Comparative Study of Haemonchus Contortus Infection in Indian Goat Breeds

Last Updated: January 22, 2026
Estimated reading time: 7 minutes

The Haemonchus contortus infection represents one of the most significant pathogenic challenges in small ruminant production, particularly in tropical climates where environmental conditions favor parasite survival. This comprehensive study evaluates the comparative resistance status and immune responses of two prominent Indian goat breeds, Jamunapari and Sirohi, against this gastrointestinal nematode. Understanding the genetic and immunological basis of resistance is crucial for developing sustainable control strategies, such as selective breeding and vaccination, to mitigate economic losses caused by severe anaemia and reduced productivity in infected herds.

Key Takeaways:

• Breed Difference: Sirohi goats exhibited significantly higher resistance to nematode infection compared to Jamunapari goats, evidenced by lower faecal egg counts.
• Seasonal Impact: The highest incidence of infection occurred during the rainy season (monsoon), while the lowest was recorded in winter.
• Physiological Stress: Peri-parturient (around kidding) does showed a marked rise in parasite eggs, confirming temporary loss of immunity due to reproductive stress.
• Vaccination Potential: Immunization with Excretory/Secretory (ES) antigens provided longer-lasting antibody levels compared to Crude Somatic Antigens (CSA).
• Haematological Correlation: A strong negative correlation was found between worm burden (Faecal Egg Count) and packed cell volume (PCV), serving as a reliable indicator of anaemia.

COMPARATIVE STUDY ON IMMUNE RESPONSE AND RESISTANCE STATUS IN INDIAN GOAT BREEDS AGAINST Haemonchus contortus INFECTION

Epidemiology and Prevalence Patterns

The epidemiological investigation aimed to determine the incidence and intensity of Haemonchus contortus infection across different seasons, age groups, and sexes in a semi-arid region. The study analyzed 1,858 faecal samples collected between June 2006 and May 2008. The data revealed that environmental factors, particularly rainfall and temperature, play a pivotal role in the larval development and subsequent infection rates in grazing animals. The overall incidence was notably higher during the monsoon season due to favorable humidity for larval survival, whereas the dry and cool winter months suppressed parasite transmission.

“The incidence of H. contortus infection in Jamunapari and in Sirohi goats was 43 and 33 percent respectively” (Agrawal, 2009, p. 92).

This finding highlights a distinct breed-based variation in natural susceptibility. The Jamunapari breed, known for its large size and milk production, appeared more vulnerable to the parasite than the hardy Sirohi breed native to the arid Arawali hills. This epidemiological baseline is critical for farmers to schedule deworming treatments effectively, targeting high-risk periods like the rainy season to prevent severe outbreaks.

Student Note / Exam Tip: Remember that rainfall and humidity are the primary environmental drivers for Haemonchus transmission; always link high moisture with peak infection rates in epidemiological answers.

Season	Jamunapari Incidence (%)	Sirohi Incidence (%)
Summer	48.08	31.56
Rainy	56.34	58.50
Winter	25.29	21.55

Fig: Seasonal incidence of Haemonchus contortus infection in Jamunapari and Sirohi goats (Reformatted from Table 5, p. 99).

Professor’s Insight: Notice how incidence drops sharply in winter; this demonstrates the parasite’s dependence on specific microclimates, making pasture management during dry months a viable non-chemical control method.

Genetic Resistance and Heritability Estimates

Genetic resistance to Haemonchus contortus infection is a heritable trait that can be exploited to breed animals with stronger innate immunity. The study utilized Faecal Egg Counts (FEC), transformed into Log Faecal Egg Counts (LFEC), as the primary phenotypic marker for resistance. Lower LFEC values indicate higher resistance. The analysis showed that Sirohi goats consistently maintained lower egg counts than Jamunapari goats across various ages and seasons, suggesting they possess a superior genetic ability to suppress worm fecundity or establishment.

“The significant effect of sire on this trait indicated that superior bucks could be used effectively for enhancing the resistance to nematode infection” (Agrawal, 2009, p. 113).

Heritability estimates (h²) varied between the breeds and age groups. In Jamunapari goats, the heritability for LFEC was moderate (0.20 ± 0.07 in adults), indicating that selective breeding could lead to genetic progress in resistance. However, heritability in Sirohi goats was lower (0.08 ± 0.07), possibly due to lower phenotypic variation within that specific herd. These genetic parameters confirm that resistance is not just an individual trait but one that can be passed down, offering a long-term solution to anthelmintic resistance.

Student Note / Exam Tip: Heritability (h²) is the proportion of variation in a trait due to genetics; a moderate h² (0.2–0.4) implies that selection based on sire performance (low FEC) will effectively improve the flock’s resistance over generations.

Professor’s Insight: The difference in heritability between breeds suggests that while selection is promising for Jamunapari, the Sirohi breed might already be naturally fixed for higher resistance genes due to its evolution in harsh environments.

Haematological and Physiological Responses

The pathogenic impact of Haemonchus contortus is primarily due to its blood-feeding habit, leading to anaemia. This section evaluates the correlation between parasitological data (FEC) and haematological parameters like Haemoglobin (Hb) and Packed Cell Volume (PCV). The study confirmed a significant negative correlation: as the worm burden increased, Hb and PCV levels dropped. Interestingly, despite higher infection rates, Jamunapari goats maintained slightly higher overall PCV and Hb values compared to Sirohi, likely due to their larger body size and physiological baseline, yet they still suffered significant anaemia during peak infection.

“The breed wise least squares mean of PCV observed in Jamunapari goats was 20.81±0.67 percent and in Sirohi goats 19.16±0.65 percent” (Agrawal, 2009, p. 121).

A critical physiological phenomenon observed was the “peri-parturient rise” (PPR) in FEC. Does (female goats) showed a sharp increase in egg shedding around the time of kidding (birth). This relaxation of immunity is attributed to the hormonal and nutritional stress of late pregnancy and early lactation. The study noted that this rise was more pronounced and persistent in Jamunapari does compared to Sirohi does, further reinforcing the superior resilience of the Sirohi breed during stress periods.

Student Note / Exam Tip: The Peri-parturient Rise (PPR) is a temporary loss of acquired immunity in pregnant animals; it is the most significant source of pasture contamination for newborn kids.

Professor’s Insight: Always verify anaemia clinically using FAMACHA cards in the field, as this study confirms the strong link between high egg counts and low PCV/Hb levels.

Immunological Response and Vaccination Trials

This section explores the host’s active immune defense and the potential for vaccination. The study compared the efficacy of two antigen types extracted from adult H. contortus worms: Crude Somatic Antigen (CSA) and Excretory/Secretory (ES) Antigen. Goats immunized with these antigens showed a significant reduction in FEC and worm burden compared to non-immunized controls. The immune response was measured via ELISA, tracking antibody titers over time.

“Only ES immunized goats maintained their antibody levels for longer period” (Agrawal, 2009, p. 120).

While both antigens induced protection, the kinetics of the immune response differed. The group immunized with ES antigens sustained high antibody levels for a longer duration compared to the CSA group, where antibody levels receded earlier. This suggests that antigens secreted by the live parasite (ES) are more recognized by the host’s immune system during an active infection, making them better candidates for vaccine development. The study recorded a 99.9% reduction in FEC in some trials, although practical field application requires further refinement of adjuvants and delivery methods.

Student Note / Exam Tip: Excretory/Secretory (ES) antigens often produce a more sustained immune response than somatic antigens because they mimic the natural compounds released by the parasite during infection.

Professor’s Insight: The success of the ES antigen trial points toward future vaccines that target the worm’s metabolic products, essentially starving or neutralizing the parasite rather than just attacking its physical structure.

Real-Life Applications

1. Selective Breeding Programs: Farmers can use the finding that sire selection reduces FEC to breed “worm-resistant” flocks. By choosing bucks with consistently low egg counts, the next generation of Jamunapari goats can become genetically hardier, reducing reliance on chemical dewormers.
2. Targeted Deworming Schedules: Since incidence peaks in the rainy season and drops in winter, veterinarians should advise farmers to deworm strategically just before the monsoon (May-June) to prevent pasture contamination. Avoiding treatment in low-risk winter months saves money and slows drug resistance.
3. Nutritional Support for Pregnant Does: Understanding the “peri-parturient rise” allows herd managers to provide high-protein supplementation to pregnant does 2–3 weeks before kidding. This boosts their immune resilience and reduces the shedding of eggs that would infect vulnerable newborns.
4. Breed Selection for Harsh Climates: For farmers in semi-arid or resource-poor regions, raising Sirohi goats is scientifically validated as a better choice due to their innate resistance to parasites compared to the more susceptible Jamunapari.

Why this matters: Applying epidemiological and genetic data to herd management directly impacts profitability by reducing mortality rates and veterinary costs, a core skill for any veterinary or animal science student.

Key Takeaways

• Breed Susceptibility: Jamunapari goats are more susceptible to Haemonchus contortus than Sirohi goats under natural conditions.
• Seasonal Dynamics: Infection intensity is highest during the monsoon (rainy) season and lowest in winter.
• Indicator Traits: Faecal Egg Count (FEC) is a reliable, heritable trait for selecting resistant breeding stock.
• Physiological Vulnerability: Lactating and late-pregnant females suffer a temporary loss of immunity (PPR), leading to high egg shedding.
• Vaccine Efficacy: Antigens derived from the parasite (ES and CSA) can stimulate protective immunity, reducing egg output by over 90% in experimental trials.
• Anaemia Link: There is a significant negative correlation between parasite load and blood health (Hb/PCV).

MCQs

1. Which season recorded the highest incidence of Haemonchus contortus infection in the study?
   A. Winter
   B. Summer
   C. Rainy (Monsoon)
   D. Spring
   Correct: C
   Difficulty: Easy
   Explanation: The study found incidence peaked at 56–58% during the rainy season due to favorable humidity for larval development (Agrawal, 2009, p. 99).
2. What does the “Peri-parturient Rise” (PPR) refer to in the context of this thesis?
   A. Increase in antibody titers after vaccination
   B. Increase in Faecal Egg Counts in does around the time of kidding
   C. Increase in body weight of kids after weaning
   D. Increase in eosinophil counts during winter
   Correct: B
   Difficulty: Moderate
   Explanation: PPR is the temporary relaxation of immunity in pregnant/lactating females, resulting in a sharp rise in egg shedding (Agrawal, 2009, p. 117).
3. Which antigen type provided a longer-sustained antibody response in the vaccination trials?
   A. Crude Somatic Antigen (CSA)
   B. Excretory/Secretory (ES) Antigen
   C. Recombinant H11 Antigen
   D. Irradiated Larval Antigen
   Correct: B
   Difficulty: Challenging
   Explanation: While both antigens were effective, the antibody levels in the ES immunized group were maintained for a longer period compared to the CSA group (Agrawal, 2009, p. 120).

FAQs

Q: Which goat breed was found to be more resistant to stomach worms?
A: The Sirohi breed was found to be more resistant than the Jamunapari breed, exhibiting lower faecal egg counts and reduced susceptibility under natural grazing conditions.

Q: What is the main method used to measure parasite resistance in this study?
A: The study primarily used Faecal Egg Count (FEC), often transformed into Log FEC (LFEC), as the standard phenotypic indicator for determining parasite load and resistance status.

Q: Why is the peri-parturient rise (PPR) important for herd management?
A: PPR causes a massive release of parasite eggs onto pastures exactly when new susceptible kids are born. Managing PPR through nutrition or deworming prevents severe infection in young animals.

Q: Did vaccination completely eliminate the parasite infection?
A: No, vaccination did not provide 100% immunity. However, it significantly reduced the worm burden and egg output, which helps in controlling the disease and reducing pasture contamination.

Lab / Practical Note

Safety Tip: When performing the Modified McMaster technique for faecal egg counting, always wear gloves and handle samples as potential biohazards. Saturated salt solutions used for flotation can be corrosive to equipment; ensure microscope slides are thoroughly washed and dried after use to prevent crystallization that obscures future readings.

External Resources

• NCBI: Haemonchus contortus genomics and biology
• ScienceDirect: Genetic resistance to nematodes in small ruminants

Sources & Citations

Thesis: Comparative Study on Immune Response and Resistance Status in Indian Goat Breeds Against Haemonchus contortus Infection, Ms. Nimisha Agrawal, Supervisor: Dr. D.K. Sharma, Central Institute for Research on Goats (CIRG), Makhdoom, Mathura, 2009. Pages 92, 99, 113, 117, 120, 121.

Disclaimer: This summary was assisted by AI and verified by a human editor. It is intended for educational purposes only.

Author: Ms. Nimisha Agrawal (Ph.D. Candidate), Central Institute for Research on Goats.
Reviewer: Abubakar Siddiq