Clinical, epidemiological, and spatial features of human rabies cases in Metro Manila, the Philippines from 2006 to 2015

Abstract

Rabies remains a public health problem in the Philippines despite the widespread provision of rabies vaccines and rabies immunoglobulin (RIG) as post-exposure prophylaxis (PEP). Detailed descriptions of recent human rabies cases in the Philippines are scarce. This study aimed to describe the clinical, epidemiological, and spatial features of human rabies cases between January 1, 2006, and December 31, 2015. We conducted a retrospective hospital-based case record review of all patients admitted to one referral hospital in Manila who received a clinical diagnosis of rabies. During the 10-year study period there were 575 patients (average 57.5 cases per year, range 57 to 119) with a final diagnosis of rabies. Most patients were male (n = 404, 70.3%) and aged ≥ 20 years (n = 433, 75.3%). Patients mostly came from the National Capital Region (n = 160, 28.0%) and the adjacent Regions III (n = 197, 34.4%) and IV-A (n = 168, 29.4%). Case mapping and heatmaps showed that human rabies cases were continuously observed in similar areas throughout the study period. Most patients had hydrophobia (n = 444, 95.5%) and/or aerophobia (n = 432, 93.3%). The leading causative animals were dogs (n = 421, 96.3%) and cats (n = 16, 3.7%). Among 437 patients with animal exposure history, only 42 (9.6%) had been administered at least one rabies vaccine. Two patients (0.5%), young children bitten on their face, had received and a full course of rabies vaccine. Human rabies patients were continuously admitted to the hospital, with no notable decline over the study period. The geographical area in which human rabies cases commonly occurred also did not change. Few patients received PEP and there were two suspected cases of PEP failure. The retrospective design of this study was a limitation; thus, prospective studies are required. Author summary Rabies remains a public health problem in the Philippines despite improvements in the availability of rabies vaccines and rabies immunoglobulin (RIG) as post-exposure prophylaxis (PEP). The incidence of rabies is highest in Metro Manila and surrounding areas. We reviewed the records of all human rabies patients admitted to the national infectious disease hospital in Manila between 2006 and 2015. This hospital treats most cases in this area. During the 10-year study period, human rabies cases were continuously admitted to the hospital, with no notable decline in numbers by year. Most patients were adult men bitten by domestic dogs. The geographical areas in which cases commonly occurred during the 10-year period also did not change over time. Only 9.6% of patients had received at least one dose of a rabies vaccine as PEP. Although the risk of PEP failure is reported to be almost zero, we identified two suspected cases of PEP failure. The retrospective design of this study was a limitation, and the exact details of PEP were not reliably available. As human rabies death is a significant public health concern, the circumstances of each case should be prospectively investigated. Further research is required to understand how to reduce the number of rabies cases.