Control of tick-borne diseases among humans using the One-Health Approach: A case of recurrent Crime an-Congo Hemorrhagic Fever outbreaks in Uganda

Executive summary

Currently there is no policy on the control of tick-borne diseases in livestock and humans yet ticks pose a serious threat to humans and the livestock industry in Uganda. Globally CCHF is the most widely occurring tick-borne viral infection affecting humans. It causes viral hemorrhagic fever of which a single human case indicates an outbreak. Uganda has had 12 CCHF outbreaks in 6 years, nine of which occurred in 2018 alone in 5 districts found in the cattle corridor region. This has left more than a dozen people infected with four deaths. The need for a policy in use of acaricides to control ticks for effective reduction in tick-borne diseases. This policy brief addresses the problem of increasing CCHF outbreaks among humans in Uganda and provides recommendations to reduce the burden of tick-borne diseases through collaborative efforts of the Ministry of Health, National Drug Authority, Ministry of Agriculture Animal Industry and Fisheries, and other partners in support of the One-Health Approach.

Background

Currently there is no policy on the control of ticks and tick-borne diseases among human or live- stock yet ticks pose an increasing threat to human life and livestock trade.(1). This is evidenced by increasing tick- borne disease outbreaks like Crimean-Congo Hemorrhagic Fever (CCHF). CCHF is a severe epidemic-prone zoonotic viral hemorrhagic fever (VHF) transmitted to hu- mans by tick bites and direct contact with fluids or tissues of infected animals (2,3). Since its first identification in 1944, human CCHF outbreaks have increasingly occurred in Africa, Asia and Europe(2,4,5). The main control and prevention measures against ticks include preventing contact with ticks as well as application of acaricides to  control ticks among livestock (8).

According to the current draft national policy on ticks and tick-borne diseases by Ministry of Animal Industry and Fisheries (MAAIF), Uganda has an objective to control ticks and tick-borne diseases using cost effective and sustainable methods. The likelihood of tick-borne disease out- breaks among livestock or humans will reduce if ticks are controlled using well regulated environmentally friendly interventions through a one health approach‖. The policy brief aims to recommend evidence-based one-health interventions to both the animal and health sectors of Uganda to control ticks and tick-borne diseases.

Approaches and Results

In August 2017, the MOH re- ported a CCHF outbreak in districts of Kyankwanzi and Nakaseke in central Uganda. We investigated the outbreak to identify risk factors and to develop evidence based recommendations for prevention and control for future out-breaks. We defined a suspected CCHF case as sudden on- set of high fever (>38oC) for ≥3 days between July 1 and September 30, 2017, plus any of the following: spontaneous bleeding or bruising, laboratory evidence of low leucocyte and platelet counts unexplained by other causes in a resident of the two affected districts. We defined a confirmed CCHF case was a suspected VHF case that tested positive for CCHF by both RT-PCR and IgM serology(9). We con- ducted case finding by reviewing medical records and community active case-search in case-patients homes and villages. We conducted 1:4 matched case-control study. Neighborhood controls were matched by sex and age (±10 years). We also collected farm livestock blood samples from confirmed case-patients communities to test for CCHF infection using IgG ELISA. We identified seven male case- patients (2 confirmed and 5 suspected) and 28 controls. Tick exposure (i.e. being bitten by a tick or squashing ticks with bare hands) was reported by 57% (4/7) of case-patients and 11% (3/28) of controls (OR=11, 95% CI=1.1-112). Sero-positivity for CCHF was found in 60% (37/62) of cattle and 24% (5/21) of goats. Farm animals were reported to have been sprayed with common acaricides available on the market.

Conclusion

The CCHF outbreak in August 2017 was most likely caused by exposure to infected ticks. Ticks remain the main vectors and reservoirs of tick-borne diseases like CCHF and need to be dealt with to avoid recurrent disease outbreaks for both human and animal health.

Policy implications

There is need for a one-health approach in controlling tick-borne diseases(2,8). This is a multi-sectoral approach where experts in human and animal health jointly work for the control of ticks and tick-borne zoonotic diseases. Policies guiding the access, distribution, and use of acaricides should be developed; veterinary health education to veterinary extension workers and farmers on use of acaricides should be conducted as well as ecological studies and further research in tick control.

References

1. Published EBATIC Paper sept 2017.pdf [Internet]. [cited 2018 Jan 8]. Available from: http://nda.or.ug/ files/downloads/Published%20EBATIC%20Paper%20sept% 202017.pdf
2. Wang LF, Crameri G. Emerging zoonotic viral diseases. Rev Sci Tech Int Epiz. 2014;33(569–81).
3. Sutherland LJ, Anyamba A, LaBeaud AD. Emerging and Reemeriging Human Bunyavirus Infections and Climate Change. 2013;