Kenya’s disease surveillance and early warning systems will be in focus Friday as the world marks this year’s Zoonoses Day to promote awareness about human diseases that come from animals.
A recent fresh outbreak of the deadly Rift Valley Fever (RVF) disease in North Eastern Kenya has rekindled debate about the country’s capacity to detect and prevent the transmission of diseases from animals to humans after a warning by experts, alarmed by the recent unusually heavy rains and floods in most parts of the country, came to pass.
Five people and tens of livestock are reported to have died of the disease that was first reported in early June.
Kenya has had a nasty experience from the outbreak of RVF. The World Health Organisation records show that the last outbreak of RVF in Kenya occurred between November 2006 to March 2007, killing 234 people.
The country also incurred billions of shillings in economic costs arising from trade restrictions, livestock deaths and mass vaccinations to tame the disease.
Although RVF may be a big focus for now, experts say the threats of other animal-to-humans diseases also remains huge.
Fresh data by the Kenya District Health Information System (DHIS) lists 36 priority animal diseases transmitted, some of which have been found to be deeply entrenched, while others have no data since they are ignored.
Of the known zoonotic diseases on the priority list with available data, brucellosis, dog bites, suspected human rabies, anthrax, Rift Valley Fever, and yellow fever respectively are ranked highly.
Brucellosis, a bacterial disease transmitted from sheep, goats, cattle, deer, elk, pigs, and dogs to humans by eating contaminated food, which can include raw meat, unpasteurised milk, cheese and ice cream, attacked 414,011 Kenyans in 2017 alone, an increase from 408,062 in 2016.
So serious is brucellosis it can cause miscarriage while breastfeeding mothers may transmit it to their suckling children. It also affects almost any part of the body, including reproductive system, liver, heart and central nervous system. Chronic brucellosis may cause complications in just one organ or throughout your body. Possible complications include infection of the heart’s inner lining.
“In some areas of North Eastern Kenya, prevalence of brucellosis can be as high as 50 per cent of all fever cases presenting at a health facility. Rift valley fever is an outbreak prone disease usually occurring after periods of flooding as it is now,” said Carolyne Nasimiyu, a medical epidemiologist at Health ministry told Business Daily.
“Other diseases such as Ebola and avian influenza have never been reported in Kenya though surveillance for them is ongoing due to outbreaks reported in neighboring countries. Unfortunately data on other zoonoses is largely unavailable due to lack of resources.”
At a distant second is dog bites, accounting for 56,243 cases in 2017, compared to 48,595 in 2016. In 2017 almost 60,000 dog bites were reported at health facilities with potential to transmit rabies to humans, says Dr Nasimiyu.
Suspected human rabies cases were 727 (2017), down from 760 (2016); anthrax 165 (2017) and 33 (2016), and RVF 216 and yellow fever 141 both in 2016. The two diseases data were unavailable in 2017.
Rabies causes an estimated 2,000 deaths in Kenya every year, and this is considered “a gross underestimate contributed by poor reporting by the health system, poor health seeking behaviour and lack of diagnostic capacity for rabies in most public hospitals,” she said.
“Anthrax outbreaks are reported all year through, especially in Central Kenya, Western and Rift Valley.”
In a joint research on prioritisation of zoonotic diseases published in 2016, conducted by Kenya’s ministries of Agriculture, Health and the University of Nairobi, scientists bemoan existence of zoonotic diseases with little or no data.
Among other 36 zoonotic diseases listed as priority are avian influenza and other pandemic influenza viruses, leishmaniasis, and leptospirosis, transmitted through direct contact with urine from infected animals or through water, soil or food contaminated with their urine.
Zoonotic diseases with limited data include West Nile virus, a viral infection spread by mosquitoes, bovine tuberculosis, plague, spread through fleas, Tularemia from rabbits, hares, and rodents.
Others are protozoans (cryptosporidiosis, toxoplasmosis), salmonellosis, Helminths (Trichinosis, Cysticercosis, Hydatidosis, Sarcopsis, Diphyllobothrium), fungal diseases (dermatophilosis, histoplasmosis, cryptococcosis, aspergillosis), and schistosomiasis, where fresh water becomes contaminated from infected animal or human urine or faeces, and trypanosomiasis transmitted by tsetse fly bite.
The report shows that viral and bacterial zoonoses makes up 60 per cent of zoonotic pathogens at 36.1 per cent and 25 per cent respectively. Zoonoses caused by helminths (parasitic worms) were 13.9 per cent, protozoan and fungi 8.3 per cent each, ecto-parasites 5.5 per cent and others 2.8 per cent.
Pathogens of zoonotic origin, it states, form two-thirds of all pathogens infectious to human including newly emergent infections.
The report highlights the importance of prioritizing diseases at country level as it presents the opportunity to focus on diseases that have the greatest public health burden and not just diseases that have greater global attention as the epidemic prone diseases.
It also suggests that neglected zoonotic diseases, which primarily impact poor rural communities, are in part neglected due to underreporting and underestimation of disease burden resulting from use of unreliable disease metrics extrapolated from scanty data.
This results in the systematic underweighting of these diseases and lower investments in prevention and control programs by health authorities compared to emerging diseases with epidemic potential that attract the attention of policy and political decision makers globally and in the developed countries.
“Overall, zoonotic diseases with limited data including West Nile virus fever, Lassa fever, diphyllobothriasis or no local or regional data including, hantavirus fever, and histoplasmosis generally ranked lowest since two of the criteria, epidemic potential and prevalence of disease relied on presence of local data, said Prof. Markotter.
“High scores were assigned to anthrax, brucellosis, RVF and Mycobacterium species, diseases for which outbreaks in livestock are associated with high direct and indirect losses in productivity and market losses associated with quarantines and trade bans.”
In ranking and aggregation scores anthrax, brucellosis and most of the bacterial infections were scored highly for potential for intervention since vaccines and treatments are available for humans or animals.
However, most of the viral diseases with the exception of RVF, yellow fever and influenza scored low in this category due to the unavailability of vaccines and drugs.
The report recommends that control of zoonotic diseases and events requires close collaboration of human and animal health sectors and their stakeholders in order to effectively and efficiently reduce their emergence and spread.