Out of total pyrexia of unknown origin (PUO), Rickettsial diseases amount for nearly 24%. Out of total richettsial infection cases scrub typhus was responsible for 62.8%, spotted fever group for 32.6% and endemic typhus for 4.7% cases.

1. Epidemiology of Rickettsial
diseases of animals in India-
Temporal and Spatial
Distribution
Radhakrishna Sahu
Division of Veterinary Public Health
&
Bhoj R Singh
Division of Epidemiology
Indian Veterinary Research Institute Izatnagar-243122

2. Rickettsia
• Prokaryotes
• Resemble characteristics of both bacteria and
virus
• It’s smaller than bacteria and larger than
virus

3. Like bacteria
• Contains both DNA &
RNA
• Multiply through
binary fission
• Staining reaction (Gram
negative organisms)
Like virus
• Obligate intracellular
parasites
• Can’t be cultured in
artificial media
• Requires living cells or
embryonated eggs for
growth and isolation
Rickettsia
Prokaryotes, resembling with both bacteria
and virus in their characteristics. There are
smaller than bacteria and larger than virus.

4. Rickettsia: A big group
Family –Rickettsiiaceae
Genus-
-Ehrlichia
-Orientia
-Coxiella (now excluded)
-Rickettsia (Typhus group and Spotted
Fever Group)
-Neorickettsia
-Anaplasma
-Bartonella quintana (Now excluded)

5. Ehrlichia
 In Canines- Ehrlichia canis (Canine Rickettsiosis)
& E. ewingii (Canine Granulocytic Ehrlichiosis)
 In Cattle- E. ruminatum (Heart Water Disease)
 In Human- E. chaffensis (Human Monocytic
Ehrlichiosis)

6. Canine Ehrlichiosis
• Also known as Canine Rickettsiosis/ Canine
Haemorrhagic Fever/ Canine Typhus/ Tropical Canine
Pancytopaenia
• Transmitted by Brown dog tick (Riphicephalus
sanguinus) and Deer tick (Ixodes scapularis)
• Iatrogenic transmission through blood transfusion
• Most of the cases occurs during spring and summer
• Widely prevalent in tropical and sub-tropical
countries
• Dog (particularly German Shepherd) & cats are more
susceptible for infection

7. Ehrlichiosis appears in 3 phases
1. Acute Phase- Characterised by fever,
petechiae, bleeding Disorders, vasculitis,
lymphadenitis, oedema of lungs.
2. Chronic Phase- It is associated with weight
loss, pale gum, thrombocytopenia, polyurea,
dyspnoea, lameness, ophthalmic disease.
Mortality is high in chronic phase.
3. Sub-clinical phase- In this form no sign and
symptoms, the dog may remain carrier for
whole life.

8. Pathogenesis
• It infects monocytes of peripheral blood and
subsequently affects mononuclear phagocytic system
(MPS ) throughout the body.
• Thrombocytopenia occurs due to consumption of
platelet, immune mediate destruction of platelets,
sequestering of platelets, decreased production in
bone marrow. Decreased blood cell count occurs due
to bone marrow depression mostly in chronic phase.
• Sometimes co-infection with Babesia and Hepatozoan
canis also occurs to complicate the disease.
Ehrlichiosis

9. Diagnostic tests for Ehrlichiosis
• Serological assays
• PCR
• Blood smear test (Not suitable for sub-clinical
and chronic phase)
• IFA, a standard diagnostic test

10. Ehrlichia organism in Monocyte
By Courtesy of S. Dhankar, R.D. Sharma, N. Jindal. Seroepidemilogical
survey of canine Ehrlichiosis in Delhi and Haryana states.

11. Indian Scenario
• In India 1st cases was reported in Punjab
(Juyal et. al., 1992)
• 47 cases were reported in Kolkata between
May 2011- June 2012 (Das et. al., 2013)
• Many serological surveys are conducted in
Haryana, Delhi, Maharastra ( Nagpur &
Mumbai), Chennai, Gujurat, Punjab and
indicated prevalence of infection.

12. Prevalence based on Peripheral Blood-Smear test
18.9
11.35
20
2.94 2.34 2.5
0
5
10
15
20
25
Nagpur Haryana Chennai Ranchi Punjab Mumbai
Kumar et. al., 2010, Parmar et. al., 2013, Samaradni et. al., 2003, Dhankar et. al., 2011, Lakshmanan et. al., 2007,
Milanjeet et. al., 2014
20132010 2012-20132002-20052003 2007
Prevalence(%)

13. Prevalence based on DOT-ELISA & Nested PCR
80
20
62.07
46.9
41.5
52.5
0
10
20
30
40
50
60
70
80
90
Chennai Punjab Maharastra Gujurat
Dot-ELISA
PCR
Singla et. al., 2011, Bhadesiya et. al., 20015, Parmar et. al., 2013, Lakshmanan et. al., 2007
20142011 20132007
Prevalence(%)

14. Heart Water Disease
• Also known as Cowdriosis/ Ehrlichiosis, and is
caused by Ehrlichia ruminantium (Cowdria
ruminantium).
• Spread through Bont long tick (Ambylomma)
bites contaminated with saliva or regurgitated
gut contents of the ticks.
• Reported in cattle, sheep, goat, antelopes and
buffaloes.
• More common in young animal than in aged.
• Indigenous cattle are comparatively resistant.

15. Clinical Heart Water Disease
• Fluid get collected around (pericardiac fluid) heart to muffle the
heart sound and lungs of animal get congested due to increased
vascular permeability.
• Neurological signs like tremors, head pressing are common.
• Respiratory signs like coughing and nasal discharge are apparent.
• Fever associated with petechiae on mucous membrane are often
observed.
• During post-mortem: Straw coloured fluid is excess is present
around heart (pericardial space) which clots on exposure to air due
to high fibrinogen content.
• Microscopic examination of blood smears can reveal extracellular
Elementary bodies (Smaller in size, Infective stage), Reticulated
body of Large size and Intermediate body.

16. Severe Lung Edema Edema of Cerebral Grey Matter
Hydropericardium
From: http://www.afrivip.org/sites/default/files/HW/diagnosis.html

17. Not Reported in India
• Common in Sub-Saharan Africa & West-Indian
Island (Zanzibar, Madagascar, Saotome,
Mauritius, Reunion)
• No clinical report in India till date.
Diagnosis
Demonstration of colony in cytoplasm of capillaries
and endothelial cells of brain seen in Squash smear of
cerebral grey matter stained with Romanowsky Stain.
Immunoperoxidase method for Formaline Fixed
Tissues. Differential diagnosis is needed to avoid False
+ve (may be confused with Chlamydia pecorum).

18. Anaplasma and anaplasmosis
1. Anaplasma marginale/ A. caudatum ( Cause
Bovine Anaplasmosis)
2. A. phagocytophilum (Canine Ehrlichiosis)
3. A. platys (Canine Ehrlichiosis)
4. A. centrale (infect cattle)
5. A. ovis ( Affect sheep, deer, goat and other
antelopes)

19. Bovine Anaplasmosis
• Previously known as Gall Sickness
• Mostly Caused by Anaplasma marginale however A.
centrale, A. bovis may also cause clinical infection.
• Bos indicus are more resistant than Bos taurus.
• 17 different tick vectors (Boophilus microplus is the
most important in India followed by Hyalomma
anatolicum)
• Mechanical carriers are Tabanus spp. and Musca spp.
flies.
• Prevalent in South and Central America, USA,
Southern Europe, Africa and Asia.

20. Distribution of Disease
• Inverse age resistance- Calves are more
resistant to clinical disease (but not to
infection)
• <1yr- Sub-clinical
• 1-2yr- Moderately severe
• Older cattle- Severe and fatal

21. Clinical signs
Disease is seen in different forms
• Per-acute- Death within few hours of clinical signs
• Acute- decreased milk production, inappetance,
rapid breathing, brown colour urine, mucous
membranes are pale and yellow, abortion in
pregnant animals common.
• Macrocytic Normochromic Anaemia (Destruction
of both infected and non-infected erythrocytes
due to phagocytosis).

22. Prevalence of Anaplasmosis
Through Microscopy (19.51%),
With ELISA (31.71%)
By PCR (42.39%) (Sharma et al. 2014)
&
Through Microscopy (11.25%),
By PCR (48.75%) (Ashuma et al. 2012)
Prevalence Study in Punjab

23. • Bos indicus are more resistant to disease but acts as a
carrier (Firozpur, with microscopy 16% while with PCR 80%
(Ashuma et al. 2012)
• Buffaloes act as a potent source of infection being carrier
(nearly 18.18% +ve in PCR, Ashuma et al. 2012)
• Use of infected needles for medication may be a source of
infection (as in Patiala & Ludhiana) (Ashuma et al. 2012)
• Less prevalent in Oxytetracycline and acaricides used areas
(Ashuma et al. 2012)
• Sub-mountain zones are at higher risk because these are
semi humid region which favours vector (Sharma et al.
2014)
Prevalence of Anaplasmosis

24. Prasanna kumar et al. (2010) reported 46.9% Overall
prevalence of the diseases in Hisar and adjacent
areas of Bhiwani District, but more on Large
organized dairy farms (59.2%). Probably due to
availability of large quantity of water which
increases moisture, increase in Boophilus ticks and
easier transmission due to bigger herd size.
Detected in animals of commercial dairy sectors
(46.07%), Gaushalas (44.1%) and Small hold dairy
units (35%) (Transmission is not that easier due to
smaller herd size and scattered population)
High prevalence without any clinical disease indicates
endemic stability.
Prevalence of Anaplasmosis

25. Prevalence studies in other
parts of India
• Tamilnadu- 2.64% (Velusamy et. al., 2014)
• Northen Kerala- A. marginale (16.67%) & A.
bovis (3.33%) (Nair AS et. al., 2013)
• Kancheepuram- 18.9% & Chennai- 12.9%
(Arunkumar et. al., 2013)
• Myesore (1.51%), Mandya (0.95%),
neighbouring district of Bangalore(2.31%)
(Krishna Murthy et. al., 1994, Muraleedharan et. al., 2005)

26. Canine Anaplasmosis
• Anaplasma phagocytophillus and A. platys
• Causes lameness (Confused with Lyme Disease)
• A. platys causes thrombocytopenia, bruise in
gum and belly and spontaneous nose bleeding
• Transmitted mainly by Deer fly.

27. Canine Anaplasmosis In India…..
• A. phagocytophillum infection is reported
from North East India (4.71%) with highest
prevalence in pet dogs (6.09%) (Borthakur et. al., 2014)
• A. platys infection cases (27 ) were confirmed
in Referral Poly Clinic, Indian Veterinary
Research Institute, Izatnagar, Bareilly (UP),
mostly having co-infection with E. canis,
Babesia gibsoni, B canis (Kumar and Varshney et. al., 2007)

28. Neorickettsia
• N. risticii (Formerly known as Ehrlichia risticii)
causes Potomac Horse Fever/ Shasta Fever/
Equine Monocytic Ehrlichiosis.
• The disease was 1st described in Potomac
River area, Washington in 1980
• It is vector borne disease. Vectors are
freshwater snails and trematodes released
from the snails.
• Found in US, Canada, Europe, India.

29. • The disease appears as acute enterocolitis
syndrome (mild colic, fever, and diarrhoea).
• Infection of enterocytes of the small and large
intestine.
• Often precipitates in spring, summer, and early
fall and is associated with pastures bordering
creeks or rivers.
• In pregnant mares, abortion, due to foetal
infection, may be seen.
• Leucopoenia and thrombocytopenia is observed
on blood examination.
Potomac Horse Fever

30. Potomac Horse Fever Diagnosis
• Isolation or identification of N. risticii from
the blood or faeces of infected horses in cell
culture (mouse macrophage cell line P388D1,
or cos-7 cell line or canine myelocytic
leukemia cell line DH82).
• PCR using specific primers.
• Serologic testing is of limited value because
of false positive reaction.

31. • N. helminthoeca causes Salmon poisoning in Dog.
• It has been reported from Oregon, California, Washington
and India.
• Spread through snail-fish-dog cycle. Its specific vector is a
fluke Nanophyetus salmincola.
• Clinical signs appear 5–7 days after eating infected fish,
and persist for 7–10 days.
• There may be up to 90% mortality among untreated
animals.
• Infection affects the lymphoid tissues and intestines and
is associated with enlargement of the GI lymphoid
follicles, lymph nodes, tonsils, thymus, spleen and other
lymphoid organs.
Neorickettsia helminthoeca

32. Prevention of Salmon poisoning in Dogs
• Restrict the ingestion of uncooked salmon, trout, steelhead,
and similar freshwater fish.
• Animals that recover mount a persisting profound humoral
immune response and are resistant to further infection but
may serve as source of infection.
• N. elokominica- It is reported to be the cause of Elokomin
fluke fever in canids, ferrets, bears, and raccoons. Dogs and
other animals become infected by ingesting trout, salmon,
or Pacific giant salamanders that contain the encysted
metacercaria stage of the Rickettsia-infected fluke. In the
dog's intestine, the metacercarial flukes excyst, embed in
the duodenal mucosa, become gravid adults, and transmit
the rickettsiae to monocytes-macrophages. The fluke
infection itself produces little or no clinical disease but the
Rickettsia may be cause of illness and death.

33. Orientia tsutsugamushi
Tsutsuga= Small & Dangerous + Mushi=Creature
• Scrub typhus/Rural Typhus/ Hairy Mite
Fever/ Keelani Fever/ Japanese Fever/
Chigger borne typhus
• In India it is most common zoonotic
Rickettsia infection

34. • A Vector (Trombiculid mites, Leptotrombidium
deliense & L. akamushi) borne disease. Only
larval stage of the mite can transmit the disease
• Scrub means a type of vegetation like
abandoned plantation, rice field, forest clearing,
river bank. It acts as Endemic Foci and these
areas are known as mite islands.
• Wild rodents acts as natural hosts to Scrub
Typhus and migration of the rodents leads to
establishments of diseases in different foci but
rodents themselves don’t show any clinical sign.
Scrub Typhus/Rural Typhus

35. World Scenario: Triangle of Scrub Typhus/Rural Typhus
Northern Japan
to Far Eastern
Russia
Northern
Australia
Up to Pakistan
& Afghanistan
Tsutsugamushi Triangle
1 billion
population are at
risk
1 million cases
occurs annually
Parag Sharma, Rakesh Kakkar, Shilpa.N.Kaore,Vijay. K. Yadav, Raj Sharma. Geographical Distribution, Effect of Season & Life Cycle of Scrub Typhus.

36. Scrub Typhus/Rural Typhus in India
 Prevalent all over India
1. In Shivalik Ranges ( From Kashmir to Assam)
2. Vindhya & Satpura Ranges in Central India
3. Deccan Plateau in Southern India
 Eight serotypes are recognized [Gillian, Karp,
Kato, Shimokoshi, Kawaski, Kuroki, Litchfield (Australia)]

37. Clinical Signs of Scrub Typhus
• Eschar at the site of bite of mite (may lead to
missing of diagnosis because in most of
Indian cases eschar may be absent).
• It multiplies and develops inside phagocytes
• Fever, headache, myalgia, dry cough, GI
disturbance are common.
• Delayed Treatment may lead to
complications like renal failure, meningitis,
myocarditis , pneumonia, multi organ failure.

38. Clinical cases reported across India
1. April2006- April 2008 (50 cases)
2. February 2011-January 2012 (57 cases
3. Septmber2012-february 2013 (53 cases)
In Pondicherry
June 2009-October 2010, 42
cases in Goa
August 2011- December 2012,
176 cases in Andhra Pradesh
October- December 2012, 42
cases in North West India
In 2003, 43 cases in Himalayan Region
In 2003-2004 & 2007, in Sikkim
and Darjeeling
January 2004 to December 2005, 115
+ve cases, Seroprevalence (37.5%) in
T&N

39. Environment Favouring Scrub
Typhus/Rural Typhus
• Most of the cases occurs after July and before
February i.e. during monsoon and during
post-monsoon period.
• During monsoon period there is increased
incidence of rain and exposure of rural
people occurs during rice harvesting in fields.
• During post monsoon period there is
increased scrub vegetation which is an
important habitat or mites.

40. Problems of Controlling Scrub
Typhus/Rural Typhus
• Lack of public knowledge/ education.
• Poverty resulting in less hospital visits and
thus low number of case detection.
• Diagnosis mostly done using Weil-Felix
reaction(High specificity & low sensitivity
test)
• IFA, IPA & ELISA are not available in India at
economic rates and are out of approach.

41. Murine Typhus
• Endemic typhus/ Urban typhus/ Shop
typhus/ Flea Borne Typhus
• Causative agent – Rickettsia typhi (Previously
known as R. mooseri)
• Vector- Mostly Rat flea (Xenopsylla cheopis)
and rat louse (Polyplax spinulosa) but also
Cat flea (Ctenocephalidis felis) and mouse
flea (Leptopsylla segnis) may act as a vector.

42. Life Cycle and Transmission of
Murine Typhus
• Normal life cycle Rat-flea-Rat.
• Rat (Rattus rattus, R. norvegicus, R. exulans) acts as a
natural carrier (no symptoms /no clinical disease)
• Also Shrews and Skunks acts as host.
• Can persist long time in cat burrows.
• Human is accidental host (vascular endothelial cells
resulting obliterative thrombo vasculitis &
perivascular nodules)
• Virulent to Guinea pigs when experimentally
inoculated produces Neil-Mooseri Reaction (Scrotal
swelling, inflammation, haemorrhage beneath tunica)

43. Source of infection for Murine Typhus
• Inhalation of infected flea faeces.
• Contact of infective excrements with
conjunctiva.
• Swatting of flea while feeding or scratching
after bite.
• Visit to hot humid area & cold semi arid area,
favourable foci/ niche of the disease.

44. Murine Typhus: Indian scenario
• Besides India, disease is common in China,
Indonesia, Morocco, Canaries, Isles, Africa,
Malaysia, Thailand and Myanmar.
• In India, Jammu and Kashmir, Himachal Pradesh,
Uttar Pradesh (Lucknow), Karnataka (Mysore)
and West Bengal (Kolkata), Maharashtra
(Pune), Andhra Pradesh (Golkunda), Haryana
(Karnal, Rewari) areas have been found infested
wuith Murine Typhus.
• Most parts of in South India are endemic areas
particularly during cooler months.

45. Indian Tick Typhus
• Also known as Boutonesee Fever/ Israeli
Spotted Fever/ Mediterranean Spotted Fever.
• Caused by Rickettsia conori.
• Transmitting vector is a tick, Riphicephalus
sanguineus.
• Has a wide host range including wild rodents,
sheep & goats, non- human primates.
• Up to 80% dogs are found to be serologically
positive without any clinical signs as observed in
case of other animals.

46. Indian Tick Typhus in humans
• Small red dish shaped ulcer at the site of tick
bite.
• Localized lymphadenitis, fever for 5-7 days,
myalgia and joint pain.
• Generalized eruption after 4-5th days of fever.
• Complication in some cases like purpuric
exanthema, renal failure, hypoxemia,
thrombocytopenia, hypotension,
hypocalcaemia may lead to mortality.

47. Indian Tick Typhus Occurrence
• Reported from Karnataka(Bangalore), Kerala, Uttar
Pradesh (Allahabad, Lucknow, Jhansi),
Maharastra(Pune), Andhra Pradesh (Narsapatnam,
Secunderabad), Tamilnadu (Trichinapally), Madhya
Pradesh (Ratlam) and West Bengal (Darjeeling).
• First reported in Foothills of Himalayas.
• Out of total pyrexia of unknown origin (PUO),
Rickettsial diseases amount for nearly 24%. Out of
total richettsial infection cases scrub typhus was
responsible for 62.8%, spotted fever group for 32.6%
and endemic typhus for 4.7% cases (Somashekar HR
et. al., 2006).