direct public health significance, since mastitis is a primary route for zoonotic transmission of MDR bacteria via the food chain, and consumption of raw or unpasteurized milk can precipitate septicemia, pneumonia, or foodborne toxicoses in humans (Cobirka et al., 2020; Farabi et al., 2025; Salauddin et al., 2020). Antibiotic residues in milk from treated cows further render it unfit for consumption and contribute to AMR development within the human gut microbiota (Abebe et al., 2016; Hoque et al., 2015). Because transmission is dynamic across humans, animals, and the farm environment, addressing this crisis requires a One Health approach combining antimicrobial stewardship, molecular surveillance, and promotion of alternative therapies such as nanoparticles or ethno-veterinary practices to reduce antibiotic dependency (Al Emon et al., 2024; Kour et al., 2023). Collectively, this pattern of resistance suggests that mastitis-associated bacteria in Bangladesh have moved well beyond an emerging concern and now constitute an active public health threat demanding urgent, coordinated action.

4.6 Diagnostic Approaches Used in the Field

Clinical mastitis is diagnosed through visual inspection and palpation for udder swelling, heat, redness, and pain, alongside gross milk abnormalities (Ahmed et al., 2023; Ali et al., 2025). SCM, lacking visible signs, requires cow-side screening. The California Mastitis Test (CMT) is the most widely used field test, using a reagent that reacts with somatic-cell DNA to form a viscous gel; Bangladeshi studies report accuracies of 70–76.75% with strong correlation to laboratory SCC (Hoque et al., 2015; Kabir et al., 2019). The White Side Test (WST), using 4% NaOH, shows lower sensitivity (57.9%) and accuracy (64.8%) (Hoque et al., 2015). The Surf Field Mastitis Test (SFMT), using household detergent, is the cheapest option but has the lowest sensitivity (~51.0%) (Hoque et al., 2015). The locally developed BLRI Mastitis Test (BMT) offers CMT-comparable accuracy at roughly 1 BDT per test versus 25–50 BDT for imported kits, illustrating the value of context-appropriate innovation (Kabir et al., 2019). Among laboratory methods, SCC (threshold >200,000 cells/mL) provides the highest sensitivity (82.5%) and accuracy (85.2%), while bacteriological culture remains the standard for pathogen identification and susceptibility testing despite requiring specialized equipment and 24–48 hours (Hoque et al., 2015; Hussein et al., 2018). Emerging biomarkers such as Milk Amyloid A may offer even greater sensitivity for early detection (Hussein et al., 2018). Despite these tools, widespread farmer unawareness of routine screening means SCM continues to cause substantial losses before detection (Ahmed et al., 2023; Ali et al., 2025). Overall, the diagnostic landscape reflects a familiar trade-off between cost and accuracy, one that affordable, locally developed tools are only beginning to resolve.

4.7 Economic Impact

Bovine mastitis is the costliest disease in the global dairy industry (Aktaruzzaman et al., 2025; Krishnamoorthy et al., 2021). An early, widely cited estimate placed Bangladesh’s annual production losses from SCM alone at Taka 122.6 million (USD 2.11 million) (Ali et al., 2025), though this figure originates from a 2003 study and has since been recycled in secondary literature without updating; more recent farm-level modelling indicates that current losses, expressed per 1,000-cow herds at prevailing milk prices, are likely substantially higher (Aktaruzzaman et al., 2025). Reduced milk output is the single largest component of loss roughly 49% in Bangladesh-specific estimates, though broader analyses report figures approaching 70%, a range likely reflecting differences in study design and case mix (Hoque et al., 2015; Wani et al., 2022) with intramammary infection also degrading milk fat, protein, and lactose content and its suitability for processing (Cobirka et al., 2020; Stanek et al., 2024). Veterinary and medication costs account for a further ~37% of losses (Kour et al., 2023; Wani et al., 2022), and persistent infection drives premature culling of high-yielding cows, with associated replacement costs and reduced conception rates (Ali et al., 2025; Mia et al., 2025). Beyond farm-level losses, the discarding of antibiotic-contaminated milk represents an additional economic drain, estimated at USD 20–50 per treatment cycle (M. A. Islam et al., 2012), and declining consumer confidence is shifting demand toward safer, organic dairy products (Kour et al., 2023). In sum, these losses illustrate why mastitis control is as much an economic priority as a veterinary one for Bangladesh's smallholder-dominated dairy sector.

5. One Health Implications

Bovine mastitis acts as a primary reservoir for the dynamic transmission of AMR pathogens across the animal–human–environment interface. MDR S. aureus and E. coli shed from infected udders contaminate bedding, floors, and milking equipment, and this contamination poses a critical public health risk in Bangladesh, where milk is often sold and consumed unpasteurized (Bag et al., 2021; Mia et al., 2025; Salauddin et al., 2020). Molecular evidence from a comparable South Asian setting (Pakistan) has demonstrated close genetic relatedness of resistance genes (mecA, blaZ) between S. aureus isolated from mastitic cattle and the nasal carriage of their milkers, highlighting occupational risk (Khan et al., 2020); direct Bangladesh-based evidence of this specific transmission pathway, however, remains a research gap. Biofilm formation further protects these pathogens from disinfectants and antibiotics, sustaining a persistent environmental reservoir (Abed et al., 2021; Cheng & Han, 2020), and MDR genes released via farm waste can enter soil and water systems with broader ecological consequences (Badawy et al., 2022; Bag et al., 2021).

For human health, pathogens recovered from mastitic milk including MDR S. aureus, E. coli, and K. pneumoniae can cause septicemia, pneumonia, and severe dermatitis, and mastitis-associated organisms have also been implicated in zoonotic diseases including tuberculosis, brucellosis, and leptospirosis (Al Emon et al., 2024; Haxhiaj et al., 2022; Salauddin et al., 2020). Because SCM allows apparently healthy cows to shed pathogens undetected, and because raw milk is widely sold directly to consumers, the risk of foodborne illness is amplified across Bangladesh’s dairy value chain (Ali et al., 2025; Bag et al., 2021). Antimicrobial residues from improper withdrawal-period compliance pose an additional toxicological threat and further promote AMR development in the human gut microbiome (Ali et al., 2025; Mia et al., 2025), while high daily contact between livestock and handlers on smallholder farms creates occupational exposure risk for farm laborers and veterinarians (Rifatbegović et al., 2024; Salauddin et al., 2020). A unified One Health strategy integrating regular herd screening, targeted antimicrobial stewardship, and environmental surveillance is essential to safeguard both veterinary and public health in this context (Badawy et al., 2022; Kour et al., 2023). These interconnected risks reinforce that mastitis cannot be managed as an isolated animal health issue, but must instead be addressed through coordinated action across the animal, human, and environmental health sectors.

6. Current Control Strategies and Challenges in Bangladesh

Mastitis control in Bangladesh emphasizes a transition from backyard rearing toward semi-intensive management, consistent disinfection of milkers’ hands and udders, and adoption of the internationally recognized “five-point plan” covering prompt case treatment, equipment maintenance, and biosecurity (Ali et al., 2025; Cheng & Han, 2020). Post-milking teat disinfection is among the most effective preventive tools, yet its uptake remains limited among smallholders lacking supplies (Farabi et al., 2025; Mia et al., 2025). Dry cow therapy (DCT), used to clear subclinical infection and prevent new cases during the dry period, is likewise underused, allowing pathogen persistence within herds (Hoque et al., 2018; Zaman Faruk et al., 2025). To address SCM’s silent burden, current strategies promote routine screening with cost-effective tools such as CMT or the BLRI BMT kit, alongside farmer education on housing sanitation and nutrition (Kabir et al., 2019; Zaman Faruk et al., 2025); vaccination initiatives remain hampered by the multi-etiological nature of the disease (Ali et al., 2025; Kour et al., 2023).

Antibiotic stewardship faces significant obstacles: most intramammary treatments are initiated without prior susceptibility testing, directly contributing to MDR emergence, and the absence of standardized national guidelines often results in suboptimal dosing by non-registered practitioners (Bag et al., 2021; Singha et al., 2021). Evidence-based treatment protocols and farmer education on withdrawal periods are urgently needed, alongside a unified One Health strategy linking veterinarians, policymakers, and producers (Al Emon et al., 2024; Farabi et al., 2025). Diagnostically, most farmers remain unaware of field screening tests, specialized diagnostic equipment is scarce, and laboratory methods such as SCC and PCR remain too costly for smallholders, while reliance on imported kits adds further cost (Ahmed et al., 2023; Kabir et al., 2019). These gaps push farmers toward non-registered practitioners offering empirical treatment without pathogen identification a primary driver of indiscriminate antibiotic use (Ahmed et al., 2023; Al Emon et al., 2024). Underlying all of this is the absence of a coordinated national surveillance program: research remains concentrated in established dairy regions, leaving Northern and Western Bangladesh underrepresented, standardized study designs are lacking, and prospective cohort data on clinical mastitis incidence are scarce (Hoque et al., 2018; Singha et al., 2021; Zaman Faruk et al., 2025). Overcoming these obstacles will require deliberate investment in diagnostic capacity, prescribing oversight, and surveillance infrastructure, rather than incremental adjustments to existing practice.

7. Knowledge Gaps and Future Research Directions

Several critical gaps constrain evidence-based mastitis control in Bangladesh. First, the absence of nationwide surveillance leaves true national prevalence, resistance gene dissemination, and emerging dairy hubs poorly characterized, and the lack of standardized study designs across investigations impedes cross-study comparison (Bag et al., 2021; Hoque et al., 2018; Zaman Faruk et al., 2025). Second, molecular epidemiological data remain sparse: while S. aureus and E. coli are well characterized phenotypically, deep genomic data on virulence profiles, phylogenetic relatedness, and animal-to-handler transmission pathways are largely lacking (Al Emon et al., 2024; Khan et al., 2020; Salauddin et al., 2020). Third, the transition from conventional phenotypic methods to whole-genome sequencing and metagenomics is needed to map the true national resistome, identify fastidious or closely related strains missed by standard culture, and support marker-assisted breeding for mastitis resistance via SNP identification (Al Emon et al., 2024; Hoque et al., 2018; Stanek et al., 2024).

Future research should prioritize large-scale, multi-regional and longitudinal surveys capable of tracing causal relationships between management practices and disease incidence, complemented by whole-genome sequencing and metagenomic profiling to characterize the national resistome. Parallel efforts should validate affordable point-of-care diagnostics building on initiatives such as the BLRI Mastitis Test and investigate antibiotic-sparing therapeutic alternatives, including bacteriophage therapy, ethno-veterinary remedies, and nanoparticle-based treatments. Economic evaluations of preventive interventions, nationally validated SCC thresholds, and exploration of SNP-based markers for breeding mastitis-resistant cattle would further strengthen the evidence base for control efforts.

8. Conclusion

Bovine mastitis sits at the intersection of Bangladesh’s two most pressing dairy-sector challenges: closing the national milk deficit and containing the rise of antimicrobial resistance. This review shows that the disease’s true weight falls disproportionately on its subclinical form, a condition invisible at the cowside yet responsible for the greater share of production losses precisely because it goes undiagnosed on the smallholder farms where most of the national herd is kept. S. aureus, E. coli, and Streptococcus species remain the consistent causative agents, and on their own would be a manageable problem; what makes the picture genuinely alarming is how routinely these same organisms now carry multidrug resistance, including methicillin resistance and extended-spectrum β-lactamase production. Combined with unregulated antibiotic use, minimal farmer awareness of low-cost screening options, and the everyday sale of raw milk, these findings place bovine mastitis squarely within a One Health problem rather than a purely veterinary one. Moving forward will require less improvisation and more infrastructure a coordinated national surveillance system, standardized diagnostic protocols, wider deployment of affordable tools such as the BLRI Mastitis Test, and genomic characterization of circulating strains to finally reveal the true scale of resistance gene spread. None of this is optional if Bangladesh is serious about both dairy self-sufficiency and safeguarding the health of the millions who depend, directly or indirectly, on its cattle.

Funding statement

This review received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

Conflict of Interest

The authors M.R.A. et al., declare no conflict of interest.

Acknowledgements

The authors M.R.A. et al., gratefully acknowledge the Department of Veterinary and Animal Sciences, University of Rajshahi, for institutional and logistical support during the preparation of this review.

​​​​​​​Author Contributions

M.R.A. conceived the study and drafted the manuscript. S.B.R., T.T., M.W.A. and A.A.M. performed data extraction and synthesis on prevalence, aetiology, and antimicrobial resistance. N.H. co-designed the methodology, supervised data synthesis, and critically revised the manuscript. N.S. assisted with literature screening and reference management. S.S.J. contributed to the One Health sections. M.A.I. supervised the research and revised the manuscript. M.S.I. conceptualized and supervised the study and served as corresponding author. All authors read and approved the final manuscript.

References