A fraction (fHS) develops symptomatic KA (IHS) whilst staying PCR-positive. == Therapy == The fractionfHSdeveloping symptomatic KA (IHS) is eligible for treatment. from a community intervention trial (the KALANET project). The transmission dynamic ofLeishmania donovaniis rather sluggish, mainly due to its long incubation period and the potentially long persistence of parasites in infected humans. Cellular immunity as measured by the Leishmanin skin test (LST) continues on average for roughly one year, and re-infection occurs in intervals of about two years, with variation not specified. The model suggests that transmission ofL. donovaniis predominantly managed by asymptomatically infected hosts. Only patients with symptomatic disease were eligible for treatment; Febantel thus, in contrast to vector control, the treatment of cases had almost no effect on the overall intensity of transmission. == Conclusions == Treatment of Kala-azar is necessary on the level of the individual patient but may have little effect on transmission of parasites. In contrast, vector control or exposure prophylaxis has the potential to efficiently reduce transmission of parasites. Based on these findings, control of VL should pay more attention to vector-related interventions. Cases of PKDL may Febantel Rabbit Polyclonal to BAZ2A appear after years and may initiate a new outbreak of disease; interventions should consequently Febantel be long enough, combined with an active case detection and include effective treatment. == Author Summary == Visceral Leishmaniasis is a neglected, life-threatening disease affecting the poorest of the poor. It has received more attention in light of the regional VL elimination program. A deterministic compartmental model was developed to estimate parameters forL. donovanitransmission and to optimise intervention success. Our simulation results show that transmission ofL. Febantel donovaniis predominantly driven by asymptomatically infected hosts who are not eligible for treatment. Treatment can reduce the prevalence of symptomatic disease, but the incidence of KA remains on similar levels because of an unchanged intensity of transmission. In contrast to treatment-related interventions, vector-related interventions have the potential to reduce the prevalence of asymptomatic infections and thus are the intervention of choice from an epidemiological perspective. Vector control, however, should be combined with treatment, as PKDL cases can act as reservoirs of contamination. This reservoir function originates from the long period of nearly two years on average during which putatively recovered KA patients develop PKDL. == Introduction == Leishmaniasis is a vector-borne disease, which is caused by protozoan flagellates and is transmitted by phlebotomine sand flies. Clinical manifestations of leishmaniasis include cutaneous leishmaniasis (CL), muco-cutaneous leishmaniasis (MCL), visceral leishmaniasis (VL) and post-kala-azar dermal leishmaniasis (PKDL). The only life-threatening form is usually VL, which is strongly linked with poor housing[1]. The majority of VL cases (>90%) occur in only six countries: Bangladesh, India, Nepal, Sudan, Ethiopia and Brazil[2]. In East Africa and the Indian subcontinent, the disease is caused byL. donovani. In Europe, North Africa and Latin AmericaL. infantumpredominates[3]. In the Indian subcontinent, about 200 million people are estimated to be at risk of developing VL; this region harbours an estimated 67% of the global VL disease burden[2]. In this region, VL has been endemic for many decades, with the first reported epidemic in Bengal in the 1820s[4]. == Disease == VL, also called Kala-azar (KA), causes more than 50,000 deaths each year worldwide[5]. The name Kala-azar (black-fever) originates from India; it refers to the hyperpigmentation of the skin during the course of the disease. In contrast to CL and MCL, where the parasites are localised in tegumentary tissue, VL is a systemic contamination of the phagocytic and reticulo-endothelial system; this contamination includes the lymph nodes, spleen and liver. Clinical symptoms of VL are prolonged fever, fatigue, weight loss, bleeding tendency and an enlarged spleen and liver. Pancytopenia is also a characteristic sign. PKDL, first explained by Brahmachari in 1922[6], can occur as a sequel to KA. It usually develops 6 months to several years after treatment and putative recovery from KA[7]. Poor treatment compliance is thought to favour the occurrence of PKDL[8], but a small fraction of PKDL cases have no reported history of KA[9]. The nodular lesions of PKDL patients usually contain many parasites[10]. PKDL is not a life-threatening condition, Febantel laboratory confirmation is challenging, and the treatment burdens the patients (in Bangladesh, current treatment guidelines call for 120 intramuscular injections of sodium stibogluconate[9]). Consequently, it is assumed that many patients.