| Course | PHLT 8072 Communicable Disease Epidemiology |
|---|---|
| Week | Week 2 |
| Paper type | Chain of infection brief |
| Length | About 560 words, 5 pages |
| Format | APA 7 student paper |
| School | Walden University |
| Program | PhD in Public Health |
| Updated | October 2026 |
Free sample paper for PHLT 8072 Week 2
Downwind of the Kidding Barn: A Chain of Infection Brief Tracing Coxiella burnetii From a Composite Dairy Goat Farm to Workers, Visitors and Neighbors
Student Name
Walden University
PHLT 8072: Communicable Disease Epidemiology
Instructor Name
Month Day, Year
Downwind of the Kidding Barn: A Chain of Infection Brief Tracing Coxiella burnetii From a Composite Dairy Goat Farm to Workers, Visitors and Neighbors
Purpose
This brief traces Q fever through the six links of the chain of infection for a composite county, where a dairy goat farm of about 600 does sits two kilometers upwind of a small town. In early spring, during kidding season, the county health department received reports of fever, headache and pneumonia from farm workers, two people who had visited the farm and several residents who had never been near the animals. The brief identifies each link and notes which of them a health department can reach.
The Agent
Coxiella burnetii is an intracellular bacterium that forms a small, highly resistant variant able to survive for long periods in dust and soil. Very few organisms are needed to cause infection, which is why outbreaks can reach people with no direct animal contact (Eldin et al., 2017).
The Reservoir
Infected goats, sheep and cattle are the reservoir that matters here. Animals often look healthy while shedding the organism, and infected does may abort late in pregnancy. The farm's records show a cluster of abortions in the weeks before human illness was reported.
The Portal of Exit
Birth products carry the heaviest load. Placentas, birth fluids and aborted fetuses from infected does release enormous numbers of organisms at kidding, far more than milk, urine or feces. Timing therefore matters: exit is concentrated in a few spring weeks.
The Mode of Transmission
The organism travels on air. Contaminated material dries into dust in barns, bedding and manure, and wind carries it off the property. In the Netherlands, people living within two kilometers of an affected dairy goat farm had a risk of Q fever more than thirty times that of people living more than five kilometers away (Schimmer et al., 2010). Person-to-person spread is rare enough to be set aside for this brief.
The Portal of Entry
Inhalation is the route of entry. Workers in the kidding barn breathe the highest concentrations, but residents downwind breathe the same organism at lower doses.
The Susceptible Host
Everyone exposed is susceptible, and most infections go unnoticed. In one Dutch single-source outbreak, infection was found by blood testing in 92% of residents and employees of the source farm and in about half of visitors and household contacts, and observed incidence in the community fell steadily with distance from the farm (Hackert et al., 2012). Some hosts face greater harm: pregnant women and people with heart valve disease or vascular grafts are at risk of complications and long-term infection.
Where the Chain Can Be Broken
Three links are reachable by the health department working with agricultural partners: the reservoir, through vaccination of the herd; the portal of exit, through management of birth products at kidding; and the mode of transmission, through barn and manure practices that keep dust from leaving the property. The host link offers protection mainly for the people at highest risk. A later comparison will weigh these options by how quickly each acts. The brief's main finding for the county is that most of the people at risk will never set foot on the farm, so the response cannot rely on telling individuals to avoid animals; it has to reduce what the farm releases into the air.
References
Eldin, C., Mélenotte, C., Mediannikov, O., Ghigo, E., Million, M., Edouard, S., Mege, J.-L., Maurin, M., & Raoult, D. (2017). From Q fever to Coxiella burnetii infection: A paradigm change. Clinical Microbiology Reviews, 30(1), 115-190. https://doi.org/10.1128/CMR.00045-16
Hackert, V. H., van der Hoek, W., Dukers-Muijrers, N., de Bruin, A., Al Dahouk, S., Neubauer, H., Bruggeman, C. A., & Hoebe, C. J. P. A. (2012). Q fever: Single-point source outbreak with high attack rates and massive numbers of undetected infections across an entire region. Clinical Infectious Diseases, 55(12), 1591-1599. https://doi.org/10.1093/cid/cis734
Schimmer, B., ter Schegget, R., Wegdam, M., Züchner, L., de Bruin, A., Schneeberger, P. M., Veenstra, T., Vellema, P., & van der Hoek, W. (2010). The use of a geographic information system to identify a dairy goat farm as the most likely source of an urban Q-fever outbreak. BMC Infectious Diseases, 10, 69. https://doi.org/10.1186/1471-2334-10-69
The Walden PHLT 8072 Week 2 instructions
The second week typically asks for a brief that traces a chosen communicable disease through the chain of infection in a specific setting. Faculty expect all six links, from the agent and its reservoir through the exit route, the travel route and the entry route to the host, to be identified accurately and explained with evidence, not just named. The setting should shape the analysis, showing why the chain looks the way it does in that place. Strong briefs end by noting which links public health can realistically interrupt, preparing for later work on control. A brief of two to three pages with three or more current scholarly sources is typical. Students choosing a zoonosis should be clear about the animal reservoir and whether person-to-person spread matters.
Inside the PHLT 8072 Week 2 example
The brief opens by describing the composite farm, the town downwind and the reports of fever and pneumonia during kidding season. Six short sections follow, one per link. The agent section notes the organism's resistance and low infectious dose, citing a major review. The reservoir section explains that infected goats appear healthy and that abortions preceded human illness. The exit section identifies birth products as the heaviest source. The transmission section describes wind-borne dust and reports the Dutch finding that risk within two kilometers of an affected farm was more than thirty times that beyond five. The entry and host sections cover inhalation, near-universal susceptibility with attack rates from a single-source outbreak and the groups at risk of complications. A final section names the reachable links.
Where the marks sit in the PHLT 8072 Week 2 rubric
Instructors grade chain of infection briefs on accuracy, specificity and usefulness. Each link must be correct for the agent: identifying birth products, not milk, as the main portal of exit for Q fever, and air, not contact, as the main route, shows command of the disease. Specificity comes from tying each link to the setting, as the sample does with kidding season and the town downwind. Evidence earns credit, and the sample cites a review and two outbreak studies with accurate figures. Usefulness is shown by ending with the links a health department can reach. Clear organization under the six headings, concise writing and correct APA references for each source make up the remaining criteria.
Common PHLT 8072 Week 2 mistakes, and how to avoid them
Chain of infection briefs often list the six links in textbook language without adapting them to the disease or setting. Make every link specific: say which body fluid carries the agent out, which route carries it to the host, which hosts are at greatest risk. Another common error is confusing the reservoir with the source of a single infection; for Q fever, the herd is the reservoir and the kidding barn is where exposure concentrates. Students also overstate person-to-person spread for zoonoses. Check whether your agent truly spreads between people before including that route. Use outbreak investigations to supply real numbers, and report them accurately. Finally, end with the links your health department could actually act on. A custom brief for your own chosen disease can be prepared free on request.
Get a PHLT 8072 Week 2 example written to your instructions
Include the Week 2 prompt, the rubric and the agent your section named. The brief traces that agent link by link, separates the routes that operate from those that do not, and marks where a measure could act without choosing one yet. There is no charge the first time, and it arrives in 24-48 hours.
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PHLT 8072 Week 2 questions, answered
Where can I find a free PHLT 8072 Week 2 sample paper?
The full Week 2 chain of infection brief is published here, tracing Q fever from a composite dairy goat farm to people downwind through all six links, with real outbreak evidence and APA references. Margin notes explain where each part earns credit.
How is Q fever transmitted to people?
Mainly by breathing dust contaminated with Coxiella burnetii from infected animals' birth products, manure or bedding. Wind can carry the organism well beyond the farm, which is why residents with no animal contact can be infected. Person-to-person spread is rare.
Why does kidding season matter so much?
Placentas and birth fluids from infected does release far more organisms than milk, urine or feces, so most environmental contamination happens during a few weeks of births. Human cases often follow kidding or lambing seasons for that reason.
Who is at greatest risk of harm from Q fever?
Anyone exposed can be infected, and most infections go unnoticed. Pregnant women and people with heart valve disease or vascular grafts face a higher risk of complications and long-term infection, which is why the sample singles them out for host-level protection.
What did the Dutch outbreak studies show about distance?
People living within two kilometers of an affected dairy goat farm had a risk of Q fever more than thirty times that of people living more than five kilometers away, and in a single-source outbreak, observed incidence fell steadily with distance downwind.