Sporadic outbreaks of cutaneous anthrax: A tip of the iceberg


Background: Although primarily a zoonotic disease, anthrax can be transmitted to human beings either directly or indirectly from animals. India being an endemic region for anthrax, the underreporting of cases from different parts makes it difficult to estimate the actual burden of anthrax, particularly in rural belt. Materials and Methods: A medical team consisting of members from medical college, public health and animal husbandry department went to visit a tribal village of Paschim Medinipur, West Bengal, from which place one person attended the skin department of Midnapur Medical College with painless hemorrhagic vesicular lesion. It resulted to high index of suspicion for an outbreak of anthrax. We interrogated the risk population of the area along with clinical examination and samples for relevant investigation were collected from them. Results: Out of 151 persons, 111 were found to come in contact with a dead cow. Among them, 11 persons had cutaneous anthrax, and all were associated with butchering animal. Attack rate was 7.3%, and the mean age was 35.9 years with a mean incubation period of 2.81 days. Six cows were found positive for anthrax in blood examination. Conclusion: Public awareness programs are to be undertaken from time to time so that early detection and treatment can prevent death from human anthrax. Regular survey and vaccination of livestock in endemic regions are to be undertaken by the animal health department.

Keywords: Anthrax, cutaneous lesion, zoonotic disease

How to cite this article:
Achar A, Satpathi PS, Mukherjee P, Bera GC, Satpathi S. Sporadic outbreaks of cutaneous anthrax: A tip of the iceberg. Ann Trop Med Public Health 2018;11:125-9


How to cite this URL:
Achar A, Satpathi PS, Mukherjee P, Bera GC, Satpathi S. Sporadic outbreaks of cutaneous anthrax: A tip of the iceberg. Ann Trop Med Public Health [serial online] 2018 [cited 2020 Oct 30];11:125-9. Available from: https://www.atmph.org/text.asp?2018/11/4/125/272553



Anthrax, primarily a zoonotic disease, caused by Bacillus anthracis, affects the herbivorous animals such as cattle, sheep, and goat and can be transmitted to humans either directly or indirectly from animals or animal products. Annually, around 20,000–100,000 cases of anthrax are estimated to occur worldwide.[1]

The disease has been eradicated from the Western world but has never been fully controlled in Asian, African, and Central American countries because of lack of standardized and effective public health programs. Adequate surveillance and proper vaccination to live stocks could prevent the animal–soil–animal transmission. India is an endemic region for anthrax and gives rise to human anthrax sporadically in different regions of the country, particularly in south India. Moreover, the application of anthrax as an agent of bioterrorism got importance after the 2001 bioterrorist activity involving the USA postal service leading to anthrax in 22 people.[2]

Bacillus anthracis, the causative agent of anthrax has got three well-defined cycles, for example, multiplication of spore in the soil, animal infection, and infection in human. The spore undergoes periodic burst of local multiplication in the soil and under favorable environmental condition increases the chance of infection in grazing animals. The spores can remain infectious for decades and that should be an important consideration in respect to the epidemiology and control of disease.[3] Actual incidence of anthrax in India is not properly known because of lack of awareness of the people in the rural areas leading to underreporting of cases.[4] There are few cases of human anthrax reported from the eastern part of India. We are reporting an outbreak of cutaneous anthrax in a tribal village of West Bengal in June 2014 because of butchering an infected dead cow in that area.


One male patient from a remote village of Paschim Medinipur attended the dermatology outpatient department (OPD) of Medinipur Medical College and Hospital, with some cutaneous lesion on his forearm. People in the said village are of tribal community and engaged in farming, so keep livestock at home for their use. On examination, a painless hemorrhagic vesicular lesion with out of proportion edema surrounding that area was seen. With high index of suspicion, history was taken from the patient who revealed that they slaughtered a dead bullock to consume it some 5 days back. The event was informed at once to district public health administration and the animal health department. A team of district health officials, animal health officials, and faculties of Medical College visited the affected area with the suspicion of an outbreak and to ascertain:

  1. The cause of the disease in the population there and to confirm it
  2. To identify possible risk factors and to create awareness among the local population and health workers
  3. To survey the livestock affected and to use prophylactic measure in them.
Materials and Methods

A team of the faculty members from Microbiology, Dermatology, District health officials, and personnel from animal health department were formed to visit the area without delay with the suspicion of an outbreak. The faculty team along with the public health officials made a house-to-house survey. The faculty team clinically examined them and gathered a detailed history of all the total 151 persons who were staying in that area. All the 11 persons having cutaneous lesions were suspected to be of anthrax, and vesicular fluid, fluid from surrounding edematous area, was aspirated from all of them along with swab from the ulcer. Punch biopsy was taken from one patient for histopathology and blood for aerobic culture taken from all 11 suspected cases. Gram stain was done from all specimens collected, and the specimens were inoculated in sheep blood agar and MacConkey agar and processed by incubating them overnight at 35°C. Mac-Fadyean stain was done for confirmation of the presence of capsule. Complete blood count, erythrocyte sedimentation rate, and baseline biochemical tests were also done in all cases. All 11 patients were treated with ciprofloxacin/amoxicillin for 60 days, and others were given medicine for 10 days. The Block Medical Officer of Health of the affected block was asked to follow-up for six months. The animal health team surveyed the animals, and out of 11 dead animals, blood was taken from 10 animals by them for processing. The team continued vaccination for rest of the 1828 animals of the area.


After complete survey of the area by our team, it was found that 111 out of the total 151 persons in the village and adjacent area came in contact with the dead animals. Forty-three persons were engaged in washing and cooking meat, but none of them were affected. Eleven persons who were involved in slaughtering and chopping the dead bullock were affected by cutaneous lesion. Rest of the persons who only consumed meat were not affected. The cutaneous lesions of the eleven persons were mainly in the fingers, hands, and forearm 1–3 days after the event. In early stage, they were more edematous with hemorrhagic vesicles, whereas in late stage there was ulceration leading to eschar formation [Figure 1]. One of the affected persons visited the OPD 5 days after butchering of dead bullock. Out of the 11 persons affected, 8 were male and 3 female. Overall attack rate is 7.3% whereas attack rate in male and females, respectively, are 72.72% and 27.27%. The age ranges of diseased population were 7–60 years with a mean age of 35.9 years. Exposure to bacteria was 100% during butchering, but fatality was nil. Most of the persons developed clinical manifestation after 1–3 days after butchering with a mean incubation period of 2.81 days. Predominantly affected site of cutaneous lesion was finger and hands (81.8%) followed by the forearm (18.15%). All blood cultures were negative. Gram-stained smears made from the materials of 5 cutaneous lesions showed few long Gram-positive bacilli with typical capsules in some and squared ends in all [Figure 2]. Culture in blood agar media from cutaneous lesions of 6 samples [Table 1] showed nonhemolytic medusa head colonies. They were nonmotile in hanging drop preparation and when gram stained showed long chains of capsulated bacilli with typical bamboo shoot appearance [Figure 3]. They were all catalase positive, and Mac-Fadyean stain was also positive. Based on the above mentioned findings, they were identified as Bacillus anthracis as per the WHO criteria. The clinical diagnosis also well correlated with the laboratory findings. Complete blood count and biochemical parameters were within normal limits.

Figure 1: Beginning of eschar formation with few hemorrhagic vesicles

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Figure 2: Gram-stain from cutaneous lesion-anthrax bacilli with chronic inflammatory cells

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Table 1: Distribution of cases in relation to age, sex, body part affected, and laboratory results

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Figure 3: Long chains of capsulated anthrax bacilli with typical bamboo shoot appearance-Gram-stain from blood culture

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As per the report of the Animal Health Department, 6 cows were found to be positive for B. anthracis in laboratory investigations of the blood samples collected from them. During the last 6 months survey by the Public Health Department, there was no relapse or new case in the same area.


Bacillus anthracis, an aerobic, Gram-positive, encapsulated, nonmotile, spore-forming, long thick bacillus, can remain in the soil in a spore form for decades and predominantly infects the herbivores such as cattle, goat, and sheep. These herbivores are used as livestock by farmers in agricultural work, particularly in rural areas. India has high density of livestock population and so prepares a favorable environment for the transmission of disease between more susceptible animals and less susceptible human beings. Human is an accidental host. Anthrax is one of the eleven major zoonotic diseases accorded a priority status in India by the expert group of Roadmap to Combat Zoonoses in India.[5]

Naturally acquired human anthrax infection generally results from direct contact with infected animals or occupational exposure to infected or contaminated animal products such as hides, bones, and hair. Human anthrax is divided into four clinical forms according to mode of organism acquisition. The major three are inhalational anthrax occurring due to inhalation of spores, gastrointestinal anthrax occurring due to ingestion of contaminated meat, and cutaneous anthrax due to the introduction of spores through an opening in the skin. About 95%–99% of the anthrax cases worldwide are cutaneous infections, beginning with 2–5 days after contact with a small, pruritic, nonpainful papule at the site of inoculation. Papule then develops into a hemorrhagic vesicle which ultimately ruptures – ulcerates – dries up and forms a coal-black scab known as eschar which is surrounded by edema out of proportion to the size of the lesion.[1],[3] Usually, there is fair chance of injury to skin in the activity of slaughtering and chopping of an animal which is not common during washing of chopped meat. This might be the reason that all persons who were engaged in slaughtering and chopping activity had cutaneous anthrax. Indians have the habit of cooking the meat adequately before consuming it. Hence, none of the villagers who consumed meat suffered from gastrointestinal anthrax. In untreated cutaneous anthrax, mortality is 20%. This is in contrast to our patients who were detected and treated early and no complications developed in them.

Animal anthrax is very common in many parts of India. Since 1953 till 2000, the number of human anthrax reported is 182.[6] All the cases have been reported from South India proving the disease to be endemic in that part of the country.[7],[8],[9],[10],[11],[12] In contrast, eastern parts of India have two previous reports from Murshidabad in 2007[13] and from West Midnapore in 2012.[2] In our study, the age group mostly affected is 12–45 years which is nearly similar to the previous two reports. The mode of acquiring the infection is also similar to the previous report from this part of India.

Cutaneous anthrax was reported in 2007 by Rao et al. from Araku Valley[14] and in 2009 by Rao et al. from Vizianagaram[15] both from Andhra Pradesh. The outbreak of cutaneous anthrax was also reported by Reddy et al. for clinically suspected 9 cases without any bacteriological proof, but all were affected by handling dead livestock and livestock were positive for Bacillus anthracis.[16] In all these, the mode of acquiring the disease was due to handling of infected animals similar to ours. In two reports, they diagnosed by conventional method. Similar approach was taken in our case. This emphasizes that a high index of suspicion on the part of the treating physician, collection of proper history, and minimum of investigations are required to detect cases even in a peripheral setup.

History of contact, clinically edema out of proportion to the size of the lesion, lack of pain in early stage, and rare presence of polymorph nuclear leukocytes in the gram-stained smear made from the vesicular fluid is strongly suggestive of coetaneous anthrax.[17] Moreover, in our observation, we found culture positivity in 6 cases of coetaneous anthrax from patients and dead cow.

We have some limitations in our study. Several methods, that is, specific enzyme-linked immunosorbent assays, enzyme-linked immunoelectrotransfer blotting, indirect microhemagglutination, and polymerase chain reaction have been used for the diagnosis of anthrax.[18] However, due to nonavailability of these tests in our set up, we depended on the conventional methods for the detection of B. anthracis in our patients.

As per the Centers for Disease Control and Prevention recommendation, the first line of treatment is with ciprofloxacin or doxycycline. Clindamycin is an alternative option if fluoroquinolone or doxycycline is unavailable or contraindicated. Although naturally occurring cutaneous anthrax are treated with a 10- to 14-day course, our cases were treated for 60 days with the idea that inhaled spores can remain for an extended period.

Early intervention by the team of public health, animal health, and the team from the medical college could prevent death of any person during this outbreak in comparison to the earlier report from Midnapore.[2] There was no death in comparison to the previous outbreak where two deaths were recorded (18%). All the persons in contact with the livestock were also given the same medicine for 10 days, and regular surveillance by the public health officials did not find any relapse or new case of anthrax in this area for the next 6 months.


To summarize, the outbreak was limited to the population involved with butchering and handling the raw meat of the dead cow with a mean incubation period of 2.81 days. Others who took meat after boiling for 1 h did not contact the disease. As 11 animals died of anthrax, it seems to be present in the area. As a preventive measure, the local Animal Health Department should continually survey the livestock and vaccination should be provided to all livestock in an organized manner. Regarding human anthrax, the health-care workers should be made aware of the deadly disease so that they can report early to prevent death. Public awareness program should be undertaken by both Public and Animal health department to educate people. Protective measures such as impermeable clothing, rubber apron, and boots should be used by those butchering and handling dead cows, goat, or sheep for consumption. All instruments used in butchering should be decontaminated by boiling for over more than 30 min.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.



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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ATMPH.ATMPH_12_12


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[Table 1]

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