African horse sickness

The African horse sickness , African horse sickness , or African horse sickness (Engl. African Horse Sickness , AHS ) is a viral infectious disease in horses , zebras and donkeys belonging to the notifiable animal diseases belongs.

Pathogen

African horse sickness virus
Systematics
Classification : Viruses Area : Riboviria Empire : Orthornavirae Phylum : Duplornaviricota Class : Resentoviricetes Order : Reovirals Family : Reoviridae Subfamily : Sedoreovirinae Genre : Orbivirus Type : Epizootic Hemorrhage Virus
Taxonomic characteristics
Genome : dsRNA linear, segmented Baltimore : Group 3 Symmetry : icosahedral Cover : no
Scientific name
African horse sickness virus
Short name
AHSV
Left
NCBI  Taxonomy: 40050 ICTV Taxon History: 201854878

The pathogen that causes the disease is the African horse sickness virus (AHSV), a non-enveloped, double-stranded RNA virus (dsRNA) of the genus Orbivirus from the Reoviridae family . So far, nine different serotypes (AHSV-1 to 9) are known of this virus . The pathogen is particularly resistant and can survive outdoors for several years in cool weather.

transmission

The African horse sickness is by blood-sucking insects , especially by the Culicoides imicola , a mosquito of the family of midges transmitted ( see also virus infection ).

The insects ingest the virus that is already circulating in the blood of an infected animal during the sucking act. From the stomach of the insects and after reproduction cycles in the insects, the viruses also get into their salivary glands. In this way, the next time they eat, they can transfer the virus to another animal that may not yet have been infected. Transmission through contact infection or smear infection between animals is just as little known as it is transferable to humans. However, infection of dogs through the consumption of meat containing the virus has been observed.

Another possibility of infection is the transmission of the virus through contaminated syringes as part of veterinary activities.

The susceptibility to this infectious disease is greatest in the horse family . These include u. a. Domestic horses , zebras and donkeys. The infection has also been found in African elephants , angora goats and dogs .

Since zebras and donkeys can be infected for a long time without becoming seriously ill, they are considered pathogen hosts or reservoir hosts .

Occurrence and Distribution

African horse sickness is native to sub-Saharan Africa and has been known there for centuries. It was first described as an animal disease by Europeans in the late 18th century, after the introduction of horses, mules and donkeys during the colonization of the south of Africa. African horse sickness occurs predominantly during the summer rainy season. This seasonal form of the disease is closely related to the flight time of the transmitting insects. The epidemic climaxes are therefore in warm, humid weather and during the swarming period. However, infected mosquitoes can be moved up to 200 kilometers by winds and then spread the pathogen in the new location. The insects can also spread to other regions as “stowaways” in vehicles and airplanes.

Probably for this reason, too, significant disease outbreaks occurred in Iran , Pakistan and Afghanistan (1959) and India (1960). The last cases in Europe were reported from 1987 to 1990 from Spain ( Madrid and Andalusia ), southern Portugal and Morocco / Algeria (1989/90). The disease has never occurred in Germany.

The spread of African horse sickness depends on the occurrence of its vector. The main vector so far has been between 40 ° N and 35 ° S. Br. Spread. However, the distribution area seems to be expanding significantly to the north recently due to global warming. Through animal migrations and the trade of infected animals on the one hand, and the spread of insects by vehicles, aircraft and strong winds on the other hand, the pathogen can be introduced into previously virus-free regions at any time. However, it is only able to survive there if suitable vectors and a susceptible host population are available.

Clinical picture

The disease is particularly severe in horses and is therefore very often fatal. The disease is notifiable in Germany.

Four classic forms of horse sickness can occur after a different incubation period:

• The peracute or pulmonary form , also known as dunkop , has a short incubation period of three to five days. This is followed by a high fever of around 40–41 ° C, coughing, foamy nasal discharge and dyspnoea (shortness of breath). With this form of the disease, horse mortality usually reaches 95%.

• The subacute, edematous cardiac form , also called dikkop , has an incubation period of seven to 14 days. This is followed by fever (39–40 ° C), swelling of the head and neck ( edema ), cyanosis (blue / red coloration of the skin and mucous membranes due to a reduction in the oxygen content in the blood), bleeding from the mucous membranes and conjunctivitis (conjunctivitis of the eye) on. After four to eight days, death from heart failure ( myocarditis ) occurs in half of all cases .

• The acute or mixed form can usually only be characterized as such pathologically.

• The Pferdepestfieber illustrating the mildest waveform with variable incubation period of five to 14 days. After a period of fever of five to eight days, there is usually complete recovery: especially in less susceptible animals (donkeys), vaccinated animals and animals that have been re-infected with a different pathogen serotype.

Prevention and Therapy in Pets

Disease prevention includes regular insect control, keeping endangered livestock in stalls at night and vaccinations (active immunization) in contaminated or suspected countries. Since there is no virus-specific therapy, all that remains is - to interrupt the chain of infection - an immediate quarantine and subsequent killing of the sick farm animals.

In Germany, African horse sickness is subject to notification under the Animal Health Act (TierGesG). According to the Austrian Animal Disease Act , African horse sickness is a notifiable animal disease. In Switzerland, African horse sickness is classified by the Animal Disease Ordinance (TSV) as a highly contagious animal disease within the meaning of the Swiss Animal Diseases Act (TSG) and is therefore one of the animal diseases whose control is classified as of the highest importance.

Individual evidence

1. ↑ ICTV Master Species List 2018b v1 MSL # 34, Feb. 2019
2. ↑ ^{a b c d e} ICTV: Bluetongue virus , EC 51, Berlin, Germany, July 2019; Email ratification March 2020 (MSL # 35)
3. ↑ Animal Disease Report 2011 by the BMELV . In: Deutsches Tierärzteblatt. (DTBL) Volume 60, May 2012, pp. 714–715.
4. ↑ Ordinance on notifiable animal diseases in the version published on July 19, 2011 ( Federal Law Gazette I p. 1404 ), amended by Article 3 of the Ordinance of May 3, 2016 ( Federal Law Gazette I p. 1057 ) in conjunction with Section 4 of the Act for the prevention and control of animal diseases (Animal Health Act - TierGesG) of May 22, 2013 ( Federal Law Gazette I, p. 1324 ), last amended by Article 8, paragraph 12 of the law of December 3, 2015 ( Federal Law Gazette I, p. 2178 )
5. ↑ § 16 Animal Diseases Act of August 26, 1909, last amended in 2006 (Federal Law Gazette I No. 136/2006)
6. ↑ Article 1 of the Animal Diseases Act (TSG) of July 1, 1966, last amended on March 15, 2013, came into force on January 1, 2014
7. ↑ Article 2 (m) of the Animal Disease Ordinance (TSV) of June 27, 1995, last amended on November 25, 2015, came into force on June 13, 2016

This article is about a health issue. It is not used for self-diagnosis and does not replace a diagnosis by a doctor. Please note the information on health issues !