Hypothesis Generation and Testing as an Integral Component of an Outbreak Investigation.

Sir,

Recently published article entitled, “Rapid response to syphilis outbreak among female sex workers” has referred an extremely topical subject of sexually transmitted infections (STIs) among vulnerable population of female sex workers (FSWs) in the country.[1] Furthermore, the evidence that STIs facilitate HIV acquisition and its transmission enhances the seriousness of the problem.[2] Huge burden of STIs has been one of the major driving forces for HIV/AIDS epidemic in India.[3]

However, we have following concerns about this study and intend to highlight here to help readers to be cautious before drawing conclusion.

Authors have aimed to identify risk factors associated with this outbreak. However, suitable statistical analysis for documenting the strength of association has not been detailed. Possibly, root cause analysis (RCA) was carried out to establish risk factors. RCA analysis can document cause and effect model for a problem to take corrective measures, yet it cannot establish association precisely in epidemiological sense. It can complement an outbreak investigation, but it cannot replace the standard outbreak investigation protocol[4]

Result section has well documented the descriptive analysis but completely missed the results of qualitative part (in-depth interview). Fishbone diagram was plotted after RCA analysis but has neither been appropriately labeled in the manuscript nor summarized

The same is true for Figure 1[1] showing epidemic curve. It has also neither been appropriately labeled in the manuscript nor summarized

Outbreak investigation demands hypothesis testing to establish risk factors. It is a critical step for future prevention of outbreaks. Comparison of variables from FSWs who developed syphilis and those who did not would have yielded important risk factors for this outbreak. Although results of in-depth interview among this group have given an important insight about factors responsible for an outbreak, yet quality of evidence would have been better had quantitative methods been utilized

The sudden upsurge of cases around April as depicted in epidemic curve need to be explained or discussed. Exploration of plausible explanation for this has potential to highlight additional factors.

Unlike to an outbreak investigation, only cases who reported to the facility were investigated, no data were collected from asymptomatic FSWs. Disease follows ice-berg phenomena, and thus ideally, all FSWs from the affected area should have been screened for syphilis for active case finding.

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Conflicts of interest

There are no conflicts of interest.