VECTOR BORNE DISEASES IN PAKISTAN

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VECTOR BORNE DISEASES IN PAKISTAN
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DISEASE VECTORS IN PAKISTAN 

• Pakistan being a sub-tropical country has a rich
  fauna of disease vectors including mosquitoes,
  sandflies, houseflies, biting midges, and other
  dipterous flies.
• In addition there are soft ticks, hard ticks,
  lice, mites, fleas, cockroaches, bed bugs which,
  account for number of vector born diseases
  including arboviruses.
• Research on vector borne diseases is sketchy
  accept for few. Major vector borne diseases in
  the country include malaria, leishmaniasis.
  

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MAJOR VECTOR BORNE DISEASES

• MALARIA
• Malaria is by far the major vector borne diseases
  in the country.
  
• Malaria in Pakistan is typically unstable.
• Both Plasmodium falciparum and Plasmodium vivax
  are widely distributed in Pakistan.
  
• Major transmission period is post monsoon i.e.
  from July through November.

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Malaria Control Programme - 2001 Data
Malaria Annual Parasite Incidence (API)/1000 Pop
ulation by District

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Mosquito Species and Malaria Vectors in Pakistan

• There are over 22 anopheline species and
  sub-species so far recorded from Pakistan
  
• Anopheles culicifacies and An. Stephensi are the
  primary malaria vectors
  
• Anopheles culicifacies is considered to be the
  most important vector in the rural areas and
  Anopheles stephensi) in the urban areas.
  
• Both species are endophilic and chiefly zoophilic

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LESIHANIASIS

• Leishmaniasis is the second major vector borne
  disease
  
• Prevalence of leishmaniasis is diffuse wide
  spread
  
• Three types of leishmaniasis are encountered
• - ZCL found in the southwestern region
• - ACL is seen in diffused foci in central
  region
  
• - VL is endemic in the Northeastern Region

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Major epidemics of leishmaniasis in Pakistan
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SANDFLY FAUNA OF PAKISTAN

• Sub genus
• Phlebotomus
• Paraphlebotomus
• Larroussius
• Adlerius
• Euphlebotomus
• Anaphlebotomus

• Species
• papatasi
• alexandri nuri sergenti
• kandelakii burneyi, keshishiani major
• salangensis, hindustanicus
• argentipes
• colabaensis
• In addition 10 species of Sergentomyia reported.
• (Munir et al 1987, 1994)

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VECTORS OF LEISHMANIASIS

• ZCL P.papatasi, P. salehi
• ACL P.sergenti
• VL P. hindustanicus (AJK)
• P. Keshishiani (Northern Areas)

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CCHF IN PAKISTAN

• CCHF is and endemic tick-borne viral disease.
• Geographical distribution includes the cold, arid
  regions of Pakistan.
  

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Vectors of CCHF

• Ticks belonging to the Genus Haemaphysalis and
  Hyalomma were the dominant species collected from
  domestic animals during CCHF out-breaks in
  Baluchistan, but virus could not be isolated.
• Further studies are required to study tick fauna
  and isolation of virus from the ticks to identify
  vector species.
  

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Major Outbreaks of CCHF in Pakistan from 1976-2000
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DENGUE HAEMORRHAGIC FEVER

• DHF first reported in Pakistan in 1994 from
  Karachi
  
• Thousands of adults were affected.
• In 1995 another 1800 cases of PUO reported from,
  Hub district, Lesbella, Baluchistan, 40
  Kilometres from Karachi
  
• Dengue type-II Confirmed on serology

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VECTORS OF DENGUE

• No information is available on the vectors of
  Dengue from Pakistan.
  
• The species recorded from NWFP Pakistan list
  following species of aedes mosquitoes
  
• Aedes albopictus, Aedes albolateralis, Aedes
  vittatus and Aedes pseudotaeniatus.
  
• Another survey of mosquitoes in Karachi in 1983
  showed the abundance of Aedes aegypti

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SCRUB TYPHUS

• First out-break reported in Pakistan in 1961 in
  Sialkot and then in 1967 from Kaghan Valley,
  Gilgit, Multan and Lahore.
  
• The vector species reported was Trombicula
  delinese.
  
• No recent studies.

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INSECTICIDES IN USE

• INDOOR RESIDUAL SPRAYING
• Organochlorines
• DDT 1963-79
• BHC 1972-1983
• Organophosphate
• Malathion 1984-97
• Pyrethroids
• Deltamethrin 1998 till date

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• Larvicides
• Following larvicides belonging to
  Organophosphates are in use since 1995
  
• Temephos 500-E
• Fenthion

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ITN Study in Four Villages of Sind

• Odds Ratio (O.R.) - protective effect of bednet
  use against falciparum malaria
  
• - In children below 5 yrs ____ 0.22 (0.05 -
  0.9)
  
• (significance level 0.016)
• - In patients above 5 yrs ____ 0.46 (0.2 -
  1.07)
  
• (significance level 0.072) -- not
  significant
  
• - In all age groups _________ 0.36 (0.17 -
  0.73)
  
• (significance level 0.003)

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Prevalence of Falciparum Malaria in different age
groupsin ITN Intervention and Control Groups
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RESISTANCE STATUS OF MALARIA VECTORS

• Anopheles culicifacies and Anopheles stephensi
  are resistant to Organochlorines (DDT and
  Dieldrin/BHC)
  
• Anopheles stephensi resistant to Organophosphate
  (Malathion)

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