Cases of Buffalopox, India's latest emerging viral threat, underline need to understand evolutionary biology

The recent spread of monkeypox to non-endemic countries has trained the spotlight on reemerging viruses such as buffalopox, which was first isolated in India. 

In 2018, some 28 human cases of buffalopox were diagnosed in Maharashtra’s Dhule district. A majority of the patients were milkers and therefore had close contact with buffalos. Twelve buffaloes and four cows were found with the virus.

Since the first case in 1934 globally recorded in India, the country has seen several sporadic outbreaks: 

• From December 1985-February 1987, buffalopox cases were reported from five districts of Maharashtra
• From 1992-1996, cases were reported from three districts of the state
• From 2008-2009, seven cases in humans and one in a buffalo in Solapur district as well as 14 human cases in Kolhapur district were recorded

Recent trends suggest that increasing numbers of outbreaks in the Indian subcontinent are being recorded, but awareness about diagnosis, treatment and preventive measures in humans is much less, according to the study that found the cases in Dhule published in the Clinical Dermatology Review journal in August 2020

The zoonotic disease endemic to India has its root in smallpox vaccines. Live virus used to inoculate buffaloes to produce the smallpox vaccine in India evolved into buffalopox over time, genome data showed.

The first sample of the virus was isolated in 1967 and the World Health Organization’s (WHO) Joint Expert Committee on Zoonoses declared it an important zoonotic disease the same year.

After four decades, the disease became “an emerging contagious viral zoonotic disease infecting milkers with high morbidity (80 per cent) among affected domestic buffalo herds and cows,” a 2020 study published in the National Centre for Biotechnology Information (NCBI) noted.

Of the 28 human cases in Dhule in 2018, 23 patients were 15-40 years old, three were above 40 years, two were children below 15 years with no direct association to milking or exposure to an infected buffalo.

The emergence of buffalopox in children with no associated link was uncharacteristic, as was the new site of involvement and development of skin lesions on the eyes and face. Typically, lesions would appear on the hands and forearms. 

“Involvement of atypical sites such as eyes, face, and occurrence of the disease in children indirectly through infected family members or other close contacts can be an indication of increased virulence of the viruses,” the authors wrote.

Zoonotic infections are not the only means for the buffalopox virus to jump from animals to humans. Exposure to infected laboratory animals or from laboratory accidents, such as needlestick injuries or self-inoculation of mucous membranes can also lead to an infection, the WHO noted.

A vaccinia virus (VACV) case was recorded by WHO from India in September 2020 when a doctoral student working at a biosafety level 2 (BSL-2) laboratory reported of a small pustule on his hand after a laboratory accident. 

VACV belongs to the orthopoxvirus family of which buffalopox is a close variant. Swelling and pain increased as the student, who was unvaccinated against smallpox since it had been discontinued by late 1970s, developed a fever by day nine as the rash spread till the forearm. 

The student was hospitalised on the tenth day of the infection and discharged four days later following a course of antivirals. Another lab-acquired case of buffalopox was reported in 2014 in Haryana’s Hisar. 

Experts have warned of VACV-related viruses re-emerging in humans and animals, with a 2019 study published in NCBI stating that buffalopox has outbreak potential in India and categorised it under biosafety risk group 2 (moderate individual risk, low community risk). 

Zika virus, dengue, Japanese encephalitis, rubella and chickenpox are other diseases classified in the same group.

India’s increasing buffalopox infections underline the urgency to understand the evolutionary biology of orthopoxviruses. It also illustrates how vulnerable the human population is to the emergence and re-emergence of viral pathogens from unsuspected sources, an August 2020 study published in NCBI argued. 

Orthopoxvirus infections are on the rise in several parts of the world. Buffalopox is on the rise in Asia, monkeypox in East and Central Africa — the current outbreak is the most geographically widespread in five decades — and novel orthopox in Georgia, Alaska and Italy.