Introduction
Hand, Foot, and Mouth disease (HFMD) is a common viral illness, particularly in children under the age of 5. As cited by Jiang et al. (2021), HFMD is caused by the Coxsackie virus and is spread through contact with infected individuals or contaminated surfaces. Although most cases of HFMD are mild and self-limited, severe cases can occur, particularly in infants. This essay analyzes the hypothetical HFMD outbreak that occurred during February and March 2022 using the CDC’s Epi curve Excel Spreadsheet. Similarly, the paper will also provide an in-depth overview of the steps of an outbreak investigation to determine the source and extent of the outbreak.
The Type of Curve and Interpretation
The Epi curve was plotted using the number of cases against the onset date, as indicated in Table 1 (see Appendix). The resulting type of curve is a common source epidemic curve with characteristics of a propagated outbreak. This implies that person-to-person transmission is the primary mode of spread (Gao et al., 2021). More specifically, the Epi curve shows an initial rise in the number of cases in mid-February, a peak in early March, and a subsequent decline in cases towards the end of March. It is also right to argue that the onset of the outbreak is gradual, followed by a rapid increase in the number of cases in early March.
The Incubation Period
The Epi curve, short for epidemic curve, can be used to determine the incubation period of an outbreak. The Epi curve, as explained by Meagher and Friel (2022), is a graph that displays the distribution of cases over time during an infectious disease outbreak. The x-axis shows the dates when cases were reported, while the y-axis shows the number of cases. The epidemiological curve can be used to identify the likely source of the outbreak, estimate the incubation period, and inform public health interventions.Therefore, to determine the incubation period, one must look for the period between the exposure to the disease-causing agent and the onset of symptoms. From the plotted Epi curve (see Figure 1 in the Appendix), the incubation period for Hand, Foot, and Mouth disease is typically between 3 and 7 days. Based on the shape of the curve, it is clear that most cases occurred between February 19th and March 11th, spanning a period of 20 days. Therefore, one can estimate that the incubation period for this outbreak is around 3 to 7 days, which falls within the typical range for Hand, Foot, and Mouth disease. However, it is essential to note that this estimate assumes most cases were infected through a common source, despite the curve exhibiting characteristics of a propagated outbreak.
Epi Curve Based on Age Factors
Table 2 in the Appendix shows age-specific information that can be utilized to determine the Epi curve based on relevant factors. To construct the age-specific Epi curve, the number of cases by date of onset was plotted against age groups, placed in columns labeled “confirmed,” “probable,” and “possible” cases. The resulting graph illustrates the progression of the outbreak in each age group, providing valuable insights into the outbreak. The Epi curve in Figure 2, as constructed based on data from Table 2, shows that most cases occurred in children under 10 years of age. The outbreak’s peak was also observed in this age group, suggesting that this group was the most severely affected. The number of cases in the 10-20 age group was relatively lower, and the number of cases in the over-20 age group was very low.
The Steps of an Outbreak Investigation
Six specific steps can be utilized to investigate the Hand, Foot, and Mouth disease outbreak. The first step is to confirm the HFMD diagnosis and determine the extent of the outbreak (Ceres et al., 2022). Here, the focus is on collecting data on the number of cases, their specific ages, and the dates of onset. The second step is conducting a case-control study to help identify risk factors associated with the outbreak, including exposure to infected individuals, attendance at daycare or school, and hygiene practices. This is then followed by collecting and testing samples obtained from infected individuals to identify the specific strain of the virus and track its spread. The fourth step involves identifying the source of the outbreak, which may include contaminated food or water, contaminated surfaces, or infected individuals. Once this is done, the next step is to implement control measures to prevent further spread of the virus, including isolation of infected individuals (Ceres et al., 2022). The final step is to communicate the findings to the public authorities and healthcare providers.
Conclusion
Tables 1 and 2 clearly show that the hypothetical outbreak of HFMD that occurred during February and March 2022 was likely caused by person-to-person transmission of the Coxsackie virus. The Epi curve shows a characteristic propagated outbreak, with an incubation period of around 3-7 days. Most cases occurred in young children, consistent with the known epidemiology of the disease. Studying the outbreak would require gathering information on its scope, determining its contributing factors, and applying measures to control and stop further virus transmission.
References
Ceres, K. M., Stanhope, M. J., & Gröhn, Y. T. (2022). A critical evaluation of Mycobacterium bovis pangenomics, concerning its utility in outbreak investigation. Microbial Genomics, 8(6), 25-39.
Gao, Q., Liu, Z., Xiang, J., Tong, M., Zhang, Y., Wang, S., & Bi, P. (2021). Forecast and early warning of hand, foot, and mouth disease based on meteorological factors: Evidence from a multicity study of 11 meteorological geographical divisions in mainland China. Environmental Research, 19(2), 110-301.
Jiang, L., Jiang, H., Tian, X., Xia, X., & Huang, T. (2021). Epidemiological characteristics of hand, foot, and mouth disease in Yunnan Province, China, 2008–2019. BMC Infectious Diseases, 21(1), 1-8.
Meagher, J., & Friel, N. (2022). Assessing epidemic curves for evidence of superspreading. Journal of the Royal Statistical Society Series A: Statistics in Society, 185(4), 2179-2202.
Appendix
Table 1 – Epi Curve Data Entry Table: Number of Confirmed Cases.
Table 2 – Epi Curve Data Entry Table: Number of Cases by Age.
