In Astrology, the critical and serious disease leading to death is predicted on the basis of 2nd house and the 7th house. They are known as Marak houses. The disease supporting to the main death inflicting disease are seen through 3rd,8th and 12th houses. Thus, whenever the Marak house (2nd and 7th) lord dasha is combined with the Antardasha of houses i.e. 3rd, 8th and 12th house lord. it gives extreme pains during that period.

Nakshatras also make almost same type of combination to predict the most difficult periods in life..The Nakshatra placed in the 3rd, 5th and 7th from the birth Nakshatra is considered to be instrumental in natives death inflicting disease or death.  During their dasha and Antardasha they give extreme pain similar to the pain of death,

Hence every person has 9 Marak Nakshatras, as each planet has 3 Nakshatras represented by that planet. For example, person born in Ketu dasha has 3 Nakshatras representing Ketu i.e. Ashwini, Magha,Mula. the 9 Marak Nakshatra for them will be Kritika, Mrigasira, Punarvasu, Uttara Phalguni, Chitra, Vishakha, Uttara Shada, Dhanishtha, Purva Bhadrapada.This 9 unfortunate nakshatra’s Dasha or   antardasha  or Gochar will lead to the disease that can become the reason of death.

This can be illustrated with an example. A person born in Ashwini Nakshatra will face the worst period in life danger during the dasha of Nakshatra represented by Sun. When the Sun will be traversing in Kritika or Mrigasira or Punarvasu and the Antadasha of Ketu traversing in Kritika or Mrigasira or Punarvasu. . In the chart below it can be seen that Kritika, Mrigasira and Punarvasu are 3rd 5th and 7th Nakshatra from Janma Nakshatra.   
:
Janma    Sampat    Vipat    Chhem    Pratyah    Sadhak    Vadh    Mitra    Ati-Mitra
[Ketu]                                
Ashwini    bharani    kritika    Rohini    Mrigasir    Ardra    Punarva    Pushya    Ashlesh
Magha    P.Phalg    U.Phalg    Hasta    Chitra    Swati    Vishakh    Anuradh    Jyeshth
Mula    P.Shad    U.Shad    Shravan    Dhanish    ShatBhi    P.Bhad    U.Bhad    Revati
[Venus]                                
bharani    kritika    Rohini    Mrigasir    Ardra    Punarv     Pushya    Ashlesh    Magha
P.Phalg    U.Phalg    Hasta    Chitra    Swati    Vishakh    Aunradh    Jyeshth    Mula
P.Shad    U.Shad    Shravan    Dhanish    ShatBhi    P.Bahd    U.Bhad    Revati    Ashwini

In this chart ,  the nakshatras listed under Vipat, Pratiyahri and Vadh are unfortunate Nakshatras and will be the reason of death or death inflicting disease during their dasha, antardasha or pratyantar dasha. In the similar way the charts for other planets can also be drawn.

The major disease related to Nakshatra are
Ashwini: Mental fever, epilepsy, malaria, etc.
Bharani: Skin disease, cold fever, eye infections, etc.
Kritika: Accident due to fire or blast, wounds, small pox, etc.
Rohini: Tonsils, chest pain, swelling, etc.
Mrigasira: cold and cough, tumor, swellings, etc
Ardra: ear infections, bronchus problems, etc.
Punarvasu: Pneumonia, pleurisy, headache etc.
Pushya: Cancer, tooth infection, scurvy etc
Ashlesha: Air borne disease, Allergy, kidney problems etc.
Magha: Back pain, Kidney stone, Mental problems, etc.
Purva Phalguni: problem of child birth, swelling in heart, blood pressure, etc.
Uttara Phalguni: plague, epilepsy, faintness, etc
Hasta: intestine related  disease,  gastric problems, lungs infection etc
Chitra: insect bite, wounds, urinary infection etc.
swati: skin disease, hernia, appendicitis. etc.
Vishakha: Diabetes, faintness, kidney problems, etc.
Anuradha: urinary infection, hip bone fracture, cough etc.
Jyeshtha: piles, tumour, shoulder pain.etc.
Mula: rheumatic pain, Arthritis etc.
Purvashada: Diabetes, gout, lung cancer, knee swelling.
Uttarashada: Scitica, waist pain, eye infection, back pain etc.
Shravan: Pleurisy, phyleria,  indigestion etc.
Dhanishtha: Leg injury, boils, leg amputation, fracture, etc.
Shatbhishag: Arthritis, skin disease, blood pressure etc.
Purvabhadrapad: low blood pressure, lever problem, gastro-intestine, etc.
Uttarabhadrapad: Hernia, indigestion, stomach related disease etc.  
Revati: deformed legs, swellings in kdney, clotting of blood, etc.

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