Vector control Module 2C

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Vector controlModule 2C

• Diseases from rodent vectors

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Rat morphology diseases

• Lassa fever
• Flea borne Typhus
• Leptospirosis

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Known Distribution of the Lassa rat - Mastomys
MASTOMYS DISTRIBUTION
LASSA discovered in 1969
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Lassa Fever

• Viral haemorrhagic fever
• 300,000-500,000 infections/year, with 5000 deaths
• Rodent-to-human transmission (Mastomys
  species-complex)
• Secondary human-to-human transmission
• Nosocomial outbreaks with high case-fatality

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Viral hemorrhagic fevers share the following
characteristics

• They are all RNA viruses
• They are all zoonotic (natural reservoir is an
  arthropod or other animal host)
• Disease is restricted to habitat of the host
• Humans become infected by contact with host
• Some viruses can be transmitted from human to
  human

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Marburg

• Marburg Virus
• Transmission from animal host (unknown/rodent
  possible)
• Human to Human (Close Contact and change of
  fluids highly suspect source of transmission)

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Marburg Outbreaks

• 1967 Hamburg and Marburg, Germany and Belgrade,
  Yugoslavia
• 1975 Johannesburg, South Africa, 3 died
• 1980 Western Kenya, 2 Died (Physician died in
  Nairobi)
• 1987 Young man traveling extensively in Kenya
• 1999-2000 Durba, Republic of Congo
• Cases linked to workers in a gold mine

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Signs and Symptoms - Marburg

• 3 to 9 day incubation period
• Sudden onset of back pain, sore throat, muscle
  pain, headache, and nausea
• Skin rash (papular or maculopapular), fever, low
  platelets, gastrointestinal bleeding
• Rapid progression to jaundice increased bleeding
  abnormalities
• Death (3-9 days) from encephalitis, fulminant
  hepatitis, pulmonary and gastrointestinal
  hemorrhage

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Rodent Reservoir

• Mastomys species complex
• Taxonomy still unclear
• M. huberti more common in peridomestic habitat
• M. erytholeucus more common in brush habitat
• Others

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Transmission

• Rodent-to-human
• Inhalation of aerosolized virus
• Ingestion of food or materials contaminated by
  infected rodent urine / excreta
• Catching and preparing Mastomys as a food source
• Handling dead rats that have urine/virus on them

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• Human-to-human
• Direct contact with blood, tissues, secretions or
  excretions of infected humans
• Needle stick or cut
• Inhalation of aerosolized virus

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Current Therapy for Lassa Marburgh

• Supportive therapy with oxygen, nutritional
  support, and hydration.
• Hemorrhage is managed by replacement of blood,
  platelets, and clotting factors
• Ribavirin is a synthetic nucleoside analog that
  is of use in treating Lassa fever but not useful
  for Marburgh.
• Passive transfer of human antibodies has remained
  inconclusive in its benefit to Marburg.

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Prevention and Control

• Village based programmes for rodent control and
  avoidance
• Active case detection and reporting
• Hospital training programmes to avoid nosocomial
  spread barrier nursing
• Early diagnosis
• Early antiviral therapy

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Rodent Control

1. Proper storage of food in rodent proof containers
2. Cleaning around house
3. Repairing holes in wall and doors to block rat
   entry into house
4. Trapping and killing rodents with proper and safe
   disposal of carcasses
5. Avoid rodents as a food source

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Lassa / Marburg Prevention and Control
Protection for Clinical Care Ideally Respirator
Protection for Culture (P4)