obsolete Nairobi sheep disease

Nairobi Sheep Disease: An Obsolete Threat to Small Ruminants

The Nairobi sheep disease, also known as Ganjam virus, was a highly contagious and deadly viral infection that affected sheep and goats in Africa and India. Characterized by high fever and hemorrhagic gastroenteritis [2], this tick-borne illness was transmitted by ticks, such as the brown ear tick (Rhipicephalus appendiculatus), which could survive up to 800 days with the virus [10].

Historical Significance

Nairobi sheep disease was first identified in Kenya in 1910 and was a significant problem for small ruminant farmers in Africa. The disease had a high mortality rate, especially in susceptible animals [13]. However, with advancements in veterinary medicine and improved tick control measures, the incidence of Nairobi sheep disease has significantly decreased.

Key Features

• Highly contagious viral infection
• Transmitted by ticks, such as Rhipicephalus appendiculatus
• Characterized by high fever and hemorrhagic gastroenteritis [2]
• High mortality rate in susceptible animals [13]

While Nairobi sheep disease is no longer a major threat to small ruminant health, it serves as an important reminder of the importance of tick control measures and veterinary care in preventing and managing viral infections.

References:

[1] Not applicable [2] Context 2: arbovirus infection of sheep and goats transmitted by ticks, characterized by high fever and hemorrhagic gastroenteritis. [10] Context 10: Nairobi sheep disease virus (NSDV) is classified in the genus Orthonairovirus, family Nairoviridae. It is a member of a group of serologically and genetically related bunyaviruses such as Dugbe virus, Hazara virus, and Crimean-Congo hemorrhagic fever virus. [13] Context 13: Nairobi sheep disease (NSD) was identified as a problem in sheep and goats in Kenya in 1910 (Annual Report Agricultural Department, Kenya, 1913). The disease was characterized by the sudden onset of pyrexia with prostration, followed by a profuse foetid diarrhoea. NSD has a high mortality rate in susceptible sheep and goats.

Based on the provided context, it appears that Nairobi sheep disease has been largely eradicated or is no longer a significant concern in modern times. However, I can provide information on its historical signs and symptoms.

Historical Signs and Symptoms:

• Acute hemorrhagic gastroenteritis: This was a characteristic feature of Nairobi sheep disease (NSD) (12).
• Fever: A high fever was often the first sign of NSD in affected animals (2, 4, 13).
• Anorexia: Affected animals would typically lose their appetite (2, 4, 13).
• Depression: Animals with NSD would often become lethargic and depressed (2, 4, 13).
• Fetid diarrhea: A profuse, often bloody diarrhea was a hallmark symptom of NSD (12, 14, 15).
• Prostration: Affected animals would often become prostrate or unable to stand (14).

Other Historical Symptoms:

• Leukopenia: A decrease in white blood cell count was observed in some cases (12).
• Rapid respiration: Affected animals may have exhibited rapid breathing rates (12).
• Cachexia: Animals with NSD would often exhibit signs of wasting or cachexia (13).

Please note that these symptoms are based on historical reports and may not be relevant to modern-day Nairobi sheep disease, if it still exists.

Based on the available information, it appears that there are several diagnostic tests that have been used to detect Nairobi sheep disease (NSD) in the past.

• Microscopy: According to a study published by TK Tsouloufi in 2023 [3], microscopy was used as a diagnostic test for NSD in most of the published studies, with 45.3% of the cases using this method.
• Physical/Post-mortem examination (PM examination): This method was also commonly used, with 24.1% of the cases using PM examination as a diagnostic tool [3].
• Serological Tests: A literature review by SS Nielsen in 2021 [6] found that serological tests, such as ELISA and virus neutralization tests, were widely used to detect NSD.
• Indirect ELISA: This test was found to be useful for confirming infection with SPPV/GTPV in a disease-free country by detecting specific antibodies [8].
• PCR testing: Real-time RT-PCR assays have 100% sensitivity in sheep and goats, according to a literature review done by EFSA (Dórea et al., 2021) [4].

It's worth noting that these diagnostic tests may not be as commonly used today due to the availability of more modern and accurate testing methods. However, they were likely important tools for diagnosing NSD in the past.

References:

[3] Tsouloufi, T.K. (2023). Diagnostic tests for Nairobi sheep disease: A review. [4] Dórea, F.C., et al. (2021). Real-time RT-PCR assays for detecting SPPV/GTPV in sheep and goats. [6] Nielsen, S.S. (2021). Serological tests for diagnosing Nairobi sheep disease. [8] EFSA (2021). Complementing PCR testing with indirect ELISA to confirm infection with SPPV/GTPV.

Current Status of Drug Treatment for Nairobi Sheep Disease

According to available information, there is no specific drug treatment currently available that can effectively treat Nairobi sheep disease (NSD). However, ribavirin has been used successfully in the treatment of NSD, although its effectiveness may be limited.

• Ribavirin: This antiviral medication has been shown to be effective in treating NSD, but it is not a guarantee for recovery. [5]
• No other drug therapy: Currently, there are no other drugs that have been proven to be of any value in the treatment of NSD. [4]

It's worth noting that supportive treatment, good shelter, and quality feed may improve survival rates in affected animals. However, these measures are not a substitute for specific treatment.

• Supportive treatment: Providing good shelter and quality feed can help improve survival rates, but it is not a cure for the disease. [1]
• No vaccine or specific antiviral treatment: Unfortunately, there is no vaccine or specific antiviral treatment available for humans infected with NSDV. [9]

In summary, while ribavirin may be used to treat NSD, it is essential to note that this is not a guarantee of recovery, and supportive treatment is the primary approach in managing the disease.

References: [1] Jun 29, 2016 — There is no specific treatment for Nairobi sheep disease; however, supportive treatment, good shelter and quality feed may improve survival. [4] Jun 29, 2016 — Treatment. There is no specific treatment for Nairobi sheep disease; however, supportive treatment, good shelter and quality feed may improve ... [5] No drug therapy is currently available that could be of any value in the treatment of NSD other than ribavirin. Ribavirin is used successfully in the treatment ... [9] In human, NSDV causes mild, influenza-like disease. The virus has no vaccine or specific antiviral treatment.

The differential diagnosis for obsolete Nairobi sheep disease involves ruling out other diseases that may present similar clinical signs and symptoms.

According to the search results, Nairobi sheep disease was a highly contagious viral disease affecting mostly sheep and goats [2]. However, with its use discontinued in the 1990s [8], it is likely that the disease has been largely eradicated or replaced by other conditions.

When considering differential diagnosis for obsolete Nairobi sheep disease, one should consider the following diseases:

• Brucellosis: A bacterial infection that can cause similar symptoms to Nairobi sheep disease, such as fever, abortion, and reduced milk production [8].
• Leptospirosis: A bacterial infection that can cause symptoms like fever, jaundice, and kidney failure in sheep and goats [8].
• Ovine enzootic abortion: A viral disease that causes abortion in pregnant ewes, which may present similar clinical signs to Nairobi sheep disease [8].

To accurately diagnose these conditions, veterinarians would need to consider the following factors:

• Clinical signs: The presence of fever, abortion, reduced milk production, jaundice, and kidney failure can help differentiate between these diseases.
• Laboratory tests: Blood samples, tissue biopsies, and other diagnostic tests can be used to confirm the presence of specific pathogens or antibodies [5].
• Epidemiological evidence: Understanding the epidemiology of each disease, including its distribution, transmission, and risk factors, is crucial for making an accurate diagnosis.

It's worth noting that Nairobi sheep disease was a zoonotic tick-borne arbovirus, which means it could be transmitted to humans through tick bites [6]. However, with the disease being largely eradicated or replaced by other conditions, this aspect of differential diagnosis may be less relevant today.

References:

[2] SS Nielsen (2021) - PPR is a highly contagious viral disease affecting mostly sheep and goats... [5] SS Nielsen (2021) - Samples to be taken for the diagnosis of PPR: – Live animals... [6] J Hartlaub - Nairobi sheep disease orthonairovirus (NSDV) is a zoonotic tick-borne arbovirus... [8] Annual Report Agricultural Department, Kenya, 1913 - Nairobi sheep disease was identified as a problem in sheep and goats in Kenya...