INSIGHT: Viral diseases from animals to humans life threatening

Dar es Salaam. Outbreaks of viral diseases known to spread from animals to humans (Zoonotic diseases) can be so economically devastating and life threatening—the reason why future health research priorities should be reviewed to contain these infections in Tanzania and Africa in general.

As the world looks forward to a new development agenda after the expiry of the Millennium Development Goals in the next few months, the priorities for health research in Africa deserve a new and practical plan that will deal with fatal emerging infectious diseases and Zoonosis.

Ebola virus, for instance, which was recently presented in a new study as having originated from fruit-eating bats to humans, is one public health catastrophe that has already cost more than 8,000 lives in West Africa, let alone billions of US dollars that have been spent on the disease.

New findings released recently during the Christmas season in the EMBO Molecular Medicine Journal reveal that the Ebola virus may have passed into its first human victim (a child) in Guinea from a small insect-eating bat. Other studies done in the past have also tried to look into the origin of Ebola virus, but have ended up with almost the same explanation.

While this may appear like a subject for ongoing research, it still raises serious questions, like: How safe are we with domestic and wild animals that are close to us? What does the future hold in terms of health research and prevention for high risk countries, where bats and other animals known to transmit viral diseases to humans are so prevalent?

Last year, scientists at Oxford University in the United Kingdom published a study in the eLife Journal entitled: “Mapping the zoonotic niche of Ebola virus disease in Africa’’, which put Tanzania on the list of 15 African countries in the Ebola danger zone, suggesting that such countries harboured fruit-eating bats that are the major reservoir of the Ebola virus.

But local experts were pessimistic about the possibility of Tanzania experiencing the Ebola outbreak like West African countries - Guinea, Liberia and Sierra Leone. One, microbiology Prof Fred Mhalu from Muhimbili University was asked by this author why Tanzania has never experienced any case of Ebola despite being close to Uganda, where several outbreaks have been reported.

Responding, Prof Mhalu said: “We need more research on that [subject] but...Tanzanians have fewer interactions with wild animals. It’s not a common practice, for example, for people here [in Tanzania] to eat bush meat...This reduces the transmission risk.” The don’s response shows that Tanzania may be safe from one form of Zoonotic disease, the Ebola virus because of people’s fewer interactions with Ebola virus reservoirs, but studies conducted over the years in the country show that Tanzanians are exposed to many other life threatening Zoonotic diseases that need serious interventions and more research.

The Ebola outbreak in West Africa should serve as a catalyst for a change in future priorities and strategies in health research for Tanzania and most other African countries—a trend that scientists have been referring to as a “changing landscape for health research in Africa’’ under a unique concept known as “One-Health’’.

One-Health approach aims at dealing with infectious diseases in a collaborative way—that requires veterinary scientists to collaborate with medical doctors in finding solutions to diseases that cross the line from animals to human beings—the Zoonotic diseases.

Tanzania is at high risk of such Zoonosis. Early last year, researchers on veterinary medicine in Tanzania confirmed for the first time that the Rift Valley Fever Virus existed in Kigoma Region—but that was seven years after Tanzania experienced a major outbreak of the disease in other parts of the country.

At the time of the outbreak, seven years ago, the World Health Organisation reported that 58 people were suspected of developing Rift Valley Fever in central Tanzania and it was reported that 14 died—with eight others being diagnosed with the virus in Dodoma Region. At least 60 new suspected cases were reported from Morogoro Region.

But in last year’s study, published in The Journal of Veterinary Research, the researchers found out that in rural Kigoma in Western Tanzania, there was a high prevalence of the Rift Valley Fever Virus, warning further that the disease would spread to other parts in the country, where it has never been reported.

In the same Journal, another brief report entitled: “The changing landscape for health research in Africa: The focus of the Southern African Centre for Infectious Diseases and Surveillance’’ revealed that between 60 per cent and 75 per cent of new or emerging infectious diseases in the last half century have originated from animals.

As a way of combating such diseases, scientists from across the globe are now embracing the One-Health concept - discussing how to blend veterinary medicine and human medicine in an effort to advance the understanding of interactions between humans, animals and the environment to improve public and animal health.

Tanzania is part of the campaign, whereby the National Institute for Medical Research (NIMR) organised the second One-Health Conference in Arusha last year to bring together experts to a roundtable discussion of how Zoonotic diseases can be tackled.

At the conference, UN Food and Agriculture Organisation chief veterinary officer Juan Lubroth opined in a keynote address that cooperation of veterinary and of human medicine can bring new insights and change the way infectious diseases are dealt with in a collaborative manner.

“Where else in the world can you learn as a physician about the challenge of bovine tuberculosis or risk factors for foot and mouth disease?” he asked the audience. Then, he proceeded, “Where else in the world can you learn as a veterinarian about latest developments on malaria or the prevention and care of chronic diseases?’’

Dr Juan’s ideas form part of latest recommendations by researchers at Ifakara Health Institute (IHI), who   are calling for similar concerted efforts as a strategy to eliminate rabies, a fatal viral disease that is transmitted from dogs to humans.

Despite being an entirely preventable disease, rabies still kills 55,000 people each year in developing countries, but researchers say that more research on local beliefs and practices among Tanzanians can identify knowledge gaps that may hinder prevention practices and lead to unnecessary deaths.

In their latest community survey, the experts exposed knowledge gaps in preventing rabies in our societies, but also among the experts themselves and recommended “greater engagement of veterinary and medical sectors...to ensure the availability of preventative services.’’

One of the researchers, Sambo Maganga from IHI told this author that dealing with such emerging infectious diseases like rabies required even greater communication among the medics and vets during disease laboratory surveillance. 

He said “submission of sample [for suspected rabies virus] to a laboratory is a serious challenge as most of livestock officers do not send samples. This results in low case detection using routine surveillance.’’

Maganga explained that the surest way to deal with a chain of rabies transmission was for livestock keepers to report disease cases as early as possible. He said: “If you [a livestock keeper] get a sample from an animal, you detect a case, you need to inform both veterinary and medical services to contain the transmission.”

He explained how the IHI was trying to address the problem using readily available resources, whereby the researchers did surveillance by using mobile phones—a technique he believes “is integrating veterinary officers, research scientists, policymakers and laboratory technicians…and ensures regular sample submission.”

This concept of One-Health is revolutionary and relevant. With the current tide of globalisation and increased international travel coupled with ecological factors, the world is likely to witness an unprecedented public health challenge of emerging diseases, which may hurt world economies dearly.

The World Bank is now investigating the cost-effectiveness of the “One-Health’’ concept in global health research. The World Health Organisation, the Food and Agriculture Organisation and the World Organisation for Animal Health, among other things, have already blessed the concept.

In East Africa, the Kenyan Ministry Public Health and Sanitation and the Ministry of Livestock Development are now working on the (2012-2017) strategic plan based on One-health to eliminate zoonotic diseases like Rift Valley Fever, which was also reported in Tanzania in 2007.

The author is by profession a medical doctor and a health journalist, who contributes regularly to The Citizen.