June 3, 2008/Volume 65/No. 3

Health Focus: Zoonotic Diseases in Texas, Part Two

• Hantavirus Infection in Texas
  Hantavirus infections are caused by members of the family Bunyaviridae and typically utilize rodents as hosts. Specific strains of hantavirus infect particular species of rodents. Infected rodents rarely show clinical signs of infection but excrete virus through urine, saliva and feces. Transmission to humans is by inhalation of aerosolized virus. The typical transmission scenario occurs within a building or structure that is inhabited by rodents. Any activity that creates air-borne dust, such as cleaning or sweeping, can accomplish transmission. There are two clinical síndromes seen with human hantavirus infection - Hemorrhagic Fever with Renal Syndrome and Hantavirus Pulmonary Syndrome. In Texas, Hantavirus Pulmonary Syndrome is the most common severe manifestation of the disease. There is no specific vaccine for hantavirus, and treatment of clinical cases is symptomatic and supportive.  Read more... (  PDF)
  
  
  
• Murine Typhus in Texas
  Murine typhus, also called fleaborne or endemic typhus, is a febrile exanthem caused by the organism Rickettsia typhi. Another organism, R. felis, transmitted by cat fleas, causes an illness indistinguishable from murine typhus except through molecular tests. In Texas, illnesses caused by both organisms are categorized as murine typhus. Although murine typhus can be found in coastal and tropical areas throughout the world, south Texas, southern California and Hawaii are the only parts of the United States considered endemic areas for murine typhus. The Centers for Disease Control and Prevention do not classify it as a nationally notifiable condition, however it is reportable in Texas to the Department of State Health Services.  Read more... (  PDF)
  
  
  
• Human Rabies Prevention—United States, 2008. Recommendations of the Advisory Committee on Immunization Practices
  Morbidity and Mortality Weekly Report. May 23, 2008 / 57(RR03);1-26,28. CDC. This statement 1) provides updated information on human and animal rabies epidemiology; 2) summarizes the evidence regarding the effectiveness/efficacy, immunogenicity, and safety of rabies biologics; 3) presents new information on the cost-effectiveness of rabies postexposure prophylaxis; 4) presents recommendations for rabies postexposure and pre-exposure prophylaxis; and 5) presents information regarding treatment considerations for human rabies patients. These recommendations involve no substantial changes to the recommended approach for rabies postexposure or pre-exposure prophylaxis. ACIP recommends that prophylaxis for the prevention of rabies in humans exposed to rabies virus should include prompt and thorough wound cleansing followed by passive rabies immunization with human rabies immune globulin (HRIG) and vaccination with a cell culture rabies vaccine. For persons who have never been vaccinated against rabies, postexposure antirabies vaccination should always include administration of both passive antibody (HRIG) and vaccine (human diploid cell vaccine [HDCV] or purified chick embryo cell vaccine [PCECV]). Persons who have ever previously received complete vaccination regimens (pre-exposure or postexposure) with a cell culture vaccine or persons who have been vaccinated with other types of vaccines and have previously had a documented rabies virus neutralizing antibody titer should receive only 2 doses of vaccine: one on day 0 (as soon as the exposure is recognized and administration of vaccine can be arranged) and the second on day 3. HRIG is administered only once (i.e., at the beginning of antirabies prophylaxis) to previously unvaccinated persons to provide immediate, passive, rabies virus neutralizing antibody coverage until the patient responds to HDCV or PCECV by actively producing antibodies. A regimen of 5 1-mL doses of HDCV or PCECV should be administered intramuscularly to previously unvaccinated persons. The first dose of the 5-dose course should be administered as soon as possible after exposure (day 0). Additional doses should then be administered on days 3, 7, 14, and 28 after the first vaccination. Rabies pre-exposure vaccination should include three 1.0-mL injections of HDCV or PCECV administered intramuscularly (one injection per day on days 0, 7, and 21 or 28). Modifications were made to the language of the guidelines to clarify the recommendations and better specify the situations in which rabies post- and pre-exposure prophylaxis should be administered. No new rabies biologics are presented, and no changes were made to the vaccination schedules. However, rabies vaccine adsorbed (RVA, Bioport Corporation) is no longer available for rabies postexposure or pre-exposure prophylaxis, and intradermal pre-exposure prophylaxis is no longer recommended because it is not available in the United States.  Read recommendations... 
  
  
  




• Dengue and Dengue Hemorrhagic Fever
  
  • Dengue in Texas.
    Although dengue is not endemic in the continental United States, cases are reported in Texas each year, primarily in persons who traveled to endemic areas. The Centers for Disease Control and Prevention considers dengue the most common arboviral disease in the world, and outbreaks occur frequently in tropical and subtropical countries. Outbreaks and localized transmission have occurred sporadically in Texas along the border with Mexico since the 1980’s during dengue outbreaks in adjoining Mexican states Read more... (  PDF)
    
    
    
  • Dengue Response Guide
    The public health response to dengue virus is important in order to minimize human illness through public education, early diagnosis of the disease, and vector control, identify locations where the disease poses the greatest threat; and identify breeding sites and implement control measures for the mosquito vector species. Because these particular mosquitoes are container-breeding insects, vector control measures and surveillance should be targeted toward the areas that provide a breeding and shelter environment for the dengue mosquito population. Control efforts will depend largely on the local authority and the public response to eliminate and locate such risk conditions. Local mosquito control and surveillance efforts should be based on the principles of Integrated Mosquito Management (IMM), legal protection measures, and ensuring that prompt, accurate information reaches the public so that they may institute personal protective measures. Statutory authority to enforce abatement of nuisance conditions that provide mosquito breeding in the county and non-incorporated municipalities is contained in Chapters 341, 342 and 343 of the Texas Health and Safety Code. Statutory authority to conduct mosquito control (including the use of adulticides and larvicides as well as source reduction) is contained in Chapter 81 of the Texas Health and Safety Code Go to guide... ... (  PDF)
    
    
    
  • Centers for Disease Control and Prevention Outbreak Notice Update: Dengue, Tropical and Subtropical Regions.
    Read more...