Academic journal article Iranian Journal of Public Health

Epidemiological Feature of Visceral Leishmaniasis in China, 2004-2012

Academic journal article Iranian Journal of Public Health

Epidemiological Feature of Visceral Leishmaniasis in China, 2004-2012

Article excerpt

Introduction

Leishmaniasis is a parasitic disease with different clinical manifestations depending on the infecting species of Leishmania and on the immune response of the host (1-3). Leishmaniasis has been consid-ered as one of neglected tropical diseases (NTD) by WHO (4). Its transmission occurs through the bite of a sandfly infected with Leishmania parasites (3,5-8).The disease occurs in two forms, cutane-ous Leishmaniasis(CL) and visceral leishmania-sis(VL) clinical forms. CL usually occurs in the form of an ulcer or nodule on the skin, which can heal spontaneously. VL manifests with irregular bouts of fever, substantial weight loss, hepato-megaly, pancytopenia, and susceptibility to oppor-tunistic infection (9). VL is a systemic disease that is fatal if leftuntreated (10,11). More than 65 countries are currently affected by VL and ap-proximately 500,000 new human cases occur an-nually. Visceral leishmaniasis accounts for 59,000 deaths per year (12-14). Desjeux indicated that in the previous decade endemic regions had spread, prevalence had increased and the number of unre-corded cases must have been substantial, because notification was compulsory in only few countries (8). Therefore, the public health impact of the dis-ease worldwide has been grossly underestimated (1, 15).

VL has been and is still an important public health problem in China. Around 1951, VL was one of the most important parasitic diseases, 530,000 cases in >650 counties of provinces in the north area of the Yangtze River in China (16, 17). After nationwide control measures (mass registration of patients for treatment, killing of infected dogs, and use of insecticides against sandflies), VL has been under controlled and essentially eliminated in the northeastern endemic regions since 1958; however, transmission of VL has not been inter-rupted in western China.

In recent years, the endemic range has been ex-panded with a corresponding increase in the num-ber of reported cases, resulting apparently in the recent outbreak of the disease that is due to global warming and rapid migration of large population in northwest China (17, 18).It is essential to eluci-date the current epidemic situation and epidemic-ological characteristics of VL for designing con-trol policy. In the present study, we describe the current epidemiological profile and characteristics of VL based on reported cases between 2004 and 2012.

Materials and Methods

Source of data

Data were collected from the online National In-fectious Diseases Reporting System (NIDRS) from January 2004 to December 2012, which cov-ered all notifiable diseases. All reported VL cases were diagnosed in accordance with the National Criteria for Visceral Leishmaniasis Diagnosis in China and reported via NDRIS. Criteria used for diagnosis of human cases were based in clinical, epidemiologic, and laboratory aspects. Most re-ported cases were clinical cases with symptoms of irregular fever, progressive splenomegaly, hepato-megaly, pancytopenia, and positive detected by rk39 immune chromatography test (ICT), very few were laboratory cases of finding Leishmania in the bone marrow, spleen aspirate smears.

Data sorting

The inaccurate and repeated case reporting rec-ords were excluded, only the final-judgment cases were saved. Analysis is based on onset date, in-cluding both clinical and laboratory cases.

Data analysis

The data was analyzed by using statistical software SPSS13.0. The annual incidence rate was calcu-lated using the mid-year population data. Relevant population data was collected from the national census database from the Bureau of Statistics. Geographical distribution was based on the cur-rent address of reported cases, and age distribu-tion was based on the calculation chronological age for the onset date minus the birth date of re-ported cases.

Results

General status and epidemic tends

Between 2004 and 2012 a total of 3337 VL cases were notified in China through NDRIS. …

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