Ocular Trematodiasis in Children, Sri Lanka.

Using histopathology and phylogenetic analysis of the internal transcribed spacer 2 gene, we found >2 distinct trematode species that caused ocular trematode infections in children in Sri Lanka. Collaborations between clinicians and parasitologists and community awareness of water-related contamination hazards will promote diagnosis, control, and prevention of ocular trematode infections.

Genotypic characterization of Orientia tsutsugamushi from patients in two geographical locations in Sri Lanka.

BACKGROUND: To date more than 20 antigenically distinct strains of Orientia tsutsugamushi (OT) reported within the tsutsugamushi triangle that cause an undifferentiated acute febrile illness in humans. Genotypic characterization of OT in different geographic regions or within the same country, is important in order to establish effective diagnostics, clinical management and to develop effective vaccines. Genetic and antigenic characterization of OT causing human disease in OT-endemic regions is not known for Sri Lanka. METHODS: Adult patients and children who were admitted with an acute febrile illness and presumed to having acute scrub typhus based on presence of an eschar and other supporting clinical features were recruited. Eschar biopsies and buffy coat samples collected from patients who were confirmed having OT by IFA were further studied by real time PCR (Orientia 47 kD) and nested PCR (Orientia 56 kD) amplification. DNA sequences were obtained for 56 kD gene amplicons and phylogenetic comparisons were analyzed using currently available data in GenBank [Neucleotide substitution per 100 residues, 1000 Bootstrap Trials]. RESULTS: Twenty eschar biopsies (Location1,19, Location 2,1) and eight buffy coat samples (Location1,6, Location2,2) examined by real time PCR revealed Orientia amplicons in 16 samples. DNA sequences were obtained for the 56 kD gene amplicons in 12 eschars and 4 buffy coat samples. The genotypes of the Location1 samples revealed that, 7 exhibiting close homology with JP1 [distantly related to UT177 Thai (Karp related)], five had close homology with Kato strain, two had close homology with JGv and JG AF [Distantly related to Kawasaki M63383] and one had close homology with Gilliam strain. The Location 2 strain was closely related to Kuroki-Boryong L04956, the genotype which is distributed in far eastern Asia. Similar to other patients in the cohort this patient also had never travelled out of Sri Lanka. CONCLUSIONS: We observed all three main OT genotypes in Sri Lanka, and the majority fell into Thai Karp related clade. These results demonstrate great antigenic diversity of OT in the studied areas of Sri Lanka.

Lymphatic filariases and soil-transmitted helminthiases in Sri Lanka: the challenge of eliminating residual pockets of transmission.

Sri Lanka has successfully met the challenge of controlling both lymphatic filariasis (LF) and soil-transmitted helminthiases (STH) as public health problems. The primary public health strategy for combatting both conditions has been preventive chemotherapy. The national programme for the elimination of LF implemented five annual rounds of mass chemotherapy in the endemic districts from 2002 to 2006 using a combination of diethylcarbamazine and albendazole. The overall microfilaria rate declined from 0.21% in 2001 before the mass chemotherapy, to 0.06% in 2016, at declaration of elimination of LF as a public health problem by the World Health Organization. Currently Sri Lanka is in the phase of post-validation surveillance. Achieving control of STH has been more difficult. Mass deworming programmes have been implemented for nearly a century, and national-level surveys reported prevalence rates declining from 6.9% in 2003 to 1% in 2017. However, neither of these infections has been completely eliminated. A situation analysis indicates continued transmission of both among high-risk communities. This paper explores the reasons for persistence of transmission of both LF and STH in residual pockets and the measures that are required to achieve long-term control, or perhaps even interrupt transmission in Sri Lanka. This article is part of the theme issue 'Challenges and opportunities in the fight against neglected tropical diseases: a decade from the London Declaration on NTDs'.

A preliminary survey of filarial parasites in dogs and cats in Sri Lanka.

Human brugian filariasis has re-emerged in Sri Lanka after a quiescent period of four decades. This study investigated the prevalence of canine and feline filarial parasites in three localities with human sub-periodic brugian filariasis, in order to determine their potential reservoir status. All reachable dogs and cats, both stray and domestic, within a 350m radius of an index case of brugian filariasis in three locations (Madampe, Wattala and Weliweriya) were screened for microfilariae using Giemsa stained thick blood smears. A representative sample of canine and feline blood samples positive for Brugia spp. microfilariae by microscopy, from each of the three locations, were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. A total of 250 dogs and 134 cats were screened. The overall microfilaraemia rates were high among both dogs (68.8%) and cats (47.8%). The prevalence of microfilaraemia was significantly higher among dogs than cats (p<0.05). Two filarial species were identified based on morphology of microfilariae: Dirofilaria (Nochtiella) repens (dogs, 54.4% and cats, 34.3%) and Brugia spp. (dogs, 51.6% and cats, 30.6%). PCR analysis of canine (n = 53) and feline (n = 24) samples elicited bands in the region of 615bp, which confirmed Brugia malayi infection. Co-infection with D.(N.) repens was detected by PCR with an additional band at 484bp, in 36 canine and 17 feline samples. Overall microfilaraemia rates of dogs (81.8%) and cats (75%) in Madampe (rural) were significantly higher than in urbanized Wattala (dogs, 62.4% and cats, 26.0%) (p<0.05). High rates of zoonotic filarial infections strongly implicate dogs and cats as potential reservoirs for human dirofilariasis and brugian filariasis in Sri Lanka.

Surveillance for transmission of lymphatic filariasis in Colombo and Gampaha districts of Sri Lanka following mass drug administration.

BACKGROUND: Sri Lanka was recently declared by WHO to have eliminated lymphatic filariasis as a public health problem, after conclusion of annual mass drug administration. Our aim was to assess the lymphatic filariasis situation, following mass drug administration. METHODS: Surveillance was done in two districts of the Western Province in two consecutive phases (2009-2010 and 2013-2015), by examining 2461 thick night blood smears and performing 250 dipstick tests on children for antibodies to Brugia malayi. RESULTS AND CONCLUSIONS: Decline in bancroftian microfilaraemia (microfilaria rate 0.32% to zero) supports elimination, but re-emergence of brugian filariasisis (antibody rate, 1.6%; one microfilaria positive) is a cause for concern.