ABSTRACT
Background:
Rabies is a disease transmitted mostly through animal bites in humans, and seasonal variation in animal bites has been reported by different studies. There has been no study in India using time series analysis for studying monthly variation in animal bite cases.
Aim:
(a) To find out long-term trends and monthly variations in new animal bite cases. (b) To make projections for new animal bite cases. (c) To find out the difference between actual and projected new animal bite cases following the COVID-19 pandemic.
Methodology:
A retrolective, record-based study was conducted in a tertiary care facility, Jaipur, and data of new Category II and Category III animal bite cases were taken from January 2007 to December 2021. A multiplicative model was used for conducting time series analysis. The projected monthly number of cases was estimated using the line of best fit based on the least square method.
Result:
An increasing trend in the annual number of animal bite cases was observed from 7,982 in 2007 to 10,134 in 2019. The monthly index was lowest for the months July to November (0.88 to 0.95), peaked in January (1.14), remained higher from January to June, and fell in July (0.95). The monthly number of new animal bite cases from April 2020 to December 2021 was significantly lower than the projected number (P-value < 0.001).
Conclusion:
Because the monthly index of animal bite cases was high from January onward, information education and communication (IEC) activities should be increased in the preceding months (November onward) for making people aware of immediate care to be provided to animal bite cases and seek prompt medical care.
Keywords: Monthly variation, projection, rabies prophylaxis, time series analysis
Introduction
Rabies is the only communicable disease of man, which is 100% fatal but vaccine-preventable.[1] Of all cases, approximately 99% are acquired from the bite of an infected dog. Around 59,000 deaths occur globally due to dog-mediated rabies annually, with an associated loss of 3.7 million disability adjusted life years (DALYs). An estimated 35,172 human deaths (59.6% of global deaths) and a loss of approximately 2.2 million DALYs occur per year in Asia due to dog-mediated rabies. India accounts for the most deaths in Asia (59.9% of human rabies deaths) and globally (35% of human rabies deaths).[2] In India, there are 17.4 million exposures to animal bites and 20,000 deaths attributed to rabies occurring every year.[3] In 2015, the world called for action by setting a goal of zero dog-mediated human rabies deaths by 2030. The strategic plan for achieving the goal of zero by 30 laid down an important objective “To generate, innovate and measure impact through policies, guidance and governance; and reliable data to enable effective decision-making.”[4] Understandably, efforts aimed at reducing the number of animal bite cases (especially dog bite cases) should be an important intervention toward achieving this goal.
Though reported throughout the year, different studies have documented that there is a seasonal pattern in animal bite/dog bite cases. In a study in northern India, it was found that the mean number of dog bite cases per month was highest in the spring season (March and April) followed by winters (November to February).[5] In another study, seasonal predisposition was found in the months of March and June.[6] In these studies, analysis was based on means/standard deviation. No studies in the context of India have been found by the authors in which a time series analysis of a monthly number of new cases was conducted for finding out the monthly variation in new cases of animal bites.[7] Moreover, whatever studies reported in the area of seasonal variation in animal bite cases have been conducted using data for shorter periods.
The present study was conducted in the Anti-Rabies Clinic of S.M.S. Hospital attached to S.M.S Medical College, Jaipur, Rajasthan with the following objectives-
To find out long-term trends and monthly variations in new animal bite cases by attending Anti-Rabies Clinic from January 2007 to December 2019.
To make projections for new animal bite cases expected to attend Anti-Rabies Clinic from January 2020 to December 2022.
To find out any difference between the actual and projected number of new animal bite cases attending the Anti-Rabies Clinic from April 2020 to December 2021 after the implementation of lockdown following the COVID-19 pandemic.
Methodology
Study setting
S.M.S. Hospital attached to S.M.S. Medical College, Jaipur, is the largest tertiary health care hospital in the State of Rajasthan. Animal bite cases from Jaipur and from all across the State come for management at the Anti-Rabies Clinic of this hospital, where records are well maintained. By and large, animal bite cases from Jaipur district come here for post-exposure prophylaxis against rabies and some cases also come from the other districts of the State. Although anti-rabies vaccine (ARV) is available even at the primary health centers, this is the only government health facility in Jaipur district that has a facility to administer anti-rabies serum (ARS) in Category III animal bites.
Study design
A retrolective, record-based study was conducted in Anti-Rabies Clinic wherein the monthly number of new Category II and Category III animal bite cases was taken from the records of the Anti-Rabies Clinic. Category I animal bite cases were excluded from the study.
Data collection and analysis
A monthly number of new Category II and Category III animal bite cases was taken from the records of the Anti-Rabies Clinic for the period January 2007 to December 2021. The strict lockdown was implemented toward the end of March 2020; for this reason, the data on the actual number of new animal bite cases were segregated into two parts – (a) data for the period from January 2007 to December 2019 were used for studying long-term trends and monthly variation in cases and for making projections in a number of monthly cases from January 2020 to December 2022, and (b) data for the period April 2020 to December 2021 for studying the change in a number of new cases as a result of the implementation of lockdown following the start of the COVID-19 pandemic. Because of the expected drop in the number of new animal bite cases on account of the implementation of lockdown, data up to December 2019 were taken for finding out monthly indices and for estimating the monthly projected number of cases. Data were entered into Microsoft Excel 2019 and the multiplicative model was used for conducting time series analysis.[7] Centered moving averages were calculated for all months for the period 2007 to 2019 followed by the calculation of monthly indices. The average of respective monthly indices was used to arrive at the average monthly index. A monthly index was then used for estimating the deseasonalized number of cases per month, and the projected monthly number of cases for the period January 2020 to December 2022 was estimated using the line of best fit based on the least square method. Once the line of best fit was determined for projecting the monthly number of new animal bite cases for this period, the final projected number of monthly new animal bite cases was obtained by incorporating the monthly index. The projected monthly number of cases from April 2020 to December 2021 was then compared with the actual number of cases during the same period and paired t-test was applied to see if there was any significant difference between the actual and projected number of cases.
Ethical issues
There were no ethical issues involved in the conduct of this study.
Results
Long-term trend of new animal bite cases
A total of 1,10,784 Category II and Category III animal bite cases were seen in Anti-Rabies Clinic for 13 years from 2007 to 2019. About two-thirds (66.4%) of all new cases attending the Anti-Rabies Clinic were Category III bite cases. An increasing trend in the annual number of animal bite cases was observed–the number of animal bite cases initially decreased from 2008 to 2010 and thereafter steadily increased up to 2019 [Figure 1].
Figure 1.
Trends of annual new animal bite cases, 2007–2019
Monthly variation in new animal bite cases
The monthly number of animal bite cases ranged from 416 to 1,012 (median 707 cases) [Figure 2]. The monthly index of new animal bite cases ranged from 0.88 to 1.14 [Figure 3]. It was lowest for the months July to November (0.88 to 0.95), thereafter increasing in December (0.99), and peaked in January (1.14). It remained higher from January to June and fell in July (0.95) to the lowest levels in August to September (0.88). The monthly index for 13 months from December to January is shown in Figure 3 for a better appreciation of the increasing trend beyond December to January.
Figure 2.
Monthly new animal bite cases, 2007–2019
Figure 3.
Monthly index of new animal bite cases, 2007–2019
Projections of new animal bite cases
The projected number of new animal bite cases from January 2020 to December 2024 shows an increasing trend from 2020 to 2024 [Figure 4]. The monthly projected number of cases shows a marginal increase for the respective months [Figure 5].
Figure 4.
Annual actual and projected number of animal bite cases
Figure 5.
Projected monthly number of animal bite cases, 2020–2022
Impact of lockdown on new animal bite cases
The monthly number of new animal bite cases attending the Anti-Rabies Clinic during the period April 2020 to December 2021 was significantly lower than the projected monthly number during the same period [Figure 6] (t = 8.81, df = 20, P value < 0.001). The difference between the actual and projected number of cases was huge in April 2020 (actual 148 compared to projected 856) and this difference kept on narrowing continuously until February 2021 (when the actual number of new animal bite cases was more than the projected number–914 compared to 892). Thereafter, from March 2021 onward, the actual number of cases once again sharply fell from March to May 2021, and the actual number of cases was constantly lower than projected cases until December 2021. The majority of these monthly new cases were Category III animal bite cases, ranging from 51.7% to 86.1% of all new cases.
Figure 6.
Comparison of projected and observed new animal bite cases following lockdown due to the COVID-19 pandemic (Apr 2020–Dec 2021)
Discussions
The increasing trend in actual and trend number of animal bite cases from 2010 to 2019 is similar to the rise in the number of animal bite cases reported by other authors.[5,8,9,10] More than 90% of new animal bite cases attending the Anti-Rabies Clinic were dog bite cases and understandably, a trend of new animal bite cases would be an indicator of new dog bite cases over the years as seen in various other studies.[3,10] This increase in dog bite cases could be because of increased chances of interaction between humans and dogs due to the increase in human and dog populations, coupled with the increase in outdoor activities by humans and improved care seeking and reporting of dog bite cases to SMS Hospital, Jaipur.
A monthly index of animal bite cases was high from December through June and low from July to November. These findings are largely similar to the findings reported in some studies and markedly different from some other studies.[11] Taneja et al. reported a lesser frequency of dog bite cases in November, December, and January (winter months) and increased frequency in February, March, and April (spring months).[9] Saleem et al.[5] reported lesser incidence of animal bite cases during winter months from November to February and higher incidence during the months of March and June. Satapathy et al. reported the maximum number of animal bite cases from October to December (winter season), lesser cases during spring months, and least cases during summer months.[11] Jethani et al.[8] reported an increasing number of animal bite cases in March and April followed by a dip in cases after May until September and thereafter a rise again in animal bite cases in the autumn season. The basis of the lesser number of cases in winter months reported in some studies is the reduced outdoor activity and movement of humans in these months, thereby reducing the chances of human-dog interaction.[5] Similarly, the increasing number of cases during the summer months reported by some studies has been attributed to increased outdoor activities.[5,12] Reece et al.[13] have linked seasonality in human dog-bite cases and breeding of street dogs, with canine reproduction and happening of peak whelping activity in November; they reported the main peak in human dog-bite cases in January–about 10 weeks after peak whelping activity–and a secondary peak in June. Thus, it may be reasonably drawn that the high monthly indices of dog-bite cases during January and subsequent months (February and March) could be attributed to the whelping activity of bitches and their protective behavior toward their puppies until such time that the puppies disperse. And the sustained high monthly indices from April to June could be attributed to increased outdoor activities of humans, especially children, thereby increasing chances of interaction with dogs.
To date, many studies on the seasonality of animal/dog bites have been reported, out of which some have concluded about seasonality based on only 1-year data.[4,14] Some other studies have reported seasonality of animal/dog bite cases by taking the arithmetical means of a number of cases of respective months.[5,8,15,16] In yet another study, the autoregressive integrated moving average model (ARIMA) was used for studying the trends in dog bite cases.[9] In the present study, monthly variation in animal bite cases was ascertained by finding out the monthly index using the multiplicative model of time series analysis, which is frequently used by business organizations/entities for estimating the monthly consumer demand for different consumables/products.[7]
The sudden decline in animal bite cases observed in April 2020 can be largely attributed to the lockdown declared by the Government of India in late March 2020 due to the COVID-19 pandemic, which restricted the movement of people. It is possible that during the lockdown period, new animal bite cases initially approached a nearby health care facility for post-exposure prophylaxis against rabies and a large number of Category II animal bite cases might have been managed by peripheral primary, secondary, or tertiary health care facilities and largely Category III animal bite cases being referred to SMS Hospital, Jaipur; this is further evidenced by the increase in new animal bite cases in the Anti-Rabies Clinic following the relaxation of lockdown. A moderate rise in animal bite cases was observed from July 2020 onward along with a sharp rise in January and February 2021, which could be because of the relaxation in lockdown declared by the Government coupled with the expected increase in the number of dog bite cases at the tertiary care hospital due to high monthly index for these months. A sharp decline in the number of animal bite cases was seen from April 2021 onward due to the lockdown yet again imposed by the government following the second wave of the COVID-19 pandemic, which was subsequently relaxed in July 2021, again resulting in a moderate rise in animal bite cases at SMS Hospital. Thus, the significant variation in the monthly number of new animal bite cases reported to the SMS Hospital, Jaipur during the period April 2020 to December 2021 was expectedly in line with the curbs imposed during lockdown by the government as also the monthly index of animal bites for the respective months.
The goal “Zero by 30” of the global strategic plan to prevent human deaths from dog-transmitted rabies by 2030 can be achieved by a combination of (a) post-exposure prophylaxis of rabies and (b) reducing the number of animal bite cases. Taking into account the monthly index of animal bite cases, interventions may be designed to (a) plan facilities for post-exposure prophylaxis of rabies and (b) design health education activities, especially focusing on those months where the monthly index is higher (December through June) for making people aware on the precautions they should take for preventing themselves from being bitten by an animal, especially dog, on immediate care to be provided to a person who has had a dog bite and to seek prompt medical care in the case of an animal bite.
Limitations
The study was based on data from the Anti-Rabies Clinic of S.M.S. Hospital, which is a tertiary health care facility attached to the SMS Medical College, Jaipur, and does not take into consideration data from other public or private tertiary, secondary, and primary healthcare facilities in the district. However, being the largest tertiary hospital in the State and being the only health care facility in Jaipur district that has a facility to administer ARS in Category III animal bites, data from the Anti Rabies Clinic of the hospital can be taken as representative of the trend of animal bite cases in the district and the State.
Conclusion
To achieve “Zero by 30,” which is the goal of a global strategic plan to prevent human deaths from dog-transmitted rabies by 2030, policy actions and interventions should be planned accordingly, keeping in mind the monthly variations in new animal bite cases. Because the monthly index of animal bite cases attending the Anti-Rabies Clinic of the tertiary hospital was high from January onward, IEC activities by the health care delivery system should be increased in the preceding months (November onward) for making people aware of the precautions they should take for preventing themselves from being bitten by an animal, especially dog, on immediate care to be provided to a person who has had a dog bite, and on seeking prompt medical care in case of an animal bite. There is a projected annual increase in animal bite cases in the upcoming years and thus intense action needs to be taken with intersectoral coordination.
Financial support and sponsorship
Nil.
Conflicts of interest
There are no conflicts of interest.
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