UNSEEN ANTHRAX PERILS -Unravelling Zambia’s disease outbreaks

Dr David Squarre Examines a hippo that died of anthrax in the 2011 outbreak of anthrax in Lower Zambezi National Park. Source: David Squarre.

Dr David Squarre in the process of safe disposal of a hippo that died of anthrax in the 2011 outbreak in the Lower Zambezi National Park. Source: Davide Squarre.

ABIGAIL CHIFUSA

AN INVISIBLE menace silently prowls beneath the soil in Zambia. 

Anthrax, a pernicious disease affecting animals and humans, has been stealthily causing outbreaks in numerous districts across the country. The discovery of this microbial threat traces back to 1922 when it first appeared in Luambe National Park in Eastern Province.

Over the years, there have been a total of 34 recorded outbreaks from 1978 to 2023, with recent surges striking key areas like North Luangwa National Park in 2011, Lower Zambezi National Park in 2012, and multiple others.

According to Department of Veterinary Services public health acting senior inspectorate and regulation officer Kenneth Chawinga, anthrax stems from a bacteria type known as Bacillus anthracis, found in the soil, capable of enduring for up to 50 years. 

“These bacteria pose a severe threat to both domestic and wild animals, particularly those that graze, such as cattle, sheep, goats, and even diverse wildlife like horses, hippos, cape buffaloes and elephants,” Dr Chawinga stated.

He said transmission of this disease occurs through contaminated grass or plants that animals graze upon, where they may accidentally inhale or ingest the bacteria. 

“Multiplication of the bacteria within the body results in the release of toxins, causing severe illness and potential death. Humans contract anthrax through direct contact with infected animals or their by-products, such as meat, hides, or wool,” Dr Chawinga said.

He said the clinical signs of anthrax in humans vary depending on the route of exposure, but typically include flu-like symptoms such as fever, body aches, and fatigue. 

“In severe cases, it can progress to difficulty in breathing, shock, and even death if left untreated,” he highlighted.

He said the primary causes of the current anthrax outbreak trace back to specific areas in Zambia, particularly known for historical anthrax occurrences. 

“One possibility is that the animals in Sinazongwe may have grazed in an area where anthrax spores were present or have been present for a long time. It is also possible that the spores were introduced to the area through contaminated materials or equipment from areas where the disease is commonly present,” explained Dr Chawinga.

He said several environmental factors contribute to anthrax outbreaks, including soil characteristics, grazing practices, flooding, wildlife population dynamics, climate and human activities. These factors collectively increase the probability of anthrax outbreaks in previously unaffected areas such as Sinazongwe.

Dr Chawinga said transmission of anthrax from animals to humans occurs through contact with Bacillus anthracis spores. 

He said the symptoms of anthrax in animals vary, and in humans manifestations depend on the form of infection. 

“Prevention strategies involve avoiding contact with infected animals or products, regular vaccination of livestock, maintaining hygiene, monitoring and surveillance of wildlife, and proper disposal of infected carcasses,” he said.

He disclosed that there is a locally produced anthrax vaccine by Central Veterinary Research Institute (CVRI). 

Dr Chawinga emphasised the adoption of a ‘one health’ approach, involving collaboration between human health, animal health, and environmental experts.

He said such collaborations are crucial in controlling and preventing anthrax outbreaks and ensure early detection, prompt response, and effective prevention measures.

He said the recent anthrax outbreak in new areas has led to widespread concern due to limited public information. 

Dr Chawinga highlighted that efforts are underway to conduct mass vaccinations by the Department of Veterinary Services, emphasising the need for cooperation from livestock owners. 

“Purchasing meat solely from trusted sources is advised, as salting and drying infected meat do not eliminate the anthrax-causing bacterial spores,” he highlighted.

Anthrax’s emergence in various parts of the country follows a common pattern shaped by specific environmental and ecological conditions conducive to bacillus anthracis. 

Any combination of factors such as soil composition,grazing practices, and many others could trigger an outbreak, as was observed in the recent Sinazongwe incident.

Musso Munyeme, veterinary public health professor under the Department of Disease Control at the University of Zambia (UNZA), underlines the crucial ‘one health’ approach in understanding anthrax. 

He emphasises that the disease originates in the environment, progresses to wildlife, and then infects livestock before posing a threat to humans.

Dr Munyeme, who is also a multiplier at the Capacitating One Health in Eastern and Southern Africa (COHESA), highlighted how floods can unearth spores, allowing them to infect grazing animals like hippos. 

“There was a period of quietness after 1914 and 1918 when anthrax cases were documented until last year, when floods uncovered numerous spores in the ground, shifting them toward the lower Zambezi areas, notably Kariba. With the drying up of the region, animals began grazing, particularly the hippo. These animals are vulnerable because of their feeding behaviour; they are bulky grazers, uprooting entire grass patches, and the spores primarily reside in the roots. This habit leads to a significant number of hippo deaths. Furthermore, their grazing patterns render the grass easily accessible to cattle, exposing them to the spores and, consequently, anthrax,” he explained.

Dr Munyeme said the subsequent consumption of contaminated vegetation by cattle further spreads the disease, making it a real and pressing concern.

“When anthrax spores enter an animal’s stomach, it transitions into a vegetative state, rapidly multiplying within the body. The incubation period can range from one to 12 days, contingent on the quantity ingested and the spores’ infectivity. 

“Additionally, for humans, contact with or consumption of an infected animal upon its death leads to potential infection,” he said. 

Dr Munyeme further highlighted the catastrophic impact of anthrax on animals, leading to sudden death and severe bleeding, and the various forms it can take in humans, including cutaneous, respiratory, and gastrointestinal types, with fatal consequences.

“You won’t observe any initial signs; the sudden collapse of an animal will be the first noticeable indication, followed by blood emerging from its nose, mouth, and sometimes ears. In severe strains of anthrax, the bleeding is not limited to the ears but extends to the entire body, signifying a severe condition. For humans, when the disease affects the lungs and intestines, it can lead to a similarly severe outcome, making it a highly concerning illness. The most prevalent form is the cutaneous one, constituting about 95 percent of all human anthrax cases, while five percent encompass the more lethal respiratory or gastrointestinal forms. 

“In Chama district, a place known for numerous hippo deaths, we encountered a severe case of a woman afflicted with the gastrointestinal form, resulting in a dire situation where we, unfortunately, lost the patient,” he explained.

Dr Munyeme said preventive strategies such as annual animal vaccinations, movement bans, and safe carcass disposal are essential in curbing anthrax’s spread.

“Vaccination should ideally occur annually. Other countries like Botswana or Namibia have a permanent animal disease control measure in place, but in Zambia you can travel anywhere and find no visible sign of disease control measures not until an outbreak occurs, which is the current situation. We must take a proactive and preventive approach and address potential issues in our animals before they escalate beyond containment within a specific area. Protective measures need to be implemented in the environment. There is a specific kind of lime [quick lime] similar to caustic soda, which effectively neutralises the spores, carcasses, bones, and skin. This process is known as environmental decontamination,” he explained.

“If an animal dies in a dry area, it’s essential to dig a deep hole, even up to two metres, and then burn the remains with a significant amount of diesel and firewood. Before burying the remains, if any bones are not entirely destroyed, you can use caustic soda with the ashes and then bury. Deep burial is vital; if shallow, during flooding, any remaining spores might be washed away and resurface,” he added.

He said the ‘one health’ approach advocates a coordinated effort among various sectors, from animal and human health experts to law enforcement, to control the disease.

“In the ‘one health’ approach, when the disease emerged in Sinazongwe district, the problem was observed in animals and the animal health sector might have noticed issues, but did not inform the health authorities, despite the potential risk to humans. 

“One health involves all relevant sectors, ensuring collaboration to enforce laws. While explanation can be ignored, law enforcement ensures compliance, making it a collective effort,” he highlighted.

Lonica Moya, a senior veterinary consultant, further underscores the broad spectrum of animals susceptible to anthrax and its method of transmission through spores present in the soil.

Dr Moya described the bacillus anthracis bacteria, explaining the production of dormant spores that remain inactive for extended periods. 

According to Dr Moya, anthrax often manifests without visible signs in animals, resulting in sudden death. 

“In severe cases, animals may display signs such as weakness, high fever, excitement, followed by depression, breathing difficulties, uncoordinated movements, convulsions, and eventual collapse and demise,” she explained.

Dr Moya pointed out that a significant indicator of the disease is the presence of bloody discharge from natural orifices like the nose, mouth, ears, and anus due to the blood’s inability to clot.

On November 1, 2023, in her statement, Minister of Health Sylvia Masebo emphasised Government’s dedication to safeguard the health of citizens. 

Ms Masebo said employing a multi-disciplinary approach, the Ministry of Health has been addressing various disease outbreaks, inclusive of anthrax, across the nation. 

Ms Masebo gave details on the anthrax outbreak, emphasising its serious nature as an infectious disease affecting both humans and animals. 

She disclosed that the current outbreak has culminated into 335 cases and four deaths across various provinces in Zambia.

Noting the focus on a ‘one health’ approach, Ms Masebo enumerated the implemented public health measures aimed at containing and preventing the spread of anthrax. 

She said these measures encompass staff training for early diagnosis, enhanced surveillance, ensuring medical supplies, public awareness campaigns, continuous monitoring, and the collaboration between the ministries of Health, Livestock and Fisheries.

The minister further urged stakeholders’ commitment to fostering community engagement and emphasising the importance of seeking urgent evaluation and management at the nearest health facilities if symptoms suggestive of anthrax develop.

The covert threat of anthrax continues to loom, necessitating a united front comprising environmental, animal, and human health sectors to combat its relentless emergence and spread. 

Public vigilance and proactive measures, combined with a thorough understanding of this complex disease’s patterns, are essential in safeguarding wildlife and domesticated animals and human communities from this silent menace that dwells beneath the surface.