Where, when, and how the diagnosis of human visceral leishmaniasis is defined: answers from the Brazilian control program

Abstract

BACKGROUND Timely diagnosis is recommended by the Brazilian Visceral Leishmaniasis (VL) Surveillance and Control Program to reduce case fatality. Attempts at assessing this topic in Brazil are scarce. OBJECTIVE This study aimed to describe where, when, and how the diagnosis of VL has been performed in a Brazilian endemic setting. METHODS Data of all autochthonous cases confirmed between 2011 and 2016 (N = 81) were recorded. The care-seeking itinerary until the confirmation of VL diagnosis was assessed among 57 patients. FINDINGS The majority of VL cases (79.1%) were reported by referral hospitals. The patients mainly sought primary health care centres at the onset of symptoms. However, they had to visit seven health services on average to achieve a confirmed diagnosis. The time from the onset of symptoms to the diagnosis of VL (T D) ranged from 1-212 (median, 25) days. The T D was longer among adult patients. There was a direct correlation between the patient's age and T D (r = 0.22; p = 0.047) and a higher occurrence of deaths due to the disease among older patients (p = 0.002). Almost all the patients (98.9%) underwent laboratory investigation, and the VL diagnosis was mainly confirmed based on clinical-laboratory criteria (92.6%). Positive results for the indirect fluorescence antibody test (22.7%) and parasitological examination plus rk39-based immunochromatographic tests (21.3%) were commonly employed. MAIN CONCLUSIONS VL diagnosis was predominantly conducted in hospitals with a long T D and wide application of serology. These findings may support measures focused on early diagnosis, including a greater involvement of the primary health care system. Key words: visceral leishmaniasis-kala-azar-diagnosis-public health-primary health care-Brazil Visceral leishmaniasis (VL), or kala-azar, is a neglected tropical disease caused by protozoa of the genus Leishmania that are transmitted to humans and other mammals via the bite of female phlebotomine sand flies. (1) In humans, the disease is clinically characterised by prolonged fever, weight loss, weakness, hepatosplenomegaly, hypergammaglobulinemia, and pancytopenia. If not treated appropriately, VL can progress to profound cachexia, systemic inflammation, bacterial infection, bleeding, and death. (2) Brazil is one of six countries that share 90% of the VL burden worldwide, in addition to being the main endemic area for the disease in the Americas. (1) Since the 1980s, VL has alarmingly been spreading to Brazilian urban centres as a zoonotic disease caused by Leishmania infantum, transmitted by the phlebotomines Lutzomyia longipalpis and Lutzomyia cruzi, with dogs being the main reservoir host. (3,4) Presently, autochthonous VL

Passive case detection for canine visceral leishmaniasis control in urban Brazil: Determinants of population uptake

“…A time delay of 2-3 months was chosen because the time between the onset of symptoms and the diagnosis of human VL in the municipality, as well as the time between the screening and euthanasia of a positive dog, was estimated in 25 and 41 days, respectively [24]. The offset term (the natural logarithm of the estimated dog population size), distance to the screening site, and demographic confounders were assumed to be constant over time and therefore were the same in all four variants.…”

Aspectos epidemiológicos da leishmaniose visceral no Estado da Bahia, Brasil

“…A LV, também conhecida como calazar ou esplenomegalia tropical, é uma doença crônica e sistêmica, que tem como principais sintomas: anemia, febre de longa duração, perda de peso, aumento do fígado e baço (hepatoesplenomegalia), perda ou diminuição da força física (astenia), decréscimo da força muscular e fraqueza (adinamia) (Gomila et al, 2017;Luz et al, 2019). É considerada uma doença com alta letalidade na ausência de tratamento e isso deve-se à disseminação do parasito por diversos órgãos do corpo resultando em alterações hematológicas e infecções bacterianas, as quais contribuem para a ocorrência de um quadro séptico que tende a evoluir para o óbito (Daher et al, 2017;Bispo et al, 2020).…”

Incidence of human visceral leishmaniasis: the importance of municipal socio-economic indicators in the state of Pernambuco, Brazil

“…However, the reference hospitals are primarily responsible for making the diagnosis based on clinical and laboratory criteria (Luz et al, 2019).…”