Tick-, flea- and mite-borne pathogens and associated diseases of public health importance in Bangladesh: a review

Background

This scoping review provides a baseline summary of the current records of the ticks, fleas, and mites of public health importance that are present in Bangladesh. It summarizes their geographic distributions and reports the levels of their infestation of livestock, pets, wildlife, and humans, and the clinical and epidemiological studies pertinent to these vectors and their pathogens.

Methods

Sixty-one articles were identified in a literature search, including 43 published since 2011.

Results

Twelve articles contained reliable information on ticks and their associated hosts. However, information on fleas and mites in Bangladesh is very limited. Seventeen species of ixodid ticks that commonly parasitize peridomestic animals and can bite humans are described: Rhipicephalus microplus, R. appendiculatus, R. sanguineus, Haemaphysalis bispinosa, Hyalomma anatolicum, and Amblyomma testudinarium. Thirty-eight veterinary articles describe livestock pathogens, including Babesia, Anaplasma, and Theileria, and the diseases they cause. Few of those studies used modern molecular techniques to identify these pathogens. Eleven articles reported human diseases or surveillance studies, 10 from the last 10 years. Two country-wide serosurveys of 1,209 and 720 patients, using Enzyme Linked Immunosorbent Assay (ELISA) and Indirect Immunofluorescence Assay (IFA), respectively, reported human exposure to Orientia tsutsugamushi (8.8%–23.7%), typhus and spotted-fever group rickettsiae (19.7%–66.6%), and Coxiella burnetii (3%). The seropositivity rates varied regionally. PCR-based studies confirmed that febrile patients in Bangladesh may be infected with O. tsutsugamushi, Rickettsia typhi, Rickettsia felis, or Bartonella elizabethae. Only limited molecular research has been done with dogs and cats. These studies have reported PCR-confirmed canine infections with Babesia gibsoni (30%), Anaplasma bovis (58%), or Rickettsia monacenis (14%, n=50), and feline infections with Rickettsia felis (21%, n=100). Similarly, fleas from cats tested positive for Rickettsia felis (20.6%).

Conclusions

These findings indicate that diseases borne by non-mosquito vectors in Bangladesh urgently require more attention from public health, medical, and veterinary specialists to establish their true occurrence.