Occurrence of rift valley fever (RVF) in Dodoma region, Tanzania and its management implications

Abstract

Rift Valley Fever (RVF) is a peracute or acute febrile zoonotic mosquito-borne viral disease affecting wildlife, domestic animals and occasionally humans. It occurs after heavy rains and floods and is transmitted to humans through infected mosquito bite or handling of infected animals and/or their products. The Dodoma Regional Authority received reports from 90 villages on possibility of occurrence of RVF in livestock in December 2006. About 315 animals were suspected of being infected by the disease. This was followed by the Dodoma Regional and District hospitals, receiving several patients from different parts of the region in critical conditions in January 2007. Blood samples were collected for disease examination. While waiting for the results the patients were treated for malaria and/or meningitis based on visual/ clinical signs. However, most of the patients did not recover and the situation worsened followed by several deaths. Most of the blood samples were negative for Malaria and/or meningitis. This led to suspicion of RVF. The number of RVF suspects however, declined from an average of 18% in March to 11 % in April 2007 suggesting reduced incidence of the disease. The objective of our study was to determine possibility RVF occurrence to humans by using case study definitions for RVF suspect’s, and confirmation by laboratory analysis in order to develop appropriate management program for the unfamiliar disease. Blood samples and/ or postmortem biopsies from all RVF suspected patients were submitted in Nairobi-Kenya for laboratory confirmation. Among 130 suspects, 71 were RVF positive. Although there was no specific treatment used to treat the disease other than provision of supportive treatment, more than fifty percent of the infected patients were discharged within two weeks. The supportive treatment included analgesic, antimicrobial and antiepileptic drugs, fluid and electrolyte therapy, food and oxygenation and intensive care. The major management used in Dodoma included preventive measures such as livestock movement quarantine, health education campaigns, livestock vaccination, disinfecting livestock carcasses and vector management and intensified surveillance. We recommend development of capacity for confirming RVF in the country and strengthening the disease surveillance and communication among communities. A retrospective household survey should be implementing to determine number of deaths and or patients with similar symptoms that occurred since January 2007 to date. This may give an indication of the extent of RVF incidence in Dodoma.

Key words: Rift Valley fever – zoonotic - reemerging – human – Dodoma - Aedes mosquito