Routine Mass Vaccination of Livestock to curb Cutaneous Anthrax Outbreaks in Arua District, Uganda Policy Brief

Summary

During May–June 2017, Arua District reported three suspected cutaneous anthrax patients (one death). All had recently handled meat from livestock that spontaneously died. A skin lesion from the deceased person and a blood sample from a bull that spontaneously died tested positive for Bacillus anthracis. Our investigation revealed that an anthrax outbreak probably occurred among livestock in Arua District since 2015, and humans contracted cutaneous anthrax by contact with livestock. Improving public heath surveillance and response in animals and humans is urgently required in the district. We recommend eating meat from slaughtered healthy livestock, safe disposal of animal carcasses, and livestock vaccination.

Background

Anthrax is an acute zoonotic disease caused by Gram- positive spore forming bacteria Bacillus anthracis (Heymann, 2015). Human infection is infrequent and sporadic often a result of occupational hazards. Transmission is a result of handling and or consuming meat of infected livestock and occurs in three forms (Heymann, 2015). The cutaneous form accounts for 95% of human cases and is characterized by itching of affected site, skin lesion that is papular then vesicular evolving into a depressed eschar surrounded by edema. Incubation period is 5-7days with a case fatality rate of 5-20% (Heymann, 2015).

In Uganda, anthrax has occurred majorly amongst animals with occasional spillage to humans. In 2010, about 82 hippopotamuses and nine buffalos died from anthrax in Uganda. The anthrax strain was limited to the Kazinga channel. From the 1950s, hippos were the most affected animals since the strain thrives in water. In 2004, an anthrax outbreak killed lots of wild- life in Queen Elizabeth, there was no evidence of human infections so mass vaccination of livestock was done (CNN, 2010). There were concerns that human deaths had occurred from people eating infected hippopotamus meat (Wamboga-Mugirya, 2004). In 2011, there was an anthrax out- break in Sheema district, killing two humans and seven bovines (Coffin, v2015).

On 7^th May 2017, a Public Health Officer from Rhino Camp refugee settlements informed the District Surveillance Officer of Arua, about three suspected anthrax cases admitted at Olujobo Health Centre (HC) III presenting with acute onset of skin lesions evolving from papular to vesicular with depressed blackened center accompanied by some oedema. All the cases were children between 1 and 12 years. They started developing blisters after consuming meat of dead cow sand goats. In one of the homesteads affected, a total of 4 goats and 2 cattle died a few hours after onset of disease. These cases were from Kololo and Walope villages in Rigbo sub-county.

On 5th June 2017, the in-charge of Rhino Camp HC IV reported to Arua District Health Officer about the death of a 35 year old resident of Ledriva Village, Eramva Parish, Rhino Camp sub-county who presented with restlessness, sweating, confusion and was admitted on 4th June The papular vesicular lesion progressed to an eschar. He first developed vesicles/blistering on the left scapular region one week before and was initially managed as suspected Herpes Zoster with no improvement at a clinic. At the HC IV, he was managed on a presumptive diagnosis of anthrax when the blisters were replaced by a black Eschar.

Despite treatment, his condition deteriorated, with difficulty in breathing and died on 5th June 2017 amidst resuscitation attempts. A sample was taken from the skin lesion and this tested positive for Bacillus anthracis. A team from the Ministry of Agriculture, Animal Indus- try and Fisheries obtained a sample from a dead bull and this tested positive for anthrax. We carried out an investigation to establish scope of the outbreak, determine exposure factors and recommend evidence-based control measures.

Approaches and Results

We held meetings with the District Health and Veterinary Teams and agreed to carry out a detailed epidemiological investigation. We also clearly defined roles of the participating teams. We mapped out the affected areas as Rhino Camp and Rigbo sub-counties. We carried out active case finding with the assistance of the Village Health Team members, Assistant Animal Husbandry Officer and other health facility staff in the sub-counties of Rhino Camp and Rigbo. We defined a probable case as acute onset of skin lesions progressing from papular to vesicular with depressed blackened center (eschar) in a resident of Arua district from 1^st January 2015.

A confirmed case was a probable case with Bacillus anthracis confirmed by PCR isolated from skin lesion.We reviewed medical records and using a standard case investigation form, we interviewed 67 probable case-patients and relatives of the two deceased case-patients. We updated the line list and conducted descriptive epidemiology by person, place and time characteristics. The key variables explored were skinning/cutting a dead animal (carcass), eating a dead animal, carrying a dead animal, contact with live animals (milking) and contact with soil. We then generated a hypothesis and this was that all people who skinned/cut the dead animal and /orate the meat got cutaneous anthrax. We conducted a case-control study to test the hypotheses. We identified 68 cases (67 suspected; one con- firmed) including two deaths.

All cases occurred following spontaneous livestock deaths. Men (attack rate [AR]=17/100,000) were more affected than women (AR=0.78/100,000). Age group 30-39years (AR=63/100,000) were the most affected. All cases were from two neighboring sub–counties: Rigbo (n=63, AR=201/100,000) and Rhino Camp (n=5, AR=21/100,000). Cases occurred throughout the 3-year period, peaking during dry seasons. Of 68 case-persons and 136 controls, 65 (96%) case-persons and 76 (56%) controls butchered livestock that spontaneously died (OR_M-H=22, 95% CI=5.5–89); 61 (90%) case-persons and 74 (54%) controls carried meat (OR_M-H=6.9, 95%CI=3.0–16); 57 (84%) case-persons and 72 (53%) controls skinned the livestock (OR_M-H=5.0, 95%CI=2.3–11). 68 (98.6%) of the case- patients had their living rooms covered with soil. 100% of the case- patients do work where they come into contact with soil. The symptoms were suggestive of cutaneous anthrax, however other symptoms were suggestive of inhalation/ pulmonary, intestinal or meningeal anthrax.

Conclusion and implications

This anthrax outbreak might be wide spread across Arua district and West Nile region. The outbreak is likely to have been caused by handling (skinning and/or cutting) of dead animals. If livestock are not vaccinated against Anthrax, similar outbreaks will occur in neighboring districts. This will culminate into socio-economic losses as a result of high morbidity and mortality of livestock.

Policy Recommendations

1. Strengthening community surveillance for early identification of cutaneous anthrax
2. Initiation of vaccination of livestock against anthrax in Rigbo and Rhino Camp sub-counties and neighboring villages;
3. Enhancing coordination between the District Health Office and Dis- trict Veterinary Office to raise alerts early and enable prompt control of the outbreak as well as strengthening community health education on dangers of handling and eating meat of dead animals including
4. Further investigation of animal cases should be done to ascertain the risk to humans.

References

1. Coffin J.L., Monje F., Asiimwe-Karimu G., Amuguni H.J. and Odoch T. A One Health, participatory epidemiology assessment of anthrax (Bacillus anthracis) management in Western Uganda. Soc Sci Med. 2015 Mar;129:44-50. doi: 10.1016/j.socscimed.2014.07.037. Epub 2014 Jul 17. Available at https://www.ncbi.nlm.nih.gov/pubmed/25066946
2. CNN .2010. Anthrax kills 82 hippos, 9 buffalo in Uganda. Available at http://edition.cnn.com/2010/WORLD/africa/07/29/uganda.anthrax/ index.html
3. Heymann D.L. (2015) 20^th Edition Control of Communicable Diseases Manual.
4. Wamboga-Mugirya P. 2004. Uganda battles deadly anthrax outbreak. Available at http://www.scidev.net/global/health/news/uganda-battles- deadly-anthrax-outbreak.html