Zoonotic diseases have been responsible for a significant number of outbreaks affecting humans in the past 12 years in South Africa. These have included influenza AH5N2, rabies, Rift Valley fever and the new arenavirus, the Lujo virus. While Ebola virus disease, the new MERSCOV and SARS have been important emerging zoonosis globally, since 2000, no cases to date have been confirmed in South Africa.

Zoonotic diseases are underrecognized in humans due to a low diagnostic index of clinical suspicion, the nonspecific nature of clinical disease, especially on a high background prevalence of HIV and TB, the absence of active surveillance programmes, and limited availability of diagnostic testing facilities. The emergence of 'One Health' as a discipline has helped to improve communications between the human and animal health allied professions, establish a combined outbreak response mechanism and affect improved public health responses and prevention endeavors. In addition, combined projects looking at prevalence of zoonoses in potentially highly exposed humans at the animal/human health interface have been initiated and provided useful information on control, prevention and treatment.

A rabies outbreak in the Vhembe District in Limpopo Province in November 2005 went unnoticed on the human health side largely as a result of an absence of communication between veterinary and human health.² Four cases of fatal encephalitis were noted as unusual and reported by paediatricians at a single hospital over a four-week period. They had never seen rabies before and therefore did not recognise the clinical signs and symptoms and appropriate patient specimens were never submitted to the laboratory. Rabies was eventually confirmed in one of the victims on a brain biopsy. This is a province which had not had human rabies reported before this period, but is endemic for animal rabies in jackals with suboptimal vaccine coverage in domestic dogs.

In 2004, a major increase was noticed of rabies in domestic dogs and also in jackals in the area, but this was not conveyed to human health professionals. An investigation into the human outbreak revealed 31 possible, probable and confirmed cases of rabies - only 3 of these patients had been to a clinic, but none received proper postexposure prophylaxis. There was low community and health care worker awareness of rabies, and there was no programme in place to give postexposure prophylaxis largely as vaccine and rabies immunoglobulin were not easily available. What followed was an intersectional meeting on human health, and vets got together for the first time and the outcome of this was a programme to raise community awareness, health care worker education around recognition and diagnosis of suspected cases, and correct postexposure protocols, and the provision of rabies vaccine and immunoglobulin. The massive increase in human victims led to an intensified dog vaccination campaign. Characterization of both the human and animal rabies viruses confirmed in introduction from an outbreak in Zimbabwe. In the year that followed and as a consequence of this One Health programme, there were no human rabies cases confirmed in that province.

The outbreak of rabies in Johannesburg in 2010/11 where 42 domestic dogs were confirmed with rabies in a previously unrecognised rabies area was another example of the importance of early communications between human and veterinary health. Rabies was likely introduced from an endemic area in Kwazulu-Natal Province into Johannesburg where dog vaccine coverage was suboptimal.⁵ While there are many dog exposures related to security incidents in metropolitan Johannesburg, rabies postexposure prophylaxis would generally not be a consideration given the absence of rabies in the area. Rapid communication of the incident from veterinary health to human health facilitated the quick raising of community awareness, training of health workers and provision of rabies post biological exposure. While there were a number of human rabies exposures during the outbreak, there was only one human victim, a child who did not receive postexposure prophylaxis following a small, superficial but nevertheless category three, exposure from a neighbour's puppy.

The Rift Valley fever outbreak in 2008/2010/2011 again highlighted the importance of rapid communication between the veterinary and human health.¹ Rift Valley fever is not a common disease in humans, and most doctors had never seen cases. The nonspecific flulike illness would typically not be considered as Rift Valley fever unless an epidemiological link is noted and there is reference to contact with infected animals or tissue. The response to this outbreak included guidelines for diagnosis: a case definition for testing - patients with flulike illness or encephalitis, haemorrhage, hepatitis or ocular pathology who were in close recent contact with animals in or from suspected RVF areas or residence in an area with animal cases of RVF, and prevention of further infections. Laboratory testing was done at the National Institute for Communicable Diseases using PCR and serology. There were 242 laboratory-confirmed human cases, 26 deaths and a significant number of patients with complications of disease - haemorrhagic disease, hepatic necrosis, macular retinitis and encephalitis. The majority of patients who contracted the disease were exposed in the occupational setting and included vets, veterinary assistants, animal health technicians, farmers and abattoir workers. Prevention of disease is difficult and centres on the avoidance of unprotected handling of animal tissue/carcasses/aborted foetuses through post-mortems, slaughtering/butchering, assisting with deliveries. Compliance with preventative measures on farms is particularly difficult to implement. Prevention of mosquito bites and avoidance of unpasteurised milk was also advised. A combined outbreak response especially around preventing human infection was put in place, albeit with limited success.

A new arenavirus, the Lujo virus, was identified as the cause of an outbreak of haemorrhagic fever that killed 4 of the 5 victims admitted to a Johannesburg hospital in 2008.³ The index case was likely a woman from Lusaka, Zambia, whose source of infection was likely rodents in the area close to where she lived and rode horses. Transmission in the health setting through blood contact resulted in 4 additional cases in health workers.

A number of outbreaks of highly pathogenic influenza A H5N2 have been confirmed in the Western and Eastern Cape provinces affecting ostriches (2004–2011). Evidence of infection through epidemiological studies and serosurveys identified that virus can be transmitted to humans with close unprotected contact but severe disease did not result. Three of 129 highly exposed farm and veterinary workers showed positive serology/seroconversion on microneutralization in the outbreak on the Eastern Cape. This would support the need for protection of workers during high-risk procedures.

A study was conducted to identify zoonoses as the cause of acute febrile illness (AFI) in highly exposed adults at the wildlife/livestock/human interface in the Mnisi community of Bushbuckridge, bordering on the Kruger National Park.⁴ There is a well-established veterinary primary health care programme and surveillance for a number of infectious diseases. Cattle are brought to community dip tanks weekly for tick control and active veterinary surveillance.

While the number of acute zoonotic infections was relatively low, there was high background exposure to TBF, Q fever and leptospirosis in the community. A surprising finding was the number of Bartonella infections, not previously described in this population. There is a need to revisit AFI treatment algorithms in these clinic settings to include antibiotic options for zoonosis and to educate the population about reducing tick and surface water contact.

A One Health approach lends itself to the diagnosis, prevention and control of many zoonoses. In this era of the superbugs, antibiotic resistance is another important One Health area that needs to be explored.

References

1.  Archer BN, Thomas J, Weyer J, Cengimbo A, Landoh DE, Jacobs C, Ntuli S, Modise M, Mathonsi M, Mashishi MS, Leman PA, le Roux C, Jansen van Vuren P, Kemp A, Paweska JT, Blumberg L. Epidemiologic investigations into outbreaks of Rift Valley fever in humans, South Africa, 2008–2011. Emerg Infect Dis. 2013;19(12):1918–1925. doi:10.3201/eid1912.121527.

2.  Cohen C, Sartorius B, Sabeta C, Zulu G, Paweska J, Mogoswane M, Sutton C, Nel LH, Swanepoel R, Leman PA, Grobbelaar AA, Dyason E, Blumberg L. Epidemiology and molecular virus characterization of re-emerging rabies, South Africa. Emerg Infect Dis. 2007;13(12):1879–1886.

3.  Paweska JT, Sewlall NH, Ksiazek TG, Blumberg LH, Hale MJ, et al. Nosocomial outbreak of novel arenavirus infection, southern Africa. Emerg Infect Dis. 2009;15(10):1598–1602. doi:10.3201/eid1510.090211.

4.  Mabunda S, Kennedy LTR, Blumberg L. Pilot programme review of human rabies prevention services in a rural district of South Africa. In: Proceedings of the 16th International Congress on Infectious Diseases; April 2–5; Cape Town, South Africa.

5.  Sabeta CT, Weyer J, Geertsma P, Mohale D, Miyen J, Blumberg LH, Leman PA, Phahladira B, Shumba W, Walters J, Paweska JT. Emergence of rabies in the Gauteng Province, South Africa: 2010–2011. J S Afr Vet Assoc. 2013;84(1):E1–E5. doi:10.4102/jsava.v84i1.923.