The epidemiology of canine leishmaniasis: transmission rates estimated from a cohort study in Amazonian Brazil

Abstract

Article:Quinnell, R.J., Courtenay, O., Garcez, L.M. et al.(1 more author) (1997) The epidemiology of canine leishmaniasis: transmission rates estimated from a cohort study in Amazonian Brazil. Parasitology, 115 (02 (Received 13 June 1996 ; revised 4 February 1997 ; accepted 7 February 1997 ) We estimate the incidence rate, serological conversion rate and basic case reproduction number (R ! )ofLeishmania infantum from a cohort study of 126 domestic dogs exposed to natural infection rates over 2 years on Marajo! Island, Para! State, Brazil. The analysis includes new methods for (1) determining the number of seropositives in cross-sectional serological data, (2) identifying seroconversions in longitudinal studies, based on both the number of antibody units and their rate of change through time, (3) estimating incidence and serological pre-patent periods and (4) calculating R ! for a potentially fatal, vector-borne disease under seasonal transmission. Longitudinal and cross-sectional serological (ELISA) analyses gave similar estimates of the proportion of dogs positive. However, longitudinal analysis allowed the calculation of prepatent periods, and hence the more accurate estimation of incidence : an infection-conversion model fitted by maximum likelihood to serological data yielded seasonally varying per capita incidence rates with a mean of 8n66i10 −$ \day (mean time to infection 115 days, 95 % .. 107-126 days), and a median pre-patent period of 94 (95 % .. 82-111) days. These results were used in conjunction with theory and dog demographic data to estimate the basic reproduction number, R ! , as 5n9 (95 % ..4 n 4-7n4). R ! is a determinant of the scale of the leishmaniasis control problem, and we comment on the options for control.

Serological, parasitological and molecular tests for canine visceral leishmaniosis diagnosis in a longitudinal study

“…Regarding the ELISA test, the lower sensitivity (43.6%) and specificity (86.3%) observed in our study, in comparison with others (QUINNELL et al, 1997(QUINNELL et al, , 2001REITHINGER et al, 2002;ALMEIDA et al, 2005;ROSÁRIO et al, 2005), may have been because we included all the samples collected over the entire period and not just single samplings. Methodological differences, such as the antigen and reagents used, are likely to have contributed to this difference as well.…”

“…The relationship between infection and serological data changes during the course of the disease (QUINNELL et al, 1997) resulting in variation in the percentage of positivity, as well as the sensitivity of each diagnostic technique. At the beginning, parasitological examinations and PCR are more sensitive; with the evolution of the infection, symptomatic dogs present an increase in serum antibody levels and parasite load (QUINNELL et al, 2001(QUINNELL et al, , 2003.…”

An rK28-Based Immunoenzymatic Assay for the Diagnosis of Canine Visceral Leishmaniasis in Latin America

“…For the in-house quantitative OPD ELISA method, the procedure described above 21 was used without significant changes: plates were washed 4× after each step, rK28 antigencoated plates stored at −20°C were blocked with phosphatebuffered saline (PBS)-Tween 20 0.1% (w/v), bovine serum albumin (BSA) 1% (v/v), plus 1/400 PBS-Tween 20 (0.1%) and BSA (0.1%), and serum samples diluted in the same volume of glycerol were added; the plates thus prepared were shaken as usual for 1 hour; after that, peroxidase-conjugated AffiniPure Rabbit Anti-Dog IgG (H+L) (Jackson ImmunoResearch Laboratories Inc., West Grove, PA) was added in dilutions of 1/50,000 in serum diluent buffer (PBS/0.1% BSA/ 0.1% Tween 20).…”

EVIDENCE OF Leishmania (Leishmania) infantum INFECTION IN DOGS FROM JUIZ DE FORA, MINAS GERAIS STATE, BRAZIL, BASED ON IMMUNOCHROMATOGRAPHIC DUAL-PATH PLATFORM (DPP®) AND PCR ASSAYS

“…Despite having presented a typical rural and wild pattern of VL until the 80's (WERNECK, 2008), current data show that the numbers have increased considerably, thus creating a new epidemiological profile, due to the spread of the disease to urban centers of the North, South and West regions of the country (JERONIMO et al, 2004;ROMERO & BOELAERT, 2010;HARHAY et al, 2011). In Brazil, domestic dogs are the main reservoir, and thus play an important role in the epidemiology of the disease, while foxes and other wild animals play a role in sylvatic transmission (DEANE, 1956;QUINNELL et al, 1997;ROMERO & BOELAERT, 2010). There is a clear positive correlation between human and canine infection rates, so that diagnosing dogs represents an important step towards the control of VL (GRIMALDI et al, 2012).…”