IntroductionHumanAfrican Trypanosomiasis (HAT), or sleepingsickness, is a vector-borne disease caused by the protozoanparasite Trypanosoma brucei andtransmitted by tsetse flies, Glossinaspp.
There are two forms: Trypanosomabrucei gambiense which presents a chronic manifestation mainly in humans inCcentraland WwesternAfrica and Trypanosoma brucei rhodesiensewhich presents acute severe symptoms in humans and also causes Animal AfricanTrypanosomiasis (nagana) in livestock and wildlife in Eeasternand SsouthernAfrica. Between the 1980s and the 1990s, African countries experienced epidemicsof HAT with an estimated 300,000 cases; therefore, the governments and foreign donors applied intensiveprogrammes of vector-control, active andpassive case detection and improvements in the availability and access totreatment. Thiseffort made it possible to decrease the number of new HAT cases to 2,804 in 2015(1). However, in Uganda which is the onlycountry presenting both active T.
b. gambiense in the north west and T.b. rhodesiense in the south east, T.b.
rhodesiense has beenspreadingd spread KF1 northward due tothe movement of livestock and people and thisithas resulted in the difference between the foci ofGambian and Rhodesian HAT becoming only 150km in 2005(2). This merger would make diagnosisand treatment more difficult since they differ in the two forms of the diseasesrelying on a basis of human patients’ geographical data. It is urgent to controlthe expansion of T.b. rhodesiense.
My main objective of this essay is to discuss the currentsituation of T.b. rhodesiense amonghuman and cattle populations in Uganda. Epidemiology of Rhodesian HAT (rHAT) inUgandaRhodesian HAT clinicallyprogresses in two stages. In the first stage, patients show symptoms of chancreat the site of the tsetse bite, intermittent fevers, severe headaches, irritability,extreme fatigue and enlarged lymph nodes. In the second stage, the trypanosomescross the blood-brain barrier to invade the central nervous system and patientsdevelop mental deterioration and other neurologic problems, which leads to deathwithin six months unless treated. T.b.
rhodesiense was traditionallyendemic in Bugiri, Busia, Kayunga, Junja, Iganga, Kamuli, Mayuge, Mukono,Pallisa and Tororo districts until the 1980s.However, the epidemic began in new districts, namely, Masindi, Sotori,Kaberamaido and Lira between 1998 and 2004. In recent data from 2009,approximately a 24.3% of the Ugandan population are at risk of infection of rHAT(3). The population at risk areispeople who engage in cattle raising or live near a livestock market since it isshown that the distance to the livestockmarket is directly linked to an increased risk of rHAT(4). Compared to that over300 cases that had been reported annually in theearly 2000s, it has steadily decreased to 28 cases in 2015 since the Public Privatepartnership, Stamp Out Sleeping Sickness Program (SOS) in easternUganda was widely implemented. However, many of the reportedcases are detected in the second stage and the cases can be underreported.Epidemiology ofAfrican Animal Trypanosomiasis (AAT) in cattleT.
congolense, T. vivax and T. brucei spp.cause AAT in cattle. In Uganda, it is estimated that approximately athird of the herd; 19 million head were at risk from AAT in 2002(5). The disease is usually chronic and the majorclinical signs are anaemia, intermittent fevers and enlarged lymph nodes.However, T.
b. rhodesiense inindigenous cattle is asymptomatic, the cattle maintain parasites acting as areservoir increasing the risk of infection to humans. Co-infection with T.
congolense or T. vivax eventually cause death in cattle if nottreated. AAT has the most severe impact of economic loss in livestock productivity in Uganda. A previous study showed that a tick-borne disease and trypanosomiasisdiminish the productivity of draft cattle by21% and household income from the use of oxen by 32% equivalent to US $245annually(6). Diagnosis andTreatmentThe diagnosisfor rHAT is the detection of trypanosomes from blood or chancre aspirate by microscopy. T.b.
rhodesiense can be more frequently observed in blood in thefirst stage than T.b.gambiense, but the two species cannot be differentiatedby microscopy. Lumbaer puncturefollows to define the clinical stage and chemotherapeutic choice from presenceof the parasites and the number of white cells in the cerebrospinal fluid (CSF).
Molecular diagnosis is available using Real TimePolymerase Chain Reaction (qPCR) KF2 orLoop-Mediated ?Isothermal Amplification (LAMP) to detect the serumresistance-associated (SRA) gene, which can differentiate the species. There are no rapid diagnostic tests (RDTs) forT.b. rhodesiense, in contrast, RDTs are used for screening T.b. gambiense in health facilities. Thetreatment for the first stage is suramin, given by intravenous injection.
Adverse reaction is frequent but usually mildand reversible. Since suramin does not cross the blood–brain barrier to kill trypanosomesin the CSF, patients at the second stage are treated with melarsoprol, which isthe only drug available for the second stage. However, It causes severe adversereactions such as reactive encephalopathy and polyneuropathy, it leads to death in 1-5%of patients with an 8.4% of fatality rate(7). All drugs are provided free of charge by the World HeathOrganization. In cattle, the clinical diagnosis is difficult because symptoms areunspecific. Microscopic examination of blood is used for the detection of trypanosomes.Curative treatment is diminazene diaceturate.
Drugs such as isometamidium chloride andquinapyramine sulphate and chloride can be used as prophylaxes. No vaccines are available for humans and cattle. SurveillanceIn human health, the National Sleeping SicknessControl Program by the Ministryof Health is responsible for HAT national surveillance in Uganda.
Dueto the transition from active surveillance to passive in 2005, it now relieson case reports from the health care system. In newly affected districts, namely,Dokolo, Kaberamaido,Sotori and Serere, three county-levelhospitals provide diagnosis and free treatment for any referral patients. It isvery important that health care workers at a lower level in the health system,where people at risk of the infection can visit, have knowledge about HAT andrefer the suspected patients to those referral hospitals. A previous studyshowed that only 60 % of the health care workers at parish level in those four4districts were aware of HAT and the major source of information was radio andnewspaper accounting for 40%(8). The reinforcement of the referral system and the trainingof health care workers at the community level are vital to find cases at an earlystage.
The prevalence infection of trypanosomes among cattle is unknown. Theofficial policy, Uganda’s Animal Disease Act, restricts the movement oflivestock from endemic areas of AAT to non-endemic areas and all cattle inendemic areas must be treated with trypanocidal treatment by a veterinaryofficer(9). According to the interviewswith farmers in Sotori and Serere Districts, it is not regularly enforced andeven when it is done, they are not informed of what treatment was given to cattleby the veterinary officer(10). In these areas, thelivestock movement restriction is widely understood byfarmers due to the past outbreaks of Foot and Mouth Disease. Enhancingcompliance with regulation of cattle movement and the treatment among theveterinary officers and farmers will prevent spreading AAT and other tick-borne diseases to other regions.Control There are threemain methods for controlling T.
b. rhodesiense: tsetse control, mass treatment of cattle, and earlydetection and management of rHAT cases. In terms of vector control, there are awide range of techniques such as sequential aerial spraying or ground spraying of pyrethroids, tsetse trapping, odorbaits, selective bush clearing and the release of sterile males to reducetransmissions. However, spaying of insecticides has to be implemented widely,which is expensive and dependent on donor support.
Decreasingthe prevalence of T.b. rhodesiense in cattle interrupts transmission amonghuman and cattle populations; cattle arethe main reservoir for T.b.
rhodesiense. Restricted application (RAP) is a method of sprayinginsecticides on tsetse predilection sites, the legs and belly of cattle, whichis effective and three times cheaper than the traditional pour-on method(11). This also can prevent tick bites, which causesother infectious diseases and anemia in cattle. In the SOS program,approximately 500,000 cattle were treated with insecticides and a single doseof trypanocides. The result shows a 75% decrease in the prevalence of T.b. rhodesiense in cattle in seven districts(12).
This approach is more feasible and sustainablefor farmers with limited resources. ConclusionTo prevent the further expansionof T.b.rhodesiense, firstly, the health services and traininghealth care workers should be reinforced, which will increase number ofdetecting cases.
Secondly, the enforcement of veterinary policy should be strengthenedin terms of preventing cattle and humans from contracting the infectionand increasing the productivity of livestock. Finally, better communicationand coordination among health care workers veterinary personnel, and communitieswill enable them to localize the affected areas immediately to address thedisease control. KF1Couldcontinue to be spreadingnow…so is the past tense better in this context? KF2Ifnot repeated, is it not necessary to write acrynom?